Calgary Jeep Association
4x4 Related Groups => Tech Talk => Topic started by: jpthing on February 12, 2010, 10:41:56 AM
-
Howdy Y'all.
I was having issues with the rear driveshaft on my XJ and I devised an interesting alternative setup which has worked well for me. It's been on my Jeep for about 6 months now and Ive been really happy with it, so I figured I would share for those who may be intereseted.
Disclaimer: It may not work for you. You may think it's stupid. If that's how you feel, I would strongly suggest not doing this to your Jeep. Go spend big bucks doing it the "proper" way. If the idea of hockey puck body lift or bumpstops or bastard leaf packs makes you upset, I would suggest moving along to reduce your stress levels. This is a thread about a cheaper alternative to the norm. I should also point out that this thread is not for those who think they know everything, since a mere mortal's driveshaft would obviously be of little concern to one of these demigods. I have taken my time to explain myself fully, so that even those who don't know everything will find the information "accessible". Again, this may be irritating to those who do know everything. Sorry. I guess...
-
So first I will tell you abnout the problems that I was having before this setup.
I am not the hugest fan of the driveshafts used with a SYE. Now stop getting all upset and let me explain. obviously if you are going to lift a TJ more than a little, there is no alternative to the SYE, double cardan joint driveshaft with the splined telescoping section. After all the driveshaft is only 1 foot long. So despite my dislikes (more about this in a second) about this type of rear driveshaft, it is the only option for the rear of a lifted TJ.\
Whats my issue with the SYE/double cardan joint rear driveshaft? Simple: Cost, complexity and ease of repair. A SYE kit is around $300, and the custom rear driveshaft is around$500-$750 more. Now this is a good setup, I'm not dissing it, but within a year or two I started to have problems. With the amount of Maclean mud I've been through, I had problems with the blue coating coming off of the splined section. When this happens, there is no option except for having a driveline shop weld on a new splined section. At this point the female side (yoke) should be replaced too, due to damage caused to the splines by running with the blue coating damaged. I also had problems with the double cardan joint itself. frequent mudbaths and less frequent greasing resulted in a need for maintenance. Although I got pretty fast at changing out the two ujoints and the ball kit which resides within, I still always found it to be a hassle. And before too long there was noticeable wear to the machined surface on the little cylindrical part that contains the little spring and installs into the cv ball. (I'm not sure what this part is called, but it's inside the double cardan joint and the joint will quickly fail if there is damage here). The problem is that the little machined surface, as with the blue coating, cannot be repaired in the garage. If you wear that part, it must be cut off of the driveshaft and have a new part welded on and the shaft rebalanced...$300+ from my experience.
So basically the reasons why I wanted to move away from the double cardan joint on the rear of the Xj was that it is more of a hassle to maintain (3 u-joints, two splined parts, ball kit, and machined stub on a double cardan vs. only two u-joints on a conventional driveshaft) Additionally, the Double cardan shaft has two parts (blue stuff on splines and machined bit) which cannot be replaced by the jeeper, which to me is lame. I like to fix my own Jeep, and I hate giving Pat's driveline money unless there is no alternative.
Of course there are reasons why the double cardan joint is so widely used by wheelers. The main ones I am aware of are that the DC (double cardan) can handle much greater angles, due to it's "splitting the angle" between the two upper u-joints. When considering angle on u-joints there are really two seperate factors, running angle, and maximum angle (almost certainly not the correct terms) By running angle I am referring to what angle a u-jopint will happily purr along the highway at without excessive wear or vibration. By maximum angle I am referring to how far the u-joint can flex before the yoke ears collide. The running angle must be within the allowance of the components or you will get vibrations. This is how it is usually explained, but it would be more accurate to say that too great of a running angle would cause "greater vibrations than normal" or "excessive vibration" since there is always some level of vibration in a driveshaft. So my goal was to find a traditional, 2 u-joint rear driveshaft which would have acceptable levels of vibration, and wher the ears of the yokes would not collide at full droop.
-
The TJ's stock rear driveshaft is a beatiful thing and rarely gets the rspect it deserves. Obviously it doesn't work with a lift, but consider the flex and articulation that a stock TJ has in the rear, then remind yourself that the driveshaft on an auto trans TJ is less than 12" long and you'll realize it's different than most. To deal with the TJ's increased rear articulation the jeep engineers devised a setup for the TJ rear driveshaft which was very different than what had come before.
The first big difference is the output housing and output shaft on the t-case. Contrary to popular belief, the rear driveshaft on a stock TJ can be removed and you will not lose your tcase fluid. (unlike the XJ and YJ which do not use this design). The TJ's output shaft has it's own seal in the T_case and rather than the output yoke sticking into the tcase and the splines being bathed in atf, The tj's output shaft is completely external and the splines must be greased. The Tj stock setup uses a rubber boot here, to keep dirt off of the splines, the others haver the splined part inside the tcase instead.
The next thing is the output shaft length. I have heard or read several people mocking the TJ engineers for the fact that in such a short vehicle the tcase output shaft was actuall longer than on yj's, leading people to assume that a longer output shaft would equal a shorter driveshaft. Beleive it or not, the longer output shaft actually results in a longer driveshaft as well, and one that is less prone to vibe out. This is because the TJ rear driveshaft components are different than most: The slip yoke is designed to allow the tcase output shaft to go all the way into the yoke, to within a half inch of the upper u-joint. This is how the driveshaft length is increased. Despite the fact that the TJ output shaft is about one inch longer than those that proceded it, it actually allows one inch more driveshaft. And the slip yoke is less prone to vibration because more of it's mass is wrapped around the output shaft rather than hanging off the end of it, flailing about.
Additionally the TJ yokes are beatifully designed for huge maximum angles before the yokes collide, compared to other yokes I have seen on other Jeeps.
So you're probably figuring out where I'm headed...using stock TJ parts on a lifted chrokee.
-
To do this set up you will need a stock TJ tcase output shaft and output housing, a stock TJ rear driveshaft (these three can usually be had for free) and the rubber boot, slinger, and two metal bands that seal up the slip yoke (i went to the dealer for these). The slinger and the bands are always damaged in removal, and better new when it comes to a rubber boot, I figured.
You will need to open up your tcase, and swap in the TJ output shaft and housing. new seals would be a good idea. Doing this is about the same complexity as doing an SYE.
Then you will need to take the Jeep to a driveline shop, and have them install a longer tube onto the TJ driveshaft components and balance. Keep in mind that thicker walls are stronger against damage but more prone to vibrations than the standard wall thickness. For this reason I had them go 1 step thicker but did not select the tuffest tube they had, as I knew I would probably have issues with vibrations with 4" of lift and a standard driveshaft.
When I did this it worked great. There was some vibration at some speeds, but way less than before with the messed up DC shaft, and way less than what some of my friends considered tolerable on their jeeps. I experimented with rotating the yokes 180 degrees, and dropped the tcase 1/4 inch and the vibes were barely noticeable.
-
Getting my driveshaft lenghthened at Pats cost around $350. I'm pretty sure they're the most expensive shop in the city, though, and that it could be done elsewhere for a little over $200.
The end result is a simple driveshaft with only two u-joints to replace or grease that has minimal vibes and can handle decent droop. Another benefit is that the vehicle can now be driven with the rear driveshaft removed without the tcase losing fluid.
I am climbing into my flame proof suit and bracing myself.
-
ok i'm gonna start the flame
why do all that work to NOT ELIMIATE VIBES? a 'little' vibe is TOO MUCH.
second; its ALOT EASIER to grease your ujoints/driveshaft after every time you wheel. thats maintenance. thats a lot cheaper than what you described.
man who do i talk to about getting the last 20 mins of my life back?
-
ok i'm gonna start the flame
why do all that work to NOT ELIMIATE VIBES? a 'little' vibe is TOO MUCH.
second; its ALOT EASIER to grease your ujoints/driveshaft after every time you wheel. thats maintenance. thats a lot cheaper than what you described.
man who do i talk to about getting the last 20 mins of my life back?
I now have a simpler setup which works better and is easier to maintain. To me that's good.
My suggestion for you: If you don't like this idea don't use it.
Go ask the guys at a driveline shop...there is no such thing as no vibe.
Oh, and talk to yourself about your lost 20 minutes...you read it!
-
man who do i talk to about getting the last 20 mins of my life back?
I believe there are several ways to do this, one of which is making "sticky". I tried to explain this to my wife but I don't think she understands. Either that or figures I'll kick the bucket that much sooner. :o
I like my sye and DSI drive shaft. No vibes from the drive shaft and it's easy to grease (I have a nice blue line on the underside of my jeep because I get bored and grease stuff). The trouble with the short drive shafts, or mine initially, was that even if they are in spec they can still vibrate. Standens was able to fix it for me so I could remove the t-case drop one of the shop in town installed because "sometimes you need the t-case drop with a sye".
-
yeah I'm not arguing that the SYE and Double cardan driveshaft is bad.
It costs close to $1000 to set up, it should be good!
My setup cost around $350. And needs less maintenance.
I'm not saying SYE's suck, I'm just stating what my setup is and why.
SYE's are great...but they are not the only option on an XJ.
Again, I prefer stuff I can fix myself, like this setup.
I would way prefer having two u-joints that wear out every 6 months to having to drop $700 for a new driveshaft every few years. The u-joints are quick and easy to do yourself.
(the u-joints do not, so far wear out every 6 moths, this was just an example of worst case )
-
Which
I believe there are several ways to do this, one of which is making "sticky". I tried to explain this to my wife but I don't think she understands. Either that or figures I'll kick the bucket that much sooner. :o
I like my sye and DSI drive shaft. No vibes from the drive shaft and it's easy to grease (I have a nice blue line on the underside of my jeep because I get bored and grease stuff). The trouble with the short drive shafts, or mine initially, was that even if they are in spec they can still vibrate. Standens was able to fix it for me so I could remove the t-case drop one of the shop in town installed because "sometimes you need the t-case drop with a sye".
which shop told you a tcase drop with an SYE was normal? That's pretty lame. And how did Standen's fix it?
-
I'd rather not say which shop it was. I still go there as they've always treated me well; although I knew the comment was bunk.
Standens had the vehicle up on a hoist and straightened it while it was mounted. Something to that effect. It didn't vibrate on the machine when they tested it (no working angle) , but it did when it was installed (working angle).
-
Are we talking about a 4x4 shop though?
Straightened what?
-
sorry, Standens straightened the driveshaft. It was off where the bottom part of the double cardan welds to the shaft.
-
Well I give credit where credit is due, 2 thumbs up!
I might try this on my ZJ. On both my old XJ and ZJ I'm still running a stock driveshaft and no vibes. That's with an 8" lift. How did it do it? The rear axle is a D60 with it pushed back about 1". The pinion snout is MUCH longer than on a D35 which negates the need for a longer driveshaft. Also by manipultaing the pinion angle I have been able to eliminate any vibes. For extra angle I'm running a YJ yoke. Works fine for me the only thing I worry about is if I do take out the rear shaft I'll lose my t-case fluid. As you described a TJ output will solve this.
If you still have vibes I would play with the pinion angle, a few degrees below pointing straight at the t-case output is a good place to start. I don't see why you shouldn't be able to eliminate vibes on any lifted XJ with a t-case drop and proper pinion angle.
I should clarify that the long arm kit on my ZJ drops the t-case about 1" and I had about a 3/4" drop on my XJ.
I'll have to think about this, my other idea was to do a homemade SYE using a yoke that would allow me to run a stock front driveshaft in the rear. More complicated, about the same money but I only need one spare shaft to cover all or could even swap the front to the back in a bind.
-
SYE's do not require CV shafts. For apps like an xj you can still run a fixed output (SYE) and 2 joint shaft.
Two joint shafts have more total angle ability then CV's. CV's can operate at higher angles without vibration but but bind sooner then a 2 joint.
Best of both worlds is a fixed output and 2 joint shaft. Like d300's and CJ's.
Just some clarification there ona few points
-
SYE's do not require CV shafts. For apps like an xj you can still run a fixed output (SYE) and 2 joint shaft.
Two joint shafts have more total angle ability then CV's. CV's can operate at higher angles without vibration but but bind sooner then a 2 joint.
Best of both worlds is a fixed output and 2 joint shaft. Like d300's and CJ's.
Just some clarification there ona few points
Yeah totally true, I considered this but I don't like the blue spline coating. All the slip shafts I could find that were for the proper sized tube had this stuff, but the Tj setup does not.
-
I could care less about any of the hack recipe you are dealing with. If it still vibes as you say, its worthless to even look at anyones. I was simply clarifying the statement about having to run CV's with SYE's.
By the way, any notable vibe in your driveline will accelerate t-case and pinion bearing wear enough to have to do them on a yearly basis depending on a the amount someone drives. A none vibrating driveline will last years and years without taking out t-case and pinion bearings.
-
I could care less about any of the hack recipe you are dealing with. If it still vibes as you say, its worthless to even look at anyones. I was simply clarifying the statement about having to run CV's with SYE's.
By the way, any notable vibe in your driveline will accelerate t-case and pinion bearing wear enough to have to do them on a yearly basis depending on a the amount someone drives. A none vibrating driveline will last years and years without taking out t-case and pinion bearings.
It's a bit of a stretch to call factorty parts a "hack recipie" no? Hey if you big bux to spend, by all means, pull out the platinum card. I prefer to find cheaper ways to do things where possible...I'm just weird that way, don't hate me for it.
Trust me my vibes are way less now than they've been for a long time with my f'd up SYE and Double cardan with damaged blue goo. And I am looking forward to whatever maintenance comes along (sort of) it's part of wheelin.
Do you disagree with what Pat's told me, that all driveshafts have some vibration, the same way there is no perfect circle or straight line, and that the trick is to get it within or near normal tolerance?
-
DSI built and balanced all my driveshfts. i have never had a vibration at any speed. This is with 33's or 37's.
So, i think no vibe is possible :)
-
I said notable vibrations. All rotating parts have inherent vibration related to them.
The difference between the two is whether or not a vehicle will see premature failure or not.
You inability to maintain your slip joint shaft has little to do anything here. Stock equipment not maintained will shake a truck apart as well.
You like to fix your stuff repeatedly because its "part of wheeling", good for you. Most the people I wheel with and help with their trucks prefer to wheel not spend money repairing their junk over and over again.
I've fixed plenty of diffs because of hack setups like the junk your are pimping. Te big lift t-case drop crowd are no better. If you cant afford to do something right, thats one thing. Pointing people in the wrong direction because of your own ignorance and lack of funds is another.
Seriously, you should keep your farmer tech to yourself.
-
On page one cLAY stated that he was running 8" of lift on the stock driveshaft with no vibes...I don't know why he would be able to pull off 8" but you guys ridicule the idea of my setup handling four inches...perhaps you could explain what's wrong with running this type of setup rather that just using insulting names to describe it...besides what do you have against farmers?
-
I just remembered that I spoke to the tech at national the other day who originally hooked me up with the tj driveshaft etc from their junk bin. When I had picked up the parts I had described my idea to him, and he asked me to let him know how it worked. I told him how it was working for me and he said he will consider using this setup on his girlfriends XJ.
Wow he must be pretty dumb eh?
-
i swear to god, reading what you have to say, i must be a god, cause i built a cj-5 with four inches of lift, and i have no vibes at all, at any speed, even in four high. got a way shorter drive shaft then what you have in your tj too. want to know how i did that?
-
On page one cLAY stated that he was running 8" of lift on the stock driveshaft with no vibes...I don't know why he would be able to pull off 8" but you guys ridicule the idea of my setup handling four inches...perhaps you could explain what's wrong with running this type of setup rather that just using insulting names to describe it...besides what do you have against farmers?
I think they were ridiculing you cause you said you still had vibes with the new setup. Slip splines should outlast the rest of the shaft. My guess is that you had vibes still from not having the pinion angle correctly setup, which is critical. Those vibes are what took out your slip spline. MANY, MANY, MANY, people run driveshafts with slip splines and don't wear them out. Installing the TJ setup changed the length of the shaft and thus changed the angle which is why it seems a bit better.
My point about running an 8" lift with no SYE was to show how important pinion angle can be. I took out a lower u-joint in 2 months with a 4.5" lift and a bad pinion angle. A set of shims fixed that right up.
I like your idea as for me it solves my dilemma of losing my t-case fluid if I do lose my rear shaft, however in your case I think you ditched a perfectly good system and spent a lot of money on a new shaft when all you needed was to adjust the pinion angle.
BTW my comment about being able to have a stock style shaft with no vibes and proper pinion angle only stands for the XJ/ZJ crowd. I've never worked on a TJ driveshaft but imagine with it being that short a SYE w/ cv shaft maybe the only solution.
-
I think they were ridiculing you cause you said you still had vibes with the new setup. Slip splines should outlast the rest of the shaft. My guess is that you had vibes still from not having the pinion angle correctly setup, which is critical. Those vibes are what took out your slip spline. MANY, MANY, MANY, people run driveshafts with slip splines and don't wear them out. Installing the TJ setup changed the length of the shaft and thus changed the angle which is why it seems a bit better.
My point about running an 8" lift with no SYE was to show how important pinion angle can be. I took out a lower u-joint in 2 months with a 4.5" lift and a bad pinion angle. A set of shims fixed that right up.
I like your idea as for me it solves my dilemma of losing my t-case fluid if I do lose my rear shaft, however in your case I think you ditched a perfectly good system and spent a lot of money on a new shaft when all you needed was to adjust the pinion angle.
BTW my comment about being able to have a stock style shaft with no vibes and proper pinion angle only stands for the XJ/ZJ crowd. I've never worked on a TJ driveshaft but imagine with it being that short a SYE w/ cv shaft maybe the only solution.
All driveshafts have some vibes, even Bnine finally admitted that, this is why I am reluctant to claim my setup has "no vibes" because that would be untrue. My vibes are completly within what is normal in the application. The reason I wore out the coating (not the splines) was from hard use and less than ideal maintenance. I ditched the system because I would have had to get a whole new CV shaft, mine was toast and $600+ was more than I wanted to spend.
Trust me I am well familiar with adjusting pinion angle, when your blue coating is worn off and your cv drive is damaged and your yoke ears are spread (my old driveshaft) a pinion angle adjustment will have little effect. A new driveshaft was called for.
To those who consider my ideas with an open mind, thanks. To those who write them off without any real consideration or thought, enjoy doing things your way. I will do the same.
-
I just finished rebuidling the rear end in a rubicon that was so beat up even the 30 spline chromoly shafts were twisted and I had them warrentied.
Anyone that knows Rick and his jeep know that his rubicon has been beat on more then just any other jeep in this club. I did the original gears nearly five years ago. I did the CV shaft around that time as well.
Moral is, in all that time and abuse, Rick is still on the original slip spline section of that shaft.
Once again, you are fixing stuff that isnt broke.
If your vibes are within whats normal, its referred to as "no vibes". This is the difference between dealing with someone that actually knows what they are talking about, and dealing with someone that is purely full of themselves, and full of sht. Like you.
This has nothing to do with an open mind, and everything to do with you being butt hurt again because we dont praise you as a hero for being the worlds greatest junkyard hack.
-
I just finished rebuidling the rear end in a rubicon that was so beat up even the 30 spline chromoly shafts were twisted and I had them warrentied.
Anyone that knows Rick and his jeep know that his rubicon has been beat on more then just any other jeep in this club. I did the original gears nearly five years ago. I did the CV shaft around that time as well.
Moral is, in all that time and abuse, Rick is still on the original slip spline section of that shaft.
Once again, you are fixing stuff that isnt broke.
If your vibes are within whats normal, its referred to as "no vibes". This is the difference between dealing with someone that actually knows what they are talking about, and dealing with someone that is purely full of themselves, and full of sht. Like you.
This has nothing to do with an open mind, and everything to do with you being butt hurt again because we dont praise you as a hero for being the worlds greatest junkyard hack.
Thank you for your kind words and thoughts. You are doing an excellent job representing your club. You obviously need to have the last word so fine it's all yours.
Remember I never insulted you or used offensive language.
Happy wheelin and wrenching
-
Thank you for your kind words and thoughts. You are doing an excellent job representing your club. You obviously need to have the last word so fine it's all yours.
Remember I never insulted you or used offensive language.
Happy wheelin and wrenching
Save the troll bait tactics. I dont care if you havnt insulted me or not. If you act like an idiot, I will call you one. Its that simple.
-
Some other takes on the subject:
http://www.naxja.org/forum/showthread.php?t=1024626
-
I just finished rebuidling the rear end in a rubicon that was so beat up even the 30 spline chromoly shafts were twisted and I had them warrentied.
holy crap. way to go Rick! get that heep back on the trail soon, spring is coming. (and pay your CJA dues ya bum)
-
I had to order some u-joints etc for my Tj so I ended up speaking to Tom Woods today.
Wow, amazing customer service! He actually answers the phone himself most of the time and was very polite patient and helpful. He was able to look up the specs of the driveshaft I ordered from him 2 yrs ago to confirm I was ordering the correct parts.
At the end of the conversation he said " so, is there anything else I could help you with?" so I picked his brain a little.
I asked him to theorize on why I was having problems on my Xj (with the SYE and double cardan) with the blue goo coming off. He said he has seen more of this lately and blames inferior quality parts, according to Tom, some blue goo just doesn't stay put. He assured me I should have no problems of this type on the driveshaft he made for me.
Interestingly enough, both of my shafts which lost the blue goo were from Pat's. The blue goo on my Tom Woods shaft and my factory front shafts has been fine. maybe not a coincedence.
The next thing I asked him about was my XJ vibes. I described my current setup, the angles, the lift height and the vibes I get: nothing until around 50mph/80kph then a little vibes around that speed which dissapear if I go a little slower or faster.
He explained a little about the dynamics of harmonic reactions or something like that.
"but what is the best way to correct it?" I asked.
His answer, no word of a lie "Put a second layer of carpet down." (he was joking but also making the point of how subjective this is, and saying in his opinion it's not major, and there is no way to measure driveshaft vibes)
I told him I have no carpet at all in the XJ.
"well there's your problem" he said. "If you had carpet you probably wouldn't even have noticed it"
I asked him if these vibes would cause premature failure of the pinion or tcase bearings.
"I wouldn't worry about it" was his reply.
I would totally reccomend his shop, whether you guys will agree with what he told me or not may be up for debate, but there is no question that his customer service is some of the best around. The driveshaft he made for me makes the ones I got locally look cheap.(bigger, deeper splines, nicer welds)
For the record my blue coating wasn't so much wearing as delaminating from the splines, that is to say, coming off in long intact pieces.
I am not mentioning what Tom said to "trump" anyone or prove a point, in fact I am interested to hear opinions on the subject whether you agree with Tom's advice or not, I am not sure what to think of his advice actually. I honestly hope this can go back to being a tech discussion, that is my only intention.
-
What's the technical term for this "blue goo" you speak of??
The carpet and thin layer of mud must be what's keeping my AA sye and DSI shaft from vibrating.
-
I
I don't think you can speek on Tom's behalf.
He is a respectable vendor, with good parts. You, explaining the tech makes no sense and is detrenantal to his business here in Canada.
Please stop.
-
As a jman mechanic and a jman welder im just appalled at some of the crap you are dumping out boone....cman man, seriously..
amazing customer service! He actually answers the phone himself
...call Rusty's offroad..Rusty will answer..doesnt make him a genius..Call 911..ask them for medical advise.
He was able to look up the specs of the driveshaft I ordered from him 2 yrs ago to confirm I was ordering the correct parts.
...yep its amazing what computers can do! im amazed my cell phone tells me who's calling!
[quoteI was having problems on my Xj (with the SYE and double cardan) with the blue goo coming off.][/quote]..its called over use of marine type grease and centrifugal force...fill a shot glass with grease and spin it between your open palms and see how much of a blue goo problem you seem to find in your house...im sure your 100 + tech boards will have a solution for said problem.
Fact of the matter is that you negelect to mention , or realize, that your homebrew crap fixes are garbage..and you just had some hairbrained idea that seemed to be cheaper, and seemed to work for you..well i farted in bed last night and my old lady "seemed" to not notice and it worked for me..your tech is garbage...that "seems" right
Do your homework....first off the 97+ xj's with a 231 or 242 t case have a 3/4" longer slip yoke..while allowing more droop in the rear it also added more suspection to driveline vibes when lifted...your tj yoke crap wont worj on my xj...231's and 242's are not the same..factor in the fact that i run a D44 ( 1" reduced driveshaft length) and your tech is whacked...do some more real world tech, and quit reading crap off the internet..cuz your crap works with your xj,leave it at that..cuz your crap dont work with mine..and i did mine the right way..not the cheap way
I would rather my jeep work flawless..than have it save me $200...and when my junk breaks, atleast i know what to upgrade, instead of find an excuse for being cheap.
If you want to do a tech write up feel free to show us how to port a 7120 or 0630 head so i can laugh, or build a stroker, so corey can shut you down, or how to set gears so Bill can contradict everything you have to say...
Please stop with your tech...if anyone has questions on tech, we ask for it...so we can do it the right way.
-
well i asked you if you wanted to know how i got my set up in my jeep to work with out vibes, and with steeper angles and a shorter shaft and you said nothing, so i will tell you anyway.
you see jp, its one thing to run around a junk yard and put parts together from different applications until something fits and then say you reinvented the wheel, its quite another to do some real homework first, and truly understand what you are dealing with. so before i did anything with my driveshafts, i did my homework. did tons of research, and talked to guys that built the things for a living. at the time, Corry at dsi was an amazing source of info, i listened to what he had to say and learned a lot. in the end my drive shaft cost me the price of two new u-joints and 80$ to get a shaft shortened at dsi. result...... no vibes.
so here is what i learned. in a driveshaft with two single cardan joints, anything more then a 0* angle is where you start to have issues.
for example, lets angle the two shafts to say 45 degrees. Now, look at the "cross" of the u-joint as it rotates. When the driving side of the cross is horizontal, it's ends are moving at the same speed as the yoke on the driving shaft. However, the driven side of the u-joint is 90 degrees offset from the driving side, but since the u-joint cross is rigid, all 4 ends are moving the same angular velocity, i.e. that of the driving shaft. However, since there is that 45 degree angle between the two shafts, the cross is also angled 45 degrees, meaning the effective length of that side is equal to the sin(45) times it's actual length or 71%. But, since it is moving at same angular velocity, the surface speed; which is equal to the angular velocity times the radius (or length); is now 71% of the speed of the driving shaft; i.e. the driven shaft is turning momentarily at 71% the speed of the driving shaft! Now, turn the driving shaft 90 degrees farther in it's rotation. Now the driving side of the cross is at 45 degrees, so it's effective length is now 71% and the driven side is 100%. Assuming the driving shaft speed is constant, then this means the driven shaft speed is now 1.00/0.71 or 1.41 times (or 141%) faster than the driven shaft! So, if you have the driving shaft turning at say 1000 RPM, the driven shaft will vary from 710 up to 1410 RPM as it rotates, averaging to 1000 RPM. This is what causes a driveshaft to vibrate.
So, how can such a setup ever work in the real world? As it turns out, if you stick another u-joint on the other end of the shaft and line it up in phase with the first one and keep the angles identical, these rotational speed changes nearly cancel each other out. While the driving u-joint is speeding up the driveshaft, the driven u-joint at the other end is slowing down what it is hooked to (usually the pinion on the differential). And while the driving u-joint is speeding up the driveshaft, the driven u-joint is slowing down the pinion. All this results in the pinion end of the shaft being driven and almost exactly the same speed as the transmission/transfer case end of the shaft.
The smaller the operating angle, the better the cancellation is, the greater the operating angle, the less the cancellation is. Also, if the angles on both u-joints are not the same, the cancellation is not as good and if the two u-joints are not properly phased to each other, the cancellation is worse yet. In fact, if you were to go to the extreme and set the u-joints up 90 degrees apart from each other, not only would there be no cancellation but they would in fact compound the rotational vibration, the first joint would induce it's component, then the second joint would take that and multiply it by it's own factor depending on the angle. So, in the above case of a 45 degree operating angle, the driven joint would be running from about 50% to 200% of the speed of the driving joint, or from 500 RPM up to 2000 RPM for a 1000 RPM input. You can imagine what that would feel like driving down the road, say at an engine RPM the should give a 30 MPH speed, the tires would be turning anywhere from 15 MPH up to 60 MPH as they turned one revolution!
so to sum up, i made sure both my output angles and my diff yolk angles were the same, and bobs your uncle.
-
jpthing... here is a "top twelve list" illustrating why you should stop posting:
12) You seem to think you have a bigger mental stick than everyone else and no one wants to watch you play with it.
11) 99.9% of the people on here either ask questions... or provide answers to questions asked. You do neither.
10) Surely... you are not accomplishing your goals or desired effect.
9) No one seems to care.
Eight) You seem to have "a nack" for turning even useful threads/topics into rubbish.
7) CJA membership aspirations or not... you are making enemies with the people you will be wheeling with (assuming you can tear yourself away from posting on 100+ internet sites to actually wheel).
6) Assuming your tech is useful to someone out there... the way in which you deliver it offends people.
5) No one likes a "know it all".
4) Life, for the most part, is a popularity contest... you are currently in last place on the CJA board.
3) The person who invented the internet has been observing your use/abuse of this technology and now requires antidepressants.
2) Being a member of 100+ internet discussion boards is not a selling feature.
1) Every single person on this board has a "specialty" that they could "spout on about" endlessly... thank god everyone doesn't.
I am not saying this to be mean spirited... I am doing this to help you.
Hopefully this brings into focus what you are actually accomplishing here... which cant possibly be what you had in mind when you start a thread?
-
so here is what i learned. in a driveshaft with two single cardan joints, anything more then a 0* angle is where you start to have issues.
for example, lets angle the two shafts to say 45 degrees. Now, look at the "cross" of the u-joint as it rotates. When the driving side of the cross is horizontal, it's ends are moving at the same speed as the yoke on the driving shaft. However, the driven side of the u-joint is 90 degrees offset from the driving side, but since the u-joint cross is rigid, all 4 ends are moving the same angular velocity, i.e. that of the driving shaft. However, since there is that 45 degree angle between the two shafts, the cross is also angled 45 degrees, meaning the effective length of that side is equal to the sin(45) times it's actual length or 71%. But, since it is moving at same angular velocity, the surface speed; which is equal to the angular velocity times the radius (or length); is now 71% of the speed of the driving shaft; i.e. the driven shaft is turning momentarily at 71% the speed of the driving shaft! Now, turn the driving shaft 90 degrees farther in it's rotation. Now the driving side of the cross is at 45 degrees, so it's effective length is now 71% and the driven side is 100%. Assuming the driving shaft speed is constant, then this means the driven shaft speed is now 1.00/0.71 or 1.41 times (or 141%) faster than the driven shaft! So, if you have the driving shaft turning at say 1000 RPM, the driven shaft will vary from 710 up to 1410 RPM as it rotates, averaging to 1000 RPM. This is what causes a driveshaft to vibrate.
So, how can such a setup ever work in the real world? As it turns out, if you stick another u-joint on the other end of the shaft and line it up in phase with the first one and keep the angles identical, these rotational speed changes nearly cancel each other out. While the driving u-joint is speeding up the driveshaft, the driven u-joint at the other end is slowing down what it is hooked to (usually the pinion on the differential). And while the driving u-joint is speeding up the driveshaft, the driven u-joint is slowing down the pinion. All this results in the pinion end of the shaft being driven and almost exactly the same speed as the transmission/transfer case end of the shaft.
The smaller the operating angle, the better the cancellation is, the greater the operating angle, the less the cancellation is. Also, if the angles on both u-joints are not the same, the cancellation is not as good and if the two u-joints are not properly phased to each other, the cancellation is worse yet. In fact, if you were to go to the extreme and set the u-joints up 90 degrees apart from each other, not only would there be no cancellation but they would in fact compound the rotational vibration, the first joint would induce it's component, then the second joint would take that and multiply it by it's own factor depending on the angle. So, in the above case of a 45 degree operating angle, the driven joint would be running from about 50% to 200% of the speed of the driving joint, or from 500 RPM up to 2000 RPM for a 1000 RPM input. You can imagine what that would feel like driving down the road, say at an engine RPM the should give a 30 MPH speed, the tires would be turning anywhere from 15 MPH up to 60 MPH as they turned one revolution!
so to sum up, i made sure both my output angles and my diff yolk angles were the same, and bobs your uncle.
Hey look, some real tech...cool!
And it only took 3 pages of 'discussion' :P
-
I am very enthususiastic about jeeps and hoped to engage in tech discussion with some local jeepers.
I'm sorry if some feel I came across as a "know it all". This was not my intention.
I'm sorry to everyone who's been irritated or who feels their time was wasted.
If my enthusiasm came across as arrogance, again I apologize.
I'm being criticized now for complimenting Tom Wood's customer service? um ok then...
-
I had to order some u-joints etc for my Tj so I ended up speaking to Tom Woods today.
.
why would you call tom woods for ujoints for a TJ?
cant' you pick them up from napa? thought you were about 'cheap' builds, now is ordering parts and shipping them across the country cheaper than stumbling down the street to a NAPA? or did you literally call just to pick his brain?
also, i have a feeling, (if you did talk to Tom) that his response to you about 'putting another layer of carpet down' might have been his way of saying 'umm, i sell driveshafts for a living; why are you toting your junkyard fix to me on the phone? i have products to make/sell, and you're not buying, so why waste time?
its also possible he thinks, that with your current setup, that is about as good as it'll get.......
-
I told him I have no carpet at all in the XJ.
"well there's your problem" he said. "If you had carpet you probably wouldn't even have noticed it"
I disagree with this point, so if I'm wrong someone please explain how this works.
I asked some of my engineering buddies, posted some questions on www.askanengineer.com and talked to a couple doctors I know.
How does carpet mask the vibrations you feel? Sure it might mask what you feel with your feet but what about your butt sitting in the seat, hands on steering wheel, elbow on door, sight, sound??? As far as I know the floor boards, steering wheel, seat, doors.... all that stuff is connected, some parts with insulators. How can carpet or more carpet mask the rest of your senses? I'm pretty sure you'd see the dash vibrate slightly, may even hear stuff rattle, even if you can't feel it with your feet. Sure carpet is dense, but if something is shaking I'm pretty sure you'll still notice it. Unless of course you have a magic carpet. Or maybe it's the amazing insulating properties of a hockey puck body lift?
-
Tom woods u-joints are $20 USD. To me that's a pretty good deal. I have not been impressed with the longevity of napa u-joints.
I also wanted his opinion on whether u-joints with the grease fitting on the cap needeed to be replaced with the same type for correct balance to be maintained.
-
I disagree with this point, so if I'm wrong someone please explain how this works.
I asked some of my engineering buddies, posted some questions on www.askanengineer.com and talked to a couple doctors I know.
How does carpet mask the vibrations you feel? Sure it might mask what you feel with your feet but what about your butt sitting in the seat, hands on steering wheel, elbow on door, sight, sound??? As far as I know the floor boards, steering wheel, seat, doors.... all that stuff is connected, some parts with insulators. How can carpet or more carpet mask the rest of your senses? I'm pretty sure you'd see the dash vibrate slightly, may even hear stuff rattle, even if you can't feel it with your feet. Sure carpet is dense, but if something is shaking I'm pretty sure you'll still notice it. Unless of course you have a magic carpet. Or maybe it's the amazing insulating properties of a hockey puck body lift?
I don't want to argue. I was simply saying what was said to me. It is open for discussion.
Maybe I misunderstood the concept of "vibes" because i get no shakes whatsoever, just a "whirring" noise.
I don't want to misinterpret Tom, but I think he was saying that vibes are highly subjective.
I'm not sure your references to "magic carpet" are relevant, and my XJ does not have a hockey puck body lift.
I sincerely wish that we could talk tech without the "digs".
-
I wasn't argueing, just asking if Tom's comment made sense. So, discuss away, will adding more carpet reduce vibes?
Also, you either have vibes or you don't. I believe the magnitude would be subjective.
-
I guess the part that's subjective is whether a given level of vibes is "acceptable" or not.
Like I said I can hear vibes at a certain speed but I can't feel them. My dash definately does not shake or anything.
I guess some tunes could do the same function as the carpet...or maybe some noisier tires?
So are vibes "acceptable" if they can be heard but not felt?
-
Are you sure it's in your drive train? Maybe something else is moving around like a cable or something? Brake drag?
-
Ya I dunno. What kind o' cable are you thinking of ? like ebrake?
Or maybe tire imbalance?
-
Maybe I misunderstood the concept of "vibes" because i get no shakes whatsoever, just a "whirring" noise.
A whirring noise? hmmm.... maybe the gears are nice and tight.... tire slap? Or maybe a u-joint is on its' way out....
-
rubber shield flapping in the wind? What under there can move?
-
Tom woods u-joints are $20 USD. To me that's a pretty good deal. I have not been impressed with the longevity of napa u-joints.
I also wanted his opinion on whether u-joints with the grease fitting on the cap needeed to be replaced with the same type for correct balance to be maintained.
i was just at autovalue and ujoints there are 25$. just wondering what the difference is between the tom woods ones? what are you expectations for a ujoint too? i don't really expect much out of them, i break em fairly easily.
-
I just need to ask....are you "Boardsnow" or "Alpine"?
-
I just need to ask....are you "Boardsnow" or "Alpine"?
What are you doing on here? Are you so addicted to the site that you lugged a laptop down to your hotel and bought wifi? ;D
-
It's free, and I figured there might be a part or two that might come up for sale.
-
i was just at autovalue and ujoints there are 25$. just wondering what the difference is between the tom woods ones? what are you expectations for a ujoint too? i don't really expect much out of them, i break em fairly easily.
maybe I've been lucky but I've never broke one, really, but I've worn out lots. I don't usually shop at Auto Value, but at NAPA the have their cheapie, which is greaseable for around $18 or their premium which is not greasable for about $30 (prices from memory). The problem I've had with the cheap ones is that they wear out too fast I think the needles are softer maybe and the premium ones don't do any better since you can't grease them.
So basically the cheap ones are too cheap and the better ones are nipple-less. I have heard non-wheelers say the napa premium are good.
The thing I like about the $20 Tom Woods ujoints is they have the grease fitting on one of the caps(much easier to grease and no worries about proper orientation in a double cardan). There is a spicer one like this too but IIRC it's around $40 locally.
not sure if you were @me but no, I'm not boardsnow or alpine.
-
maybe I've been lucky but I've never broke one, really, but I've worn out lots. I don't usually shop at Auto Value, but at NAPA the have their cheapie, which is greaseable for around $18 or their premium which is not greasable for about $30 (prices from memory). The problem I've had with the cheap ones is that they wear out too fast I think the needles are softer maybe and the premium ones don't do any better since you can't grease them.
There is nothing wrong with non-greaseable u-joints. That is all I have on my rig because I am lazy and don't like greasing u-joints after every run. Plus the high-end spicer have a very good triple seal that are only about $30 at Pat's
-
the cheap ones just need to be maintained; but due to freqeunt mclean mud baths and less than frequent maintenence (from your first post) i can see why they wear out. will the other non sealed units last longer than the cheapies without proper maintenence?
from the sounds of your driveshaft build i thought you were trying to lesser maintenence. i figured a sealed ujoint would suit that need better......
-
Spycer 760 is the ONLY way to go on that type of axle... D30 & Ruby axles
They are $28 at Pat's (if you have your CJA card) and at DSI
I ran the cheap joints only once and it costs me a set of new axles. U-joint blew...took the ears off the yoke and destroyed my Superior axle outter seal....
Protiture yourself, get extra $$ and buy yourself some Spicers 760.. and stop being cheap.
-
Ok ...I might not have read the the hole thread.
you might be talking drive shaft u-joints....
None the less...never cheap out on parts... If you wheel with people and break all the time, it sucks for the rest of the group.
-
ya we're talkin driveshaft u-joints....the tom woods ujoints are for my tj anyway which has a sye, not my xj which has the stock tj driveshaft setup. Do you guys think the spicers are better than the tom woods "gold seal" type?
I don't really know which ones will last longer, I know the spicers are good, and the tom woods gold ones I have in the tj now lasted about 2 yrs, which seems pretty good to me.
with the ujoints I picked (grease nipple on a cap) and with the driveshaft setup the goal was more 'easier maintenance' than 'less maintenance', in that the xj driveshaft only has two ujoints to grease and 'because I find having the grease fitting on the cap makes greasing a lot easier, you don't have to turn the shaft to get at the fittings as much.
I read a few posts back that someone had thought the "blue goo" was marine grease, when I referred to the blue goo I was talking about the coating on the male splines of the slip shaft.