Calgary Jeep Association
4x4 Related Groups => Tech Talk => Topic started by: murray195 on February 15, 2011, 03:54:41 PM
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Hello all,
Well, while I wait for my AMC 360 to arrive from BC I figured I could attempt to address a slight issue I'm having with my YJ. On acceleration from a stand still for maybe 3 or 4 seconds she gets a little hoppy :P. From what I understand, this is due to me not running a SYE. I have a RC 4" lift with the TC drop. I've been reading up on shims vs. shackle lifts to get me to the 2 degrees that everyone says I should have. So here's my questions:
1) are the shims my new leaf packs came with sufficient?
2) would extended shackles change my driveshaft angle for the better? (I need to replace them anyways)
3) would lowering the TC another 1/4" reduce the hoppy hop hop?
4) could everything be fine and its actually engine/trans/transfer case mount related?
I don't have any prominent vibrations at high speeds, and don't have any after that 3-4 second mark either. Thanks guys!
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Hoping is caused by axle wrap and won't be solved by a SYE or driveshaft angle adjustment.
If you think its bad now wait till the V8 is in!
Do you have any lift blocks? If so those will need to go. Otherwise stiffer springs or a traction bar maybe needed.
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:-\ Well thats no good... my lift is MAYBE 4 months old and no lift blocks were used. I used the track bar relocation bracket for the front and reinstalled the factory track bar. She rides like a school bus haha! So, going stiffer would be the closest thing to having the axle bolted directly to my frame.
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Is there anything else it could be?
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track bars and traction bars are different things ;) you can ditch your track bars that'll help with the harsh ride; and don't over tighten your shackles:
are you runnin the leafs under your diffs? shouldn't be so bad.....
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Taadaaaaaa, just happened to be looking at this while I was researching some part numbers for my TJ.
http://www.mountainoffroad.com/_e/Trac_Bars_Traction_Bar/product/TB500/TB500_Traction_Bar_for_Rear_Axle_CJ_7_and_YJ_s.htm
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The Rough Country lift is your first problem, I bought one of those pieces of crap and bent the rear springs the first trip out, V8 + cheap springs = bent stuff. Also if you torqued the bolts to their specs your bushing are probably binding and causing your hop. Do yourself a favour and ditch the Rough Country stuff, its cheap for a reason
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Johnny C, thank you for clarifying that there is a difference b/t track and traction bars. I'm running leafs all the way around. Maybe I should loosin up my shackles a little.vantagetes, thanks for the link. I was looking at something similar before:
(http://www.4x4wire.com/news/skyjacker/5th-link/5th-link.jpg)
And here I was thinking I'd never need anything like it with a mild build lol.
rangerdanger, other than being a little bumpy The Rough Country Lift has been excellent. It's held up very well with no collateral damage. If I go with a shackle lift with new bushings, could this help a little? The Traction bar looks like something a could build when I get some ME time lol. Thanks again for the replies guys!
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generally a traction bar is only needed in SOA applications as axlewrap is when that becomes a problem. if you're running spring under, it shouldn't be a problem.... mine isn't at least!
ditch the track bars; CJs didn't come with them, they aren't much different than YJs are they???
and loosen your shackle mount bolts. mine are so loose you can almost turn em by hand ;) makes the ride much better. (i think its less than 20 ft lbs) i'd also go with some aftermarket shackles with greasable bolts; well worth the 200$ to upgrade (Rubicon express and a bunch of others have the greaseable bolts)
but as clay said, that won't fix your hop.
try softening your suspension, maybe your hop is just new springs with tight shackles???????
if its still there, traction bars are a possibility, but if ur jeeps already ridin' like a dumptruck, it won't make a huge difference in ride quality/flex
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Ok JohnnyC, I'm gonna loosin up those shackles today if I get a chance. I'm SUA and don't plan on changing it till I upgrade my diffs. I'll look into those greasable shackles as well. Maybe I'll give national a call after lunch. I think you guys are onto something with those shackles. My jeep having ride quality :o?!?! Is there really such a thing in a YJ? :P
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My jeep having ride quality :o?!?! Is there really such a thing in a YJ? :P
yes: but you still won't be able to keep up to those silly boys with their coils when they baha it at Waiparous.......
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Haha, true... maybe one day a TJ will be in my driveway. Until then all I can do is improve my YJ right? ;D
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yes: but you still won't be able to keep up to those silly boys with their coils when they baha it at Waiparous.......
I kept up pretty well in my YJ... and I still have my trackbars too ;)
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Ah silly boys and their YJs, always trying to keep up with the TJs :P
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c'mon now lol
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On a serious note it took a while for my RC springs to break in (TJ with coils), rode like a freaking tank until I loaded it with a bunch of tools etc and flogged it down the rocky road of doom a couple times in McLean. Also the same company that I linked you to for the traction bar (M.O.R.E.) makes greasable shackles as well.
While I'm sure it has nothing to do with the hopping your tire pressure will make a huge difference in ride quality too, I had to go down to 18psi to get proper tread wear on my 33"s and it rode sooooo smooth after.
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I've hardly broke in the new suspension. I've only taken it out a few times since the lift and the most strain I've put on it was checking the articulation courtesy of a forklift :P. I'm running Goodyear Duratracs which are not exactly a balloon tire so maybe letting some pressure out would help as you said.
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A general rule of thumb to get you close is watch the sidewall where the tread touches the ground. Just keep letting air out until you get a little bulge then finetune from there.
What size/tire pressure are you running now?
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I'm running 33's. Max pressure is 80psi! I was running them at 55 and brought em down to 35 for wheelin last saturday. I realize load range e tires are overkill, but it's what I ended up with.
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Whoaaaaa. Did the tires even flex at 35psi?
Here's my thread when I was trying to figure out what a good ballpark to start at was.
http://forum.calgaryjeep.com/index.php?topic=19930.msg119307#msg119307
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That's a good thread vantagetes, thank-you for that. I guess I should air way down to like 20 or so and see what happens. I was more or less concerned about my sidewalls and abnormal wear. From reading that, one thing I think I gathered is that tires with a load rating of E (3200lbs max per tire?) on a jeep that weighs 2800lbs or so can cause cupping? Please correct me if i'm misunderstanding.
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Not having your tire inflated to get full tread contact will cause either the inside treads or outside treads to wear faster.
This "test" only works when the tires are newish, once you wear them down they will be worn flat at the pressure you were running. The problem with that is if you started with the tire overinflated only the middle tread is worn down until the rest contacts. When you drop the tire pressure after that happens the middle pulls up which is what he meant by cupping I think. In "correct" tire terms cupping is wear on the blocks of tread, usually caused by misalignment or suspension issues. Basically chunks of the tread are missing, aka "cupped" treads.
To check for full tread contact you're supposed to take some chalk etc and run a line across the tread from one side of the tire to the other. Then drive down the street and back. If all of the line has worn off evenly you're good. If you only wore off the middle you have too much air, and just the outside means they are underinflated and the middle is "cupping" upward.
That test isn't going to work out very well due to the snow and all. What I did (cause I got sick of driving around the block and jumping in and out of my jeep) is parked in the garage (nice flat smooth surface) and slid a piece of thin cardboard under my tire. If I could slide it under no problem I knew there was too much pressure and the tire was sitting on the middle of the tread. Once I started getting some resistance I knew I was close.
(http://www.mpi.mb.ca/Images/60SecondDriver/tireinflation.jpg)
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Ok, I'll pull the jeep into the shop tomorrow and do the cardboard thing and see what kind of numbers I come up with for tire pressure.
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1) are the shims my new leaf packs came with sufficient?
2) would extended shackles change my driveshaft angle for the better? (I need to replace them anyways)
3) would lowering the TC another 1/4" reduce the hoppy hop hop?
4) could everything be fine and its actually engine/trans/transfer case mount related?
1. Need to know what size shim you got before we can answer this question
2. Putting on extended shackles (no longer than 2" extra inches) will help with your pinion angle a little, and you might get lucky and it gets your angle where it needs to be. Extended shackles will also allow more movement in the leaf spring which is good
3. I don't believe lowering the TC will exactly help the hop because the hop is created when the axle wants to twist with the rotation of the driveshaft. Do you have a TC drop now? How much drop? A 1/4" probably won't help much, but you may need to go 1/2-1"
Also Vantagetes, don't be knocking the YJs because my little ol'YJ has gone lots of places where TJs did not
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BlackYJ, thank-you for answering my original questions! I already have a TC drop (the one that came with the kit; approximately 1.5"). Seeing as the general concensus is to get greasable shackles, I always like to upgrade if I must replace a part.
After shopping around a little bit, it looks Like I'd be better off getting the greasable hardware and bushings and building my own to my own specifications. $200-600 per pair is a little up there for a couple pieces of polyurethane and a couple pounds of cold rolled steel. Any thoughts? Anybody built their own greasable shackles?
For the hardcore people out there, I think these are pretty cool:
http://www.national4wdonline.com/cart.php?page=parts_look_up_and_search
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After shopping around a little bit, it looks Like I'd be better off getting the greasable hardware and bushings and building my own to my own specifications. $200-600 per pair is a little up there for a couple pieces of polyurethane and a couple pounds of cold rolled steel. Any thoughts? Anybody built their own greasable shackles?
shackle kits (rubicon express) were 90$/piece at modern motors. bushing kits were some 25" it shouldn't cost you more than 250$ replace all your shackles and hardware.
also, maybe look into adding the boomerang shackles both front and rear; i haven't don this yet, but i've heard its a worthwhile upgrade, and will get to it sooner than later i hope.
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The boomerang shackles apparently increase articulation as well as ride quality. I have access to a fab shop and quality steel so as long as I can track down the greasable hardware and some decent bushings I think I'll be golden. I'm going to take some measurements and do up a quick sketch of what I intend to build. I'll try and post it later for opinions.
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The boomerang shackles apparently increase articulation as well as ride quality. I have access to a fab shop and quality steel so as long as I can track down the greasable hardware and some decent bushings I think I'll be golden. I'm going to take some measurements and do up a quick sketch of what I intend to build. I'll try and post it later for opinions.
i'd like to see your designs :)
i wanna goto front boomerangs, but last time i asked in modern motors, they only come in a kit. the kits 90$ or something like that; i guess the expensive part is the hardware; ( accord to REs site the hardware kit is 60USD, shackles w/bolts were 79$)
might be worth it just to buy a kit?
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This is what I came up with for a sketch with Microsoft Paint lol.
(http://i1019.photobucket.com/albums/af313/murray195/BRACKET.jpg)
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Those shackle plans look pretty nice, I was thinking of ordering a pair of the M.O.R.E shackles myself to help the articulation a bit. Also air down those tires 55 psi is way too much for your jeep, I run about 22 psi on road in my truxus radials to get full contact and a nice ride. Offroad I air down to 15 psi or so in the radials and 8 psi in my bias ply boggers
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Thanks :). I've aired down to 24psi and things have gotten a little better. I just made a template of the shackle out of puck-board, so hopefully all is good with the design. I'm going to get 8 pieces made so I can do the front and rear.
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I have MORE boom shackles front and rear. They are VERY beefy and should only be about $100 / set. In the rear booms kick the shackle out so it does not bind on the frame and in the front in you invert them so they look like a 7 from the side, they prevent shackle inversion and save your leafs. Booms do not do anything to improve ride quality or anything. If you want to improve ride quality on a YJ you need good quality shocks and high-end springs like OME or Alcans.
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Thanks for the info BlackYJ. I guess I'll be lookin at picking up some shocks in the near future. My shackles should be done by mid next week, hopefully they're a good addition!
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This is what I came up with for a sketch with Microsoft Paint lol.
(http://i1019.photobucket.com/albums/af313/murray195/BRACKET.jpg)
I can measure my MORE shackles when I get home tonight for you. I would probably look at increasing the distance between the top and middle holes a bit because that is the portion that is going to hit the frame.
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That'd be great, I'd appreciate it :)