Pinion angle, ride quality, tire pressure, homemade shackles :D

[vantagetes]

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.

[murray195]

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  . I'm running Goodyear Duratracs which are not exactly a balloon tire so maybe letting some pressure out would help as you said.

[vantagetes]

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?

[murray195]

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.

[vantagetes]

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

[murray195]

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.

[vantagetes]

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.

[murray195]

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.

[BlackYJ]

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

[murray195]

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

[JackstandJohnny]

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.

[murray195]

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.

[JackstandJohnny]

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? 

[murray195]

This is what I came up with for a sketch with Microsoft Paint lol.

[rangerdanger]

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