Hey all. I very recently did the 4 inch lift plus 1.5 inch (3 inch longer than stock) shackle lift. Now there seems to be a driveline vibration i especially notice when slowing down in NEUTRAL. It may be present under accelleration but goes unnoticed because of the engine noise. It seems to be getting worse over the 500 or so miles i've put on the new suspension. I've ordered 2 degree shims from MAF.
1: DO i need them front AND rear, and is the fat end of the shim to the front or rear?
2: WHat is the other possible source? I did a front end rebuild about 2000 miles ago, using all new bearings, and checking the pre-load with the fish-gauge. I am reasonably sure it is the suspension since it started a day after i put it all in..
3:does it go above or below the leaf spring (the shims)?

Thanks all...I am relegated to driving the wife's CIVIC till i get this fixed.
:emb4:

Have you checked the ubolts since the lift was installed? They always have to be retightned several times after they are installed.

tp

yeah i retightend the ubolts with my air wrench.. should i do this, or use a torque wrench (and the proper torque is??) I was just cranking it as tight as i could...now the axle is off, awaiting my shims..:crybaby2: boo hoo.

hmm...the dude at MAF said i should check my U-joints for the rear drive shaft... what do you all think? crap, virtually EVERY time i modify my rig (brakes, ignition, PS, seats, etc) some unexpected problem pops up..:mad3:

Shims should do the trick and its probably related to the u-joints. When I did my 2.5 lift I used 2 degree but you might want to go for 4 or 6 and be sure to get steel ones from a good source like foothilloffroad or a spring shop. The al ones will break and you'll be back under the truck. The thick part is used to tip up the pinion shaft up and if your sua to the front....any more q's.....check your driveshaft and make sure the ujoints are good and free from binding but most likely its an angle issue and under load you'll see it everytime.....

You vibration is most likely the result of the longer shackles...adding those in the rear tips the pumpkin upwards, and changes the harmonics on the rear driveshaft....you would add the shims to tip the pumpkin back down, and get your t-case output and pumpkin input back into the same plane. Unless you regularly run the truck with the hubs locked or in 4wd, you shouldn't need shims for the front axle since the driveshaft doesn't normally turn.

Alum shims sucks....they will eventually flatten a bit and spit out. You may also need longer spring center pins to ensure the shims are properly contained and to make sure the pin contacts/penetrates the axle perch alignment hole too. (sometimes a double nut is enuf, but a special pin is better.)

IIRC, u-bolts on cruisers are torqued to 80 ftlbs??

Shims go between the axle and the spring.