freddy

I know this has been rehashed a thousand times and ive done my reading but its still nice to hear it again.I installed new rear springs with poly bushings, new front coils with a .075 spacer to level it off.yes it vibrated.not bad but it was there nonetheless.I hate tc drops but I did a 1/2 inch drop anyway with steel bars.still a little flutter there.my tc measures 10 degrees down and my pinion is 12 degrees up. Would a 2 degree shim at the axle suffice? I need to lower my pinion angle correct? Would new u joints correct it without shimming? Any opinions greatly received.thanks.its a 96, manual transmission if that matters.

TRCM

do you have a SYE ??

IF not, then it won't help as much, and you have different requirements for the front & rear joints on the driveshaft.

stock D/S & no SYE, angles should be the same

MoparNJeep

Yes it will defiantly help without a slip yoke eliminator. Just make sure they are installed the correct way when you put them in. Bigger part of the wedge towards the back of jeep. If you have a sye then the bigger part of wedge go's to the front.

Also you are measuring at rest for angles, when you get on the gas the pinion will point more up a few degrees. That is usually when the vibrations occur. That being said I would go with 3-4 degree shims.

Also I would try and get steel shims if they're in the budget.

TRCM

Didn't mean to say they won't help, but the angle requirements are different, and from the numbers he mentioned, it sounds like he is trying to get SYE & double cardan shaft angles with a non-SYE & stock shaft setup, and that won't work.

If he truly just put in new springs and coils, with no lift, he shouldn't need any shims at all....just maybe some new u-joints.



I do have a SYE, and the bigger part of the wedges go the the REAR of the jeep.

Yes, wedges will help, but without a SYE, the angles at the tcase & the pinion must be the same.

If you have an SYE, then there should be no angle at the pinion, and all of it should be at the tcase.

Very, very few people actually need the wedges to have the big end towards the front....and usually then it is because of other issues (welded perches on wrong, springs in backwards, bastard pack, etc).


OK, are the 10 deg down & 12 deg up with or without the homemade drop ?
If they are with, then take the drop out and remeasure. My guess is you had 12 & 12 before hand, which for stock springs, driveshaft, and no SYE is good, but you got vibes from bad u-joints. You could also be getting vibes from the driveshaft in that the part in the tcase is now riding in a slightly different spot.


If you just put new stock springs on it, then you do not need wedges. You probably need new u-joints, and that is what I'd replace first.

Also make sure the ubolts are tight. And this may sound dumb, but are you sure you put the leaf springs in correctly ? not backwards ?? backwards will give you all kinds of vibes due to the pinion angle being off. I've seen it done many times, even by dealerships & 4x4 shops.


New u-joints will not correct pinon angle, but they may get rid of the vibes you have.

If you do in actuality need shims, get steel, and get the kind that actually bolt to the spring using the center pin, not the ones that have a big hole for the center pin to go thru.



Pics would help as well

freddy

I do not have a sye. its a stock drive shaft .the springs are stock replacements with a 3/4 inch spacer in the front.after putting in new springs and spacer the jeep was slightly lifted and it caused a vibration. i could tell the angle at tc was off by eyesight so i dropped it 1/2 inch. it helped a lot but a flutter is still there.since i don't wont to drop tc anymore i measured the drive line angle and came up with tc 10 degrees down and pinion measured 12 degrees up.ive deduced this to mean i need a 2 degree shim at the axle with the fat end toward the rear.thus giving me 10 degrees at both ends. Is my thinking correct? The jeep did not vibrate before i installed new springs and the u joints are less than a year old.

caged

if you're at stock height, it sounds like you just need the new leafs to settle in. therefor, no t-case drop or shims needed.

just go with what TRCM said and replace the u-joints in the rear shaft. they will now be spinning at a different angle, thus giving off the vibes.

all those numbers look good on paper, but in the real world, you have trial and error to find out what actually works. don't just read everything on the internet and assume it's the only way.

i have over between 6 and 7 inches with no sye or t-case drop with a stock driveshaft and a 6 degree steel shim and that's what it took to get rid of any vibes. it drives smooth down the highway at 100kph, hands off the wheel.

every jeep is different. use what you have to.

MoparNJeep

I agree , I would replace the u joints

freddy

Sounds like good advice.ill replace u joints.thanks