HELP! new rear leafs, now drives awful! NOW W/ PICS!
 

ok I need some input here to either chill me out or confirm my paranoia something is not right.

I just had ome cs009 med. Duty rear leafs put in. New poly bushings all around, new shackles with greasable bolts. Allpro +1.5" over stock?

I still have my tired monroe sensa watevers for shox. I know I have to get the ome's.

so, yes the ride is stiff. Jumping on the hitch I can barely bounce the truck. I expect that thinking it should relax over time.

but i'm freakin out over this vibration that now feels like its in the driveline. Accelerating and engine braking, the whole truck shutters and vibrates like yur on a washedout rutted road, or like the lines they cut in the pavement shoulder to alert the driver when you drive over them. it's not there when i'm clutch-in coasting.

the angle of the truck is much higher in back than before, like 2 " up. i expected some relax, and then bring the t-bar up to match. But the driveshaft angle still looks ok at the back. I could not see the front. The axle appears to be a tad to the left judging by tread sticking out past mudflaps, by maybe 1/2" tp the left

the stock flat springs I removed were 3 + 1 overload. The new ome's are 4 + 2 overload. A long and a short. Should I remove one? right now my u bolts are barely bolted, no threads stick past the nut. i will resolve this either with new u's or removing a leaf.

could it be drive line? Or is it just the springs afe super stiff til they relax? Or do I need that one overload out? Or is itt cuz my factory length shocks are too short? Or is the axle too far to the left?

any advice is greatly appreciated. I'm supposed to be driving it over the weekend to relax them, so monday the t-bars can be brought up to match ride height. But i'm afraid i'm gonna do driveline damage. Its that scary sounding.. Very loud from the back. I have new bfg a/t's, not old chunked mudders.

thanx y'all :(
tj

I have had my OME medium duty leafs in for about a week now and I can tell you the first few days the ride quality worried me also. It was very rigid, you could feel every little bump, and crack in the road. But not like the old saggy stockers. I did notice some significant vibration also. But now it is almost as smooth as the wifes 04 4runner sport. It will relax in a few hundred miles. If your rear is higher than the front by 2", i.e. you did the rear but not the front. You may experience some drivabilty problems. Just not good geometry. Also I would take a look and see if the old stock shocks are not "holding up the springs". May not be working in good order with the new higher leafs.

I still have some body wobble/sway, the body bushings need to be replaced, and it is more noticable now the the suspension is normal. And I need to get my tires balanced.

Hope it helps.

Find a 3-4 foot piece of railroad track, and place over the axle, that l help till it settles in, dang pieces are HEVeeeeeeeeee.

ok, i drove all day. i can definitely tell the difference between rear spring stiffness and something funky with my driveline.

i get a horrible vibe starting out in first, get much worse accelerating in 2nd, still there in 3rd.

at highway speeds, it's gone.

i stopped by 4wheelparts and asked for some advice there. he grabbed the d-shaft where it slides apart, and said there's a tiny bit of slack there. he recommended i go to a d-shaft shop on monday. i may need a rebalance.

while i was there, i went ahead and ordered the OME N94 light duty shocks for the rear, in case the limited travel of the existing units were having adverse affect. they gave me a great price of $76 each. free ship when i pick them up local.

so monday i will go by this d-shaft shop and see what they say.

HAS ANYONE PUT IN THE OME LEAF PACK AND PULLED ONE OF THOSE TWO OVERLOAD LEAFS? i'm wondering if it's over kill. plus i need to replace my U bolts now cuz the new packs are so much thicker than the stock. i barely have the nuts on the bolts.

more info, and pics as i can put it up.

They will settle in over about 1000 miles or so or one good trip off in the woods. :hillbill:

:guitar:

thanx Wab. i'll go give it a work out ASAP.

i had the alignment shop look at it this morning. he said it appears the u-joint angle on the trans side is too steep. he suggested dropping the t-case an inch, using spacers where the crossmember attaches to the frame. they also greased up the fitting at the slip yoke, but that didn't make any difference.

the vibration/deep hum i get is primarily from start off in first, and accelerating at the shift to 2nd and 3rd. once i'm up to speed it sounds fine.

i'll give it some more time to settle, it's still stiff as petrified wood, and look into swapping out the factory crossmember for something flatter. so i can drop the t-case but don't lose clearance.

has anyone taken out the bottom load leaf in the OME springs?
 

the factory leafs i pulled out were 3 +1 overload.

the OME dakar cs009s are 4 leaf + 2 overload, a long and a short.

the springs are now so thick i have to replace the u-joints so they're long enough to give me some extra thread past the nuts.

HAS ANYONE TAKEN THAT BOTTOM, SHORT LEAF OUT? i don't tow much, and i'm usually empty inside. right now the back is hopping over speed bumps.

also, i just ordered the OME light duty shocks for the back, so i can eliminate the monroes as contributing to the harshness.

i haven't done anything with the brake proportioning dealy or the brake lines yet. i'm wondering how that's going to work out. i think i'll have to wait for these leafs to break in before i can get any idea of flex limits.

again, all advice is greatly appreciated! now i'm going to search for a different t-case crossmember. maybe i can have something made out of 1/2" plate. hehe

Lowering the t-case is the wrong thing to do, measure the shaft angle and shim the axle if needed:
- http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ1

Also check your drive shaft phasing, might have been pulled apart and then put together incorrectly (that can cause low speed vibration):
- http://www.4crawler.com/4x4/CheapTri....shtml#Phasing

haha, speak of the devil. i'm reading your "driveline 101" right now. i think i'm going to go by a d-shaft shop in a minute and get their opinion before i try dropping the diff. i'm not sure if i need a spacer at the t-case, or a shim.

from what i'm reading here, it appears i need a shim on the rear FROM THE FRONT.

i have steeper angle at the front U joint than at the rear U joint.

i'm assuming the alignment guy wanted to drop the case to reduce the front angle to match the back. your page is telling me that it's not the steepness of the angle that's as important as having them match. right?

i do see looking at the yoke that it's slipped longer, maybe an inch. that's why i'm wondering about a spacer at the case.

thanx, Roger

Correct, your longer shackles have tipped the pinion up:
- http://www.4crawler.com/4x4/ForSale/...es.shtml#FAQ12


Having too little slip yoke engagement can cause vibration, see if you feel any side-side play there.

pictures! i'm out of phase
 

well, i don't know if i need shims yet. but i do know i'm out of phase. now that i know what that means. i looked underneath and its plainly visible. i took some pics.

here's the front and back side by side. i guess i need to unbolt at the t-case, pull out the front piece of d-shaft, line it up, and put back together. right?

is there only one way to do it right? or can i do it either of the 180* positions that line up the yokes on the shaft?

i'm thinking theoretically i'd turn the rear joint in the direction of the little green arrow, so the flange yoke is where the purple sketch is. to do this, could i roll the truck about an inch? OR, should i put the t-case in neutral and turn the front flange by hand? hmmm...

http://i46.photobucket.com/albums/f1...0cl/UJOINT.jpg

pics of new leafs and shackles
 

here's the OME dakars and the AllPro shackles. i think the angle looks ok. you don't think this shackle is too long do ya?

ome shocks are on order. when they come in, i may pull out that bottom overload leaf. any advice/experience with this? the back is kind of high and i don't want to have to crank the t-bars too far to level the truck.

oh, p.s. check out the weights on that wheel. that's a new wheel and tire. i'm still arguing with them for a new tire. but i have to eliminate all possible reasons there's a shake in the rear so they can't say it's not their tire when i know it is.

http://i46.photobucket.com/albums/f1...l/CIMG0121.jpg

Take a picture of your pinion angle and rear driveshaft.

If you have hubs up front, make sure they are unlocked and you can rule out the front driveshaft.

Also did you over-tighten the shackle bolts? They need to be snug, but not too tight.

If the shaft is built right, then either orientation should work, but put it in one way, if the vibes go away, you are done, if not, rotate the slip yoke 180* and try again. Sometimes one orientation will be a little better than the other. I usually just throw a pair of jack stands under the rear axle then you can spin a tire with your foot to turn the pinion flange to line up the bolt holes.

You should have 1-2" of slip yoke compression travel at normal ride height to allow for the suspension bottoming out and compressing the shaft (so it does not push into the t-case).

shaft angle pics
 

pics are below. you can see the joint angles aren't obscene, but they're not the same.

BUT if you look at the blue lines i made, and compare them to the white parking lot stripe, you can see the t-case is fairly parallel to the ground, while the rear diff certainly is not. looks like a shimming is needed.

hubs are unlocked.

they were tight. i backed off each of the 4 nuts until the bolt turned with the nut. i didn't do it to the front spring to frame bolts though.

you can see i am pretty high in the back. i still have about 900 miles of break in to go, and i will need to bring the front up some. hopefully not much. eventually i'll have a rear tire carrier so i am ok with a little height, but right now it's a dragster.
http://i46.photobucket.com/albums/f1...haftangles.jpg

this is good to know. thank you.

ok, then the 1" of shiny portion i see on the shaft is for compression travel. good. i was hoping i wasn't short on spline to spline contact. cool.

i am going to phase this up, see how it feels. hopefully i won't need to 180* it. if that don't work, i'll move on to shimming.

thanx again man. and thanx as always for the 4crawler site.

Subscribed. I recently lifted the rear of my 4runner w/ ome springs and have had the exact same problem. While at highway speeds the vibration goes away, but while accelerating, especially thru 2nd and 4th, it vibrates a good bit. I also lifted the front w/ 4crawler's bj spacers and a little tweak of the torsion bars to leave me w/ about 1" rake. I thought it was related to the front at first, but may have to look at the rear. I still need to lower the front diff an 1" to get a little better cv angle.

you can see from my pics that 4crawler has used the psychic method to identify two existing problems: the out of phase of the shaft, and the rear diff angle is not parallel with the t-case or the ground.

i didn't know what either of these meant until studyin' up today.

i'll post again when i get the shaft phased right. hopefully i won't have to shim. and i'll follow up later when the shocks and new ubolts go in.

putting d-shaft into phase has improved it
 

after unbolting the front flange and turning the short piece of the d-shaft to align ends with the rear, the vibration has decreased. but it's still there.

i don't know if it's now 180* out of phase, or if it's the pinion angle that's still causing some vibe. i am going to try to take an angle measure and get the appropriate shim for the axle to get it parallel with the t-case.

Definitely looks like the pinion is tipped up too high.

Easy enough to use a tape measure from flange to flange to get the angle difference:
- http://www.4crawler.com/4x4/CheapTri...n-Measurements

http://www.4crawler.com/4x4/CheapTri...oint_angle.gif