Shudder on takeoff

jackeneses

New Member
Joined
Nov 14, 2022
Messages
4
Location
Alva, OK
Hello everyone!

Recently purchased a 1992 YJ (well the body is a 1992, the rest is pieced together, a real frankenjeep.)

it is a 4.0 5 speed that is lifted 4.5inches on 33s. PO put in a t-case drop. Front driveshaft is not in, so it is 2wd until I order a new one. Just recently replaced all steering linkage, the steering column, and got it aligned.

I have a shudder on takeoff. It is only when starting to move in 1st and reverse. I can feel it in the steering wheel and the clutch pedal mainly. I doesn’t feel like it’s shaking the whole Jeep. I believe it looks like the tranny is shaking as well, but it’s hard to tell since it always shakes some. The Jeep runs fine, and doesn’t feel like the clutch is slipping, but I don’t know.

It does not shudder if I turn while taking off. Tight turn left or right when releasing the clutch and it’s smooth.

From reading other posts I’m thinking it’s either clutch chatter or a bad transmission mount? The PO told me he put in a new clutch and everything with it, but he used Oreillys parts. I have a new mount coming in for when my SYE gets here. I’m hoping that since it doesn’t shudder when turning, that the problem is the mount (the weight shift from a sharp turn may be keeping the transmission in place and not shaking back and forth, is my best guess.)

Anything else it could be or I should check? I’m a shade tree mechanic on my best day so I can’t think of what else it might be.

Thanks for reading!
 
Its hard to guess what you mean by shutter. A messed up clutch can make for some serious jumping upon take off as it grabs and lets go from warped/worn or contaminated parts. Say you have the clutch out all the way and are barely rolling and you hit the gas, does you get that jumping or shaking feeling? if you do with the clutch out then Im gonna say drive line issues, like big angels exaggerated by bad mounts possibly. Two very different sensations, wasted clutch or driveline problems.
 
Its hard to guess what you mean by shutter. A messed up clutch can make for some serious jumping upon take off as it grabs and lets go from warped/worn or contaminated parts. Say you have the clutch out all the way and are barely rolling and you hit the gas, does you get that jumping or shaking feeling? if you do with the clutch out then Im gonna say drive line issues, like big angels exaggerated by bad mounts possibly. Two very different sensations, wasted clutch or driveline
Its hard to guess what you mean by shutter. A messed up clutch can make for some serious jumping upon take off as it grabs and lets go from warped/worn or contaminated parts. Say you have the clutch out all the way and are barely rolling and you hit the gas, does you get that jumping or shaking feeling? if you do with the clutch out then Im gonna say drive line issues, like big angels exaggerated by bad mounts possibly. Two very different sensations, wasted clutch or driveline problems.
Since I have 33s with such a high gear ratio, my first gear is no longer a “starting” gear like it should be. I can’t let out the clutch all the way without giving it some gas. However, if I hold the pedal to where it barely grabs and accelerates, or accelerate hard and drop the clutch, it still shudders. It feels as if something is banging against my steering column a couple of times, but I don’t fell it in the seat, only in the steering column and the pedal.

I have a SYE coming in the mail, and plan to install 2 new Tom woods driveshafts once I get that in. Combine that with the new trans mount and that should (hopefully) eliminate those as possibilities. If I still have it after then would that mean it’s clutch chatter? Or could it be something entirely different?
 
Better check the motor mounts as well. cant recall if you did already but it sounds like your on the right track. It kinda does sound like clutch chatter but hard to say over a computer.
 
  • Like
Reactions: jackeneses
Can you tell if the engine rear main oil seal is leaking? It could be one reason the previous owner changed the clutch. I don't know why turning the Jeep has any effect on it but I've seen stranger things happen.
 
Can you tell if the engine rear main oil seal is leaking? It could be one reason the previous owner changed the clutch. I don't know why turning the Jeep has any effect on it but I've seen stranger things happen.
Yes the rear main seal is leaking. It’s not terrible but it’s noticeable. I was under the impression that the rear main won’t cause oil on the clutch because the flywheel is in the way? And yes zero shudder when sharp turning.

No I haven’t checked the motor mounts besides visual, if after everything else that would probably be my next guess (really don’t want to start messing with the clutch if I don’t have to)
 
As for the seal it depends on how long it been leaking. Oil can get on the back (front - forward facing) side and sling all over the inside of the bellhousing and creep down onto the clutch/pressure plate. Or, it could be the front seal of the transmission Or, it could be a leak from the slave cylinder.

I have seen several chattering clutches in trucks and usually there's an oil leak and the clutch is very old. One thing that's more certain is you will usually have slippage at the clutch and smell the oil after a short drive. In your case it sounds like it's not too old and not a bad leak.

Front and rear mounts are not too difficult to change depending on skill and rust. If they're original then yeah, they're due for a change.
 
  • Like
Reactions: jackeneses
Yes the rear main seal is leaking. It’s not terrible but it’s noticeable. I was under the impression that the rear main won’t cause oil on the clutch because the flywheel is in the way? And yes zero shudder when sharp turning.

No I haven’t checked the motor mounts besides visual, if after everything else that would probably be my next guess (really don’t want to start messing with the clutch if I don’t have to)
Oil slings...It will get everywhere inside the bellhousing and combined with clutch dust creates the nastiest, Hardest to clean paste like substance that you'll ever see....I'm manic about oil leaks as they are the root of most problems.....
 
Pinion is now at 17 degrees, but driveshaft looks too long
20230610_114714.jpg
 
Pinion is now at 17 degrees, but driveshaft looks too long
View attachment 121404
Needs to be sitting on the wheels to accurately measure anything. That pinion angle looks too high, by the time you’re sitting on the wheels it should be even worse.

You’re going to need to shorten that driveshaft. PO probably ordered it too long. Doesn’t sound like he knew what he was doing.
 
PO says it was made with a manual transmission that was shorter.

Is Tom woods worth the extra money?
View attachment 121414View attachment 121415
Not sure what you mean about is Tom Wood's worth the extra....it's a fine brand, as are others. I always order from Adam's Driveshafts. I have ordered shims from Tom. either way for a driveshaft I would order non greasable u-joints and a non greasable centering ball.

I'm very confused by your angles listed in the pic. what is the current status of the Jeep? Is it sitting on all 4 wheels when you measured? Are shims removed or installed? What size shim at this point?

You had a 17 degree driveshaft angle with the axle drooping, I don't see how that turned into 19 unless you changed the shim. Same for the pinion angle, I'm pretty sure stock is 6 degrees, so did you swap to a 4 degree shim for this latest measuring to get 10 degrees?

Also....the yoke is not a good place to measure driveshaft angles. The best place is the cast in circle on either side of the diff cover at the back of the axle housing.
 
If the PO didn't resurface the flywheel, you could have ," hard spots" on it, that'll cause a shutter on take off.
Some mount bad will also cause that.
Take a rachet strap and bind down trans and see if that changes anything!
Joe