Shaking in 2nd and 3rd Gear

D-Fox · 06-04-2010, 10:32 AM

This is my first post and I tried the forum search, so forgive me if I might have missed a thread that covered this.

I have an '02 TJ with the 4.0, 4" lift & 33's. The problem I have is when I'm in 2nd and 3rd gear accelerating. At about 1500 to 2k on the tach, I get a bad shaking/vibrating that feels like it is going to shake the dash apart. It also happens a little bit in 4th gear but not quite as bad. However, when I'm in 4hi, the shifting/accelerating is as smooth as can be. The PO also said they had the clutch replaced a short time before I bought it (not sure if this has to do with the problem). Thanks!

**roundlitefan** · 06-04-2010, 10:49 AM

I don't know these vehicles even a fraction as well as some of the people here, but if it was mine I would start looking for problems in your front driveline.

Intuitively, I would suspect it is possible that you have a front yoke that has a loose strap or something of this nature. When you are accelerating in 2wd, the front DS is spinning, but not being driven.

I think it is possible that your vibe goes away in 4HI because you are forcing the slack out of whatever is loose while you are accelerating.

Just a guess, take it for what it is worth.

D-Fox · 06-07-2010, 09:08 AM

So if I were to take a look underneath at the front yoke, what might I be looking for?

The vibration is pretty annoying and I'd hate to run around town in 4hi putting undue wear and tear on the jeep.

aussied97tj · 06-07-2010, 10:50 AM

At a 4 inch lift you will have driveline vibration in rear driveshaft if no sye/cv drive shaft is being used and that creates a steep driveline angle on your rear driveshaft. Also check all u joints.

**roundlitefan** · 06-07-2010, 10:58 AM

The only reason I suggested looking at the front driveshaft is because the OP says the vibes go away when he is in 4-Hi. If it was rear DS ujoints binding, I would suspect you would have vibes regardless of whether you are in 2-Hi or 4-Hi. Maybe someone else can give a reason why this would be, I was just taking a guess.

OP, just get under and take a look. If you are missing a strap or have something loose you should be able to see it pretty easily. Turn your DS's by hand, see if you notice any clunking or anything that doesn't feel right. You could even pull the DS's one at a time and see if the symptoms go away while one or the other is removed. That was at least you have narrowed down where the problem could be.

D-Fox · 06-07-2010, 11:27 AM

roundlitefan, thanks for the advice! When I get off work I'll have to crawl around underneath and see what I can find (or not find).

aussied97tj, the 4" lift was put on by the previous owner, as was most of the other aftermarket parts. The more and more I read JF, the more I wish I'd researched Jeeps in general before buying one. Right now I'm trying to read as many threads as I can to try and figure out what was actually done to the Jeep by the PO. One mod that I originally thought was a bonus (K&N CAI) , is now a negative after reading the CAI thread.

**freeskier93** · 06-07-2010, 11:47 AM

Quote:

Originally Posted by roundlitefan

The only reason I suggested looking at the front driveshaft is because the OP says the vibes go away when he is in 4-Hi. If it was rear DS ujoints binding, I would suspect you would have vibes regardless of whether you are in 2-Hi or 4-Hi. Maybe someone else can give a reason why this would be, I was just taking a guess.

OP, just get under and take a look. If you are missing a strap or have something loose you should be able to see it pretty easily. Turn your DS's by hand, see if you notice any clunking or anything that doesn't feel right. You could even pull the DS's one at a time and see if the symptoms go away while one or the other is removed. That was at least you have narrowed down where the problem could be.

Your idea sounds more plausible. I would check the front drivetrain then the rear.

D-Fox · 06-15-2010, 07:40 PM

So I was finally able to get around to getting underneath the Jeep. Everything looked pretty normal and in place. I also turned the DS's and there was no clunking and no play when trying to move it around. The only thing that looked maybe out of place was where the DS met the rear differential. There seemed to be some oil right around the seal where the DS mates to the differential. I'm not sure if a little bit of oil would be normal or not (my previous vehicle was an '83 Bronco so everything leaked). I also do not have the equipment or know-how to pull the DS one at a time to see if that will correct anything.

For further clarification, the shaking is worse in 2nd and 3rd but occurs to some extent in all gears in 2wd. Starting out in first I have to be extremely smooth in applying the clutch otherwise it feels like something in the drivetrain spins a quarter turn before the wheels do (almost a clunking). Driving in all other gears, even above the 1900rpm threshold, feels rough/loose/not smooth at all. The only thing that makes driving feel like a normal smooth manual, is driving in 4hi. Any suggestions would be greatly appreciated as I will be going on a long roadtrip in 2 months. Thanks!

D-Fox · 06-21-2010, 09:27 AM

Bump. Any ideas?

**roundlitefan** · 06-21-2010, 10:08 AM

Please don't take offense here, but if you don't have the tools or desire to pull a drive shaft, I am not sure anyone here can help you. A small ratchet and socket and a little time lying on your back is all that is required to drop a driveshaft. Probably would take about an hour on a bad day if things went wrong, more like 10-15 min if it all goes right.

If you don't feel comfortable doing that, you should probably pony up the $$$ and take it to a mechanic before something breaks on you for real and costs you some serious cash.

**Sundowner** · 06-21-2010, 10:36 AM

Don't have the know-how? TIME FOR YOU TO LEARN!

Seriously, it's not that bad. There was a post a few weeks ago from someone that was nervous changing spark plugs...proof that when you first get started wrenching, every task seems intimidating. With experience comes ease.

I think your issue is definitely in the driveline somewhere (sometimes people ascribe steering wobbles/vibrations to the driveline). The "quarter-turn before clunking" sensation I would have applied to a u-joint, possibly. However, if you've noticed that driving in 4-High seems to cure the problem, then perhaps you have an issue in the t-case...although I am unsure as to what it would be. Someone more knowledgeable than I will have to chime in on this.

D-Fox · 06-21-2010, 11:22 AM

Perhaps I should have used a different choice of words. I guess I am more intimidated than anything (drive shaft work sounds pretty serious). :P

When I get home I'll post up some pictures I took, to see if anyone notices anything out of the ordinary. Thanks for all the suggestions (and encouragement to grow a pair and get under the jeep) this far.

Hopefully someone super knowledgable chimes in soon.

D-Fox · 08-09-2010, 10:33 AM

So thought I'd post what the actual outcome of this was. I decided to take it into the dealer to see if they could diagnose the problem.

The service manager confirmed what the obvious answer should have been. Extreme driveline angle from the 4" lift was causing the vibration. The reason it went away in 4wd hi, was because it took some of the stress off of the rear driveshaft. So, after lots of reading up, I finally understand what a SYE and CV (DC) driveshaft are, and how they work. Now the big decision. I'm getting ready to go down to Texas from Omaha, NE for some training and I am taking the jeep. How bad (U-joint, t-case damage) will this long drive be if I do nothing? A local shop has quoted me $800-$1000 for a SYE, new driveshaft, and installation. Is this reasonable? I have a lot of outprocessing appts right up until the trip and so I won't have much time. I do however have a buddy with fairly decent mechanical skills (mainly in imports). If I were to get the parts myself, how much time would an install like this take?

I appreciate all the input this far and I apologize for taking so long to update it.

aussied97tj · 08-09-2010, 08:17 PM

You might be able to get away with just putting about a inch worth of washers to space skid plate down away from frame that will help.

D-Fox · 08-10-2010, 06:26 AM

I actually noticed the other day that it already has a spacer kit to drop down the skid plate. :/ Another benefit of throwin' the SYE on there is I'd be able to get rid of the spacers and tuck it back up where it's supposed to be.