Frustrated over shudder from rear end. Can anyone help?

**stratocasterWS6** · 09-12-2010, 03:36 PM

Hey all. I have an '02 ws6 m6 (w/o tcs) w/58k mi. whos rear end shudders and clunks when engaging the clutch in 1st and reverse. The problem began years ago as a light but noticable pulsating at freeway speeds and grew progressively worse. I replaced the harmonic balancer, u-joints, and tranny mounts, but drivetrain still vibrates and shakes.

Had the car on a lift months ago and noticed a ticking sound in the housing when spinning a wheel by hand. Took the cover off, spun & eyeball'd the gears and saw nothing obviously wrong. Replaced cover w/fresh gasket and fluid, problem still persists.

Car is stock, w/exception to adj. panhard & control arms, Spec stage2 clutch. Also replaced pinion seal shortly before problem began at around 26k mi.. I followed the steps in the shop manual and haven't had a leak since replacing it, but this car has become a bear to drive. Not my daily vehicle, luckily, but still want the thing to run right on weekends.

Has anybody on here had similar issues or have any idea what could be wrong and how to correct this problem? Any help would be greatly appreciated. Thanks!

-Paul

**Cutlass** · 09-12-2010, 05:15 PM

It could be that Spec clutch chattering at take off in 1st and reverse. The other vibration at hiway speeds could be driveshaft angle related. maybe the adjustable suspension has the pinion angle screwed up a bit. Or the trans mount could also be at fault. You didn't say if you used a stock trans mount or a poly mount. Almost everyone who uses a poly mount has had vibration issues unless they modify the mount.

**stratocasterWS6** · 09-15-2010, 04:12 AM

Tranny mount is uerethane, but my buddy(a mechanic whos lift I used) spotted me while I eased the clutch in 1st and rev. said he could see the rear axle shaking around. So I believe it's something after the tranny. Interesting point about the pinion angle, Cutlass. I'll try researching that some. Thanx!

**Supershafts** · 09-15-2010, 07:51 PM

Ever have the shaft balanced? pinion angles are 99% of the time an issue on excel and load or decel, not crusing...

Changing joints can and many times does throw out the balance...\

A driveshaft is a balanced ASSEMBLY, that you have molested when changing joints.

Did you index the slip yoke to the shaft?, use the same joints?

Most likey it sounds as though the shaft just needs to be rebalanced

.

**xmarkx** · 09-16-2010, 08:40 PM

my car was doing this same thing when I lowered it but still had the stock TA. It was annoying but I just lived with it, then the last time I changed springs I installed an adjustable TA and I noticed that the vibration while letting the clutch out is almost gone.. my TA is not all the way dialed in but it's pretty close. if I can get it perfect I think the problem will go away completely

**natews6** · 09-16-2010, 10:31 PM

does it vibrate the same at all speeds?

**stratocasterWS6** · 09-18-2010, 12:18 PM

supershafts- I did actually notice a steady, dull vibration at freeway speeds after changing u-joints(installed new lakewoods). However, changing them out did nothing for the chattering and clunking at standstill(didn't seem to make it worse, anyway). I agree with you on the balancing issue. I will definitely look into that.

natews6- The pulsating I mentioned in my original post is noticeable from about 55 mph on up. It is most pronounced in gears 5 and 6 between around 1700 and 3000 rpm. At a steady speed it goes wubwubwubwub, but if I drop into 4th it seems to go away. This led me to believe it may have been an engine balance issue. I inspected the factory harmonic balancer while the engine was running and the rubber bead on the front of it looked a bit off. Hence I replaced it with an ATI SuperBalancer(not worth the money for a stock car, IMO, but beside the point), which seemed to help on the freeway, but not at takeoff.

Any ideas on what could cause the ticking coming from the rearend? Is that normal when spinning a wheel in midair? I'm hoping to avoid having to take my car to a shop for repairs. Also, what is a good way to check pinion angle? Thanks!

-Paul

**Supershafts** · 09-19-2010, 05:29 PM

Originally Posted by stratocasterWS6

supershafts- I did actually notice a steady, dull vibration at freeway speeds after changing u-joints(installed new lakewoods). However, changing them out did nothing for the chattering and clunking at standstill(didn't seem to make it worse, anyway). I agree with you on the balancing issue. I will definitely look into that.

between around 1700 and 3000 rpm. At a steady speed it goes wubwubwubwub, but if I drop into 4th it seems to go away. This led me to believe it may have been an engine balance issue.

That sounds like you have a shaft out of balance and possibly maybe something in the trans, if 5th & 6th are on the same rail and 4th is not, it could be the trans..

[/quote]Any ideas on what could cause the ticking coming from the rearend? Is that normal when spinning a wheel in midair? I'm hoping to avoid having to take my car to a shop for repairs. Also, what is a good way to check pinion angle? Thanks!

-Paul[/QUOTE]

pinion angle check on Flat surface....

The ticking can be many things, could be the increased angle with the rear hanging and the joints, could be a rotor hitting the pad, not everything is easily diagnosed on line... entirely to many things can do that...