In my 98 Z28 when I go around corners (getin on the gas) the rear end makes a really loud noise and the car vibrates. Also when im driving in a strait line at low speeds (not getin on the gas) the rear end makes a noise. On top of all this my drivers side rear tire is bald while the passenger side tire has around 20% tread left on it. Does anyone have a clue to what is wrong with it?

 

Blown/malfunctioning posi unit, sounds like.

 

remove the inspection cover, look for metal, shiny metal shavings spell carrier bearings, darker metal chips spell posi parts

 

If the problem is a malfunctioning posi unit what parts will i need to replace?

 

The diff itself.

 

sounds like the pinion has shifted and is hitting the carrier....mine did the same thing, heres the end result....

 

austinb324 - I have a '95 Z28 w/~95K miles on it, and I'm now starting to hear some strange noises from the rear, similar to what you've described. It *usually* happens when the following is true:

1. I've been driving the car for a while (>25 minutes).
2. I'm coming to a stop, and the car is in neutral (M6).
3. My speed is somewhere between 1-10 MPH (usually lower than higher).

The actual sound is hard to describe - Sometimes it's a quick 'clunk-clunk-clunk' sound, and other times it sounds like something is binding, and then popping with a metallic kind of sound. I wish I could somehow record it because that description really doesn't help.

What I do know is that the car is just about stock and the only change recently is to put new shocks and 1" lowering springs on the car, which did changed the pinion angle. Also, the 'clunk' sound was there prior to the suspension upgrade, but it's now much more prominent and frequent.

I thought it might be one of the following, but I haven't got under the car to check things out yet: Bad u-joint; Bad posi-unit; Rear-Brake issue (warped rotor, etc). It just doesn't sound too good and I'm afraid something is going to pop back there.

SMOKKINU - Was your rear-end stock, or did you change gears, etc? How many miles were on it before this happened? With the sound my car is making, it could very well be the same thing is happening to me.

 

my rear end gear has been changed to a 3.73 and this problem started at around 70,000 miles, I now have 76,000 miles

also does anyone know what kind of shop i should take it to to get it fixed because i dont have the experience or know-how to work on the rear end.

 

same problem here...help!

 

my rearend at the time (10 bolt) had been rebuilt a number of times... some shitty rebuilds where a seizure prone blind man with one arm could have done a better job, others absolutley superb.... ive also been through numerous gear ratios... those gears are 3.73's. the time this happened, the rear was actually setup properly, with the exception of the pinion nut becoming loose and causing the pinion gear to shift.

a bad bearing race in the pinion shaft, or bad bearing could potentially cause the same problem (Shifting of the pinion.)


My suggestion, even though im sure you wont want to hear it if you dont have the funds, is to junk the 10 bolt, and buy a 12 bolt, ford 9 inch, or dana 60.


my opinion on all of those rears is a 12 bolt will last and can take great abuse. Ive seen cars go into the 7's on 12 bolts. they also have a tendancy to whine greatly, and sometimes they just plain fail like the 10 bolt. IMHO, the 12 bolt is not up to par when you consider the other 2 options.

A ford 9 inch is a proven rear, its also proven to be an absolute pig with robbing power. Drivetrain loss is huge compared to the other 2 rears. But they are pretty much indestructible. If you break a 9 inch, your either driving like an idiot, or it was setup by the same blind seizure prone one armd guy.


The dana 60... Bigger then a 9 inch, Ring gear is 9+ and is a FEW (Keyword, few) pounds heavier then a 9 inch. It is however, proven to be more EFFICIENT then the 12 bolt, and of course, the 9 inch. I have 4.56 gears, i launch on full slicks, in an m6 car at 5000RPM and she is still extremely quiet. I also got it with the detroit locker...which i LOVE. The other thing the S60 from strange has going for it, is the price...its cheaper then a 12 bolt, and cheaper then a ford 9 inch. at $2,300 you cant go wrong. it was the best upgrade ive made on my car thus far...


Rebuilding the 10 bolt will cost you $1000 +

why spend $1000+ on parts and labor, of which will fail garunteed. Especially in a M6 car. those who will reply saying "My 10 bolt has lasted me this long blah blah blah"

its a ticking time bomb... you dont know WHEN it will go, but it will... and there is NOTHING you can do to a 10 bolt part upgrade wise, to make it stronger....NOTHING. No, a aluminum cover with braces wont help...

 

just pay the 2400 for a ford 9" 35 spline locker ( if u plan on big hp) that or 9" with true tac. DO IT RIGHT the first time! Save you time(which is huge) and money in the long run. I am very happy with my 9"!

 

well guys, it looks like I'm having this same issue. I read on some other thread (that I can't find now) that it may be something with that thud in the same speed range (under 10mph) and I actually have 76k on my 98 Z. So it looks like I'm in the same boat as you guys. Jb442, yeah, thats hard to pin down that noise, but its pretty easily understood when you have it too...and THAT is definately my problem.

So sounds like this thread was about to go to the "please upgrade to the 12 bolt, its worth it." Before we get into that debate, which MIGHT be a feasible solution....I'm not 100% certain thats the problem.

Hasn't someone out there had this same problem and definatively found out what exactly the problem is? I'm thinking about just getting a used rear end anyway and just upgrading the gears (from 2.73 to 3.42) anyway....but before I bust my little car "budget" to do it....i better make sure this will actually FIX what needs to be fixed!