95jersey

This is ridiculous...I just broke another rear Monday at Summit Point. I was only 8 laps into my first session...and just gettung the tires up to temp and bam...stinky diff fluid and the dreaded gear whine!!!

Once they replace this rear, I will now be on my 4th rear in less than 2 years...what gives? I NEVER drag race the car and drive really smooth on the track...no more abusive than 1/2 of the guys on this forum and racing T1. What gives...does anybody know what could keep causing my rears to break...I am beyond fustrated.

Bill Dearborn

Are you overheating it? I lost the diff on my 97 at Watkins Glen after a particularly hot day with some really long sessions. The next day it was howling.
Bill

cyclerage23

How much power are you running? D36 or D44? When you are replacing these, what are you replacing? Maybe your housing in warped?

95jersey

This was the first session of the day on a completely new rear...and I only got 8 laps in on a 60F day before it broke. I can't imagine the rear was up to temp.

luvmy92

What year car and what gears are you putting in it? Exactly what is breaking?

I went with the HD 3.73's from Randy's Ring and Pinion and am pushing 400+ rwhp. These gears come with a D44 ring gear and a D60 pinion gear. They come in a Yukon box but they are Dana gears (etched into the gear).

Mike

95jersey

The car is an 01 z, so I imagine the rear is a 44? They first time they replaced the entire rear assembly, the second time they only replaced the ring and pinion. The motor is stock except for intake, headers and exhuast...no big power adders

John Shiels

They probably didn't rebuild it properly. I bought two NEW 3.42 rears from GM. One when it blew up in April. The car was back together in Sept. The first one went bad in 400 + miles so I bought a new one in Sept. 400 + miles later it was bad. NO abuse on either just breaking in the motor on the street. Number three has been fine. I guess it's really the 4th in the car counting original.

95jersey

We'll you making me feel better that I'm not alone, but that is absolutely ridiculous...I have never heard of this being such a problem with corvette's.

John Shiels

Mine were growling LOUD. ECS can rebuild them but you have a warranty as I remember.

Bill Dearborn

The C5 diffs are from ZF in Germany. They require some special tools to rebuild them. When the one in my 97 went bad in 98 GM authorized repair of the diff but when the dealer got it out of the car they found the special $4K C5 tool set didn't have the proper tools. The GM tool person told them the diff tool set wouldn't be available for another 6 months and so GM authorized a replacement instead of a repair.
Bill

95jersey

The car is under warranty, and they are replacing the entire rear assembly...again. That is the good news...the bad news is that it will take about 3 weeks. They think it is a deformed/warped or improperly machined housing. I hope this gets it!

With that said, I won't be seeing you guys at Pocono until June or July. I have called to cancel this Saturday on the East course, and have to cancel next Friday with CART. This really sucks

ErnieN85

I read somewhere that it takes 500 miles to breakin and if you get on it hard (track) that it will not last very long. seems that they may need to work harden after a new install i think it was a GM tech bullitin

John Shiels

mine were just being broken in like a granny was driving it.

ErnieN85

Right!

Oyishdog

mine went bad...the dealer I go to is pretty large and well know (Terry LaBonte) so they just said "we cant pin point the problem, so we are going to replace everything". Sure enough, everything is new and no problem...i did spend 500 miles driving EASY before getting on it again.. good luck on the next one

zr1mike

First off, let me say I have never worked on a C5 rear. I know C5s have a transaxle and subsequently a heat issue. I have setup gears on 12 bolt GM rears, Dana 44s and have rebuilt numereous transmissions. I don't know your break in procedure but when I do a ring and pinion, I run the car on jack stands and monitor the temp. I let it cool, drive it for 20 minutes in street driving and pull over and check the temp. I used to just use my hand but now I used an infrared gun. Too much heat kills these thing and destroys the lube also. I realize you may not have time to do much street driving if you have a race car. Therefore you need to get the parts bedded in without having an extreme heat issue. After a little street driving I would suggest getting a load on the ring and pinion by making a hard 1/8 mile run followed by a cool off period. I'm talking about being able to hold you hand on the rear for 3 seconds without cooking yourself. Then some 1/4 mile runs, again cooling off between runs. The worst thing to do is to hit the track for 20 minutes without doing anything prior. You have to give everything time to loosen up and bed in. Pinion bearings have preload as well as carrier bearings for the differential. Change your lube before you hit the track. Change it again after the event. It's cheaper than replacing rears. You'd be smart to run 1/2 of a session each time the first day out. Pull into the pit area and use an infrared gun. I'd like to see 200 deg. but I doubt that's going to happen. I'd say if it gets to 225 I'd be quitting and letting it cool off. That's plenty hot for the first day. Most lubes start to breakdown at 250 or so. I'd use a good synthetic, Mobil or Red Line.
I know you C5 guys absolutely need coolers and I suspect a good many of you need to change lube more often. Obviously a cooler will prolong lube change intervals.

John Shiels

Matts roasting them tranny next

95jersey

Or the motor... It hasn't been feeling very strong lately.

Not sure how much longer that thing will last...they had several blown up LS6's at Pheonix. I'm talking rod through the block grenade, with a salad of metal parts inside...need to get that warranty
extended

luvmy92

I put about 100 miles on mine and then just started thrashing it. Solid as a rock... no gear whine, nothing. My feeling is if it's going to go, it's going to go. Why beat around the bush?

Mike

ErnieN85

Darned if I know however the fellow (Zo6 driver) who had the problem did just that and blew the brand new rear gears he said the whine started right after the hard use and it went bad. The rep then said that 500 miles was in order before hard use.
Now if yours doesn't break Good! and I really think I'd have a hard time staying off it for that long also.