New gears = cracked diff
Thread Starter
Pro
Joined: Aug 2006
Posts: 527
Likes: 0
From: Clarksville TN
New gears = cracked diff
Recently had a shop here in KC put in a clutch and 3.90 gears among some other things. I was out of town, so I had a friend pick it up. He was driving back to his apartment when he took a slow right-hand turn and let the clutch out in 2nd. As soon as he let the clutch out, he heard a pop and stopped the car. It was leaking diff fluid and he towed it up to his apartment to find that the diff is cracked on the front passenger side. The diff had no more than 100 miles on it and the only time it was under full power was on the dyno. I'm guessing installation error but it was quiet as could be when I drove it. I guess I should also say that I picked the car up a couple weeks earlier and the reason it was back at the shop was for a Racetronix fuel pump and tune. I flew back and had the car towed down Friday morning and was told they would have it out and inspected by later that evening. Now its Monday and I still haven't heard from them. They told me when they get in there if they find that it was installation error and not parts failure then they would fix it. How would one tell if it is installation error and what course of action would you recommend for me to take?
Thanks,
Kevin
Thanks,
Kevin
Thread Starter
Pro
Joined: Aug 2006
Posts: 527
Likes: 0
From: Clarksville TN
100% sure he's telling the truth. He's also a car guy with an 11 second Silverado SS. He wouldn't wring on it even if I told him to.
Melting Slicks
Joined: Oct 2005
Posts: 2,877
Likes: 9
From: Ottawa Ontario
Melting Slicks
Joined: Oct 2007
Posts: 2,464
Likes: 2
From: Cedarburg, WI
Thread Starter
Pro
Joined: Aug 2006
Posts: 527
Likes: 0
From: Clarksville TN
The gears had about 100 miles or so on them over about 8 outings just feeling the car out before the tune and dyno pull were done. They never mentioned that being a problem so I never thought twice about it.
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Melting Slicks
Joined: Feb 2007
Posts: 3,194
Likes: 10
From: New Smyrna Beach Florida
If my memory serves me correctly, they recommend that you put 500 miles on new gears before getting on it. That being said, it still should not have failed, some gear whine maybe.
Melting Slicks
Joined: Oct 2007
Posts: 2,464
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From: Cedarburg, WI
Race Director
Joined: Nov 2003
Posts: 11,061
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From: Menifee CA
when i did my 390s Andy (A&A) told me to take it easy for at least 500 miles to make sure everything settles in and no whine develops
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
I believe the reason why our owner's manuals recommend driving at speeds under 55 for the first 500 miles is to properly break in the gears, not the engine. failure to do this could result in annoying gear whine at some point.
Team Owner
Joined: Apr 2001
Posts: 54,204
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From: S.W. Ohio. . . . . . NRA Life Member
Still not a good thing to do IMO; but can't be blamed for the case cracking.
Melting Slicks
Joined: Oct 2005
Posts: 2,877
Likes: 9
From: Ottawa Ontario
That is the norm with these diffs and rear ends. I see them bust at the track all the time but not on the street as the tires will spin before that happens
Team Owner
Joined: May 2003
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From: East Meadow NY
St. Jude Donor '12