Z51 E-diff failure first time at drag strip
Instructor
Joined: Jun 2006
Posts: 158
Likes: 3
From: Houston Texas
He needs to learn to slip the clutch slightly on the launch. I've never driven a C7, but in other vehicles it helps to not hold the clutch all the way on the floor when launching. Try and hold it just where it starts to engage, but the car doesn't creep forward. This will help to reduce some of the shock to the drivetrain.
Former Vendor
Joined: Feb 2012
Posts: 1,095
Likes: 70
Dang, hopefully its a rare thing.
That is some carnage. However when a gear case of any kind lets go, its usually never good. (MASS DESTRUCTION at its finest)
Did he get any good passes in at all, before that?
That is some carnage. However when a gear case of any kind lets go, its usually never good. (MASS DESTRUCTION at its finest)
Did he get any good passes in at all, before that?
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
With runflat tires it's hard to determine, tire pressure with runflats is far less important because the sidewalls are so inherently stiff to begin with. There is so very little 'give' or 'flex' in them even at 0psi.
Personally, I would lower them to maybe 26psi at the drag strip but again it really makes very little difference.
Personally, I would lower them to maybe 26psi at the drag strip but again it really makes very little difference.
PS: I ran my 2002 C5 with custom made C4 16" wheels that had 4-5 " sidewalls--Simply that change increased my 60' time by 2 tenths and overall ET by 3 tenths !!
Pro
Joined: Nov 2013
Posts: 686
Likes: 11
what is a new E-Diff going to run?
I am running Mickey Thompsons.. I try to slip clutch on launch to help not break parts often..
tried over 4K launch last time at drag strip slipping the clutch but slipped it too much and it just kept slipping and didnt grab..
I am running Mickey Thompsons.. I try to slip clutch on launch to help not break parts often..
tried over 4K launch last time at drag strip slipping the clutch but slipped it too much and it just kept slipping and didnt grab..
Burning Brakes
Joined: Feb 2010
Posts: 878
Likes: 61
From: Louisa, Ky
My experience with owning now 4 (2- C5's---1--C6 and now a C7) is to run the rear pressures with any tire down to around 10-12 PSI at a drag strip---Any Z rated tire has extremely short and stiff sidewalls--so getting them as soft as you can helps
PS: I ran my 2002 C5 with custom made C4 16" wheels that had 4-5 " sidewalls--Simply that change increased my 60' time by 2 tenths and overall ET by 3 tenths !!
PS: I ran my 2002 C5 with custom made C4 16" wheels that had 4-5 " sidewalls--Simply that change increased my 60' time by 2 tenths and overall ET by 3 tenths !!
Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
I always added air to keep the center of the tire planted with increased weight transfer, with street tires that is. This advantage for me worked better than the rest, at the time that was running low pressure and recaps or bald tires. I put an end to the streak at the local dragstrip of the consistent winner in my class and the optional class we were allowed to jump into with that little trick. How different our experiences are!
10-12 psi is great for a 29-31 inch bias ply slick.....drag radials should be 15-20 psi......street tires are good high 20s.
Platinum Supporting Vendor
Joined: Sep 2001
Posts: 3,665
Likes: 341
I know of another that failed very early on. However that failure really had nothing to do with the E-Diff. That spider gear is the same one that is used in the C6 I am pretty sure. We looked at them and compared but did not spend much time on it since I was really interested in the new e-clutch. The diff is expensive from GM if you can get one. It took a couple of months to get the ones that we have.
I am sure that one could be repaired depending on how bad the rest of it is. If all the carnage stayed inside the carrier we should have the parts to fix it if needed.
Justin
I am sure that one could be repaired depending on how bad the rest of it is. If all the carnage stayed inside the carrier we should have the parts to fix it if needed.
Justin
Instructor
Joined: Dec 2013
Posts: 204
Likes: 20
I did the same thing Friday...
I also have a 2014 C7 with a Procharger M7... took it to the track Friday with new NT01s (only thing readily available). Did an easy launch with 26psi in the tires at about 2800 and ran a 11.5 @ 125. Then dropped them down to 20psi and gave it hell at 3800rpm and kaboom...
Hasn't been tore apart yet but is def in the dif, output shaft or axle. Stay tuned
Hasn't been tore apart yet but is def in the dif, output shaft or axle. Stay tuned
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Pro
Joined: Nov 2013
Posts: 686
Likes: 11
I also have a 2014 C7 with a Procharger M7... took it to the track Friday with new NT01s (only thing readily available). Did an easy launch with 26psi in the tires at about 2800 and ran a 11.5 @ 125. Then dropped them down to 20psi and gave it hell at 3800rpm and kaboom...
Hasn't been tore apart yet but is def in the dif, output shaft or axle. Stay tuned
Hasn't been tore apart yet but is def in the dif, output shaft or axle. Stay tuned
sorry to hear that though..
Racer
Joined: Feb 2014
Posts: 457
Likes: 10
From: Baxter Kentucky
Wonder if the new Z06, is going to have a beefier rear end ? You would think that GM would have built our rear end to hold at the drag strip. Even with power adders. GM should have known that we are not going to stay stock for long. They are going to build a hot rod, GM should have built it to handle it. Im surprised the clutches are still holding up on the M7's
Pro
Joined: Oct 2008
Posts: 606
Likes: 7
From: Nashville, TN
Wonder if the new Z06, is going to have a beefier rear end ? You would think that GM would have built our rear end to hold at the drag strip. Even with power adders. GM should have known that we are not going to stay stock for long. They are going to build a hot rod, GM should have built it to handle it. Im surprised the clutches are still holding up on the M7's
Pro
Joined: Nov 2013
Posts: 686
Likes: 11
Yea about right. At 630whp on camaro I broke a rear end a year. Been slipping clutch on corvette a lot to keep from breaking things.
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
I'm betting that it will be a little stronger, though even the base C7 LT1's rear appears to be notably stronger than the previous base C6 LS3's rear.
I agree, but in all fairness we just don't know for sure if it was some bad wheel hop and/or that sort of 'hook-spin hard-hook again' sequence that is typical of sticky, stiff sidewalled road race/autocross tires that's causing these breakages.
I'd like to know how many people have broken their rears while using PROPER drag radials or D.O.T. legal street slicks. And also how many have broken while still on stock/OEM tires as well. That would tell us if it's a 'weak rear' issue or simply a poor tire choice.
I'd like to know how many people have broken their rears while using PROPER drag radials or D.O.T. legal street slicks. And also how many have broken while still on stock/OEM tires as well. That would tell us if it's a 'weak rear' issue or simply a poor tire choice.
Platinum Supporting Vendor
Joined: Sep 2001
Posts: 3,665
Likes: 341
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Well that all depends on how serious you are about the semi-pro drag racing---if you are--and not concerned about the$$$ of breaking parts--and making the car hook up the best---then 10-12 PSI will give you the fastest 60' times--However such an extreme hard launch can break parts--If you wanna save your diff yeah run 20-25 PSI and it will live --- you may not have the best launch--but it's just bracket racing so Yes I have to agree with the previous poster--running 10-12 PSI is not recommended unless you are willing to risk breaking something--
Safety Car
Joined: Apr 2010
Posts: 4,231
Likes: 451
From: Maryland
I would listen to this man!!!
, he is giving a big secret away for free! A stick may almost be as easy on the drivetrain as an auto using this method and put down the very best times. I did this years ago and when the stick trans case broke in half one weekend at the drag strip after "many" years of drag racing with no breakage what so ever I installed a built 350 turbo trans with a high stall torque converter and proceeded to slow down by two tenths the very next week with better weather conditions to boot running the auto.PS: If you dump the clutch i.e. shock the drivetrain rears will blow and higher power through more rpms or just more power will take care of the rear/axles in shorter order. Also adds to wheel hop which breaks rears in short order too. Shock is a killer. One suggestion, launch at a rpm for "your" car that doesn't bog nor spins the tires, if you mess up it's better to spin a foot or two. Then proceed down on the gas pedal as fast as possible without breaking traction.
Edit: I also know how to drive/get the best out of automatics.
Last edited by C7/Z06 Man; Nov 19, 2014 at 03:46 AM.
