Mikelly

Guys, I'm helping a Buddy "D Autry" with a new DE trans build... Please help us with advice on building a strong DE trans. Dennis just had a broken output shaft issue, and he's a beginner/ intermediate DE driver with a C5Z06.

Dennis will chime in shortly...

Mike

2000BSME

I have never heard of that being a weak link in these trannies. Fix it stock and go with it. That was a fluke.

wallyman424

That is definitely a fluke if he's at stock power and a beginner in HPDE. My first inclination would be to get a used stocker and slap it in there.

If he wants something bulletproof and nice give George at Rockland Standard Gear a call.

travisnd

The stock output shaft will break when drag racing on stickey tires, but I've never heard of it getting messed up road racing. Did he buy his car used? Maybe it was drag raced a good bit previously?

geerookie

My thoughts exactly.

Bill Dearborn

If this tranny actually broke on a road course that would be the first time in the 11+ years I have been on the forum that I had heard of such a thing.

Bill

gmccreary

Check out the OP's avatar. Maybe his buddy has the same hobby

Mikelly

Nope, Dennis' car was not used for drag racing. His car is a 2002 Z06 that has been mostly used as a street car, except for the weekend at Summit Point in the beginner group and I think he had it at MIR about 3 years ago when the pic in my avitar was taken.

During Dennis' one and only weekend at the track he was on Kumho MX street tires. I was his instructor and there were no major issues with his driving or shifting.

We bought the trans in question used from Ross Miller and it has less than four months use on it since it was installed. That's another issue for another day and you get what you got when buying a used transmission. I've spoken with Ross, and he knows the condition the trans was in before we installed it, and can speak to that condition. The pics clearly show the shaft sheered at the base where it leaves the trans and goes into the diff. Also there was a bit of carnaige internally.

We have the stock Z06 box from when we did the swap to the above trans and we're going to use it as the core for the build. That trans had a 3/4 pop-out issue, so we swapped it...

Mike

dautrey

Hey thanks Mike for posting, sorry guys it took me a few days to comment. I appreciate any and all comments.
A quick background: Several years back I have done 1/4 mile racing--running low 8 seconds, dirt tracks, short track and an old school moto- cross runner--and still run one. I am very familiar with racing and understanding the handling of the car and my own abilities. I am not a stranger to the track. I recently built (at my farm) my own dirt go kart track to simulate road coarse and moto racing. I built my own 2500 sq/ft mechanic shop with lift that is used for my construction business I started in 1987 and still going. This allows me to use it for for fun play time stuff. Mike can attest to all of this because we both have run moto and karts here.

Yes Mike is correct and I went to VIR 3 years ago (once) but with original stock trans and has lasted until last year. Last September Mike and I changed out the original trans due to some minor issues with it but I was still driving it. We installed this trans. I drove it at Summit point and now back in January was at a traffic light--pulled off normally and it broke.
Everyone needs to understand one thing--I am the guy who has wanted a corvette all my life now 52 and thanks to mike (found this vette) and have enjoyed the hell out of it since! It is also a daily driver. I do not push the car to its limit because as a previous racer I know you have to know your limits as a driver but as important you have to know what a cars limits are also. The one who doesn't gets in trouble. Mike was my instructor that weekend and he was pushing me more that I was pushing myself and is a great instructor and friend.

My plans now are to be able to build this entire drive train to its limits with out tearing it up. So I need to know what that is? I what to have a trans/rear-end strong enough to handle this. Since the car is on my lift and parts removed---now is the time to re-build-trans-rear-end-toque tube. I will re-build the motor later this winter. Thanks for any comments guys!

GO_BLUE_VETTES

Unfortunately it happened to me running Grand East at VIR in 2008. Went for a 4-3 downshift, all I had was neutral and 4, luckily I limped it back in and was able to get it on a trailer with 4th gear only....

Broken input shaft bearing on a 2002 C5Z MN12.

Had it rebuild by a local T-56 wizard using parts from D&D.
http://www.ddperformance.com/shop/in...?cPath=110_103

I got the seal kit, syncro rebuild kit, bronze shift pads all around, 3/4 billet inserts, 3/4 billet shift fork.

Did the swap myself with a friends lift. No problems since then. Don't know if I was too hard on the tranny or if it was a fluke...

drivinhard

For a RR car that should be fine, just fresh blocking rings/seals, and the beefier bits (fork pads, synchro keys, steel fork, etc).

One of these days I need to upgrade the inside of my 01 before it breaks a key. I agree with Danny though that a lot of trans problems are caused from clutches that aren't releasing fully.

exracer28

Miht look at how it was installed.

Mikelly

Uh this is my ninth install of a drivetrain on a C5 Vette. It was removed as one single unit *(torquetube/trans/diff) and disassembled "unstressed". It was re-assembled the exact same way.

Pics of the damage:






Dennis, It's all yours. Hopefully you'll get some good solid advice from some of the more senior and knowledgable road racer types here. I'm slinking back to lurk mode now...

Mike

gmccreary

That's a chocolatey mess

Wicked Weasel

you dont need to drag race to break the output shaft.

Obviously dropping the clutch at high rpms with sticky tires is potential for destroying the rear and why ECS is building/installing specific trans for high HP 1/4 mile cars. I cant even count the amount of broken output shafts at the 1/4 mile track, but I have also seen street cars break the output shaft under wheel hop.

I would think for RR you would see more bent forks and bad syncros (both of which I replaced when I was running 1/4 as well as the output shaft. I also have a trans brace which may or may not be needed for RR, but a nice to have).

Since you are rebuilding this would be a good time to put in hardened output shaft since they are not expensive and buy you some extra insurance. As far as other components I am not sure what is overkill or not. Forks and syncros probably a good idea. As stated I have trans brace. I think it is a good idea, but others might think it is not needed for RR. Yesterday at the shop I was looking at a new torque tube. Much stronger than mine, but then again mine is stock from 2001 and still working fine.

If you want call Doug@ECS or PM him and he can give you some ideas. Obviously he will know extreme from his 1/4 mile knowledge and should be able to tell you what is too much for a basic RR setup.

travisnd

I would think road racing is hard on the synchros since we have the rear mounted trans and the entire drive-shaft has to get up to sped when making a downshift. Not sure about you guys but I don't double-clutch so the synchros do all the work.

Technically you could clutch, put the gearbox in neutral, clutch out, rev match to speed up the engine and drive-shaft, then clutch in again, select gear, clutch out....

I don't have the time for all of that every downshift and I've never had to double-clutch anything in my life. On my old Z06 the 3rd gear synchros wore out to the point it wouldn't make a 4-3 downshift at speed w/o grinding. Had it rebuilt with beefed up parts from RPM Transmissions: Beefed up 1/2 shift fork, steel 3/4 fork, better keys/pads, etc.

dautrey

Hello and thanks to all for input on the trans stuff. I have not torn it down all of the way yet, but did notice that the sync and gear do not look worn out or broke. In the pic though you can see the shift link broke right in two. I have a call into rpm transmission in ID.
Thanks for the help!

Wicked Weasel

You are in good hands with RPM.