10 bolt gives up and wipes T400 out

[hwholder]

Went to T&T in SA wed night with normal settings, i.e. nothing changed from many previous passes.
First pass, launched on the transbrake with 19 lb of boost @ 5200 rpm.
Felt good and log looked good for first 0.25 seconds, then all hell broke loose.
Oiled the right lane down for the night. Made a lot of folks unhappy.
Best I can tell is the 10 bolt with a girdle and 390s sheared some teeth (see photo) and the T400 blew up.
Thank god for the CSR carbon fiber super shield which probably saved serious damage to the car and/or me.
The down pipe also took a hit.
Attached are photos.
Lesson learned - My gut was telling me that I was pushing the 10 bolt and I did not listen.
Now I am looking for a 9", building another T400, buying a new shield and drive shaft, and sending converter to PTC for cleaning and inspection. Looks like the only things I might save out of the tranny is the valve body and the cast pan.
This was an expensive lesson and thought I would post up to maybe help someone else think about listening their gut.
Anybody out there got a 9" rear end for a G-body and/or a 9" 3rd member with 389s and air locker for sale?

 

[Eticket]

dang this sucks....thankful you had the shield.

 

[Eticket]

I think the 400 blew up and shoved the driveshaft and broke the rear in that order.

 

[Eticket]

http://www.pbnation.com/showthread.php?t=3362495

You can't see the blown up part of the 400 in your picture, but I wonder what that front (drum?) looks like on the bottom side where it isn't clocked to right now?

 

[KEVINS]

I think the 400 blew up and shoved the driveshaft and broke the rear in that order.

Ditto... The caps in the rearend are still intact so the rearend didn't give out first, imo.

ks

 

[Slow91z]

I don't know about that guys, I bet he's right it sheared the ring gear 1st over reved the drum in the 400 and boom...known issue with 400's.

How fast is the car normally?

 

[johnplogii]

I had a ring & pinion break once and damage the tranny. Didn't look anything like that though & the tranny made it 4 passes more than the rear. That was with the stock gears.

Still running the ten bolt with motive gears now, pushed it pretty hard with no more problems.

How fast is the car? what does it 60ft?

 

[tom robison]

I don't know about that guys, I bet he's right it sheared the ring gear 1st over reved the drum in the 400 and boom...known issue with 400's.

How fast is the car normally?

X2

 

[forcefed3.8's]

I have seen many 10 bolts shear the ring gear with trans brake launches. I foot brake with my 10 bolt, no problems in the 9's, and 8's.

 

[Eticket]

I don't know about that guys, I bet he's right it sheared the ring gear 1st over reved the drum in the 400 and boom...known issue with 400's.

How fast is the car normally?

ah I see.. that makes sense....

glad to say I did meet Bill just a few weeks ago - pleasant surprise at our local track and unfortunate this happened to a good guy. His car is fast.

 

[jdpolzin]

Had a similar situation on one of my cars. Aluminum third member on my nine inch gave out, pretzeled the driveshaft and blew the entire trans to pieces. I run a modular iron third member now!

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[TT/Ameasap]

My aussie 9 bolt grenaded on me in front of my house. Cap let loose and the rest was carnage. Luckily it didnt damage the tranny, but it sounded like a bomb went off! Sucks breaking parts.

 

[hwholder]

I had a ring & pinion break once and damage the tranny. Didn't look anything like that though & the tranny made it 4 passes more than the rear. That was with the stock gears.

Still running the ten bolt with motive gears now, pushed it pretty hard with no more problems.

How fast is the car? what does it 60ft?

Consistent low 10s with one 9.97
mid 1.40s to high 1.40s 60'

 

[johnplogii]

Consistent low 10s with one 9.97
mid 1.40s to high 1.40s 60'

That's where I was at when I broke the stock ones back in 2008. The new ones have taken me to high 8's over the last five years. I don't launch at as much boost or rpm as you but go consistent mid 1.2x 60ft's.

Could the gears have had a lot of wear/stress? Or have been set up wrong? Or possibly like others said, the tranny went first?

 

[tbone87]

Either way that sucks but good it did not hurt you.

Posted from the TurboBuick.Com mobile app

 

[Nick Micale]

I think the 400 blew up and shoved the driveshaft and broke the rear in that order.

I agree, over the years I have replaced about 5 ring and pinion sets that have sheared gears worse than that, and never damaged the trans or anything else.

When I greatly increased my RWHP, I then put many billet parts in my TH 400 especially after seeing a twisted input shaft.

Instead of going to a 9", I decided to stay with a built up 8.5" rear and 33 spline axles, and now replace the gears after 200+ 9 sec. runs.

Sorry about your mis-fortune Bill, but that is the price you pay for having too much power and traction!

 

[hwholder]

That's where I was at when I broke the stock ones back in 2008. The new ones have taken me to high 8's over the last five years. I don't launch at as much boost or rpm as you but go consistent mid 1.2x 60ft's.

Could the gears have had a lot of wear/stress? Or have been set up wrong? Or possibly like others said, the tranny went first?

Who knows about the chicken or egg scenario. Wish I knew for sure.

The guy that set the gears up for me was a friend in my home town that was a heavy equipment mechanic for CAT with a lot of racing mechanic experience (Power Glides and rear ends).
We checked the tooth pattern before bolting the girdle on and it looked good to both of us. These gears had less than 50 passes. Ummmmmm!!!!

I am curious about your ride.
How in the world do you get mid 1.2x 60' times.
What have you done to your suspension?
What is your race weight?
Launch boost and RPM?
Transbrake or footbrake?
10.5 slicks?
Does it wheelie more than 4-6"?

For me, a 1.2x would be the holy grail.
I had a 3900 lb BBC chevelle with a lot of NOS that I did everything I could to get the stock suspension tuned (adjusted instant center, shocks, etc) with aftermarket parts and the best I ever got was a 1.36 with low to mid 1.4x being normal.
This Buick wanted to wheel stand at first.
Finally worked it down to 4-6" wheelies with boost ramp control and shocks.
Obviously, I have a lot more to do to get a 1.2x 60'. Hope I live long enough.

 

[johnplogii]

Who knows about the chicken or egg scenario. Wish I knew for sure.

The guy that set the gears up for me was a friend in my home town that was a heavy equipment mechanic for CAT with a lot of racing mechanic experience (Power Glides and rear ends).
We checked the tooth pattern before bolting the girdle on and it looked good to both of us. These gears had less than 50 passes. Ummmmmm!!!!

I am curious about your ride.
How in the world do you get mid 1.2x 60' times.
What have you done to your suspension?
What is your race weight?
Launch boost and RPM?
Transbrake or footbrake?
10.5 slicks?
Does it wheelie more than 4-6"?

For me, a 1.2x would be the holy grail.
I had a 3900 lb BBC chevelle with a lot of NOS that I did everything I could to get the stock suspension tuned (adjusted instant center, shocks, etc) with aftermarket parts and the best I ever got was a 1.36 with low to mid 1.4x being normal.
This Buick wanted to wheel stand at first.
Finally worked it down to 4-6" wheelies with boost ramp control and shocks.
Obviously, I have a lot more to do to get a 1.2x 60'. Hope I live long enough.

My susp is all solid heims, all double adjustable control arms.
Car weighs 3300
I leave anywhere from 4psi to 9psi, try for around 42-4300 rpm
Transbrake everytime
275 drag radials
afco double adjustable shocks.
If its too loose it will wheely too high.

 

[turbobitt]

This type of failure is difficult to analyze. This failure looks similar to what would happen when you do first gear burnouts and the sprag takes a shock load. With that being said the rear could have failed and caused a monetary high spin up and grab then boom. Looking at the pics It appears to be a direct drum failure from over speeding. Forward drum looks intact and never usually fails.
Or
The sprag could have failed or been compromised and after the band release it decided to make parts. An instantaneous load/unload/load condition may be to much shock on the rear.
AG

 

[kidglok]

Where was the backlash on the ring & pinion?