M200 breakage

[Bob Gullett]

We use a stock rear mount on our Malibu M200 and the same trans has over 1000 runs without any breakage. We have a Mark Williams driveshaft with about 1 degree pinion angle. Smooth as anything.

[Bill Edgeworth]

Thinking about it more I would agree with what Bob and Mark both said. With the 60 foot you had the trans and drive shaft did not see a huge amount of torque. And I assume from what you said it did not shake or shudder on launch. It didn’t happen until the trans was in drive and starting to get up in RPM.
So probably something driveshaft related. The one thing I would check on the remnants of your transmission is the tail shaft bushing to make sure the yoke was not super sloppy in it. Could your drive shaft have been bent or dented? or overall length or yoke length a little short? Or touching drive shaft loop?
When Jim works on it you may want to also consider a roller bearing in the tail shaft.
Is that Peter Legg’s old car?
Are you going to have it back together for Bosie?

[Dave Jung]

Bill, it was smooth with no shake. The driveshaft was perfect length for sure, u-joints were good with fresh grease. The tailshaft looks ok, other than the seal has a slight bend when the yolk came flying out. The shaft looked good with no dents or any other signs of damage. Not touching the loop either. Could the shaft just have failed? seems rare to me that a shaft would twist and break like that.

It is Peter's old car, its not going to be back together for Boise now, all plans have changed, hoping to be ready for Mission.

also guys, I am using solid motor mounts along with the poly trans mount. so strap is not gonna do anything. Are the solid mounts not a good idea?

Grant,
I will e-mail you, thanks

[Grant Eldridge]

Dave,
I had several case failures with my TH-200, fortunately caught before catastrophe struck. I tried to buy a brace from McClay, but he only supports his own transmission customers, or at least did at that time. I built my own brace connecting the two "eyes" on the passenger side of the trans with 1/2" thick by about 1" wide aluminum. I tried to upload a photo but the file is too big. Email me at grant4060@yahoo.com if you'd like a few photos. I also bought an aluminum deep pan from Turbo-Action to act as a girdle and give more strength to the case. I run this behind a big block stocker, 3570 lbs. with best of 1.41 60' and since the changes have had no further troubles. The transmission is a reverse pattern unit built by Jim Mantle, who is the greatest guy to deal with, and his units have always performed perfectly. Ditto on using the stock rear mount, also would suggest the left front torque strap from earlier posts. Make sure there is enough spline depth in your driveshaft yolk so that it cannot bottom out when the car launches and the rear end pushes it ahead. Hope this helps,
Grant

[Grant Eldridge]

Dave, I'll try to do these photos again....
Grant
P.S. No one will confuse these with the McClay brace, but so far so good...lol

[jim powers]

call frank lupo or shawn at dynamic he can get you a professionally made brace

Leon Mirainian also builds a Tubular brace with heim joints. Great looking piece. I have had one on all of my metrics since I've been racing them. he also builds a great 200...

[Dave Jung]

Todd, do you have a number for Leon?

thanks to all the guys who have replied. I really appreciate the help.

Dave

[Ken Haase]

I raced an Olds with a 455/th400 and put many passes on the stock driveshaft that had a rubber slip connection close to the rear u-joint. Genius that I am, I figured that a solid shaft would be this huge improvement. On the first pass at 100+ it roused me out of my slumber by reconfiguring the floor contours. Found half of the shaft and the slip yoke was still in the back of the trans. The bellhousing was busted almost all the way around, plus lots more damage.
So, my wager would be the driveshaft failed for whatever reason. I don't think TH 400's have a reputation for weak bellhousings.

BTW, for Olds freaks, that was a "W" code tagged trans.