Any help appreciated.
I'm running a Hobby Stock dirt track Nova.
I changed the sub frame 2 years ago,and installed urethane motor mounts and trans mount.
I bought a TCI 10 circle track converter.
Turbo 350 transmission.
No issues after 2 seasons.
The Case broke across the Bell Housing,and broke front pump gears.
Replaced case and front pump.
Next race,same thing happened,broken case across bell housing,and front pump gears broken.
Put in new transmission,same TCI converter.
I measured 3/16" between flex plate and converter flange.
Set trans down on mount with loose bolts,so no binding,then tightened everything up.
No issues during heat race, but 3 laps into the main,same thing,it's like I put it in neutral,engine revs,but doesn't go. From just looking,I can see transmission bell housing is broken all the way across again.
I checked end play on crankshaft by prying from the front,then prying from the back of crank.
It does not budge.
What else can be causing this to happen?
That's 3 broken transmissions.

I read don't use a solid trans mount,could the urethane trans mount cause this?

Make sure your yoke is not bottoming out on the output shaft splines

Drive shaft is fine,no bent axles, plenty of space for yoke.
I keep going back to that urethane trans mount.
Nova is a subframed car,so I think the chassis flexing,and that mount is to stiff.
Any other suggestions?

i run solid motor an solid trans mount never a problem

Change the converter.  It is the only thing not changed.....It must be out of balance or locking up completely.

Also... and this is important to consider... If you have broken 2 cases in the last 2 races, and never had the issue before and ran the urethane mount the entire time, its not the mount that is your issue.  something had to have changed, like bent axle, driveshaft etc. Excessive chassis flex will cause it to break no matter the mount from what I was told.  Check it all out!

are the motor mounts solid?

Put stock rubber trans mount in.
Broke 4th transmission case in 4 races.
I give up. Anyone want to donate a Saginaw 3 speed.

Check drivetrain alignment. If anything is not square or true it could cause that.

To me it sounds like the drive line is out of balance or your u-joints are binding up and not rotating smooth. Even check your torque converter to see if its balanced.

Lacy Racing #13 wrote on 08/27/13 at 1:36pm:


Great idea!  Also get the car up on jack stands, fire the motor and put it in gear with the tires off and watch the axle... the slightest bend would be hard to see on the ground rolling but is enough to mess up a trans case from the vibration.  Happened to me.