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Author Topic:   Cracking Saginaw Transmission Casing
Dirt Full Roller

Total posts: 34
posted July 19, 2005 10:45 AM  
I have been experiencing a problem with my manual saginaw transmissions. Everytime I race the car I end up cracking the upper left ear. I have replaced the transmissions about 5 times now and the problem just seems to keep coming right back. I even changed the bellhousing, the drive shaft, the pilot bushing, clutch and pressure plate and I have even put the motor and transmission back onto the factory original rubber mounts. The problem existed even when the transmission was supported with the midmount engine plate. The car itself is only 3 years old and it is a square tube (camaro) chassis.
I even put an aluminum bellhousing in and ended up cracking it and the transmission after one race????? Has anyone else ever experienced this? Magic82

Dirt Full Roller

Total posts: 36
posted July 19, 2005 10:48 AM  
Try balancing your driveshaft.


sc1 racing
Dirt Freak

Total posts: 419
posted July 19, 2005 10:52 AM  
need to check the squarness of your block, drive shaft could be out of balance, or car could be twisting to bad..couple of more things but those 3 are the main problems..

Dirt Freak

Total posts: 461
posted July 19, 2005 01:56 PM  
We always leave that bolt out so it dont break plus it dont hurt nything to leave it out...............lighter weight LOL

Dirt Full Roller

Total posts: 34
posted July 20, 2005 04:34 AM  
Thanks for all of the help. I will try each of the suggestions and see what happens.

I had actually thought of leaving the top left bolt out but I wasn't sure what the final out come would be.

Thanks Magic 82

Dirt Maniac

Total posts: 170
posted July 25, 2005 10:40 PM  
i weld gussets on the top and bottom.

i also do not mount the rear of the tranny. i leave it floating.

Dirt Full Roller

Total posts: 34
posted July 26, 2005 10:58 AM  
This past week I pulled out another cracked transmission and I also removed the clutch disc, pressure plate, ect. Upon further inspection I noticed that the pilot bushing in the end of the crackshaft was worn oblong. I replace it, put another (non-cracked)transmission in and raced it this weekend. Guess what, NO-CRACKS. I will keep you posted. Maybe it was just a worn bushing.

I believe it might have happended when I ran a mid mount engine plate without using long dowels. I think the bellhousing was slipping down and allowing the transmission to bind in the back of the crank. Anybody Agree??? Disagree???

Dirt Freak

Total posts: 402
posted July 26, 2005 01:47 PM  
Aligning the bell to the engine prevent's that very same thing. Harmonics from a flailing input shaft.


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