th350 crack

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bowtie421pc
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th350 crack

Postby bowtie421pc » Thu Dec 10, 2015 5:46 pm

12325037_1230590800291030_1160956072_n.jpg
run for 20 feet .....what can cause this

bowtie421pc
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Re: th350 crack

Postby bowtie421pc » Thu Dec 10, 2015 5:53 pm

more pics
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cgarb
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Re: th350 crack

Postby cgarb » Fri Dec 11, 2015 10:28 pm

Is it leaking fluid?

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Alan Roehrich
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Re: th350 crack

Postby Alan Roehrich » Sun Dec 13, 2015 9:59 am

Normally caused by chassis flex, or some sort of driveshaft problem. When I was managing a transmission shop that built racing transmissions, I most often saw that in cars with inadequate roll cages, and/or solid transmission mounts. We've always had the best luck using a urethane transmission mount, or a rubber mount with hose clamps. Even with motor plates.

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af2
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Re: th350 crack

Postby af2 » Sun Dec 13, 2015 10:47 pm

Alan Roehrich wrote: and/or solid transmission mounts. We've always had the best luck using a urethane transmission mount, or a rubber mount with hose clamps. Even with motor plates.


Every time with a plate I run a rubber trans mount. It doesn't take much to break the trans...
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Re: th350 crack

Postby mike22l » Sun Feb 14, 2016 12:48 pm

An unbalanced driveshaft and or crank to tranny alignment will also do it every time. FACT!

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Re: th350 crack

Postby rapidride2 » Tue Nov 22, 2016 8:24 pm

Back in 1993/4 as a young 19 year old with a 400 hp 454 with a turbo 400 in a 12 second malibu. The custom driveshaft was just 1/4'' too long. When driven on the street it wasn't a problem. The second i bolted on slicks and took to the track and had more suspension squat i was cracking cases. Two to be exact before i looked to the 1/4" too long driveshaft. It was just long enough to cause havoc.

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Re: th350 crack

Postby peejay » Fri Nov 25, 2016 12:33 pm

I don't know why people even run solid trans mounts or even urethane ones. All it does is twist the back of the trans, even if the engine is solidly mounted the chassis WILL flex more than the trans can handle. The trans mount only affects the engine's pitch, the engine mounts control the roll, and pitch isn't ever a problem.

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Re: th350 crack

Postby Pro Built Automatics » Sun Jan 29, 2017 2:05 am

If you run solid motor mounts, make sure you run a rubber transmission. I have seen a few and heard of others TH350's breaking the bell housing area of the transmission from using a solid transmission mount and solid motor mounts. The transmission must be able to flex to prevent the transmission from breaking. I have seen the pictures of the transmission flexing when under power. I found that using the old Pro Stock idea of using a torque chain and using rubber mounts stopped the vibration, the harmonics and other problems created from using solid motor mounts or urethane mounts.


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