CLASS RACER FORUM - Breaking bell housings

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Re: Breaking bell housings

Quote:

Originally Posted by Alan Roehrich (Post 425951)

I would never use a steel or solid mount on a transmission. I've put in dozens of race car transmissions.

I use an ordinary stock replacement mount, with two radiator hose clamps around it as a safety device. Or a urethane mount. In 30 years of working race cars, including a lot of years as the person in charge of race car work in a well respected transmission shop, I have never seen a properly installed rubber or urethane transmission mount cause a broken case. But I have stopped several cars from breaking cases by replacing a steel mount with a correctly installed rubber or urethane mount.

If I'm not using motor plates, I use urethane mounts, or one steel mount on the driver's side and a urethane mount on the passenger side.

You do have flex, a vibration, or a misalignment. You may not have it identified, but it is there.

Adding a bolt on bellhousing merely moves the weak point to the case behind the pump, and when it breaks there, it will dump fluid under your tires.

I agree 100% solid motor mounts and a poly trans mount is the best way to go

Re: Breaking bell housings

jb,
When I first built my bracket Camaro many years ago, I broke two TH400 bellhousings in less than two months :( My trans guy told me to get a driveshaft made. That took care of the problem. Put over 2000 passes on the car after that and never had a single trans problem. I never felt any type of vibration at 7200 rpm's but the old driveshaft must have been out of balance or out of phase or something.

By the way, I had the same setup as you, solid engine mounts with a rubber trans mount. The car was a full chassis with cage so there was not a lot of flex.

Re: Breaking bell housings

One trick that Alfe Weibe shared with me was to use "Hockey Puck's" in place of Body Mounts on GM "A" and "G" body (full-frame) cars where aftermarket mounts are unavailable! Just drill holes in them & replace the worn and sometimes deteriorated body mounts!

Reasoning is that you are "making the body part of the chassis" by adding stiffer body bushings, it will "decrease"the flex that the "factory rubber bushings" offer in absorbing vibrations, body twist, and ride comfort that "stock body mounts" are supposed to do!

More often you will also find with "stock body mounts" the body lines will move as body bushings wear out, signs that the body is actually twisting.

Just make sure that "during installation", you tighten the body mounts with the weight of the body on the chassis and suspension, "NOT ON A LIFT OR JACK STANDS! This will bind the chassis (found out the hard way) and in "Stick Applications" "buckle the rear quarters"
I final tighten them on an open car trailer.

Alfe's way of telling me to "Go Puck Myself" LOL

Re: Breaking bell housings

One odd thing to check, the passenger side motor mount to the frame. Many moons ago I kept breaking TH400 bells, car had solid mounts, turn buckle on drivers side, rubbery trans mount. Finally one day while I was doing dry hops in the drive way with the hood off, everything looked great until I backed up and the engine raised up about 20* off the frame. I found out the original motor mounts on the frame had torn off the welds under the mounts. I had checked all the attaching bolts first for being tight but the frame metal was torn out of the crossmember on the passenger side. After replated the frame and adding turn buckle never had another trans issue.

Good luck finding your problem