Transmission mount and motor plates...

[The Dartman]

Guys:

I am running a motor plate in my big block Duster, and I am hearing conflicting stories on what to do with the transmission mount. Some of my buddies (including my tranny man) say that if you run solid mounts or a motor plate you have to run a typical rubber transmisison mount to absord the vibrations. My other buddies state that if you run solid anywhere, then all of your mounts have to be solid. What's the deal?

I currently run a rubber mount, but my transmission cracked the tailshaft last year (for one of several reasons), and I would like to avoid any transmission problems this year if possible. One reason was that the output shaft on the transmisison was damaged, and the other was that the driveshaft was out of balance becuse of a ding from the trailer. I have replaced the transmission tailshaft, had the converter rebuilt by TCI, and I had a custom driveshaft built. I am ready to go racing again but need to know about this!

Thanks!
Dartman

[dwc43]

I run the ears on my big block Duster and I'm in the process of rebuilding it now and looking for a good price on some aluminum heads.

To answer your question, with a engine plate or ears you must run a rubber or poly tranny mount. Mines a poly. If you mount it solid and get any chassis flex it will break the tail shaft. Now if you was to use a solid mid plate then you would not need a rear mount at all, but that would be very hard to install in the car. I thought about it, and passed on the mid plate for my car.

[The Dartman]

I actually have a mid plate but I could not get it installed easily in the space provided. My next motor (read: badder) will have it installed.

Thanks for the reply...
Dartman

[dwc43]

Welcome. YEah, I looked into the mid plate for mine, but there's just not a lot of room. Lot cheaper to add the poly mount to the rear and be done with it. Mines more of a street strip car than a full time race car. IF it was race car only I'd find a way to put the mid plate in.

[BJSracing]

It is quite possible that you had the engine and trans. walk forward or backwards. Do you have any type of a limiter that will keep the engine from going front to back? I would run solid on all of them and use a limiter. The plates will keep you from twisting and side to side but not front to rear.

[The Dartman]

Good point. Do you have an exmaple of your limiter setup? Where in the car and on the motor does it attach? I can't imagine this being anything but a custom part.

Thanks!
Dartman

[BJSracing]

I don't but I can explain it to you. If you weld a pair of tabs on the frame that are drilled to accept a heim joint and then add a set of tabs on the back of the front motor plate. You will install a rod with heim joints on both ends. You will want the rod to run as parallel with the center line of the motor and as close to the motor as you can with out interfering with anything as you can. It would look something like the crap baked drawing below. I'll try to see if I can find a good pic of what I am talking about.


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[BJSracing]

Here is a pic of what I am talking about.