Transmission mount with engine and mid plate.

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max512wedge

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Today I’m starting to put my 512 build into my 72 duster. Question #1 I’m running an engine and mid plate should the transmission mount be a solid mount with no bushings. #2 can my 904 transmission mount be modified to work. #3 where can I get a big block transmission mount that I need that can take 685 hp on motor and 885 hp with a shot of nos. The reason I’m asking is I’ve heard I need the mount to be solid so I won’t crack the case using the trans brake. It’s going to be 50/50 street and race if that helps. Thanks

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I’ve modified stock transmission mounts and fabricated my own. I ordered a nice aftermarket one from Summit three years ago but haven’t taken the time to fab it in.
 
max512wedge said:
Were you running a mid and engine plate? If so did you run a solid trans mount with no bushings. Thanks
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You gotta remember I’ve had like 7 different drag cars from high 11’s to 8.40’s. Only my Daytona had a mid plate. I ran some with rubber mounts, solid mount, and no mount. My 9.80 running 1974 had a stock mount with a stock rubber transmission mount. That car had super stock springs and it probably saw the most abuse and held up great.
 
I run a motor plate and a mid plate, I use the later poly through bolt transmission mount and have had no problems. Just remember, my car is race only amd leaving on the trans brake at 45-4800 RPM.
 
I run a Hurst front mount (Basically a steel motor plate) and a mid plate in my Cortina.
I fabbed a trans crossmember for my glide (original owner had a Lenco in it), and use the softest transmount I could find. Just to help support some weight. IF engine and trans move (not f-ing likely) i want the trans mount to move too.
 
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I think that you should have engine limiters with a front plate and mid plate .
 
I used a steel front mount of a style that was popular 50 years ago (Hurst), and a steel mid plate. Add in a trans crossmember and mount.
Sure didn't need a limiter, it wasn't going anywhere.
 
The only thing nice about a mid plate is you can install the engine in the car and start and run it without a transmission technically turning your car into a break in stand.
 
Im making my own trans mount.....

The Poly unit i got from Mancini looked ok on the web, but was on an angle once in front of me.....!
So im using that bush in a new bracket >>> basically starting from scratch.....

The joys of muscle cars and Hot rodding as they say ..........!
 
A solid trans mount is asking for trouble. I have a very stiff tube chassis, yet use shock biscuits, four of them, to allow give for chassis flex. Build it to put some upward pressure on the trans, (about enough to support its weight) and let those shock biscuits limit the loads the case has to put up with due to chassis flex. And i don't care how good a person thinks their chassis is, Everything bends some!
 
gregsdart said:
A solid trans mount is asking for trouble. I have a very stiff tube chassis, yet use shock biscuits, four of them, to allow give for chassis flex. Build it to put some upward pressure on the trans, (about enough to support its weight) and let those shock biscuits limit the loads the case has to put up with due to chassis flex. And i don't care how good a person thinks their chassis is, Everything bends some!
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Greg i am using a polygraphite mount from Mancini Racing and fabricating my own cross member, the 1/2" front motor plate will also be rubber mounted too. Yes big blocks twist everything my 440 proves this !! I still love my .528" mopar cam
 
This link is somewhat relevant to this thread.

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I’ve run the front engine plate, engine limiters and a poly trans mount without issue for a number of years on my trans brake b body car.
I believe that the poly mount allows for some movement but the same is very possible with my chassis. So a little give & take works together.

Engine Limiters on the Dart and poly mount.
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