Transmission Brace

Hello everyone, I am a newbie to this site and I have previously owned 4-speed muscle mopars; a 70 340 4-spd duster, 2 different 70 440 6-pack 4-spd challengers, and a 78 318 4spd roadrunner. I haven't had much experience with automatic cars, just pickups.

A couple of years ago we purchased a 71 dart 318/904. I had a 68 340 sitting in the basement for 20 years so I replaced the 318 with the 340 using the same transmission. The problem was that the car would overheat in hot weather so the radiator was replaced with an aftermarket 3 core which took care of the overheating but put the clutch fan very close to the radiator. Upon a local mechanics advice, sold motor mounts were installed due to the close clearance. The transmission mount was left stock.

Everything was fine until I raced the car. During the race the car would not shift into 3rd and I later found out the transmission case broke almost completely in half at the bellhousing.

I later found an a999 that I rebuilt and installed. It worked just fine until I raced it. Again, on the very first pass the transmission case broke. By the way, the back tires are only street tires, 255/60/15 and the converter is a Mopar Performance 2800 stall.

I asked the local mechanic who recommended the solid mounts about why the transmission cases were breaking and he said it was because I didn't install the transmission braces that go from the transmission to the bottom sides of the engine (such as my 95 dakota).

Recently I have purchased polylock polyurethane motor mounts, poly transmission mount, and a torque strap to replace the solids. I am currently replacing the a999 internals in another case.

I looked at my 95 dakota's (5.2/518 trans) transmission braces and there is no way they will fit on the 340 because the tti headers are in the way.

So my question to you out there is do any of you had the same problem I'm having and do you have transmission braces installed?

I would really appreciate any help on this because I'm getting tired of breaking transmissions.