My ride is a 61 comet. I have a 2 speed auto trans currently. The engine is a 170ci 6 cyl. I would like to change tranny out and get more gears to increase mpg and to be able to cruise at 65-70 without so high of RPMs. Can I put a c-4 or an AOD trans? Like to do the job with minimum effort and cost. Consider all ideas.

 

From what I'm finding on-line, you'll need an adapter plate for the 170 to put an aod or c4 transmission on it. If it was a 64 or later, it would probably fit a C4 or AOD with no issues (other than drive shaft length). For your 61, it'll be a custom job for sure. nd as with everything custom, that means more $$.

 

Is an adapter a custom made item or is it available from transmission vendors?

 

sometimes they are available, but most of the time they are a custom piece.

 

Transmission plate adapters are common in the Electric Vehicle world. They need to bolt the electric motor to the transmission, so they plot out the bolt holes on a piece of paper and transfer it to half inch thick steel or aluminum and do the same for the motor. Just make sure the two bolt patterns are perfectly centered so the coupler doesnt vibrate at high rpms.

It can be done at home, but an extensive metal workshop would be ideal.

Go to your local welder/metal working place and ask for an estimate. It mighht be less than you suspect because it's only a large piece of metal with holes in it.


You'll need to find a coupler, too to put the engine and transmission together.