New Trans For A 65 Mustang

Jim Pawloski

Member
Apr 17, 2012
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Would like to keep it automatic, but I'll probably be putting 500-600 hp at the crank when this build is done. Would my C4 trans be able to keep up after a rebuild? Or should I move up to a C6? Recommendations welcome!
 
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a properly built C4 can handle the power you intend to make. but it wont be just a "rebuild". you are going to have to upgrade the clutches, as well as the bands, and depending on the materials used, some of the internal rotating parts as well. also you are going to have to upgrade the valve body, the input shaft, etc.

by the way, you will have to do many of the same upgrade with the C6 as well.
 
I once worked with a guy who ran an Aamco trans shop. He had a Factory 5 Cobra which he ran 9s with at Rocky Mountain Raceways in SL. It was a 5.0 with a paxton setup. He chose to run the C4 trans. Seemed to work fine for him.
 
I'm trying to find a performance rebuild kit for a 65 C4. I guess in 66 they redesigned it so the bell housing bolts to the case, not the pump. I don't know if that changes anything internally.
 
a properly built C4 can handle the power you intend to make. but it wont be just a "rebuild". you are going to have to upgrade the clutches, as well as the bands, and depending on the materials used, some of the internal rotating parts as well. also you are going to have to upgrade the valve body, the input shaft, etc.

by the way, you will have to do many of the same upgrade with the C6 as well.
This answer is spot on!
 
After talking with Performance Automatic, they don't have a rebuild kit that will handle that power for a pre 1970 c4. Looks like I got to buy a new trans anyhow. I'll look into those AODs. Thanks.
 
After talking with Performance Automatic, they don't have a rebuild kit that will handle that power for a pre 1970 c4. Looks like I got to buy a new trans anyhow. I'll look into those AODs. Thanks.

be sure to upgrade the input shafts on an AOD, the stock ones snap quite easily when the power level starts reaching beyond 350hp. also with the AOD, NEVER do full throttle up shifts into O/D as you will burn out the O/D band.