i need opinions on which trans to run. Money doesn't matter. I have a 76 f 250 with a 460. Around 500hp. I go through these 4 speed trannys like nothing. I'm on my 4th. Was wondering if a built c6 would be faster than the manual. And would i loose some power with the auto? Thinking a 2500 stall. Has 411s and 38s. But going on 35s eventually

 

I have no experience with a 4 speed. From what I've read, the C6 can be built to stand a lot of HP and TQ. I know it's heavier and sucks some more HP than a C4 and some people will switch from a C6 to a C4 with hopes of shaving off some tenths at the strip, but potentially losing durability. My 460 had a mild build, 427HP 510TQ, and I didn't rebuild the C6 it had when the 460 was built. It wasn't long before the C6 was dropping metal chunks into the pan and I was losing gears. I got another C6 that WAS built and never had another problem putting it through the same abuse the 30+ year old C6 went through (Burn outs, manually shifting up and down at high rpm's, trips to the drag strip occasionally, etc). When I got the new C6 I paired it up with a Hughes torque converter with like a 2,000-2,500 stall I think. This was on a 2wd truck though and it didn't have large tires like you have.

Having said all that, I would love a stick in my current truck. Autos are convenient, but I like to be engaged and DRIVE. My cars have always been manuals. If money's no object, I'm sure there are more transmissions to choose from if those two you're choosing from won't do it for you. How about a Tremec T56 6 Speed manual?

 

The C6 can be tough... so can the manual... I prefer manual even though my Dent has a C6. I have had a manual outlast 2 1/2 engines without even being opened up. Truck retired with swiss cheese frame.

In part it depends on application. Which manual are you running and how do you run it?

 

You did not say what 4sp you are going thru and what keeps going on them?
My guess it is a truck 4sp - it shifts slow and you are trying to shift it fast like a car 4spand that will tear up a truck trany every time.


In that case you would be better off with a auto and from the sounds of it a built up auto.
Besides an auto will be easier on the rest of the drive train, less shock when shifting.
Dave ----

 

My sons truck has an NV4500 behind a warmed up 429. No issues. The clutch needs to be up to task as well though. Don't think his is quite that much HP though.

 

I'd stick with the stick.

 

Tremec TKO..... and glory.

 

How about an old Top Loader 4 speed? It would be better suited to hot-rodding, than an NP-435 or T18 or whatever.

 

A built C6 would handle everything you can throw at it. Just keep it cool.