How much HP will a C4 hold?

pdw5000 · May 29, 2008

I am building a 408W that is going to be making around 500-600hp. I have a rebuilt 68 C4, 26 spline tranny with high performance clutches and a B&M shift kit. My engine builder tells me that pre 1970 C4's are junk and I need to get a 70's C4 to handle the power because of the bigger input shaft. Is this necessary?

D.Hearne · May 29, 2008

Question is, How much money do you want to spend? The 24 vs 26 spline input sizes aren't that much different. Either one's going to be stressed with a 408. It ain't the HP, it's the torque that does em in.

pdw5000 · May 29, 2008

I think I made a mistake...my current trans has a 24 spline input shaft. I would imagine my torque would be about 500 to.

blown65 · May 29, 2008

Yup, its all about what you want to spend.

If your going new, Id go the Performance Auto route and get the lifetime warrenty with it. They do rate them at 1000hp for the super comp. (Dunno if I would put that much to one) Its what a few here run, and what I just bought for my car. Big thing, have a good trans cooler though, heat is probably the #1 reason they fail.

pdw5000 · May 29, 2008

I am just thinking about buying a junk 70 era C4 and rebuilding it. I imagine that's basically what P.A. , B&M, etc. are.

fastcoupe68 · May 29, 2008

pdw5000 said:
I am just thinking about buying a junk 70 era C4 and rebuilding it. I imagine that's basically what P.A. , B&M, etc. are.

NO!!!! Just rebuilding a junkyard c4 aint going to cut it if your making 500 lb ft of torque. Check out Performance auto and they list the mods they do to there trannys. Way beyond what most can do in there own garage, and most of the parts they use are not stock c4 parts. Do some research on this or you will be sorry when your tranny goes BOOM!!
ken

blown65 · May 29, 2008

ya no kidding. You could do it yourself it you have the knowledge though. There are a couple ppl that buy the parts from PA and do their own, so you would end up with the same trans.

BUT, by the time you get those parts, do the time to put them in, how much are you going to save, and now you have no warrenty. PA is LIFETIME. Peace of mind, break it. Pay the shipping and have it like brand new again.

10secgoal · May 29, 2008

Built mine from a 70 trans. PA input shaft, stock A servo, transbrake valve body. I have freshend it up once. That was pretty much because the first time I built it, I didn't know the HP I would be making 3 years down the road. So I finally burned up the forward clutches I was cheap on at first. Now I've upgraded to Alto reds, and I'm still beating on it with 13psi from a turbo.

rbohm · May 29, 2008

a properly built C4 can handle as much as 800hp, though i wouldnt put that much power through one on a regular basis unless i had a strict maintenance program, including freshening up the trans at least once during the race season.

my recommendation would be to contact lentech automatics and get one of their terminator AOD's with a full pressure valve body. these transmission will handle the power of your windsor easily, and give you an overdrive to boot.

brianj5600 · May 29, 2008

Dustin, how many forward clutches in the first build? Second build? How many in the direct?

fast shelby · May 30, 2008

I have a 427 Small block with 2 stages of NOS and make over 850 hp. I use a Dynamic Racing tranny. It is the Mighty Mite C4 X6. Here is there website http://www.dynamicracingtrans.com/fordtranny.htm

alexb_ · May 30, 2008

I can't find a web site for "Performance Auto transmissions" - they have an annoyingly generic name. The first hits on Google are TCI and Campbell... does anyone have a link?

fastcoupe68 · May 30, 2008

alexb_ said:
I can't find a web site for "Performance Auto transmissions" - they have an annoyingly generic name. The first hits on Google are TCI and Campbell... does anyone have a link?

http://www.performanceautomatic.com/index.htm

57fairlane · May 31, 2008

If you are going to build a hot windsor and want a 3spd . . . turbo 400 is the way to go.

If you have your heart set on a c4 . . . dynamic mighty mite.

Seen 4-5 cars trap 115-125 in the 1/8 with them.
Any c4/AOD will have to be rebuilt yearly at 600-700 flywheel if you race it hard/often.

alexb_ · May 31, 2008

fastcoupe68 said:
http://www.performanceautomatic.com/index.htm

Thanks

10secgoal · May 31, 2008

brianj5600 said:
Dustin, how many forward clutches in the first build? Second build? How many in the direct?

Sorry, computer is F'ed. One steel and clutch extra. The only reason the cheap clutches went was I put it in third and foot braked it to see when it spooled before I had a trans-brake. The direct clutches looked brand new.
If you are thinking about building your own, talk to Jay at Broaderperformance.com
Only does Fords, know his stuff. Can send you hard parts already machined.

How much HP will a C4 hold?

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