polo708

I have a C4 tranny and havent really taken a look at it since I got the car. Im building a motor that will be close to 500hp when its done and im not sure if the C4 in it will hold that much power. Ive read comments saying "well, if its build right it will hold". What exactly am I looking for? How can I tell if it will take 500hp?

my77stang

if its a stock C4 it wont. you can build them or order the right parts to have one built to properly handle the power, but by the time you add it all up your probably better off getting a performance automatic C4

cprstreetmachines

The stock hard parts will take it. But better clutches and steel will help, and make it actually grab when it shift. A extra clutch and steel is really nice two. I built mine a few years ago and cost me about 500 bucks to do it myself. Even took a beating just fine from the turbo.

socalwrench

500hp will kill a stock C4 transmission very quickly- say 15k miles. Trust me, I have put two C4s, (one C5 technically) into his supercharged Ranchero, and both were slipping after 15k miles of use. Also, we gave the 2nd C4 basic upgrades like clutches, plates, shift kit, seal kit, and firmer servos- didn't matter. It's the hard parts that break.

Currently, he is using a race prepped C4 transmission with hardened main gears, kevlar clutches, hardened input and output shafts and an upgraded planetary set (extra rollers). It's built to withstand 600hp, according to the manufacturer. There is also a rollerized bearing version, that can withstand 800hp.

my77stang

add a better planetary to that setup right there and it should be good for 500 ponies unless your using it as a drag car. for a street performance machine the above build with the better planetary would be good.

i killed my last C4 (stock with shift kit and 2800 stall) with my old 12:1 302, planetary was starting to walk. didn't have the cash to buy a better one, so i built it with everything you mentioned in bold and its now behind a 289 thats a little tamer than the 302. fingers are crossed, but i believe it will hold up pretty good.

69RunningHorse

so why not try to find a C6? If you can find one for cheap wouldn't that be better?

polo708

that was going to be my next question... do you guys recommend a different tranny for my setup? Which will take the most abuse and cost me the least? haha

nba1341

because they are boat anchors not transmissions


what kind of torque are we talking out of this 500 hp motor because i believe that is whats going to matter

socalwrench

horsepower was just the number being thrown around. torque is what will twist a transmission apart.

C6? I suppose they good for towing, but not performance applications.

my77stang

C6's are great for performance when you get to the point that you can't build a C4 strong enough. yes, they will eat a little more of your horsepower and they weigh more - but they are also tough as nails.