I probably only need to ask THUMPIN455 but I figured I would try and get everyone opinion on the matter

I need to rebuild my transmission soon and its currently a C4 Auto
I'm pretty sure the smoking problem with the engine is from trany fluid getting in there some how because I am going through 2qts of trany fluid every week or two and I'm not dripping much of anything on the ground and the engine is very responsive and smooth (except for the smoke).

anyway, I am getting close to heaving enough money for a rebuild with the current trany and my question is... would the C4 rebuilt with a shift kit or something give me a good clean crisp shift and be able to support 350-400 hp (that is my HP goal for this car)? I would like a manual for the fun but I would also like to keep maintenance costs down since I have been told autos are less maintenance (change the trany fluid and filter every 2 years or 30k miles right?) and better for drag racing stuff since no manual can shift faster than an auto... anyway the input would be great.

 

C4 can handle the power pretty easy. You have a light car and it wont make mountains of bottom end power. Its not like you have 550ftlbs of torque and a 4000lb car is it? Figuring out the stall speed needed is the more involved part of running an auto. Get the stall speed right and the clutch has no advantage in the power/ET range you are talking about.

As far as the oil leak, check the modulator. If there is oil in the line, then the diaphragm has ruptured and its sucking the oil out of it. $10 fix if thats it, replace the modulator. Alternately I have seen transmissions lose fluid while driving but not at idle or when sitting. Cooler lines can leak under load and not at idle. Higher line pressure and the weight of the car creates a situation where the fluid is forced out. Check those two items before pulling it out. Im bettin on the modulator..

 

the cooler line thing could make sense because I had to do a "patch" job on the cooler lines (the fuel hose connecting either end) but I did put allot of hose on there to try and prevent fluid leak but ill check the lines to see if they have been leaking or anything and how much does a rebuild usually cost? given I do the work myself? ill be getting my self a book/video at the time of rebuild so I know what I'm doing.

How much do prebent cooler lines usually go for? or do I have to bend them my self?

 

bump... Up to what year was the C4 on my 66 interchangeable? like would a rebuild kit for a 67 work on my 66? or even if I got a trany from the junk yard and rebuilt that would there be a problem with the bell housing if I got one from a different year? I am trying to keep the cost minimal if possible with a little compromise for time of my car being out of service...

 

Thumpin wasn't talking about the cooler line, he's talking of the mod. valve vac. line at the right rear of the pan. Just pull that hose off and fluid will likely come out if the mod. valve is bad. If your car is a 66, it will have the funny green dot shifter PRN2DL. For HiPo use, you should go with a 73 or later C4 which is stronger and will have the normal PRND21 valve body. If you want info on how to overhaul a C4 please check the BadShoe Productions sponsor link to the right.

 

I also mentioned the cooler line. Had that happen on a GM vehicle and two Fords. The ex burned the trans out of my 72 GTO when it had a cooler line leak, oh yeah just keep on revin it and it will move sometime...lol

Some parts places have rebuild kits for as cheap as $75, you can spend up to $200 on other kits. You dont need anything special, no kevlar, no outrageous friction discs, just a simple seal and clutch pack kit. Replacing the bushings is well advised but most people arent going to spend the money for the bushing drivers. Get a video and watch it a few times. The toughest part of a C4 is not cutting a seal when you install the clutch pistons, and getting the band struts in there right. The struts tend to fall into the trans and gun under the reaction carriers and drums.

Torque specs are crucial on a C4 because they have an aluminum valve body. If you overtighten ANYTHING on it you will have alot of strange issues, like not shifting, late shifts, early shifts, anything that can go wrong will. If you decide to do it, PM me and I will give you my phone number incase you have trouble with it. As far as the transmissions swapping and years, there are two large case changes, one has the dipstick in the pan, the other has it in the case. As long as you keep the same stick location you should be ok. There are other changes but for what you are doing it wont matter much.

Also a C3 and C5 look like a C4, but they have lighter components and fewer clutch plates in them. Stay away from the later transmissions, like very late 70s and early 80s. Most of them are not C4s.

There should be a tag on the transmissions you have, if you have an extra core, get me the info from the tag and I can find out what it is and what fits it.