C4 Clutch Pack Question

When assembling the clutch pack, the pressure plates have missing guides in two locations on the outside diameter of the ring.

In assembly, should all these gaps line up with each other? It would seem they should so that oil can get to the inner clutches.

It has been 10+ years since ripping apart a C4 for me, so I kinda forget....

Secondly, this 1968 has an over flow tube on the low reverse servo cover, Has anyone ever modified this tube to go a little higher to keep slightly more fluid in the case?

Thanks Mike

I always align the missing teeth on the steel plates when I assemble the clutch pack and I line them up with drilled holes i the drum. That way the oil between the clutches can get out when they apply.
The vent tube is already higher than the oil level should ever be in your C4 case. To answer your question, yes you can either bend the tube that is there or make a new one with fuel line. You can also run a line up the back of the bell housing and connect it to a hose to a small collection can on the firewall. That is common with the four wheeler guys - It keeps the oil in at all the wierd angles and keeps the water out.

Originally Posted by PaulS1950

I always align the missing teeth on the steel plates when I assemble the clutch pack and I line them up with drilled holes i the drum. That way the oil between the clutches can get out when they apply.

I do the same ...

Thank you both for the quick answer.

How about opening up those draining holes in the drum? I have heard that was a popular modification.

They are 5 clutch plate drums. This is the 1968 C4. If it is OK to open them up, what drill size hole would be good?

Also this is an H-Servo Tranni. Any mods in the oiling holes I should consider?

I do not plan any mods to the Valve Body. Unless there is a spring or valve you recommend I change?

You can't go wrong listening to Gregaust!
I think he is one of the few people I would let build me a tranny. Too bad I don't live "down under", we could have a great time testing new mods.

Open the holes to at least 5/16". I use 3/8" and it seems to be fine as far as the strength goes.
Drill the rear cooler passage to 3/16".
Reconsider the valve body... I would suggest a TransGo 47-2 reprogramming kit. It will help your transmission live a lot longer and make you grin when it shifts under hard acceleration.
Add a large auxillary cooler too. That will double it's life

I value both of your inputs. Greg is #1 for sure. He did a thread on C4's about a 2 years ago, and I could not belive the science behind the mods...YIKES!!!

My drum only has one hole for the leak out. It is a 68 if that makes any differance. It is a slant bore hole.

The front drum does not have any leak out holes, at the clutch pack.

When I put the new clutches in the rear drum, the tripple thick spacer plate at the top was too thick. So, I used 2 old compressor plates for the top (under the lock ring) and had about .012 less gap then the original installed gap under the lock ring when I was finished.

The front drum, same thing. The new clutch plates are so thick I needed to eliminate the triple thick spacer ring. The front drum also had only 4 clutches, so I added a 5th. Same gap difference. .012 less wiggle room then the original.

The front clutch pack, the clutches looked new, but the compression plates looked overheated, where the clutch pack in the rear drum had a lot of ware, but the compression plates were not overheated....

What is the rear cooler Passage? Where the cooling tube enters the rear of the tranni? If so, whats the deal with the front one? A different bore?

I have about 2 dozzen springs from many kits I bought in the past, but never used. I think I have 1 TCI kit and one B+M Kit.

In the past, I have rebuilt C4's about 10 times, but always 70's and up. I even had a FMX. I liked that one a lot. Wish I still had it, but it did not last past 250,000 miles before it flew apart on 450 HP motor.

Originally Posted by Mikes66

When I put the new clutches in the rear drum, the tripple thick spacer plate at the top was too thick. So, I used 2 old compressor plates for the top (under the lock ring) and had about .012 less gap then the original installed gap under the lock ring when I was finished.

I think you are saying that you took out the top pressure plate and stacked 2 steels to replace it? That's a bad thing to do. The steels are not hard and will warp under the hydralic pressure. Many people have tried this unknowingly. I've rebuilt a few C4s that had this done and they have not been in good shape. The clutch packs will burn quickly.

A better method to gain clearance is to cut a step around the diameter of the pressure plate, or raise the snap ring groove.

Originally Posted by clevelandstyle

I think you are saying that you took out the top pressure plate and stacked 2 steels to replace it? That's a bad thing to do. The steels are not hard and will warp under the hydralic pressure. Many people have tried this unknowingly. I've rebuilt a few C4s that had this done and they have not been in good shape. The clutch packs will burn quickly.

A better method to gain clearance is to cut a step around the diameter of the pressure plate, or raise the snap ring groove.

Thanks for the heads up. Then maybe I should go with just 4 + 4 clutchs and take up the extra slack by adding one extra compression plate under the pressure plate....?

What should the final gap range under the retainer spring be for the front and rear drum when the full assembly is together?

The TCI clutches are a hell of a lot thicker then the original clutches. The compression plates are almost the same exact thickness. I have measure ments on everything, but they are at home. Won't get to them till tonight.

Ok the rear drum/forward clutch pack should have 5 frictions at .061" each .Clearance i keep to the low side of specs around .025" up to .030". Cut a step on the thick pressure plate to suit. Some guys use the lower plate that already has a step on it but just check the clearance above that the fwd ring gear hub doesnt touch the p/plate.

The high reverse clutch normally has 4 frictions at .078" thick.. Clearance at approx .030-.040" but can go a touch less ..

C.S is correct 2 steels wont work..

The drum with the slanted hole is the rear drum/forward clutch..Gets confusing hey..lol Line up the missing teeth is good..
Paul mentioned drilling the drum that is the hi/reverse clutch or the drum at the front.. Drilling that helps get the oil out on application. 4 evenly spaced holes as mentioned is good.

Rear cooler passage is the one where cooler line returns at the back of the case yes..The front passages are already big enough.

The transgo kit is the go to help the trans live as Paul mentioned.. The springs you have left from other kits may be pressure reg springs .You could use maybe but there is more to firming the shifts than just the springs..

Thanks for the kind words too...