C4, C6 Question
 

I guess I'll start this by saying that my health is a limiting issue on doing heavy work on my car. That said, given one of each transmission comparibly prepared with similar convertors, EXCEPT, the C6 has a 2.75 gearset in it & my car is still a little light for "N". (the car 72 Cougar 351C 2BBL that has yet to touch its index) Opinion's ?

Re: C4, C6 Question
 

Without a doubt, the C4 is the better choice. Lighter, faster, cheaper, more room for headers. With a 2.91 low gear set, that 2V Cleveland will be very happy.

Re: C4, C6 Question
 

How well do those 2.92 gear sets hold up ? I killed one of the stock 3 gear planets in my last C4. My headers will clear a C6, now..

Re: C4, C6 Question
 

get a pro trans gear set for the c-4

Re: C4, C6 Question
 

AS few years back, we swapped from a C6 to a C4 in a 2900# bracket car, small block, both trans were 8" converter, no trans brake. It went .25 quicker. Wasn't a perfect back to back test but pretty close. I have no question that there would be significant improvement switching to the C4. Lots of good parts for C4's these days, no reason for strength issues to be a problem.

Re: C4, C6 Question
 

C4 it is,Thanks Guys. Guess I better get to selling some stuff to get one of those gearsets.

Re: C4, C6 Question
 

Talk to Brian Thompson, I believe he runs a Broader C-4 with a low gear.

Re: C4, C6 Question
 

I run a Broader 2.92 set and also have a ATI 2.92 set C-4. The Broader set looks more robust than my ATI set and held up for about 3 years of hard abuse before it looked like it needed rebuilding. The actual planetary is from a 125C GM, so I just rebuilt it using those parts every few years. But last I heard that set may or may not be available, check Broader Performance website. Good guys.
Where the Broader stuff uses Ford hubs and GM gear sets the ATI uses GM hubs with Ford splines pressed and welded in and just gives you GM clutches to make it work in a C-4.
I haven't used my ATI set yet but, it looks like it will hold up ok. Wasn't as impressed with what I got vs the Broader set up. With all of the C-4's the front planetary is the weak point usually with thrust washer wear on the side of the planet pinions. There are limited manufacturers of the 2.92 sets for C-4 and I haven't seen a 6 pinions 2.92 set yet. If you can find ones with Torrington bearings on the planet pinions even better. Maybe some others can chime in.

Re: C4, C6 Question
 

Well since it came up, I'm real curious how you rebuild those. I just checked Broader, they still show one. What about the ACT Automatics unit ? All I see on ATI is for the 6 pinion stock ratio & the low drag piece.

EDIT: Okay i can how to rebuild the stock piece if I had a Bridgeport still available to me, BUT ........ Is that GM piece the same way ?

Re: C4, C6 Question
 

If your looking for an inexpensive way out and don't mind running the stock ratio, the early 64 -66 C4's had a brass and steel washer at each side of the planet gears and would stand up much longer than the steel washer only later sets.

Jim Mantle V/SA 6632