Hey everyone, so I put together a 400 for my 79. We are making 500+ hp N/A and I have been thinking about putting a nitrous plate on it, most likely a conservative 100-150 shot so it stays together.

I broke the bell on my existing trans. Since the C6 is one case, I needed another trans. I had a spare PAJ-C2 coded C6 floating around from a 72 Torino. I gutted it and have yet to pull the existing trans back out of the truck.

So far the thing has an external filter system, a B&M super cooler, deep sump aluminum pan from B&M, a 10" billet converter 3k stall, pink band modulator and a stage 2 street/strip shift kit. I believe it has the S code servo, not sure what the apply lever for the band is. The spare has an L code and an E apply lever, so I think it had a 429 in front of it. The trans ran great and shifted nice and firm, but I figure what the heck I got it apart, lets throw some speed parts at this thing.

First things first. I want a solid, reliable trans. I'm going to drive this thing like I stole it, and I have absolutely 0 issue spending money on high quality, top of the line parts so it stays together.

What direction would you all recommend I go? I have done a little research, apparently Lincoln drums are the way to go for an extra clutch pack. Steel rollerized planetary gears with an E4OD gearset and an R code servo seem to be the go to performance stuff for a C6. I also read about putting a check ball in the governor or taking it out completely, getting an adjustable modulator, and getting a wider band.

What would you all recommend I do? This truck will see 99% of its use on the street, mostly cruising around and showing off, but definitely will see some hard racing when the opportunity presents itself as well. I would love to hear from any professional builder if any of you guys are on the site. I haven't dabbled into transmissions like I have engines so this is new to me. Thanks!

 

Slashfan,

Any drum can be machined with a groove high enough to fit five frictions. The E4OD parts are a solid upgrade too. You can replace most of the thrust washers with bearings (machining required). Bearings can be installed in positions 10, 9, 8, 7, 6 (already a bearing), 5, and 3 (also already a bearing).

Just make sure your clearances are okay and you should be good. They are a very simple transmission and easy to rebuild. I can't comment on a 3,000 stall converter, as my application is a more off-road focused 78 Bronco. I have read you really don't want the E apply lever with the R servo as it can apply the band had and fast enough to split the case... and that's pretty tough to do to a C6.

 

I was unaware that any drum could be machined for it, but I know the Lincoln drums come with the groove up higher than the rest of them. I'm likely going to do the E4OD stuff. I don't hav eany way to measure clearances, and I'm not sure what needs to be machined for the bearings instead of thrust washers. This is all new to me.

The E code apply lever I still don't think is the stiffest one you can get, but I'll keep that in mind. It might be better to stick with my L code servo.

 

Measuring the clearances is easy. All you need is a dial indicator on a magnetic base and some compressed air. There are a few really good write-ups online if you do some looking around, complete with plenty of photographs. I also used an ATSG manual and the SA book "How To Rebuild And Modify Ford C4 And C6 Transmissions". There is also a Haynes manual that is pretty good if I recall correctly.

The nice thing about a servo upgrade is it can be done easily and with the transmission installed in the vehicle. The apply lever must be done with the guts of the tranny removed.

Do some research on stall speed before you drop money on a torque converter. You may not want to run a very high stall on the street as they tend to build up a lot of heat. No personal experience on that mind you, just what I've read. An effective cooling system for a transmission is always a key element to longevity.

 

I built an E4OD first time last year, and a lot of parts are same as C6. With that said, a lot of the upgrade parts I used were for diesel 4R100 trans, similar parts again but the case.
Here is a good writeup using E4OD/4R100 parts into a C6: C6/4R100 Frankenstein - The FORDification.com Forums

 

My monster truck customer ran two trucks Big Dawg and Tailgator with C6 transmissions for many years before switching to aftermarket Powerglides. The C6's number one problem is the shift timing. Get that right and it'll hold up very well without any fancy parts. If it is breaking stuff that's where to look. His transmissions were built by a guy named Matt Heady who really did a great job but I don't think does transmissions any more.

They had the stock C6 planetary gear sets (some were the 3 gear type) that were modified to use roller thrust bearings. The transmissions had really heavy aluminum pans, a billet servo cover, a VERY heavy duty band that was as wide as possible and welded together. I don't remember what combination of levers were used but when you'd air check the transmission you could see the case flex when the band would apply. I don't think that it ever broke a case and the heavy pan must have helped to hold it all together. Most of the time they would get run a year and then freshened up. Of the hard parts I think that the band was probably the weakest link in the C6. They used 2nd gear a lot and if the driver suddenly felt it give he better get off the gas.

I found this video from about 10 years ago which would still be with the C6. 2nd gear, band holding a heck of a lot of torque:

 

Nice video Dave! Thanks for posting!

I really don't know if you could ask for a tougher truck transmission than the C6. I know the TH400 is great and doesn't have the problem with shift timing, but the cases aren't all that strong.

 

Appreciate all the feedback gents. I didn't know the 4R100 was a distant cousin, that's something I'll look into. I plan on being nice to it but being hard on it when I want to be, so anything that's over built would be better than under built for me. I figure now is the time to do it since it's apart. I've already got a converter for it, I bought that a few months ago. 10" billet aluminum, anti balloon plates etc.