Ideas for C4 tranny upgrade options

[chuzie]

Ok, I have to rebuild my C4 auto on my '77. No big deal even though I have no transmission experience except for removal and installation. I am always eager to learn how to do something just as long as there is not too much trial and error and I don't waste a lot of $$$.

Anyway, before I order all the parts to do the overhaul I wanted to know what the consensus is out there on available C4 upgrades for our applications (valve bodies, clutches, etc.)

I am running a '77 with stock Xfer case, 4.11 in rear on my 9" and 4.10 in front on my D44 all on 35" tires with a 302HO EFI.

-Mike

[badbronco]

This is what my next move will be if my c-4 blows up.Summit racing sell's some aftermarket transmission stuff for the c-4. Different planatary gears for a lower first gear. Different servos for more holding power. Hardened input shaft for less breakage. Kevlar clutches for more heat tolerant applications. They also sell a video to show you how to do it. 50$. I know a little cause I tried it once but that was about 10 years ago. I feel I could do it now. The c-4 is a great transmission. Art-Carr builds these to hold 1000 horsepower.So enough said. Make sure you use petroleum jelly to hold parts together while assembling. NO silicone on pan gasket. Just watch how it comes apart and you will be fine. Keep everything clean with compressed air while assembling. Go for it!

[High Pressure]

Chuzie,

First... I have no real reason to recommend anything...only to describe my limited experience. I had to rebuild my C4 after I destroyed the forward hub I.D. spline...(lengthy story on how that happened)...The good news was the new hardened input shaft was fine.

Originally I had the transmission rebuilt with new frictions and kevlar bands a few months before I destroyed the forward hub spline. When I tore down the transmission all of those items seem to be fine from the recent rebuild. I did replace the seals and thrust components because my time has some value and I believe this cost less than $100..can check if needed. The forward hub cost me $45 used. I used the Haynes manual and watched the short clips on youtube for testing the C4. I, like you have experience rebuilding various work related items.. CNC lathe spindle bearings... etc. So.. I understand cleanliness, shimming for preload of bearings and/or end play, ect. Along with the fact I have gained more patience over time and I don't worry about the clock!!
I rebuilt my Dana 20 6 months prior to this and that seemed to go well.. and I found the C4 a little more difficult but not impossible.. Of course, I only have about 400 miles on my rebuild! As I understand the C4 is the easiest of all automatics to rebuild that we would use in a Bronco.

Here's some sources for parts and information that I used.

http://classicbroncos.com/forums/showthr...p?t=119632

The owner of Broader was very helpful over the phone when I was considering the purchase of a "welded" reinforced forward clutch hub. This was before I really understood the cause of the failure!!

http://www.broaderperformance.com/


Bad Shoe Videos
http://www.youtube.com/watch?v=ucTqlOHhCxM
http://www.youtube.com/watch?v=As5lBDy10...re=related

Good Luck, Chris

[chuzie]

Thanks for the info. It is a super big help

[Bighorn]

There is a ton of really good information on BroncoHowies post up on Classic

http://classicbroncos.com/forums/showthr...p?t=119632

Keep us posted!

[High Pressure]

Chuzie,

First... I have no real reason to recommend anything...

I crack myself up sometimes..:hysterical: I must have been asleep when I typed that at 5:30am!!!

[bucketobolts]

The EB C4 will have a good "H" servo, 5 Forward clutches, and a hardened input shaft. I usually add one clutch to the Direct pack making a total of 5. I prefer to use Alto Red Eagle frictions and Kolene coated steels. On a C4 I run .005" clearance for each friction, .025"-.030" total in each pack. A Kevlar intermediate band is also a good investment.

Another couple worth while modifications are to the oiling system. The drain back check ball and spring needs to be removed from the pump stator housing. This restricts the cooler circuit to the cooler. Then I ream the return port to 3/16" and clock the rear bearing so that it allows full oiling to the output shaft. The #9 thrust washer needs to have a .125" hole drilled through it to this passage to prevent it from galling.

To help prevent a 2-3 slide shift I like to vent the Direct hub. This helps release the band and apply the clutches a little faster. Also you don't need to buy a shift kit. The valve body can be reprogrammed to shift as firm as you need without any parts. I also don't see a need to upgrade the Low/Reverse band or servo. Though it is cheap insurance to replace the Low/Reverse Sprag.

Remember the key things to make a C4 live is to make it shift quickly and keep it cool. I have also upgrade to roller thrust bearings before. But I don't think this is a necessary upgrade unless the tranny is going in a strip only drag car. The gains will not be noticed on the street or trail.

[chuzie]

Do you have write-ups to reference your suggested mods? At this stage, I have no idea what those parts are or where they are located in the tranny. I am sure that will change when I get it torn down. I am definately game for modifying it but really need to have some material to reference to ensure I do it correctly.

[bucketobolts]

Here is a link to the article I wrote for ClassicBroncos.com http://classicbroncos.com/c4_improvements.shtml

I took all of these pics when I built the tranny for my rig.

I also buy most of my parts from a local transmission supply shop. Some stuff I could get cheaper of the net, but I like to take care of the local guy. He's taken care of me in the past.

[chuzie]

Perfecto!!!

Thanks