C6 behind 7.3 IDI 1990. First gear holds great. When it changes to second, it barely pulls. If you let up off the gas it changes to third and third holds great too. I changed the fluid and screen inside the pan and also the spin on filter. No difference. Used dextron mercon III. I beleive the trans has to come out. If theres nothing externally that I can check like servos or governor, then tomorrow im gonna pull it out and take it apart. The transmission pan was extremely clean with normal wear particles on the magnet. Screen was not clogged. There was one bolt in the screen that was stripped. I tightened it lightly. I dont know if it holds back fluid pressure or what but when i took those bolts out, fluid poured out of the valve body. I set the VRV in about 5 different spots and it made no difference just seemed like when it was set really sensitive, it could almost skip 2nd gear all together.

 

Sounds like a plan.

 

Years ago you could tighten the bands on ford Transmissions. That was back in 1968 with a mustang with a 289 and an automatic. I"m not sure about these c6's.

 

try manually shifting 1-2-3, see if it helps. maybe the 2nd gear apply piston seal is bad, putting it manually in 2nd will apply the band as well. if it drives normal when you do 1-2-3- manually, you have a bad 2nd gear apply piston seal. if it seems the same, then i guess everything is 'fubarred'. either way it gotts to come out for a rebuild, but if the 1-2-3 manual shift works than you can get away with it for a lttle while---until 'catastrophic failure' time....which of course will be at 3 am in the freezing rain 250 miles from the nearest help and your cell phone battery will be dead and.............ah, you know the drill !

 

There is a band adjustment on the c6, left side, bolt with a 5/16 square head and a 13/16 locknut against the case. Make it snug with a short wrench and back of 1.5 turns and try that. Also the servo could be crispy but if so the band will be toast .

 

typefour has it nailed. Do that first.

 

Thanks guys, thats the info i was looking for. Manual second slips too. Im gonna try to adjust the band today.

 

The actual spec for adjusting the band is to torque the adjuster to 10ft.lbs (120in,lbs) and then back off exactly 11/2 turns. However you need a torque wrench that is accurate at that torque. Make sure you hold the adjuster while you retighten the lock nut to prevent it turning.

 

at least the c 6 is way cheaper on a rebuild compared to tht e4od. ive been told 1000 bucks for c 6 even 700 if u pull it and put it back in yourself. on a e4od ive been told 1400 cash up to 3 grand on a rebuild.

 

Hope it works out for you. This last tranny I got for mine was a hard find for the yard. They were afraid they would have to give me my money back cuase they couldn't find a good used diesel c6.

 

Well, I tried the band adjustment today, it still slipped the same amount. I went ahead and removed it today. I also took it half way apart and saw the intermediate band was down to the rivets and the direct drum is smoked. The drum had groves in it where the rivets cut into it. I need a drum and a kit now. The return springs inside the drum were twisted and laying over and I could remove the snap ring by hand. I think somebody put it together wrong and the springs twisted. Anybody know the best place to get a direct drum cheap? I also found out the diesel C6 is different from the gas. It has a different bolt pattern and some better stuff inside it.

 

I get my parts here: C4 C6 Performance Transmission from PATC, C6 Transmission Also I use the Alto red eagle clutches and steels and added a clutch when I reassembled with new drums and wider red band and diesel shift kit along with many other performance add ons. They also offer a pretty good assembly manual.

 

the forward drum has some extra clutches in it. I doubt it was assembled wrong, just lots of hard miles will do that. Most trans parts suppliers will have a new or reconditioned drum. wish you were closer I have several core trannys. And I have built hundreds of c6.s for airport equipment. I could do some tricks that would break u joints.

 

Transmission shop gave me a gas intermediate drum today so i gotta take that back and try to get the one that holds 4 clutches for the diesel. Found a broken forward clutch disc spring and i got a new one for it. One thing that puzzles me is, the new steels that the trans shop gave me are all the same except for one which has 2 tangs missing on opposite sides. I cant find any steals that look like that in this transmission. Looks like they gave me the correct number of clutches and steals. I think the forward clutch and intermediate clutches are the same size. They gave me 8 friction discs and 8 steels of the same size the smaller size, then four or five of the bigger ones that goes into the case at the bottom. I appreciate all yalls help with this transmission. Also, do yall think i should dissasemble the valve body or not. I dont know if theres anything serviceable inside it but id like to not mess with it if i can. Same question for the pump, should i take it apart or leave it alone.

 

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