C6 Finally Died

[firesire]

The C6 in my 1985 F350 finally went out and I have several questions:

1. If I rebuild, what rebuild kit, shift kit, and valve body do you recommend?

2. Or if I go the remanufactured route, which remanufacturing company should I use? I’m thinking Jasper, TCI, or All Trans (through Orielly’s)...

2. What are the best modifications to make for performance and longevity? Deeper transmission fluid pan, auxiliary cooler, temp gauge, transmission fluid spin on filter, heavy duty torque converter for towing, are what I’m thinking...

With the price of trucks out there, this is probably my forever truck so I want to do it right and get another 35 years out of her ().

 

[quickster]

If my c-6 took a dump, I'd be looking for a zf5 setup. But coming across the parts is getting rare.

 

[Cubey]

How many miles did it last? The original C6 in my RV is still going, but it's only got 75k original miles. It's had a filter change at least twice in it's lifetime, since I found a 4wd version filter in it when I changed the fluid last year. Needs bands adjusted I suspect but seems fine otherwise.

I would look for a local shop to do a rebuild rather than buying one to have them install it. That way if it has problems, you won't get screwed on excessive labor.

 

[firesire]

It has 150 thousand miles. I changed the transmission fluid and it was dirty with metal flakes. The truck won’t move except for in reverse. It’s a 6.9 diesel with the C6 transmission. I’ve never considered converting to a zf5. I don’t tow that much, but I do put heavy loads on it to go to the dump.

 

[firesire]

It’s my fifth vehicle so I don’t drive it much unless it’s to haul. I know I need to replace the rear main seal and clean out the transmission lines when I change the transmission. I’m looking for advise on rebuild or reman...

 

[5 oclock]

I am sending mine in to monster, soon to be picked up. 3 years. Unlimited mile warranty. Originally I thought I would do a rebuild myself and ordered their kit. IT WAS STOUT, with quality parts. Justed didn't want the liability without recourse. Seems like it included a shift kit along with other parts that you don't normally find included.

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[71 Highboy]

It’s my fifth vehicle so I don’t drive it much unless it’s to haul. I know I need to replace the rear main seal and clean out the transmission lines when I change the transmission. I’m looking for advise on rebuild or reman...

If it lasted 150,000, with the right parts and shop, it can easily do that again. I had mine gone thru about 2 yrs ago, and the new converter has a stall speed of 1800 rpm so it works well for the power band of the engines. It is imperative the trans pressure, and TPS for the shift valve are properly balanced and adjusted, after installation. C6's were bullet proof, and with proper gearing and an OD unit will work quite well for a long time. I welded a drain plug in the pan for regular fluid changes while it was apart years ago so that's easy to monitor whats going on. I also run two additional coolers for more capacity. if you can put a deeper pan on, I would. Some are available with a temperature gauge port.

 

[Cubey]

I welded a drain plug in the pan for regular fluid changes while it was apart years ago so that's easy to monitor whats going on.

I put one of these cheap aftermarket chrome pans with a drain bolt while I had the factory pan removed for filter replacement, since I can't weld. Kind of wish I had also installed a bolt-in bung for a temp sensor, but I didn't.

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[Knuckledragger]

The C6 in my 1985 F350 finally went out and I have several questions:

1. If I rebuild, what rebuild kit, shift kit, and valve body do you recommend?

2. Or if I go the remanufactured route, which remanufacturing company should I use? I’m thinking Jasper, TCI, or All Trans (through Orielly’s)...

2. What are the best modifications to make for performance and longevity? Deeper transmission fluid pan, auxiliary cooler, temp gauge, transmission fluid spin on filter, heavy duty torque converter for towing, are what I’m thinking...

With the price of trucks out there, this is probably my forever truck so I want to do it right and get another 35 years out of her ().

1 I used a Trans-Go shift kit and a deep cast pan with my rebuild ten years ago. I think there are heavy duty parts to fill your need for the rest of the rebuild. C6 transmissions are used on tow vehicles at airports, so they are plenty tough.

2. Have it rebuilt by a reputable outfit or a known person.

3 look into a converter full lockup kit, I hear they are good for multiple reasons, keep the trans cooler, better mileage, other stuff I do not remember.

 

[franklin2]

the new converter has a stall speed of 1800 rpm so it works well for the power band of the engines.

If you drove one of these trucks with a manual transmission, you would re-think that statement a little bit. Automatics, especially the c6, throw a lot of the low end grunt these engines have out the window. Like I mentioned in another thread though, everything is a compromise.

 

[Farmer Rock]

If you drove one of these trucks with a manual transmission, you would re-think that statement a little bit. Automatics, especially the c6, throw a lot of the low end grunt these engines have out the window. Like I mentioned in another thread though, everything is a compromise.

Very true. My 88 and 87 are both rclb,4x4, and 6.9 (88 was swapped), so it is a perfect comparison with the 87 being a t19 and the 88 a c6. To put it simply, the 4 speed will walk all over the c6 and eat lunch on the way! Don't get me wrong, the c6 truck is still impressive for what it is, but it's really no competition. I can't stand the lag on an auto either. Being that I am so used to manuals, when I drive autos I keep thinking I left the parking brake on because of the lag,lol.



Rock

 

[IDIBRONCO]

Needs bands adjusted I suspect but seems fine otherwise.

IIRc these are adjusted on the outside of the transmission and aren't very hard to adjust.

3 look into a converter full lockup kit, I hear they are good for multiple reasons, keep the trans cooler, better mileage, other stuff I do not remember.

I didn't know that there was such a thing made. This would certainly move the C6 up a couple of notches in my book.

 

[Cubey]

IIRc these are adjusted on the outside of the transmission and aren't very hard to adjust.

Yeah, but it calls for a very low torque value (10 ft-lbs, then back off 1-1/2 turns). I need need a 1/4" beam type torque wrench for that. And I keep putting off getting one. Yes, shame on me.

EDIT: Oh, the cheap 1/4" HFT one is actually fine, 120 inch lbs is mid way on it. Well... next time I get to a HFT I guess I'll grab one. I get confused between ft/in somewhat.

 

[quickster]

I need to get some info on that lock up kit. Sounds interesting. In the meantime , I'll keep looking for a donor truck w/ a zf5.

 

[71 Highboy]

If you drove one of these trucks with a manual transmission, you would re-think that statement a little bit. Automatics, especially the c6, throw a lot of the low end grunt these engines have out the window. Like I mentioned in another thread though, everything is a compromise.

I understand your point, and have driven many of them with sticks. It is practically impossible to make a smooth shift with Ford manuals and hyd. clutch system. Made me spill too many beers, and I was done shifting. I was comparing the performance of the new converter against the one that had been in there since the original install in about '93. The power band is moved up with the boost and load, and 1800 lock up is well below where this engine runs best, whether in direct or OD, which is about 400 rpm difference with 3:54's and 33" tires. Also on the market is stand alone electronic lock up converter's for the aftermarket, but I don't think there is one available for our rigs. I think the original thread was asking about rebuilding a C6, so I was sharing my most recent experience. The price of the overhaul was more than I expected, but the follow up service and tuning was well worth it. It included the shift kit, new converter, and in shop labor on the trans I took him. No leaks. Press the go pedal hard, and each shift will hang to 3400 if you stay in it, but it spills the beers so I drive nicely. It has a Mustang shifter positioned at the front edge of the seat, right above the shaft on the trans, and I use the crap out of it because I will shift it manually for engine braking and driving conditions. The total seal rings help in the slow down department. No CDR, just a catch can and tube to the inlet of the compressor side.
Like you said, it's all a compromise to get what you want...