C-6 Dies yet again...

Yeah, I bought this truck a year and a half ago. F250 with a FE 390. I installed header, 2.5" dual exhaust, Flowmaster delta 40's, MSD AL6 ignition/Pro Billet distributor, Holley SA 670 carb, edlebrock intake... It ran awesome after some carb adjustment...

The tranny had issues from the get go. Shifting was slugish. I installed a B&M shift kit and it was good for about a month. Installed it according to the street and strip directions. It shifted good, nice and strong, I liked it.

Then after about a month (don't know what happend) It reverted back to before... slow long drawn out shifts and now some slipping (especially when kicking down). It was actually worse than before.

I then had the tranny rebuilt. Paid $1,200.00. Had a high performance shift kit installed. It was more than awesome. I could chirp the tires hitting second. Kicking down worked flawlessly. That's all I wanted. That was all I was after. I was a satisfied customer.

Six months later...

I don't know what happend (again). I only drive the thing around town. I had the street and strip shift kit installed (yet I never take it to the drag strip).

Now I get these long drawn out shifts (makes me feel like a homo) and when I slam the gas and it attempts to kick down, all I get is rev'ing and slipping. It makes me sick. I don't even want to drive it anymore. It's worse than ever.

WTF! Is it to much to ask to have a tranny that shifts hard and last more than 6 months. I was thinking $1,200.00 bucks would be good for at least 5 years. I guess I was wrong.

What do I need to do? Do I give up on the C6? Is it possible to make it do what I want it to do (shift hard, last 5 years). Or should I jettison the C6 and go with something else? What?

Thanks in advance...

samckernan

 

I'd start by having a conversation with the outfit that did the rebuild. I'm no transmission expert, but in the Ford world the C6 is considered the "tough one," just like the Turbo 400 is in the Chevy World. I sure wouldn't expect a nice 390 -- good exhaust, intake and ignition, but nothing radical -- would tear up a properly built C6 in such a short time.

 

I have 32 years and 240K on my 72 F250 with a 390 and C6. I have adjusted it from time to time, and changed the fluid 3 or 4 times. The first time I changed the filter and installed a drain plug, since then the pan has never been off the tranny. I did install a temp gage in the lines to the radiator and watch my temp when I work it hard or it gets real hot outside and traffic is heavy. Other than that, it is all stock.

The C6 is as close to bullet proof as anything mechanical gets.

I would take it back to the shop that did the work - it may be a simple adjustment they can do in a few minutes. If they want to rebuild it again at your cost - run.

C6s are not that expensive - I just helped a guy do his, in a later model Bronco. We found a local rebuilder who would swap his old trans for a rebuilt one for $375. I expect you would do better to have such a shop rebuild yours (instead of exchanging it) - you already have many of the new parts.

It took us all weekend to remove the old tranny and install the new one, and, while it was a hard job, it was not demanding - well within the ability of most shade tree mechanics.

However, before I did anything like that, I would want some experienced tranny people to look at it and see that it is adjusted correctly.

Good luck and let us know how it turns out.

 

Maybe.... vacuum line or Modulator valve??
Roger

 

The C6 is more than capable. I had mine rebuilt about 3 years ago for around $800, and thought I spent too much. You can get a complete reman TCI unit for around $750. Mine has run solid for approx. 10,000 miles since the rebuild. And I'm running a stroked 428 with over 500lb-ft of torque (416 at the rear wheels).

I don't know enough about transmisssions to say what is actually wrong, but I can say that that tranny is up to the task if built right.

 

After that I would put a p.s.i. gage on it & see where your at in each gear.

 

Thanks guys! I was mostly interested in whether or not people opinions were that the C6 was up to it or not. That and I felt like venting my frustrations...

I'm not even going to bother taking it back to the place that did the rebuild. I wasn't happy with them at the time of rebuild... you win some and you loose some...

 

You win some, you lose some. Ain't it the truth?! I guess you just have to chalk some things up to "tuition," the cost of continuing education in the School of Life and Hard Knocks. I bought some cell phone batteries from an outfit called Vision Wireless on e-bay. Both were crap, one so swelled I couldn't get the back of the phone closed. But I only blew $15 to learn NEVER to buy from Vision Wireless. That's "tuition."

A buddy at work has a friend who rebuilds transmissions. He's over near Spokane somewhere, so my buddy will haul my C6 to him (once I finsh taking it out). He'll do the job for $400, parts and labor.

Good luck in the future.

Lane

 

The C6 is just about the easiest and cheapest tranny to rebuild and it can be done at home.
Start off with a Haynes Ford Transmission book.

Since it was used back in the pre smog era behind 460 Linolns, Mercs, Birds, etc and that engine had 500 lbs torque AND it lasted hundreds of thousands of miles there aint nothing wrong with the design. Late model 460 trucks/C6 had higher pressures and more discs in the clutch pack but all that stuff is over the counter thru mail order.

 

Smacker, them is a tough trans, only a person with a GM (garbage Made) mentality can wreck one. I have said before, under normal, hard use or after a filter change specially if the filter has paper under the bolt vs metal filters, torque will go away. This unloading of torque will allow a thin gasket (in width) to blow (between seperater plate and shifter body) and cause a slow trans death. This takes weeks, months, miles later and you thought you were doing a good thing for your trans. Hand lap and install without gasket is my rule (law). Have another shop remove the shifter body and have a witness, if blown, (photo time) small claims court you go. If you let the old shop tear into it they will find (fab) another failure to protect their *** and you pay again. With the radiator cooler, then extra cooler, thru a remote spin-on filter (all hard piped) with magnets in the pan and one in the spin-on filter your good for 600 lbs torque and long life, over 200,000 unless your Mr. GM.
Carl.......o&o>......

 

Sam, like said before, the C6 is virtually bullet proof. I had mine rebuilt a year ago for $600 before I knew I could get a TCI Streetfighter C6 for $800 delivered from Summit. Having said that though, mine leaks and has a shifting problem when coming to a stop. But I still hit the drag strip today and got a 9.90 in the 1/8th mile. I can light the tires up smoke em as long as I want to get em sticky. The C6 is a great transmission and fairly cheap.

 

Have you adjusted the intermediate band lately? It sounds like the band could be slipping?

 

I drove the truck today with a little more objectivity (now that my frustration has subsided a bit). What I noticed is that I don't have a second gear! It shifts from first to third!

One other thing that I did, to try to get a better understanding of what I'm up against is: while going about 60mph, I manually shifted from third to second. It acts like a manual transmisson vehicle with the clutch pushed in. I could rev the engine and there was no effect to the drive wheels.

I'll admit, I don't know crap about transmissions... I did install a shift kit early on... remove the pan, remove the valve body etc...

This thing with it not shifting from first to second seems like it may be something like a stuck valve in the valve body.

Maybe I'll drop the pan and see what I can see.

I've got a question for you all. I know that the trans hold about 12 quarts of fluid, but when you drain it, only about 5 quarts drain out. More just dribbles out all the while the pan is off making a big mess. Is there a way to drain it all, right from the get go? I'd like to drain it all initially, and just to be done with it. That way I could put the drain pan aside vs. having to work around having it sitting there all day.

Thanks for any ideas, suggestions, or thoughts...

Oh, and yeah, I probable paid to much for the rebuild, but for the record, of the $1,200.00 spent, $300.00 was for removal and installation on the thing. So, the rebuild was only $900.00. Like I said, I probably paid to much.


samckernan

 

You can drain a few more quarts from the torque converter by removing it's drain plug. More fluid can be forced out of the cooler lines and the fluid cooler in the radiator.

 

mine does this every couple of years and i replace the modulator and i'm good to go.