More 727 Questions

[Rebel Machine]

Okay, been messing around with a 727 trans I bought from Coan Racing a year ago and it's never worked right when manually shifting 1-2. Drive works fine but seems to bind on a manual 1-2 shift. The only thing I can think of is the rear band isn't letting go right away. The servo has a spring to push it back in the bore and loosen the band. Is there a path for the fluid to get pushed out?

Also, what is the advantage of a reverse valve body?

Thanks,
-Steve-

[tactransman]

You have to have the rear servo piston shimmed solid, the piston itself has a spring on it also,that piston needs shims inside the spring ON the servo itself to shim it solid. See this pic from some TCI instructions.  Reverse pattern V.B.'s started out so the driver would be shifting away from neutral as they were going down the track. A reverse pattern V.B. also has a simpler fluid flow path which usually means quicker shift reaction (when you move the shifter to each gear) The only reverse pattern I like is  C.R.T. with low band apply.

[Rebel Machine]

Thanks for the reply Tactransman. I'll pull the piston out and see if Coan shimmed it.

I pulled the pan & valvebody out of that transmission today. It's definitely got a non-stock separator plate. Speaking of which, I've seen several valvebodies with different numbers etched through the separator plate on the accumulator side. What's the significance of that number?

-Steve-

[tactransman]

I am not sure on the numbers. You mean the numbers that are actual a hole thru the separator plate,right?

[Rebel Machine]

Yes, the numbers actually punched through the plate.

Got the low/reverse band servo piston out and it doesn't seem to have the shim in it. Looks like this could be why the band seems to let go too slowly.



Guess I should get hold of them and see if it was overlooked.

-Steve-

[tactransman]

Yup,it needs to be shimmed. Any washers will do that will fit and still let you put the little snap ring back on. (just don't over spread the little snap ring)

[tactransman]

Yes, the numbers actually punched through the plate.

I have never figured out a pattern to the numbers in the plate.It doesn't go by the year is stamped in there I know that,I am sure some one out there in the Torqueflite world knows.   The year is cast into the aluminum part of the V.B. though.

[tactransman]

  The year is cast into the aluminum part of the V.B. though.

Here is where I am talking about,it is on the back side right in line with the manual valve. (this one is an '84 model)

[Rebel Machine]

I see. Thanks for your patience & knowledge. I'm learning a lot.

I've got a Transgo kit here that I've never installed. It has the L/R servo shim. Looks like it takes out all the spring play. Should it be rigid like that? I'm guessing that's the fastest way to release the L/R band.

I sent Coan an e-mail. They suggested a 0.065" shim. Doesn't seem to me like that would do much.

I'll shim it as you suggested and let you know if it corrects the problem.

-Steve-

[tactransman]

The shim (or a combo of washers) should be around .220 ,.065 will not be enough.

[Rebel Machine]

Got the trans back together and took it for a road test. MAN what a difference! No 1-2 bind anymore. Really bangs second like I wanted.

Thanks to all who responded to my problem, especially Tactransman. He nailed the diagnosis. I knew the L/R band wasn't letting go as fast as it should but he knew why.

-Steve-