Another transbrake thread, & tires

[Keith 944]

my question, how to shim the solenoid, between the trans case and solenoid or the plunger itself ? and how much shim? use washers, or is there a shim for this purpose?

[Bryan Gillespie]

mine had 2 shims (washers), but brake wouldn't hold @ high rpm, unscrew solenoid and place shim or shims and screw back in.

[63corvette]

Keith, you shim between the solenoid and the case with a washer or washers.
You need to have the pan off and it is much easier to do with the trans on the work bench. Back out the solenoid to see when the reverse piston is engaged into the valve body .010 to .020 with the solenoid in the activated position. Then measure the distance between the case and the base of the solenoid and find a washer that is that distance thick or just a few thousands less and install that washer.
I have found transmissions that needed as much as .150 and some that needed nothing with the average being around .090.
I would guess and that is only a guess that if you needed a shim of .090 you should pick up about .020 of reaction time or maybe just a little more. There are lots of variables on this but it will help the reaction time for sure.
If you shim it out to far the trans brake will not hold or it will shudder the whole car and not hold so be careful if you are not sure what you are doing.
Just My 2 Cents

[Bryan Gillespie]

What is there a ECHO around here ?

[S/G 386N]

Just an update. Moved the 4 link bars back to Don Davis' factory settings and picked up about .040 on my reaction time. Think I'll just keep them there and bracket race on the throttle stop. Unfortunately, had a lifter collapse and take out the camshaft as well. Looks like I'll be missing US Nationals now.

[1968 SS]

Originally Posted by S/G 386N

Just an update. Moved the 4 link bars back to Don Davis' factory settings and picked up about .040 on my reaction time. Think I'll just keep them there and bracket race on the throttle stop. Unfortunately, had a lifter collapse and take out the camshaft as well. Looks like I'll be missing US Nationals now.

I have a Don Davis 57 Corvette,
What are the factory 4 link settings?
I am having trouble on a Four O tree.
Thanks

[Bill Baer]

Originally Posted by 63corvette

Keith, you shim between the solenoid and the case with a washer or washers.
You need to have the pan off and it is much easier to do with the trans on the work bench. Back out the solenoid to see when the reverse piston is engaged into the valve body .010 to .020 with the solenoid in the activated position. Then measure the distance between the case and the base of the solenoid and find a washer that is that distance thick or just a few thousands less and install that washer.
I have found transmissions that needed as much as .150 and some that needed nothing with the average being around .090.
I would guess and that is only a guess that if you needed a shim of .090 you should pick up about .020 of reaction time or maybe just a little more. There are lots of variables on this but it will help the reaction time for sure.
If you shim it out to far the trans brake will not hold or it will shudder the whole car and not hold so be careful if you are not sure what you are doing.
Just My 2 Cents

63 Corvette

I build my own powerglides and have been using a (cast iron) Trans king pro-brake an I was interested when you describled shimming the solenoid to improve reaction times do you need to disassemble and install only part of the valve body so you can see when the valve uncovers the port that drops reverse?
I'm a little confused.

Bill Baer

[Michael Pliska]

Originally Posted by Bill Baer

63 Corvette

I build my own powerglides and have been using a (cast iron) Trans king pro-brake an I was interested when you describled shimming the solenoid to improve reaction times do you need to disassemble and install only part of the valve body so you can see when the valve uncovers the port that drops reverse?
I'm a little confused.

Bill Baer

Just bumping this thread to see if anyone has any input. I want to do this on an old TCI trans brake, but not sure what I should be looking for. With just the pan off, can you see enough of the piston into the valve body to know how much to shim?

Thanks,

[63corvette]

I sent this procedure to Bill in a PM and will post it here to let everyone know how I do the shimming.

Bill, sorry I have not responded earlier but I have been out racing the last 3 weeks. I am retired and go out for weeks at a time before returning home. We came home last night.
What I do is with the trans out and on the bench with the pan off is get a good light pointed into the trans in the piston port area on the valve body. The valve body is not square with the piston and opens up at the top of the piston first so you have to look into the trans closely to see when it opens up there.
With the solenoid in the energized position unscrew the solenoid until the piston starts to open a gap with the valve body.
Then screw the solenoid back into the case 1/2 a turn or a little more then measure the gap between the solenoid base and the case. That is the size of washer you need or .010 less including the gasket if you use one. I usually just use a little silicone on each side of the washer. This really helps on the GM cases and not so much on an after market case. I guess the after market case builders add a little more height to the base where the solenoid screws in. I have not found an after market case yet that need shimming.
I build my own washers on my lathe.
Hope this helps.
Good Luck with the trans.
Rick