Another transbrake thread, & tires

[Bryan Gillespie]

What is there a ECHO around here ?

[ray sowers]

Originally Posted by 63corvette

JJ, you want to stay away from the aluminum valve bodies in my opinion.
I build race transmissions and that has been my experience.
Ten or fifteen years ago I worked with B&M on their development on their alum. valve body for a powerglide.
Those just did not work out very well at that time. My personal feeling is that the pistons and valve parts are steel and with the body being alum the growth rates being different the clearances changed as the transmission heated up. That in turn affected the consistantcies and another problem was if the pump pressure ever fell below 150 to 170 at idle when you applied the brake the car would back up a short distance. That issue was a major one as you stage the car. I first thought it was a clearance issue with the band for first gear or the reverse pack but found it was with the body.
Just my opinion is that you stay away from the alum bodies.
Most of the GM bodies that have been converted to a brake are all done the same.
The major difference on all the manufacturers is whether they use a spring on the reverse apply piston in the body.
Most all the major manufacturers will work the same if the brake solenoid is shimmed.
The torque converter also has an affect on how fast the car leaves and if it matches the cam torque band.
JJ, with a Davis car you should be able to go red anywhere. I can with mine which is an 07 model.
Good Luck at the races.
My 2 Cents
Rick

Rick, I also build/repair Powerglides for our car and friends that are having lots of problems.
We have ran Hipster modified stock pro valve bodys and their Aluminum Pro ones for some years and on the aluminium ones they have a totally seperate steel screw in pressure control that also has an adjustment for setting the line pressure as you wish, Ray.

[63corvette]

Ray, the B&M had the same pressure adjustment you describe. The issue was with the pressure falling off (just a short blip) as you apply the brake. That was a pump pressure/volume issue with the passage size. To make the brake react quickly the volume is reduced in the passages to dump quickly for quick reaction but you have the same issue on the apply side. Applying takes longer that dumping with the port size. You could remedy that issue by going to an after market pump with the larger gear set or using a stock pump/gear set and setting the engine rpm no lower than 1200 to 1400 in low gear as you stage the car. It was just an issue that could bite you at the wrong time as you go rounds and I decided not to build those problems into a transmission I was using or selling a customer.
I build them and I race them so I don't want any possible issue I can get away from. I also do not want a customer with any of those issues either.
Everyone has his or her own way to do things and their opinions but for me I stay away from the aluminum bodies from all the manufacturers if at all possible. All the major transmission people still have the cast body model and that is what I always use. Some of the people I build for want a specific brand of brake. I believe most are all about equal so I give the customer the choice of what they want.
My 2 Cents

[Floyd Staggs]

Another question, Guys.
What size wire and where do you pull the power from. A buddy said he increased the power to his brake and quickened it up. Mine is coing from the fuse block under the dash with what looks to be about 14-16 guage wire. That's what my trans guy put in.
Thanks

[Michael Pliska]

One more question-
How and how often do you adjust your band? Here is some info I found on the web:
http://www.racewithjw.com/techNotes.php
Loosen the 9/16” jamb nut tighten the bolt within 7/32” allen wrench to 72 inch pounds.
Back the adjusting screw to 3 ¾ turns. The band should be adjusted every 25 runs.

Is this what everyone is doing?

Regards,

[63corvette]

Floyd, I personally do not think the power to the solenoid will make the reaction faster. To release the brake the solenoid is de-energizing not powering up. The wire size to the solenoid depends on the length to the solenoid but generally I would say #14 would work in most cases. Shorter distance is better where you are pulling power from to the solenoid.

Michael, the procedure you describe is correct. I use 3 1/2 turns out but a quarter of a turn is not much difference. I usually adjust my band about mid season and then go through the transmission at years end. Mid season for me would be in the 60 to 80 passes range. On the transmissions I build and use I do some additional oiling holes in the drum which also helps band life and adjustment needed. Adjusting at 25 runs seems a little excessive but it depends on what shape the transmission is in with pump pressure etc.
It does not hurt to check things often.

Hope the info helps.
Rick

[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.

[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