Another transbrake thread, & tires

[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