Griner t/brake UPDATE

My Griner LBA brake sometimes won't hold the car on the starting line. Sometimes it works OK. Always feels like it engages, but sometimes the car will roll thru the beams.
Where do I start the diagnostics?

Check your line pressure. My 904 is about 175. I dont remember what a 727 is off the top of my head.

do you bring it up to 2000 rpm when you stage

check your rear band adjustment

yes, I stage it at 2000 rpms or a little more. Please keep the suggestions coming.

Mine engaged just off idle (1100-1200)
Something else going if it takes 2k and still sometimes doesnt hold

High clutch slipping. High gear ok?

I had trouble with mine once. It was shifter cable adjustment.

Check the switch for resistance - make sure wiring is not damaged.
Had a Turbo Action unit do the same and the switch was bad.

This is correct.

How long do you have on the trans? Has this been a problem since day one?

My 904 would occasionally do this with a Griner LBA Brake. later it wouln't hold at WOT and I had to chip it down. Eventually high gear failed. We tightened up the High gear clutch pack clearance on rebuild, and added 1 1/2 turns of pressure. Never had a problem in the 5 years since.

Thanks for all of the input! looks like I have a few things to check. Any more suggestions are welcome.

Whenever I’d get creep with my Griner I knew it was freshen time. More times than not the teflon seals I use on the reaction shaft support we’re going away. Fresh trans would lock at 1000rpm

OK, Maybe I really am as dumb as a box of hair! I just tryed checking my line pressure at the center port on the pass side .... no pressure in any gear!
Where do you check line pressure with this valve body?

Most current transbrake VB's have the center pressure tap blocked off, only way to check line pressure is at the front tap with the trans in high gear.

I was getting ready to try that and see what happens. Thank you for your assistance.

reverse servo with brake on should be 180lbs

Another thing to check ... good to know! Haven't had much time recently ... plumbing problems in the house.

Finally got a chance to look at this. The pressure in the rear servo is about 135psi in low gear, then drops to about 125psi with the brake engaged. Will turning up the pressure fix this? or do I have a deeper problem that is going to require trans disassembly and inspection? As always, thank you for your assistance.

Thought I would update this, just in case anyone else is a nube to the transbrake world. Turned the line pressure up to 165 lbs, seemed to cure the holding problem ... but I think another problem has reared it's ugly head. engaging the transbrake causes line pressure in the rear servo to drop to 75 psi. Am I correct in assuming that there is a problem in the front drum/clutchpack? Could it be in the rear clutchpack? Guidance is always appreciated.

"reverse servo with brake on should be 180lbs"
Are we still talking about a 727 ? I've seen those numbers tossed about for a glide.
Any and all input is welcome