Transbrake reaction time

[Beyond]

Hi Hutch,

What would be considered a real good reaction time for a transbrake in terms of seconds from release to drive shaft movement?

Thanks - John

[Hutch]

Thats a trick question. How are you testing this yourself and how much driveshaft movement is shutting off the timer? What is the maximum stall speed of the converter and what is the test rpm.

I have tested this on my crappy dyno. The timer starts on release and the driveshaft has to move approx 1/2" on a 3" radius. It really only gives me a baseline and I have always used the same converter for testing.
It seems on this method I get readings of .035 sec to .3 the worst. The average for most has been about .050 and this is for purchased untuned common transbrake valve bodies.
The fastest has been .014 and all the tests are done at approx 150 degF.

Hope this helps,Hutch

[Beyond]

I'm measuring using a data logger from the point the brake is off till the drive shaft sensor shows a change which on my car is .080, if i use a change in engine rpm, it's showing slightly faster about .040/.050. In this case the car was on a RPM limiter about 2-300 rpm below flash on the converter. I assume if the limiter was set a little higher it might react a ltttle quicker w/ less flash in the converter?

This is on a TH400 with the CO2 solenoid. I'm going to experiment with that a bit more to see if I can improve it a liitle (take muffler off/different dump valve). I'm using a modified hipster brake by Neal, would a Griner be faster?

[Hutch]

I take it you are using the Co2 setup instead on the electric solenoid. It will be slower with the Co2. Yes if you close the gap between rev limit and actual stall speed it will show a faster reaction. There are many internal mods you can make to the trans to make what you have release faster. The advantage griner brakes have is that they can be "tuned" on the bench perfectly and thats whats makes them quick. What you have can be made faster through tuning but VB manufacturers have to make transbrakes somewhat a fitsall and try to make the pieces to fit all the different 400 cases, they just aren't all machined just the same.

Talk to you soon ,Hutch

[Beyond]

Yes, the CO2 from Contender Performance. I'm going to experiment with it and see if I can get it to dump faster. Nobody I talked to had tried one when I bought it last winter, so thought we would give it a try.

Thanks for the info,

John

[Shawn Morrell]

I have been using CO2 solenoid for 5 years now with not one problem. I wouldn't trade it for nothing.

[Beyond]

Shawn did you make any changes to it to speed it up any?

[Shawn Morrell]

I use a delay box so it doesn't matter how fast it reacts for me. Mine is home made after burning up a few electric ones from forgeting to shut off the switch when I back up into my pit area. My car runs 8.40 with 1.18 shorts(7.90 next year) and with no delay in the box on a .400 tree it will go red by .030/.035 seconds. The exhaust side is wide open and the cylinder is at maximum speed, air is regulated to 60 psi. I use the same type of cylinder for my shifter and my throttle stop.

I also use a hypster brake(in a powerglide) which is externaly adjustable also, it is set to leave fairly hard as I use a 36 x 17.5 pro-mod/alcohol dragster tire(goodyear) and it needs to launch hard to get up on the tire. Hope that helps.

[Beyond]

Thanks Shawn.. I'll pull the muffler off mine and look at what pressure its set at. Guess it doesn't need anymore than what it takes to apply.