I was reading my new issue of HOT ROD today and a trans-brake came up a few times and i dont know what it is. Its obviously a hi-performace automatic transmission utility.

 

The transbrake "locks" the transmission. This allows the motor to be brought up to the desired rpm against the converter prior to launch. The car is launched by releasing the transbrake, which is controlled by an electrical solenoid and a relay. It is similar to bringing the rpms up by holding the car with the brakes. It is more effective than "brake torquing" because a powerful car will easilt overcome the brakes and the car will either move or the rear wheels spin before the desired rpm is reached. It is used only in racing.

Rich Krause

 

From what I understand, a trans-brake (activated by pressing an electrical button) simultaneously applies the forward and reverse gears of an automatic transmission, effectively putting the transmission in "closed loop".

This configuration presents a load to the engine without having to hold the car with the braking system, and will allow a turbocharged engine to build high boost on the line. The torque converter is brought to or near it's stall speed with the throttle, and at the moment the trans-brake is released (by releasing the button) the reverse gear is released and the car will immediately lunge forward at full power.

 

Yep, forward and reverse at the same time, I bet thats great for the life of the trans

Automatics suck anyway

 

Great comments so far! The t-brake is a solenoid that controls reverse electrically. Reverse and neutral basically become the same, and the car will no longer go into reverse mechanically...the t-brake must be applied.

 

So if it brings the car up to the desired RPM, does it replace the need of a high stall convertor?? You just get it to where you want it and release the trans brake to launch?

 

No, the converter (for a given engine) will determine how high the motor will rev against the brake, that is stall (by deifinition).

Rich Krause

 

You can still get your stall of choice, it is not a replacement in that regard.

 

I'll give you an example with my combo. The converter is a Hughes 5800 rpm, and I have an adjustable rev limiter connected to the t-brake...usually set at 5600 rpm. I stage the car, hold my finger on the button and release the foot brake (the t-brake is keeping the car from moving). Next just hold the gas to the floor, wide open, and the rev limiter holds the motor at 5600rpm. When the lights come down simply release the button and hold on. 1.19 60' time!

 

Wow!! That's impressive! I guess the only limiting factor then is TRACTION, but if you're running in the 8's, I guess you've got that sorted out eh?!

Quick Q: is a trans-brake (kit?) expensive, and how difficult to install? (self-installation, or tranny shop??)

THX.

 

Isnt that hard on the tranny?, I have always wanted one but i dont think the average tranny will be able to take too many of these launches. It really reminds me of putting the car in neutral and giving it about 4k rpms and putting it in drive. I know thats not good for the tranny or the rear end. So how do you guys keep from going through trannys?.

 

Yes it is brutal on the drivetrain, and is overkill for the average street car. My trans can handle 2200hp, and I run a Mark Williams 9 1/2" rear and MW driveshaft. If the car is built for it you won't have any problems. The t-brake is worth about .15 at the 60' for me.

Spend more money! lol

 

A transbrake should only be used on a race transmission. Depending on the amount of hp and the comonents used it won''t necessarily shorten tranmsion life. The input shaft takes the brunt of force. So, it's all a matter of $$$ as a good forged input shaft may add $3-500 to the price of the transmission.

Rich Krause

 

haha....a few more things i haven't read yet but the good Dr was getting to:

1) Every second on the transbrake is pretty equivalent to 100* of tranny fluid temp So you must know how to use a t-brake efficiently or plan on buying plenty of trannies and converters as spares until you rebuild the ones you just burnt up

2) No more automatic shifting, was you have a transbrake (this doesn't apply to trans-brake equipped 200-4Rs which still allow automatic shifting) the tranny will not shift on its own anymore. It will be a "reverse manual" automatic. Meaning YOU will have to shift every gear and the tranny will start out in any gear as well. The "reverse" means that instead of the lowest position of the shifter being 1, then 2,3; it is reversed. Now the normal "D" position is 1, then 2,3. Get it?