The most popular automatic transmission in drag racing is GM’s two-speed Powerglide. A lot of those ’Glides have trans-brakes in them. Put those two thoughts together and voila—instant tech story.
So, we decided to show you a few tricks on installing a TCI trans-brake in an aluminum-case Powerglide. We’re not going to take you step by step through the process; TCI’s instructions do a good job of that. Instead, we’ll show you a couple things our installer, Bob, has learned from many years of modifying transmissions.
As an added bonus, we have a trans-brake troubleshooting guide to help you diagnose your ailing Powerglide. If you haven’t torn down an automatic trans before, you might want to farm out the work to a shop that specializes in performance and racing transmissions.
What’s Wrong With My Powerglide?
TCI includes this handy troubleshooting guide in their instructions to help you figure out what’s ailing your Powerglide. It’s so handy, in fact, we figured it was worth repeating here.
| Symptom | Possible Problem |
| Transmission slips in all gears | • Bad low band • Bad low band servo • Bad converter stator |
| Transmission slips or chatters in first gear | • Bad servo seal |
| Symptom | Possible Problem |
| Car backs up when trans-brake is applied | • Worn pump • Bad low gear servo sealing ring • Worn or cracked servo bore • Too much clearance in reverse gear |
| Forward gears OK, no reverse or trans-brake | • Wrong rear case gasket • Early plate on late model case • Late plate on early case • Detent cover reinstalled • Broken C-clip on detent valve • Low current to solenoid • Stuck trans-brake valve • Wrong governor • Stuck Low/drive valve • Case not drilled for trans-brake • Solenoid has wrong stroke • Exposed block hole in low/drive valve • Bad reverse servo |
| Brake is slow or won’t release | • Stuck aluminum valve • Stuck solenoid • Improper or too short valve spring |
| TCI-748200 | TCI Trans-Brake for Powerglide, Aluminum Case |
How do you dertermine if the solenoid on a P/G tranzbrake is applying to the proper depth??
In speaking with the Summit tech team, it doesn’t seem like this specification is shared in print by any of the manufacturers. We’d start by placing the call to the manufacturer and consulting with them on the exact proper depth.
I have a power glide with a pro brake when I put it in first gear and push the button the transaction goes into reverse. When I put the transaction in reverse and push the button trans. Is very lazy.
Transbrake works fine when applied, but reverse seems not to have a lot of power when reverse is needed by it’s self for backing up seams to slip is this normal is there an adjustment needed.
Because “Transbrakes” are not all the same, it would depend upon whose it is and if it was installed properly! You might consider asking your trans builder or the manufacturer of the brake.
I changed sealinoid, but still no tranbrake, hear the clicks but no hold on the brake
Why do I have to drill hole B and what
Is the purpose or drilling it . I have a TCI 628200