help with launching my car

[Tom Tom Turbo]

what is going on here? With the mods in my sig I can only hold about 3 psi before the tires start breaking loose. I want to be launching around 8 or 9 psi to get an awesome 60' time. Right now the car's best with slicks is a 2.0, but that was with a set of control arms that were kinda goofy. Do I need a line lock to hold that kind of boost or just the bigger shoes in the rear?

 

[V6POWER]

Line lock is for locking front tires while doing a burn out, not launching the car. A transbrake is used to hold car at line and launch hard.

 

[turbo2nr]

Try a trans brake. Best bang for the buck. I have 100% stock suspension, even the original shocks and arms. I get an easy 1.51 with a tranny brake. Never tried higher boost. I've gone up to only 9-10PSI launch. VERY fun! Cheap also. Don't get carried away with the He-Man, Uber-launches, the axles may brake around 10PSI. I upgraded that and the wheel studs to the next size up. Driveshaft loop is a good idea.

 

[DonnieShort]

If you want to foot brake it then you will need the larger wheel cylinders from an S-10, manual tranny, non AC ( I think, just search S-10 wheel cylinders ) and get two sets of brake shoes and use the long ones out of both sets. After that you should notice a real improvement. And for whatever reason that doesn't work there's always the transbrake.

 

[rodman99999]

That's S-10 manual brake cylinders. Ron's Automotive used to offer a kit with a bypass valve that diverted all the hydraulic pressure to the rear cylinders at one time. With that, the S-10 cylinders, and a set of all-long brake shoes: you oughta be able to hold whatever boost you want. Are your brake drums fresh(round/no scoring)? If they're not: have 'em turned. That'll help a bunch too! I always wonder about the added stress a transbrake must put on the drive train after the tranny. Has anyone experienced a higher-than-usual failure rate on axles/rearends/lugbolts, using one?

 

[neogeo87]

trans brakes

I installed a trans brake with a 400 turbo trans and was leaving at approx. 15-18lbs of boost when the 28 spline axles and factory posi unit let go. The LH axle twisted off and damaged the posi. I now have 33 spline Moser axles and a spool. Not the best for everday driving but tolerable. With a transbrake everything in the drivetrain will be stressed to the max.

 

[XLR8]

Do I need a line lock to hold that kind of boost or just the bigger shoes in the rear?

You NEED a line-lock. Using a line-lock while doing your burn-out will keep the rear brakes cool and allow you to hold more boost with no other changes. I am able to hold between 12# - 14# depending on track prep with stock brake pads/wheel cylinders. And when staging hold the brake pedal down HARD.

 

[turbo2nr]

I installed a trans brake with a 400 turbo trans and was leaving at approx. 15-18lbs of boost when the 28 spline axles and factory posi unit let go. The LH axle twisted off and damaged the posi. I now have 33 spline Moser axles and a spool. Not the best for everday driving but tolerable. With a transbrake everything in the drivetrain will be stressed to the max.

I say keep it under 10PSI, or just be ready to get towed home. The guy above is a prime example.

Cal Hartline is still running the Buick rear!