Power Brake issues when racing

[styx21]

I power brake my car when racing but have had problems with creep. Have tried to power brake on numerous occasions but car will hold the line only about 20% of the time, the rest of the time it rolls a little and I red light. Can't seem to hold it on the line. So I leave at idle. Have done fine with that but thinking maybe I am leaving something some time at the line by not leaving at a higher rpm. I don't have a line lock and not sure if that will help or not. Don't want to go to a transbrake at this time as I am running stock 5r55s. Anyone have any ideas on what to try or is it just the way it is until I get a transbrake.
Thanks

 

[07TGGT]

Lol wow. Have you ever heard of a stall torque converter?

 

[styx21]

Why yes I have. It's a PTC 3000 stall TQ and that's what I have

 

[05moneypit]

How high can you get the rpms before it starts to push? Most converters list the "flash" stall as the advertised stall and it is normally on the high side anyway.

I have a PI that has been upped to 4200 and I can't hold it by foot past about 2800

 

[styx21]

Once I get to around 1200 it wants to start moving. I have my brake pedal going through the floor but the rear end just wants to push on through. Will having a line lock help hold it since I would have all the braking effort up front and not split?

 

[05moneypit]

Line lock won't help, it will just push the front tires, it is most likely doing that now. Sounds like the converter is just to tight from PTC.

My PI came at 3500 and could get it to like 2200 on foot, when they upped the stall I gained another 500-600 on foot. On the trans brake it stalls at 4200-4300

 

[styx21]

Can the converter be loosened through the tune or does it have to go back to ptc for the to correct?

 

[05moneypit]

Can the converter be loosened through the tune or does it have to go back to ptc for the to correct?

Manufacturer has to re-stall it. Have you called PTC to see what they say?

Maybe someone here that runs one will chime in with some constructive input.

 

[styx21]

No, I am going to be going to the shop that does work on my car and talk to them about it. Thanks for your help

 

[rayS197]

A line lock is for burnouts. I have the same converter/stall and trans. You should be able to footbrake to around 1500 before the car moves forward. Just keep messing with it to find what the converter likes.

 

[oh5gt]

Another route would be to install a 2-step.

I have a 2-step, line lock and PI 3200 stall converter. The line lock and 2-step have individual switches and a common 'hold' button on the steering wheel.

I switch the line lock on and hold the button for the burn out. After the burnout i roll forward and pre-stage, stage, set the 2-step switch, set the line lock and hold the button. When the other car is staged and just as the lights are comming down i floor the throttle. At the green light ( or last yellow) or whatever is your perfered launch light, release the button and go.

You have to play with the 2-step a bit to find the sweet spot but I've found because the 2-step limits the rpms and because of the erratic firing while on you can raise the launch rpms.

Alot of us 5R55S guys are using this system.

 

[kazman]

Get better rear brakes. The rear brakes hold the car on the starting line. A line lock can help. Pump the brakes, engage the line lock button, pump the brakes several times then release the line lock button (foot still on the brakes). This will build additional line presure to the rears allowing you to footbreak at a little higher rmp.

 

[styx21]

Thanks for the tips. I will give it a try. I appreciate everybody's advice.

 

[irishpwr46]

not having a line lock, youre most likely destroying your rear brakes and rotors doing burnouts. you may have actually warped the rear calipers as well. get your rotors cut, or at least sanded since they are most likely glazed, and upgrade your rear pads as mentioned before. look into redoing the torque converter since you cant get the rpms up into a good launch area.

 

[conexion914]

I have a PTC converter and can't stall much past 1800 without skiing through the beams. I have the two step set at 1500 or so and a momentary switch on the brake pedal.

Before the two step I would bring the rpms up just enough to load the suspension and I've been .00x many times.

Its just making the best of what you have. If you want to leave harder you will likely need a smaller(diameter) converter to allow it to be looser.

Good luck. PTC is a good company. They will get you set straight.

Sent from my SAMSUNG-SGH-I747 using Tapatalk

 

[styx21]

Well, I never thought of pumping the brakes before I get to the line. Will try that first to see if it holds better and I can get the rpm's up. I will also get a line lock for the burnouts. Right now I just hold the brake for a second till the tires get spinning and keep them spinning for a few seconds and roll out. Will look more at the two steps. I had thought those were for manual transmissions but after researching see that some people with auto's use them. Last resort will be the torque converter. Those aren't cheap so hope one of the other ideas work. Thanks for everybody's advice.