I recently had the chance to take my car to Great Lakes Dragaway and quite a successful day for my first time ever at a track. Overall, everything went great and I was able pull a 1.510 second 60' time launching at only 2,000 rpm's. However, my main constraint is that I am preloading the drivetrain using the brakes and my wheels start to spin if I rev any higher than 2,000 rpm's.

I am looking for a way way to increase the line pressure to the rear brakes other than a brake proportioning valve. Ideas that come to mind are:

1) Removing or shimming the OEM bypass valve for the rear brakes to raise the pressure.
2) Joining the front and rear brake circuits so that the pressure is 50/50.
3) Hydraulic E-Brake, possibly with a secondary caliper in the rear for simplicity

Overall, any recommendations on how I can attempt to increase rear braking power to overcome my engine power a bit more would be much appreciated. I can't run larger brakes in the rear so that is out of the question. I am leaning towards the hydraulic E-brake although it adds weight to my car and I am trying to keep the car under 2,800lbs.

Thanks in advance for any technical help that anyone can provide.

 

Does anyone know if the master cylinder or the ABS unit controls the stock brake bias? I would gladly remove the OEM ABS unit if this would allow for 50/50 braking.

 

when you say you cant run larger brakes, do you mean rotor diameter? have you considered using a larger rear caliper? something with a bigger piston would give you more force without having to mess with the bias...

 

I have considered it but I would rather change the line pressure if possible. I will be running 15'' rims at the track so space is at a premium. My preference is to modify or remove an OEM component. If I were to buy a different caliper I would just mount it as a secondary caliper and run it idependently off a hydraulic hand brake.

 

Line lock? http://www.autopartswarehouse.com/de...e&apwidbhcym3E

 

Line lock holds pressure, not increase it. He needs more pressure

Quamen, I think The hydro hand brake will be the easiest solution. That way (if it is driven on the street too) it doesn't affect normal braking, just when you need the added pressure.

 

I already have line locks. I have found that if I use line locks in reverse by pressing the line lock button first and the brakes second I can get to 2,500 rpms. This is essentially locking "out" the front brakes rather than locking them "in". I am not a big fan of this method though.

 

I agree. I think I may just look for a set of used rear calipers from someone upgrading to a BBK. Mount them on the rear rotors and make my own hydraulic E-Brake using a Wilwood master cylinder. I can make my own brackets and handle with ease so that isn't a problem. Lines are easy also.

I just wish I knew how to modify the stock master cylinder and/or ABS system for the time being. I think to start with I may just remove the ABS unit as I don't use it anyways. I am going to do some more research tonight on if the pressure regulation happens in the ABS unit or the master cylinder.

 

Here is a diagram of the master cylinder. If I were to guess, the brake bias is happening inside the master cylinder and the ABS unit is only capable of slightly modifying the bias.

 

I was going to suggest this but I hear u on not feeling it..

I remember seeing proportioning valves that were adjustable jus cant remember where...

http://www.stoptech.com/tech_info/wp...g_valves.shtml

Jus a quick search but its something relative to this...If I come across anything else Ill be sure to let u kno...

 

um get a transbrake and stop messing with half a$$ed ideas!

at this point, just pull your stock brake system and plumb in your own system.

that way you can use a bigger master cylinder and bias however you want with a proportioning valve.

 

Check this out!

http://forums.pelicanparts.com/porsc...nder-help.html

 

Jus an example n as str 8 stated get rid of that oem Nissan crap n build ur own system with all new lines...

 

Lol. I know where you're coming from but I think I'm going to lose traction launching if I can't preload the drivetrain. I think a trans brake will get real expensive real quick since shocking the drivetrain seems to bring out the worst of the IRS. I think I'm more likey to break axles also.