Too much stopping power on front...

[diegom6]

since I updated my front brakes with Wilwood 4 pistons in my e30, it locks easily the front making my car slide and could result ina crash easily. I do have ABS but wasn't working right so I need to make it work first but anyways I notice the power of braking it's a lot for the front a nd maybe poor or almost nothing for the back.

In the back I have the ti brakes (5 lug swapp). A friend of mine told that in his Gti (VW) when he was autoXing it, some dudes suggested him to increase the force/clamp on the rear since he had upgraded the front switht he Audi TT rotors and calipers and would improve their times in the AutoX because the stoping power would result more balanced and overal powerfull.

I really need make my e30 brake/stop faster...any other BMW I drive, stops faster with out lock up the tires first or activate the ABS.

I also have a upgraded brake master pump froma 7 series model wich is larger, up to the task for the giant 4 pistons Wilwood.

Any suggestions there? Maybe Lee has the answer?

Thanks for any input.

-Diego

[Farbin Kaiber]

bias valve

http://www.wilwood.com/Products/006-MasterCylinders/001-PV/index.asp

[Teaguer]

^ Forget the biasing/proportioning valve .

Best and first thing you should try is to remove the factory reducer/regulators (basically a factory biasing valve that limots the pressure to the rear) from the rear brake lines ...thus increasing the pressure to the rear .

Then you can see if its balances out or if the front stil has too much bias ......if the front still locks up prematurely then you can add in a biasing/proportioning valve to limit the fronts .

[Mike B.]

You could also go with dual master cylinders spec'd specifically for F/R.

[diegom6]

Thanks Teager, I will do what you suggested...gotta find that regulator/restrictor int he back. Will report...but in the mean time my car it's under new setup of turbo.:)

[StereoInstaller1]

^ Forget the biasing/proportioning valve .

Best and first thing you should try is to remove the factory reducer/regulators (basically a factory biasing valve that limots the pressure to the rear) from the rear brake lines ...thus increasing the pressure to the rear .

Then you can see if its balances out or if the front stil has too much bias ......if the front still locks up prematurely then you can add in a biasing/proportioning valve to limit the fronts .

Hey man, where are those?

[rs4pro3]

they are up front below the master cylinder and above the frame rail, over right on the inner fender. Just follow the rear brake line down to where it goes under the car.

[StereoInstaller1]

they are up front below the master cylinder and above the frame rail, over right on the inner fender. Just follow the rear brake line down to where it goes under the car.

Thanks, man. One of these days I am gonna do a 300mm.de type BBK with Wilwood calipers and attempt to find a set of Z1 rear rotors.

I expect at some point I will need to know where the factory proportioning valves are at...thanks.

Luke

[Massive Lee]

Hi Diego, probably your front pistons are too big. They should be no bigger that 1.38"... Many kits supply calipers with 1.75" pistons. Beware.

As was said previously, remove the pressure limiting valve located in the engine bay.

Lee

[z31maniac]

Am I the only curious of what tires you are running?

If you are running some cheesy no-grip tire you will overpower your tires very quickly.

[diegom6]

Thanks Lee, I will remvoe the restrictor and see how it goes....will report later (need to finsih the turbo swapp first). And I do have the biggest pistons :(

I have 16 inch rims with Dunlop Direzza ZR but previously in the front I had SUmitomo HTRZ II I think but never tested the brakes with the Dunlops yet (they are brand new recently installed).

[golde30]

interesting, i will have to remove my that rear regulator on my e30, as im also locking up the front brakes with my RPI kit...

[Massive Lee]

In any case, if the front pistons are too big (1.75" vs 1.38" = 60% too big), even removing the fixed limiter will not help much. The initial lower end of the pressure will stay the same, and only the higher pressures will be affected as they will not be clipped anymore by the limiter you just removed. The next solution is to install very soft front pads, and very aggressive rear pads. Then if it still doesn't work, the last solution is to upgrade the rear brakes to a 300mm x 32mm kit to match the front or change the front calipers to smaller pistons.

BTW an adjustable prop valve will not affect the whole range of pressure, but only he top end that it will clip at the desired level. It is very artificial and doesn't replace a properly sized kit.

[diegom6]

Ok, got a chance here to do it (since I just bought a Gemran E36 325i auto for daily drive) so checking the zone I found only this....it's actually this part that you guys are talking about?

So do I remvoe this, join each side by plumbig it or does it has a restrictor inside than can be taken out?

Thanks,

-Diego

[Massive Lee]

This is the fixed pressure limiting valve.