Brake bias valve not changed - whats the impact?

[RLambert]

Just realised that I still have a 45 bar brake bias valve even though the car has had the larger rear caliper upgrade (bl**dy sloppy Americans not doing a proper job !).

I'm going to change it to the 55 bar one but wondered what impact the 45 bar one has had on my cars braking ability. Have the rear brakes been under or over working ?

Cheers

 

[Steve Brookes]

You're not getting full use of the rears. When you brake hard (which you obviously do when you're racing []) you'll quickly reach the 45 bar limit and no matter how much harder you press, no more pressure will go to the rear brakes. Getting it changed to the specified 55 bar regulator should see an improvement in your overall braking system. I've heard that some racers who prefer a little more rear bias, even go to the 60 bar version.

 

[RLambert]

That's why I've been getting through so many front pads and cooking the front discs then...!! It's all starting to make sense now, no wonder I've been struggling with the brakes.

Perhaps at Thruxton I'll actually have some brakes that work properly.

 

[h_____]

You may want to ensure you have tested your new setup prior to Thruxton! It has a couple of big braking areas, not least into the chicane after church. Thats probably going to be the fastest you will see on a UK circuit in the car. Not a circuit for the weak! Truly terrifying when taken well. Something I've never manged when I've been. If you arent sure that the change is going to be right, consider putting an adjustable one in (if your regs allow). However changing brake bias is for the advanced, or simply useful in the wet. More than sheer stopping power it will affect the cars balance in to the corners. This appears to the key to driving 911s fast, again not something I managed to achieve. I spent some time with last years Pro-Am 1 Carrera Cup winner, he can do things in a car under the brakes that I could only dream of. Very impressive.

Oh and race report on Thruxton when you get there pls? [] We all love reading about this stuff.

 

[Steve Brookes]

Well done on the race win at Thruxton Richard []

Does this mean you've sorted the brake problem now?

 

[RLambert]

Thanks Steve.

The car was amazing in the wet, really good balance and the brakes were brilliant.

In the dry though it was a different story, I was still getting the hard peddle. The brakes were getting quite hot which they wouldn't be in the wet so perhaps that is a factor? I don't have any cooling other than the air deflector on the A-frame. the brake balance was good though with no rear lock up, I might even get away with a bit more bias to the rear.

I've put new ABS sensors on the front as the old ones were a bit melted, so the last thing to try is a different ECU.

I may do Silverstone later in the year so I'll see if I can borrow one for then.

This weekend I'm racing an in the Ma5da MX5 champ at Oulton so that will be an interesting experience !