Boxster 986 (S) brake balance adjustablity ?
Discussion
We're not allowed to alter anything with the braking system other than cooling ducts and pads.
The easy way to alter brake balance is simply to put a restrictor valve in line on the pipe to the rear brakes (assuming they are split front/rear - some cars are diagonal). I did this on a 944 track car I prepared and it worked well - became more balanced rather than having a propensity to lock the rear. The valve was about £70 and just needed a bit of pipe and some unions to fit.
Just looked, it was one of these I used:
http://www.demon-tweeks.co.uk/Search.do?method=del...
there are similar ones in the same section.
The easy way to alter brake balance is simply to put a restrictor valve in line on the pipe to the rear brakes (assuming they are split front/rear - some cars are diagonal). I did this on a 944 track car I prepared and it worked well - became more balanced rather than having a propensity to lock the rear. The valve was about £70 and just needed a bit of pipe and some unions to fit.
Just looked, it was one of these I used:
http://www.demon-tweeks.co.uk/Search.do?method=del...
there are similar ones in the same section.
Intersting stuff, I wasn't aware that the racing rules forbid it (how bizzare).
Regarding the pad route, I thought about it, but it would I would like the same behaviour at various temepratures (so really road and track), not sure how easy it is to achieve.
Btw, the 'problem' is with the rears that could definitely take more (as with most other mid-engined cars I have experienced).
Regarding the pad route, I thought about it, but it would I would like the same behaviour at various temepratures (so really road and track), not sure how easy it is to achieve.
Btw, the 'problem' is with the rears that could definitely take more (as with most other mid-engined cars I have experienced).
only some rules forbid it, it depends on series but certainly the two big places for boxsters to race do.
as cmoose said, pad selection is the easiest way to fine tune front/rear bias. regarding your concerns over different conditions, most pads respond similarly in terms of friction as heat changes across working range so any new feel will be fairly constant both on the street and the track.
as cmoose said, pad selection is the easiest way to fine tune front/rear bias. regarding your concerns over different conditions, most pads respond similarly in terms of friction as heat changes across working range so any new feel will be fairly constant both on the street and the track.
fioran0 said:
only some rules forbid it, it depends on series but certainly the two big places for boxsters to race do.
We're not allowed to do it either, so between thegoose (PCGB) and me (Logson Group BRSCC) that's both major series covered. We can't even change the pads. On the other hand, in CSCC you can probably do what you like - stick a parachute on the back if it takes yer fancy!Edited by spyderman8 on Wednesday 1st August 13:05
Sorry, that should have read don't not do. worst mistype ever!!! I knew what I was saying but my fingers or iphone spellcheck sabotaged me.
PCGB don't, specbox in the US don't and if you guys don't either that's pretty much everywhere I can think where boxsters race in numbers that aren't allowed to use adjustable bias.
That's crazy you can't run free choice on pads in your series.
Marcus, are your pad choices free?
PCGB don't, specbox in the US don't and if you guys don't either that's pretty much everywhere I can think where boxsters race in numbers that aren't allowed to use adjustable bias.
That's crazy you can't run free choice on pads in your series.
Marcus, are your pad choices free?
BertBert said:
Interestingly, my gut reaction is pretty negative on either trying to do brake bias with choice of different pads front and back or (in the case of trying to move the bias back) by fitting a limiter to the fronts. No real science involved!
Bert
Except that's what almost every race team does when allowed/necessary and why there's lots of pad choice. Bert
996 Cups were delivered from the factory with different front and rear pads to add bias to the rear since they had no adjustment.
It's a tried and tested method of fine tuning braking. The key of course is selecting appropriate pads.
chris7676 said:
Trev450 said:
I know its not pork, but we have experimented with different pads front and rear in my Evo in an attempt to reduce nose dive under braking.
Would it not be due to soft front springs (factory Boxsters do the same) ? Anyway, what are the results ?
Trev450 said:
Quite often yes. In this instance though we were happy with the spring rates and didn't want to upset that so we tried a more aggresive pad in the rear in an attempt to balance the braking efficiency. What it actually achieved is that the car now squats under hard braking instead of diving thereby making it more stable.
That must have one hell of a lot of pro squat geometry on the rear!! Are you sure that's what it actually does under braking?uktrailmonster said:
Trev450 said:
Quite often yes. In this instance though we were happy with the spring rates and didn't want to upset that so we tried a more aggresive pad in the rear in an attempt to balance the braking efficiency. What it actually achieved is that the car now squats under hard braking instead of diving thereby making it more stable.
That must have one hell of a lot of pro squat geometry on the rear!! Are you sure that's what it actually does under braking?thegoose said:
We're not allowed to alter anything with the braking system other than cooling ducts and pads.
We can run braided hoses but that ain't going to alter brake balance. One could replace a factory proportioning valve with another such as from another car but strictly speaking this isn't allowed by the rules. A lot of the racers stateside for example fit the 928 valve into their 944 race car but ISTR this increases rear bias which IMHE is the exact opposite of what one would want in this car.
Oh and the correct term is 'are'. 
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