Been on a number of tracks now and starting to get the hang of the indy Rs performance. It's now time to turn attention to the brakes though which currently i'm not happy with. Braking is good, but could be so much better. Although better than the standard car, currently the car requires a 'hard as you can' pressure to get strong track day braking, and it's quite difficult to modulate while heel and toeing.

Once the tyres are up to temperature I find it nigh on impossible to lock the wheels with Ds2500 pads on the front wilwood powerlite calipers and standard sierra pads on the rear, and I have noticed heavier caterhams able to brake substantially later than me, so it's time for a change of compound. I don't want to change master cylinders as that would require all new brake lines.

Looking at the graphs of coefficent of friction the polymatrix A pads look like a marked improvement with a coefficient of friction 30% higher than the Ds2500s at almost all temperatures. So those are about to go in, but should I change my rear pad compound to keep pace with the new poly As? If so, any recommendations on a rear pad to not overbrake the rear axle(busa engine already has a lot of engine braking)

Any suggestions - is it possible to use a brake bias valve if you have only one brake master cylinder for all the wheels?

Thanks!

Have a look at Green Stuff Pads, they will do the trick.

Pedal ratio or master cly bore ? changed mine a while ago, gave much better breaking performance.

Green stuff did it for me. Excellent and specific for lighter cars such as Wfield and sevens.I would put them on the rear as well.

Mikef

Mintex 1144 for me - way better than the green stuff

i found the hawk DTC30 better than the 1144's

I had the same problem spent loads of wedge on different things, ended up fitting larger discs and brembo calipers. Pictures are in my archive.

I would go with Mintex. Had very mixed results from EBC offerings. Some ok some terrible.

It is advisable to go with the same pads front and back so they perform consistently and retain balance.

It does sound though like a master cylinder issue though if you can't get such a light car to lock the fronts. Unless the current pads just aren't getting up to temp?

I am with Mook, Mintex 1144, used them on my old Indy, a good all round pad, nice feel

It is mainly due to a combination master cylinder bore, pedal ratio and lack of servo,
All production tintops that came off the production line without are/were fitted with need a smaller bore master cylinder than the servo equipped models.
On modern cars servo's provide about 60+% of the force applied to the mastercylinder piston.

Add the fact that in a Locost style car because of lack of foot well height brake the pedal leverage ratio is usually between 4:1 and 5:1 compared with nearly 12:1 on a Sierra donor and you can see why your brakes require such a hefty shove.

Fitting a smaller bore mastercylinder will go a long way to reducing the pedal force required to stop the car and giving the brake pedal a better feel. it is an easy mod for a pocket money price using a Fiat 124 master cylinder from brake International.

Ok thanks for the input. Was going to go the route of pads/pedal/master cylinder in order of easiest to do first. I have a fiat 124 cylinder on the shelf but will require all new brake lines for it. I'm also happy with the sierra mc with DS2500s for damp/cold roads as on the road I don't want to lock the wheels readily, which will be easy when the R888s are cold. So I will try going the pad route - for reference see below - a more aggressive pad should make a difference.

My current pads, DS2500 with a friction of 0.42 in my temp range.



Mintex 1144, very similar.



Greenstuff, slightly stronger initial bite, but weak at higher temps.



My new pad experiments, the polymatrix A. Rising past 0.6 for my brake temperatures on track, considering the coefficient of friction is roughly a multiple of braking power I hope this will also get the brakes hotter too...silverstone is booked for may so will report back, possibly with some yellow stuff to try on the rear. If that doesn't work I will try the pedal ratio and Mc.

The mintex 1144 initial bite is way better than the green stuff from cold - that's one of the main reasons why I prefer them.

I am speaking from experience by the way not just looking at graphs.

Not tried DS2500's