Markie J

I took part in my first airfield day last week at Abingdon Airfield. This was the first time if have had the opportunity to explore the limits of the car - an STi IV - in full.

To cut a long story short, my first two 15 minutes sessions resulted in heavily smoking brake pads and decreasing brake performance. As they day wore on and confidence grew, brake performance suffered and resulted in heavy fading curtailing the sessions. I came away amazed at the dynamic qualities and performance of the car but rather dissappointed with the brakes - which were comprehensively cooked. I had never been impressed with the "feel" of the brakes but they had always performed adequately under normal road use.

I resolved to rectify this problem before my next track/airfield outing.

Having read much of the comment on the BBS and at the various supplier sites, there seems to be a massive range of upgrade options. All roads seem to point to a complete upgrade kit consisting of AP or Brembo callipers disks, pads, hoses etc. as the preferred option.

My question is this: How superior is an AP or Brembo calliper (both 4 pot) to a Subaru 4 pot calliper? - what I'm talking about here is the calliper in isolation - same disks, pads, hoses & fluid. Has anybody tried this out?

I may be missing something here (please correct me!), but I believe brake callipers are essentially simple devices. The overall performance of the braking system is determined by the sum of the parts (stating the obvious I know) and the role of the calliper is relatively straitforward: apply braking pressure in a linear manner, dissipate resulting heat from rear of pad. Could it be that the braking performance improvement offered by the Brembo/AP kits is largely due to the improved disks (grooved etc), pads, hoses and fluid rather than the calipers themselves?

My reason for asking is the hefty price for the replacement callipers & associated kits against the cost of purely replacing the weak links in the chain i.e. pads, disks (need groves or X drilling), hoses (need to be braided to minimise expansion under load), brake fluid (to prevent boiling) and finally, addition of a master cylinder support to reduce the bulkhead flex.

I wonder if people may be chucking the baby out with the bath water? Or to put it another way, do I really need to spend £1600 improving the brakes?

May this be a long and happy thread!

HUNTY

I have Brembo's from scoobysport and the difference to standard is totally mind blowing.

I have done 2 track days and you can push and push them, the limits are huge.

You know they are special when you open the box and the compare the size and quality of the discs to the ones you have taken off.

Give your credit card some hammer, you wint be dissapointed.

Rich_R

Hi Mark,

See you found it then

The size of the 4 pot callipers on those uprated kits are larger than the 4 pot OE on STI's and UK MY99/00. Saw a P1 this morning with the (non standard) uprated Prodrive brake kit - callipers were huge.

I also suffered badly with brakes that day - checked that evening and the pads had started to crumble.

Great day though!

Rich.

Doc

I believe the Prodrive brake upgrade is made by Alcon

Andrew Dixon

Where did you buy these bits from Gary? The brakes on my car are screaming for mercy right now!

A.

Andrew Dixon

As far as I can tell, the main reason that the Brembo, AP, etc. kits give a big braking improvement is due to the increase in disc size. This mean that the caliper is fixed further away from the hub, and thus for a given pedal pressure is able to exert a greater braking force on the wheel. The larger disc also leads to better heat dissipation.

Other advantages of these kits over the standard brakes are the fact that the discs are wider (i.e. there's a bigger air gap between the faces of the discs) and also that the calipers themselves are made from an alloy - both these improve heat dissipation further. They also use better pad/disc materials to give better friction through a range of temperatures.

Some kits use a seperate disc & mounting bell arrangement. This decreases weight, allows the disc to expand and contract more easily, and once again aids heat dissipation.

Multi-pot calipers are also supposed to improve brake 'feel' and ease of modulation making it easier to sense the locking point and modulate the pressure accordingly.

There is a less pricey option available though! There's a firm (called Hi-Spec or something like that?!) offering a kit which allows you to use a bigger disc whilst retaining the standard caliper. This is acheived by mounting (and modifying?) the caliper futher away from the hub. Try a search on the BBS to see if you can find out any more details (I'm sure I read about it here.) I reckon that this kit, combined with an uprated pad material (Mintex 1155, Ferodo DS2000, etc.), steel braided hoses, etc. may well give you most of the benefits of one of the complete kits for significantly less outlay.

Sorry for the long reply!

A.

GaryC

Before you lay out £1500 on AP/Brembo kit try fitting

Mintex 1155s - £60/pair
Bremsport Grooved discs - £106/pair

Difference is awesome - on full pelt these things create so much neg G as to give a split second headache. And I've not had any fade as yet - even after 20 'enthusiastic' minutes on moorland roads!!! A friend with a 993RS (famed for superb brakes) rated this combo as easily as good as his RS!!

Have no doubt that AP/Brembo option will be a bit better still, but £1300 better?

GavinP

I had my brakes uprated on Friday by Hi Spec - now 315 x 28mm grooved disks with standard (2-pot) calipers.

Geoff (the owner) is working on a 330mm x 24 disk conversion which would elevate the Subaru 4-pot setup to a much higher level.

This will be available apparently in a month or so...

Maybe worth considering ?

Thanks

Gavin

Andrew Dixon

So how are the brakes Gavin? And could you give some idea of the costs involved? As I'm going to have to replace discs & pads soon anyway, I'm interested.

Cheers!

Andrew.

GavinP

Andrew,

I am still bedding my brakes in but you can feel an improvement already.

The Hi Spec kit will cost approx £430+VAT and consists of 330mm disks, bells and new mounting brackets for your existing calipers (i.e. move them out a bit due to the wider disks).

Please give Geoff a call at Hi Spec (Dartford) on 01322-286850.

Thanks

Gavin

sasim

Gary,

Where did you get your Bremsport disks from?

SS

Jo Peters

Gavin P

Will the Hi-Spec kit be OK with 16" wheels? Need to seriously uprate the brakes but can't afford 4 pots or 17" wheels.

Was also at Abingdon on Friday (nice to meet Rich R and the others) and after the initial brake fade, we did get the brakes back and they were actually OK by the afternoon.

Jo (passenger in white STI iv)

GaryC

Bremsport Discs from TAS in Leyland. They prepare Gp N Imprezas so 'know their onions'. Tel - 01772 454647, mention my name.

1155s from Falkland

Lars

You can of cause improve your brakes by adding new stuff, but take care how you use your brakes.
If you go early on your brakes applying low pressure and keep it for a long time, your build up heat insteed of braking power.
When you do track racing, go late on the brakes, apply max pressure and allow the brakes to cool down. Shortest possible braking distance will allow more time for cool down.
It is normal for people doing tracks days for the first time to break soft and early - just to feel confident, but you destroy your brakes.

This advise will give your better brakes,and will not cost your a fortune.

Lars

pnebbs

I have the Hi spec large disc conversion -front and rear, 315*28 front, 312*20 rear, on 17" wheels and there is so much spare room that it certainly looks like it would fit under 16" wheels - No positive though - phone Hi spec on 01322 286850

Paul

pnebbs

Dave

Is your 335 a Hi-spec upgrade with orginal callipers

Paul

GavinP

Jo,

Dave is right - I have 17" wheels which will take upto 335mm disks.

The current conversion (which I have) is 315mm x 28mm which will also fit 16" wheels.

The new kit will have larger 330mm disks but are thinner (24mm). I would think that Hi Spec will continue to offer both options.

Best to speak to Geoff at Hi Spec.

Thanks

Gavin

JamesS

Be warned the 330*28mm disk kit from Hi-Spec will not fit behing the 97MY STD 16inch prodrive wheels (S02 I think).

I went to hi spec got the kit, modified one caliper bracket got it all on (looked great) went to put the wheel on - bloody thing would`nt fit. The S02 wheels have a thick camfer on the internal face so it would`nt fit over the outer face of the caliper!!!!!!!!!!!!!!!

Stef

I couldn't resist this....
Anyone who wants an unbiased view on the 'Great Brake Debate' should look at this weeks (May 17) Autocar.
Turn to page 25 and read column 3, paragraph 2.
Quite amusing....

Stef.

Gustavo Martins

Stef:

Could you please transcribe to the BBS the Autocar paragraph in question so that people that do not have easy access to Autocar Magazine (I think it is not published in Portugal, country where I live) can know what you are trying to state?

Thanks,

Gustavo

pnebbs

Stef

Nothing to do with the APs being larger of course

Paul

Stef

Ok, here goes.....

The article is talking about the mental Mitsubishi EVO RS 450, which in standard form is of course equipped with Brembos all-round.

"Just as impressive are the brakes. The standard rear Brembos remain, but a four-piston AP set-up at the front ups the braking performance substantially."

Nuff said!

Stef.