Performance Brake Characteristics

[Rudiger]

Hi all.

Recently fitted a PBR-M performance brake kit to my BF XRT. This has 6 pot fronts and 4 pot rears.

I have just bedded them in and and still wearing them in feeling limits ect.

They definately have a lot more bite that the premium package fitted to the XRT. From 140+ KPH the old brakes would quickly "hum" when braking force was applied and the and you could feel them strat to fade as heat was built up.

With these, as I imagine with Brembos/AP ect, when brake force is applied at these speeds there is no fade, just intense nagtive gs and extreme braking force is experienced.

Now I know there are a lot of factors involved expecially when braking from high speed where you wish to reduce velocity quite quickly. Road camber, tyre pressure, tread paterns, road undulation etc and unless your on a track with good road surface, camber etc, you may find it difficult to stop in a completely straight line. I also realise that I have more than trebled the braking force to the rear wheels by upgrading to 4 pots.

My question to anyone with a 6/4 config is, under very heavy braking from high speed has anyone experienced the feeling that the back wants to come around and meet the front? There is no bias adjustment in these cars and if there was I would say that it may need more front bias, but I am just wondering if its just a standard characteristice when braking so efficiantly from high speed.

Its not an overwheliming force, but being attuned to the car I can sense it and correct.

Anyway, your comments would be appreciated.

For anyone who has not heard or seen the PBR-M series, so far they seem bl**dy awsome.

Thanks guys/girls?

[Wenier]

If you gave it more to the front it would try and spin round even more. If your car is giving you that feeling it is because the back end of the car is lifting so much that the wheels havent got the same traction and this allows it to kinda fishtail under braking. You get this easily on bikes, so really less front is what you would want. But I would just drive it and counter it as the front is where most your braking happens. Anymore at the rear would probably lock your rear wheels.

Where did you get the calipers and rotors? Are they direct bolt on?

Edited 05/02/10 02:57 AM by Wenier

[ZAP]

Our cars have Electronic brakeforce distribution. This system is designed to gove maximum braking performace to the wheels. This should prevent the car swapping ends, but aftermarket brakes could affect this.

I have had 2 cars with the 6/4 Brembos and neither had the oversteer feeling under hard braking, even on a track, unless I was braking mid corner.

It is possible you are just not used to the feeling that big brakes can give, but it would be worth having it checked out properly as it is not a problem you want to find out about the hard way.

[Rudiger]

Hi Zap and Wenier.

The PBR -m is a driect bold on with braided lines. Not nearly as expensive ast the Brembos and no one know much about them. They are basically Corvette braks and with supplied mounting brackets bolt straight on. I got them from Hitech Brakes in Moorabin (Vic). The APs were just too expensive and overkill I think, and Brembos wouldn't fit under my 18's, but then these didnt either and I had to get 19's anyway.

I have ridden bikes for years and never actually thought of that (silly me) so yes I would say it is me not used to it yet. The brake force distribution I had totally forgotten about.

I'm going to post some pics shortly. Bloody awsom looking and the good thing is they feel normal in street mode but the few boots ive given it , well im confident this early that they wont fade.

Gunna let them settle then I'll recheck everything. Im pretty sure its me getting used to it but just wanted to see what others thoight. Thanks guys.

[Wenier]

damn, im after something to fit under 17s and 18s.

[tray_182005]

Zap u r the brake man in the no arent u ? What do u believe r the best brakes Brembo,AP,PBR or Alcon? How far behind do u think the m series r behind the rest?

Thanks Trav

PS they r a nice looking set of brakes mate cant wait to see the photos

[Guest EGOXRT]

Our cars have a proportioning valve built into the master cylinder.

[ZAP]

I am by no means a brake expert, and as far as opinion on brands go, I would only stick to name brands.

The YumCha Chinease ones I would steer clear of, all the ones you listed are all very good brands.

The only suggestion I make when upgrading brakes, is ensure you have a performance tyre to match them.

Sticking 6/4 calipers on your car and then using cheap crap tyres, is pointless. You would be far better spending money on the rubber not the brakes.

I doubt there would be any noticable difference between the PBM-M series and the Alcon/Brembo/Etc as you would never see their limits on the road and would be unlikely to see it on a trackday.

[tray_182005]

No worries thanks for that. Has any1 heard any thing about JBT brakes ive seen the street ford build up use them on there ford

??

[Rudiger]

Well said ZAP.

I got rid of the standard Dunlops recently. Horrid tyre. I researched but in the end the Bob Jane guy set me up with Yoky S-Drives. At first a very quite tyre and seemed to suit the harder Bilstein/King spring setup I have. But I have driven on a lot of tyres and to be honest, I just didn't have confidence in the S-Drives in the wet. They were quiet but I was told by a guy in the know that they would have noised up as they wore.

Now what people have to realise is a good 18" tyre, may not translate to a 19" tyre. I have found this anyway.

In any case, when I got the 19" wheels I went for the Maxxis MA-Z 1. A unidirectional tyre with angualr tread pattern as opposed to the sort of straight channel of the S-Drive and Sport Maxx.

A little bit noisier and a slightly harsher ride going from 18 to 19 and lower profile.

But from the out they grip in the dry and thus far I have confidence in the wet.

I do agree totally with your opinion re tyres. A dud set will have a lower friction coefficient under heavy breaking and as soon abd the pad/rotor friction exceeds that maximum, the tyres slip. The more friction therefore grip the tyre generates allow more braking force to be applied.

Sorry if I sound like an egghead but it is all basic physics and I had to know it when investigating fatal car accidents.

The PBR-M seem to be a good package. As I said earlier the APs were overkill and the Brembos a little to expensive and wouldnt fit under the wheels I had, but in the end it didnt matter.

The one brake package I would avoid would be the $65 caliper covers that change the look of your standard calipers so they look like Brembos.

WTF???????