Poor mans brake upgrade!

[Glen Chamberlain]

I.ve had the engine in bits so its not been running for a while but due to run tomorrow and the brakes are on so i chould be able to give a good opinion with prices too in a bout a weeks or so, cos they need to bed in to be fair! Iam confident they will be a huge improvment over the stock ones but bear in mind they are the cheap option so we cant expect to much? I'll keep you all posted as i go on!

A rough price would be a be about £200 for pads all round and discs on the front but ill cost it up properly later and let you know?

[Glen Chamberlain]

Well as for prices? I wouldn't be far out with £200. The set-up was completely stock, and is now: Zimmerman x drilled discs on the front with EBC reds and stock discs on the rear with EBC greens. I fitted the fronts first (cos i couldn't be assed to do the backs at that time!) and run them for 3-4 days and then fitted the rear pads. With only the fronts fitted there was defiantly an improvement in fade and slowing power but not earth shattering I must admit. Now the rear pads are in (only fitted yesterday) the brakes now seem much better, better response and feel but i desperately need to change the fluid cos I think I’ve boiled the water in there due to fade being knocked back a few degrees.

Overall impression so far is good. In a week or so when everything has settled down and the fluid has been changed then I expect it to be a bit better still.
If you just haven’t got the funds for the hispec kit or anything else, and want an easy kit to fit, then for £200 its not bad at all. Even if your still only feeding the 230 horses Audi supplied then its still worthwhile.

However if your goin to big BHP then spend it on bigger disc and callipers cos i guess this set up is reaching its limit @ the 320BHP mark that iam running.

You'll never appreciate brakes until they save your *** and your cars, on that bend that you slightly miss-judged!! Only then will you pat yourself on the back for getting the right brakes for the right job!

On a final note, most of our cars are worth a pretty penny and the fact that we love’em (and hate’em) isn't worth risking losing them or us! for the matter of a few hundred quid!

[2raudi]

Better pads (mintex) have already saved mine

Boy when you stomp on the Mintex, they heat up and bite like the hounds of hell.

[APNess]

On the subject of 'poor mans upgrade' - my local GSF wants to know if I'm interested in S6 (model year 2000) discs - they are 320mm, which doesn't really sound big enough to me. The A8 323mm discs and 314mm discs sound cheap, but again, I figure if I'm gonna get em done, might as well try for big as possible.

Anyone ever pursued possibilities on Merc brake discs? They are the same PCD yeah (5 x 112)? Or is it more complicated than that?


PJ

[Lee]

Mercedes hubs have a different hub centre boss. They are 66.something mm dia instead of 57.1mm. But, this dimension is the diameter that engages with the wheel. Where the Audi disk interfaces to the Audi hub is slightly larger than 57 mm (more like over 60mm). It might be worth going down to your local breakers yard armed with a vernier caliper to find out what the sizes are for Audi and Mercedes where the disks interface to the hub. I recently investigated fitting some of those ceramic disks and merc calipers from the new topline models. It is expensive but would work out cheaper than my current option in the long run (disk replacement now would cost me about 550 quid a pair if I went to Audi for my RS4 disks again). I got my fist pair secondhand, but hardl worn, for 50 quid but that was a one-off!! My floating AP disks should be a bit cheaper to replace but using 2 sets of pads for each disk will mean new disks once a year for me! Look out VISA card, you're gonna get fecked next year! I might be mad but I still haven't ruled out the ceramic disk option becasue they don't wear and are good for over 200,000 miles on a 2,000kg, 200 mph car! Yummmmy.

[Lee]

Sorry, Mercedes ceramic disk brakes is the last thing you want to read about in a post entitled 'poor mans brake upgrade'! Bit relevant cos it was Mercedes!

[Alistair C]

Originally posted by Lee
ceramic disks....and merc calipers......550 quid a pair.....floating AP disks .....2 sets of pads for each disk.....over 200,000 miles.....200 mph car......Yummmmy.

ahem - nutter - ahem!

[Lee]

I am not certified yet!! The way it's going they will take me away he he ha ha hoo hoo............

I don't **** about much. Do it once, do it right, then you don't regret it or throw cash down the pan trying lots of different stuff. There is so much to do so sort it once and move on to the next. My brakes always had a development program (hence running second hand RS4 disks whilst saving cash for the floating setup!). Problem is I now use aggressive pads and the disk replacement thing has got me thinking a bit more! Will stick to my trusty AP 6 pots tthough in the end because they are the next best thing to the ceramic jobbies.

[Glen Chamberlain]

Final note about this setup

I've now changed the fluid and let them bed in and can now honestly give a fair opinion. They are denfinatly a big improvment over the stock ones but arnt earth shatteringly good. The Red pads take a bit of warming but not much really, 1 stop of the mway will do it. once warm bite is good and fade is reduced but still achiveable with a little effort! I was probably just pushing them too hard before when they were fading.

Are they woth £200? Umm? yeh i suppose they are, but if other pads are used then price may come down making them good vale for money? Pads cost me about £120 all round which i thought was quite expensive for what is only uprated standard pads! (I used EBC's)

If you are planning to exceed the 300 bhp mark by a decent amount then go for bigger rotors and calipers! Up to that i'd say try this set up.

[Josh-stateside]

what about the 2000 -2002 S4 brakes.

They are a "floating"? two piston design.

From what I have read People have used porsche brakes with Rs2 caliper brackets on the 2000 s4.

Just food for thought.

Cheers
Josh

[Josh-stateside]

They are used on the Rs4 too:

"The diameter of the ventilated brake discs is 360 mm on the front axle and 312 millimetres at the rear. There is a dual-piston floating caliper on the front axle, and a single-piston floating caliper on the rear axle. The parameters of the ABS system and the electronic brake-force distribution system have been specifically modified to reflect the increased dimensions of the brake components."

[desmo888]

Originally posted by dan_b
I know that a 4-pot caliper makes a mammoth difference, but I need something I can afford.

About this...
There has been some argument that the 4 pot is not much (any?) better than a 2 pot (2 pots on same side).
The reason being that the force of the "sliding" pad must equal that of the "pushed" pad in a 2 pot set-up.
The 4 pot set-up accomplishes the same thing but by pushing on both pads.
So for a specific pressure or brake pedal force, the braking is theoretically the same.
Please comment...

[Pisobiker]

Dave youre right.

Given same total surface of pots and giving force for dragging the sliding pad is not rilevant, total force applyed will be the same:

Force = pressure x surface

Marco

[desmo888]

Originally posted by Pisobiker
Dave youre right.

Given same total surface of pots and giving force for dragging the sliding pad is not rilevant, total force applyed will be the same:

Force = pressure x surface

Marco

So why do high performance brakes use 4 (or 6) pots? I am not sure...
Seems hte gains are minimal if anything at all.

[Pisobiker]

Need to make a clarification to what previously stated:

Condition is: resultant force applyed at same disk radius point.

As a matter of fact force applyed to the disk will of course be proportional to the pressure of brake fluid (supposed the same) multiplyed by total surface of pots. But BRAKING FORCE is a "momentum":

F x r

Where:
F=force (=pressure x surface)
r = radius from center of disk to applyed resultant of force (about middle of pot)

So there must be said that when going from 2 to 4 to 6 pots (no matter if one side or opposed) at same disk diameter and total pot surface, resultant of force will be applyed with a bigger radius (due to pot's diameter reduction).



As an example lets say you have a 300mm disk, then

1) 2 x 50mm Ø pots = 3925 mm2;
resultant of force will be applyed lets say at about 138mm of radius;

2) 4 x 35,4mm Ø pots = 3935 mm2;
resultant of force will be applyed at about 141,2 mm;
=> ~ +2.6% in braking efficiency compared to 1);

3) 6 x 28,9mm Ø pots = 3934 mm2;
resultant of force will be applyed at about 142,8 mm;
=> ~ +3.8% in braking efficiency compared to 1).


Marco