Uprated brakes

[CliveH]

I read a lot on here that the stock S4 brakes are "next to useless" and similar expletives, so I guess if I'm going to have an ECU remap, I need the stopping power to match.

I took a look at the Porsche upgrade from AMD, and then thought again when they quoted me nearly £1,900 fitted! Does anyone have any experience of what the "other tuners" offer, pricing, and how effective they are?

[smurfbus]

Dont believe everything you read.

Stock brakes are good in normal driving. If you track the car then you'll need the bigger brakes as the stock brakes cant take the heat .

[Dippy]

Clive,

Do you really need others to tell you if your stock brakes are good enough?
For surfbus they are fine for his driving style.
For me, I TOLERATED them for a year but they never had the stopping power I expected for such a car. When I drive any B6 or B7 A4 (as I did yesterday) I am reminded about just how poor the stock S4 brakes were by comparison.

Personally I think that referring to brake performance on the track is misleading. Yes it is important for the track, but how they perform on the road is more important. And I'm not talking about normal driving. That is irrelevant. What is relevant is an EMERGENCY STOP!

So I suggest you find an open section of road and accelerate hard. Then do an emergency stop, but do NOT let the acceleration drop (remember that the force required to decelerate a vehicle is greater when it is accelerating than when at steady speed).

Now make your own decision. Was that good enough for an emergency stop?

It wasn't good enough for me which is why I upgraded mine.

However to your original point, although I have the AmD fitted Porsche brakes, I am unconvinced that they are good value for money compared to other solutions. As well as waiting for further answers to this post, I suggest you do a search and you'll find quite a few useful posts on the subject.

[CliveH]

Many thanks Dippy,
That is really useful stuff. Actually, the reason I raised it is that I do find the brakes very good (and had a rear-end shunt recently from a Renault Megane, who couldnt stop as quickly as me to prove it! - not that I would want to compare with Renault brakes).
But whilst waiting for further posts, I will do as you suggested and hit them hard under acceleration and also search the other threads on here.
Cheers,

[derdle]

I had an S4 and thought the brakes were merely OK. I've since bought an RS4 and again thought the stock brakes were "adequate". I then drove a standard A6 loan car and thought that the RS4 brakes were crap by comparison. On advice I upgraded the RS4 brakes to Mov-its (Kim Collins - QST) and the difference is amazing. The car now brakes the way I thought it always should have done! Much lighter touch required on the pedal for normal braking, but when pressed in anger the car stops so quickly my eyes almost pop out.

I guess a similar upgrade for the S4 will provide similar results.

Good luck.

[CliveH]

Thanks derdle.
Do you mind me asking what you paid for the Mov-its upgrade?

[derdle]

The S4 upgrade will be different to the RS4 - have a gander at the QST website:-


http://www.qstuning.co.uk/list_for_car.asp?car=s4v6

Paul

[smurfbus]

Stock S4 brakes were the second best in the S4 shootouts brake test! There were a lot of bigbrake kits in the cars that were tested.

Stopping is mostly dependant on the tires you have. The problem with stock brakes is that they fade when they get hot enough, but IMO emergency brake is ok with stock brakes + good fluid.

I've got movit 342 fronts for track use and they are fine also in normal driving and no squealing yet with the less agressive movit pads! I think they were about 2500eur shipped (got some discount as we made a small GB).

[tartan_rob]

I agree with smurfbus...for what its worth. Three main components to a brake set-up, discs, pads and fluid. Fluid -get the best you can afford, it is made to withstand high temps without boiling and change as often as you dare, after about 1year in the car it has soaked up about 20-30%moisture. Water boils at what temp?

Discs - sorry to say it chaps but the co-efficient of friction between most metals that could be used for discs is very similiar. The only way to make a big differance is to goto carbon fibre discs but a tad expensive + wear quickly + need to get on the far side of 400degC to work.

Pads - now thats where you can make a decent difference...not sure whats best but try buying the cheapest set you can find and then, do a brake test and swap them for a good set (say pagid fast road). Differance is immediate.

Then we come to tryes and suspension. A worn set of shocks will reduce overall braking efficiency by as much as 50%...! Tyres make the biggest single differance. Try it out immediately before and after changing tyres? The more grip the trye has with the least amount of flex is the tyre that will compliment the brakes....I don't track my car but do drive hard and I have never had many issues with the brakes (std but dot5.1 fluid) apart from always stopping a few yards earlier than I thought I would, I would put that down to a decent combination of good condition shocks, clean and fresh fluid, good tyres (S03's) and high friction levels of road surface....but thats just my little opinion (with a few facts thrown in)....

[Nige_RS4]

Stock S4 brakes were the second best in the S4 shootouts brake test!

Did I miss something - what shootot?

[smurfbus]

'European car' S4 shootout two years ago.

[jeffw]

Do you have any links to the article ?

[KayGee]

It can be found here........

http://toasthost.com/achtuning/gallery/album14

[UKS4APR1]

Discs - sorry to say it chaps but the co-efficient of friction between most metals that could be used for discs is very similiar. The only way to make a big differance is to goto carbon fibre discs but a tad expensive + wear quickly + need to get on the far side of 400degC to work.


Tartan_Rob I think you are overlooking the ability of the disc to dissipate heat i.e. keep cool, the thickness of the disc & design of the internal venting vanes is very important. Also sliding calipers are much inferior with regards to pedal feel and even application of pad to disc compared with a 4-pot setup. Sliding calipers have much more movement/slop in them. A multi-pot design allows for a larger pad and therefore a larger friction/contact area with the disc.

[KayGee]

Seems some confusion on this thread about brakes and what components affects what. For a quickie guide to brakes try this post one of the best I've ever read.

http://forums.audiworld.com/s4/msgs/2015761.phtml

Rob you missed tyre pressures of your list! Affects acceleration and decelleration equally. Often neglected.

I agree S4 brakes are OK, however go to a track or drive across Milton Keynes (same effect on brakes) and you'll find brake fade after three or four roundabouts.

During normal road driving repeated braking doesn't happen very often as you tend to maintain your speed. Under these conditions S4 brakes work OK.