Movit discs on RS4 (problems) solved by AP Racing. Discuss

[Chubby]

The Movit disc picture, shows face cracking, (I also have pic's of both AP and Movits with the same problem) this is due to the disc's reaching more than 750 C and the outer coating cracking under cooling..

Brake cooling depends on size of wheel and how the barke was heated in the first place (gradual braking, or track day braking).

The only real answer for the RS4 is to either lighten the car or add cooling with ducts or such.

I have spent a long time sorting the brakes out on my car and find that I use different pads for the track as I would for normal day driving.

I am also looking into a different disc for each as well, and cooling ducts which I hope will help the cooling problem.

Hope that helps...

As i said you can't have the best of both worlds... pity but that's life..



R.

[bakerdcb]

I have found that the cooling ducts from the Phaeton which a few people have had fitted seem to provide a bit of a solution to this problem. Since fitting them I have noticed that my brakes stay sharper for longer on track sessions and my yellow pagid pads, which I use for the track seem to last slightly longer. I presume because they're not getting quite so hot.

Its only anecdotal evidence, not very scientific, but I reckon if someone were to fabricate a larger ducting arrangement it would make a very noticeable difference. The Phaeton one is really very small and simple to fit and I'm sure its benefits are clear but limited by its design. As Richard says any brake set up, however powerful, will suffer due to heat build up as our cars are just too heavy for this kind of treatment over anything longer than about 15 minutes. There has to be a certain sense of realism here about what our cars can do on a track. The laws of physics cannot be defeated merely 'bent' for a short while

[Hutch]

I've been through 4 sets of discs, all of them warping, cracking or both. Very frustrating! and i run the phaeton ducts.

Looking forward to trying the AP discs soon.

Thanks FlashyG for sorting out movits mess.

[flashyg]

They have a set for you Hutch No worries Mine are going strong after 5 track-days and 20k.
Over the moon and they are still perfectly silky smooth and uncracked.

G

I use pagid pads.

[Chubby]

All brakes are designed for different reasons, and have to admit that it also depends on what the driver wants and how he / she drives.

As stated I was happy with the stopping power of the AP kit but feel that they were too soft (wear wise) which means they didn't last long.

With regards the current set up, I am doing as many track days as possible this season and have made some fairly drastic improvements to the car including, exhaust mods, induction and brakes...

Time will tell if they were the right ones..

Regards,

R.

[derdle]

I had Movits 4 pots on the front of my RS4 and after a few thousand miles experienced cracking from the drillings. I then got bad vibration under braking..but it would come and go. Whether soft braking or hard braking sometimes the car would shudder really badly and other times it was nice and smooth. At 9,000 miles the cracks reached the outer edge of the discs.

The car was tracked once with this set of discs .

Last year the car failed it's MoT because of cracked discs and they were replaced under warranty. The new discs lasted barely 6000 miles before the inside surface of both discs had worn away. The outside surfaces were fine. And with the costs of these discs I had to make up my mind what to do. I even bought stock calipers and was going to return the car to stock front brakes. In the end I went to MRC and had the RS6+ brakes fitted. I now have pretty decent brakes on the car and no shudder on braking - fine for tracking and everyday use. At the time of changing AP didn't have anything to offer.

I can honestly say that the Movits were "stonking" brakes - so powerful. But their lifespan was appalling. I must rate my experience with Movits as "poor".

Paul

(I won't say it's my 2p...cos it cost a shed load more than that to get sorted.)

[flashyg]

Thanks for that information derdle, I can totally understand your position.
Having now resolved the Movit garbage with a proper fat heavy floating AP disc, I'm elated.

I have posted here to share this with others so they are not as severely disadvantaged as you.
Sorry for your trouble and thanks for posting.

I'm now confident I don't have to spend £800 every 5k and the breaks are fantastic.
G

[derdle]

Going back to Chubby's and Bakerdcb's comments - I put the phaeton cooling ducts on my car when the second discs were fitted. As you will see from my earlier post I had to ditch these discs quite quickly because of uneven wear. The inside edge (i.e. the face receiving to cooling air via the ducts) wore so badly that the discs were u/s ... but the outside (uncooled) faces looked perfect. So uneven wear on the inside edges of both discs... so do the cooling ducts provide so much cooling effect that the inside faces wear more for some reason (c'mon there must be a scientist out there who can explain it!!!)

In addition I ran track day pads for the track, and road pads for the road and at all times the pads had plenty of meat on them to aid heat dissipation.

Flashyg - I went in blind with the Movits so only have myself to blame - didn't know about this forum before I blundered into the buying decision. Hey ho as they say. Quite happy for others to learn by my experience.

We must understand that braking efficiency is going to be a product (mathematically) of vehicle weight, and the compounds used for both pads and discs. Braking is all about friction - the better the braking the greater the friction being applied/used and transfer of energy comes into it somewhere too. Greater braking forces must be at the cost of wearing something away?

I guess we are all looking for the utopia of stonking brakes, long life pads and discs and many other factors too. I guess the best overall compromise on all factors is probably the stock setup - after all Audi may well have spent 100's or 1000's of hours researching this.

I hope that the AP setup you have provides you with what you want. I know that what I have on my car provides me with what I want and I think Bakerdcb will confirm that his stock setup (plus uprated pads) gives him exactly what he wants too.

This, indeed, a whole can or worms!

I've now got a headache after that lot, so off to bed and await the snow in the morning.

Paul

[waitey1]

I too have problems with my 6 pots. Much vibration even under normal use.I thought naively that cos I dont track it and drive fairley steadily (blued them tho`) I would be immune from all the probs you hot rodders have, sadly no.Got the Phaeton cooling ducts no radial cracking of the discs but all the driving pleasure is threatened.
Seems the answer is to take flashys experience with AP as the way ahead and dig deep again.

[derdle]

So do owners of Porsches experience these problems too?

[flashyg]

Yes when the drive a bit. They go for Alcon / AP - non drilled and many other manufacturers of non drilled.
It is stated that with today's pad and fluid technologies the benefits of drilling are lesser.

[foggy75]

I bought the Disk's and calipers from Chubby and I was shocked on how badly cracked the apracing disks was in fact they was not just surface cracks they was structural failure of the complete top plates.

I replaced these with AP Racing Strapdrives and EBC Yellow stuff pads which are meant to be very harsh on Disks I have had no cracking or show much signs of wear compared to other disks I have seen.

My gutt feeling on the B7 and rs6 Calipers is they are exceptionally good OEM products but are designed to sacrifice stopping distance over wear so if you want good stopping go aftermarket if you want good life dont break as hard on your aftermarket to match oem (o;


Strap drives are for me the way to go but as we are all individuals and some people like ghetto booty ill leave you to decide!!!!

[clived]

Apologies for being a bit slow on this guys (please feel free to blame my current dose of (real, not "man") flu and the morphine based pain killers I've found in the back of the cupboard....) but is there now an AP solution that works with the Movit 4 pot calipers? Ta

[flashyg]

AP 6 pot only, You could use these with the 4 pot as they are identical to the Movit 380 BUT....
Sorry, I don't know if the 4 pot can take a 36mm thick disc?

You need to measure a set of pads and the width of the internal carrier part of the 4 pot calliper and work out if a 36mm Diameter disc will fit in. If so your on. But I'm a little concerned the width 36mm is too much.
G

[derdle]

I think the Movit 4 pots are 32 mm. Having said that, if this is a good solution, then surely there is no harm in machining the pads down by 2mm each? OK you are effectively reducing pad life but this may be a good interim workaround.

Paul