big brakes

[Teutonic_Tamer]

How often have you had the brake fluid changed?  I just think that as an earlier poster said, it seems to be as a result of more frequent fluid changes by the race teams.  But if you are into track days on a road car, and need to change the fluid regularly, then it just might become an 'issue'. 

....Fluid changed from stock > AP when brake kit fitted > VWR when working on suspension (accidently punctured a hose) - All over a period of 4 years exactly.

  That really doesn't seem very often - so if I work that out correctly - twice in four years?

Again, now you are a green hell addict (how things change, heh!  ) - you really need to be changing the fluid at least every year, maybe every 6 months if you do more than two such track days public toll-road visits!    And as discussed previously, I would earnestly recommend going back to the genuine OEM fluid, which really is excellent - and is actually better than the vast majority of these 'aftermarket' 5.1 fluids - not to mention, being 100% suitable for ESP systems.  I know you have been running 5.1 for a long time, and as yet (I hope I havn't just tempted fate) havn't had any issues or probs with the ESP.  However, it is a very well known issue that the wrong fluid in ESP systems can ruin their tiny little innards - and an ESP system will be a very expensive 'dealer-only' replacement.

Re VWR's brakes - apart from being very expensive, they do snatch but have totally gobsmacking stopping power! VWR are apparently working on a cheaper and more road friendly version.

Oh yus - the VWR brakes have mighty stopping power, there is no doubt about that!    Cost-wise, well that really isn't a deciding factor for me, so it wouldn't have mattered if they were £500 or £2500.  The real big issue is that the SWMBO isn't very 'delicate' with the brake pedal  - so the brakes must have much greater progression than what VWR were offering, hence why I have to rule them out.  But if you say they are developing some newer ones - are they ready yet? 

As an aside, though, I was mighty impressed by their on-track racing operations, and have to say that Sam is a really nice, top bloke.

....I'm speaking to VWR later today (all being well) and also plan to be up there next week, so I'll ask how that is developing.

I'm sure that if you wanted to ask Sam anything he'd be very helpful but I know he's away until later next week.

OK, thanks Red.  Keep us updated.  BTW, did Sam discuss with you my meeting with him at Snetterton?!  PM me if you prefer.

[Teutonic_Tamer]

Yes it was the original RS4 that had the problem.

OK, thanks for clarifying.

So that really is quite a valid 'reference' - because the original RS4 can't be much different in weight to a Mk5 GTI - and will therefore be putting similar forces on the rims. 



Red, do those wheels have 'official' road use?  Or are they supposedly just a 'motorsport' product?

I think Audi ended up replacing a great many wheels under warranty or maybe they even did a recall on it? It was a long while ago now......

Yeah, there was a two 'method' approach.  They ether replaced the original 'soft' alloys when they were damaged for upto five years.  Or they offered a 'one time only' replacement of a harder, heavier wheel.

[RedRobin]

....

Sean, you asked me about VWR's next stage of brakes development - I spoke with them this afternoon and the kit is expected to be available in about a month and to cost in the region of £1,500 in comparison to the £2,500 for their other kit.

HTH

[RedRobin]

Sexy wheels Red, but I'd recommend ordering a 'spare' too.  When you make alloys that light, there has to be compromises to get the weight that low - and if you happen to hit a pot hole at a particularly unlucky angle (or speed  ), then they have a tendancey to fold like origami.  The original Audi RS4 (or was it 6) was plagued with this problem.

....OZ assure me that the Alleggerita's are designed as a 'Fast Road' wheel suitable for track days rather than a motorsport-only wheel. They are well aware of such 'folding' problems because one of their wheel designs suffered from it a few years ago. They aren't the prettiest wheels you can buy but my choice is based primarily on handling and feedback. The Team Dynamics 1.2 perform similarly and are half the price of the LeggyRita's but look much more motorsport and utility.

There is a bit more meat to the Alleggerita's than their sexy marketing pic shows : -

[RedRobin]

However, uprated pads on the standard disc can offer some valuble increases in performance, though with pads alone, the gains wont be large.

But for the biggest improvements in braking, then larger discs, or even standard sized discs, but with improved cooling, such as better integral vanes or drilling, along with uprated calipers - are really what is needed.

....Whilst I could simply go out and buy a pair of rear AP's I want to firstly investigate if there are any less expensive options such as just changing the rear pads to match the DS2500 fronts. I've put in a call to AP's Senior Race Engineer but he's away until later next week. I expect he'll advise the same as you, Sean, but the pads may be a short term compromise as I'm off to The Ring in a few weeks and am currently short of funds.

But just upgrading the rear pads on your set-up still wont provide the necessary bias improvement.

I honestly think that you need to be looking at the whole rear R32/S3 schebang - because not only does that set-up come with larger diameter discs, it also has larger diameter pistons in the calipers - and it is the piston diameter which will provide the greatest result in 'evening' the bias.

....I've now spoken to my man at AP and he advises me that, in the context of my style of driving at places such as on The Ring (I'm not slow but I don't go through a set of tyres!), I need only put some DS2500 pads on the stock rear discs. His concern was how even rear oem pads could easily overheat in track use and without it being fully realised. He also advised that on the Mk5 GTI plain discs were fine and any grooves were mainly on a disc either to keep the pads clean or because some people like their appearance.

I can see how this doesn't appear to address a bias improvement but I'm going to start off with just the DS2500's all round.

VWR tell me that stiffening the front end will help weight transfer and hence reduce rear end twitchiness under braking but, as Hurdy says, this runs the risk of greatly reducing that margin of feedback and the car potentially letting go! I think I'd rather experience the twitchiness as a warning sign than extend my car's limits but with the risk of no feedback before losing it!

[MAT ed30]

the new vwr brakes will be on mine soon   

[RedRobin]

the new vwr brakes will be on mine soon   

....The new new VWR brakes? The ones only very recently developed?

[Teutonic_Tamer]

However, uprated pads on the standard disc can offer some valuble increases in performance, though with pads alone, the gains wont be large.

But for the biggest improvements in braking, then larger discs, or even standard sized discs, but with improved cooling, such as better integral vanes or drilling, along with uprated calipers - are really what is needed.

....Whilst I could simply go out and buy a pair of rear AP's I want to firstly investigate if there are any less expensive options such as just changing the rear pads to match the DS2500 fronts. I've put in a call to AP's Senior Race Engineer but he's away until later next week. I expect he'll advise the same as you, Sean, but the pads may be a short term compromise as I'm off to The Ring in a few weeks and am currently short of funds.

But just upgrading the rear pads on your set-up still wont provide the necessary bias improvement.

I honestly think that you need to be looking at the whole rear R32/S3 schebang - because not only does that set-up come with larger diameter discs, it also has larger diameter pistons in the calipers - and it is the piston diameter which will provide the greatest result in 'evening' the bias.

....I've now spoken to my man at AP and he advises me that,

But he is simply looking at it from a RACING, ie motorsports point of view.  As I have repeatedly said in the past, race car brakes are set up very different to road car brakes!

in the context of my style of driving at places such as on The Ring (I'm not slow but I don't go through a set of tyres!), I need only put some DS2500 pads on the stock rear discs. His concern was how even rear oem pads could easily overheat in track use and without it being fully realised.

Erm - then that is a blatant admission of just how much 'load' the rear brakes are under.  A road cars rear brakes play a MASSIVE part - not only in stopping the car, but also in terms of vehicle dynamics.

He also advised that on the Mk5 GTI plain discs were fine and any grooves were mainly on a disc either to keep the pads clean or because some people like their appearance.

I fully agree with the comment on the grooves, but strongly disagree with the 'plain discs' comment.  On a remaped GTI, and even more so with big front brakes, the rears really cry out for ventilated discs.  You just need to monitor pad wear rates on cars with standard brakes, to see how agressive the Mk5 is on its rear anchors!

I can see how this doesn't appear to address a bias improvement but I'm going to start off with just the DS2500's all round.

If you just use DS2500s all round, then you might actually make the bias worse - simply due to the compound of the DS2500.

VWR tell me that stiffening the front end will help weight transfer and hence reduce rear end twitchiness under braking

But that will only really work when you are in a dead straight line, on a flat and level road.  The moment you apply some steering input, or get lateral forces due to leaning road surfaces, or even noticeable side winds - then there is a high probablility that the back end will brake away much sooner, and with much less warning - those traits are fine on the race track, but highly undesireable on the public road.

but, as Hurdy says, this runs the risk of greatly reducing that margin of feedback and the car potentially letting go! I think I'd rather experience the twitchiness as a warning sign than extend my car's limits but with the risk of no feedback before losing it!

Very wise! 

[RedRobin]

But he is simply looking at it from a RACING, ie motorsports point of view.  As I have repeatedly said in the past, race car brakes are set up very different to road car brakes!

....No, sorry but he's not. The AP kit I'm using has been specifically developed for "Performance Road" (fast road) use as opposed to their "Competition" (racing) offerings. Plus he knows me personally and my car and my non-race driving activities - I haven't just bought a product off a retailer.

If you just use DS2500s all round, then you might actually make the bias worse - simply due to the compound of the DS2500.

....Oh dear! Rear DS2500's have just arrived yesterday in the post. Please send me a get well soon card to the local Nurburgring hospital.

I'm going to try them out. Wish me luck!

[Teutonic_Tamer]

But he is simply looking at it from a RACING, ie motorsports point of view.  As I have repeatedly said in the past, race car brakes are set up very different to road car brakes!

....No, sorry but he's not. The AP kit I'm using has been specifically developed for "Performance Road" (fast road) use as opposed to their "Competition" (racing) offerings.

And this is where our opinions are poles appart.

What is absolute fact - is that the sole remit of the AP Racing company, is that they are only authorised to 'develop' products for motorsport/competition purposes.  They do NOT have any remit for developing products for road car applications.  It is just Brembo who have the authority to develop road car products - and is something they do exceedingly well.

Secondly, the calipers you have are NO DIFFERENT to their normal 'racing' calipers - they have not been 'specifically developed just for you', nor any other 'road car' application !!!!

Finally, your claim of '''"Performance Road" (fast road) use''' applies simply to the brake PADS - and this is no different to the offerings from say Mintex or Pagid.  Trying to describe either discs or calipers as 'fast road' is utterly misleading - and is not the 'norm'.

Plus he knows me personally and my car and my non-race driving activities -

And . . . . .

It still doesn't alter the fact that APs products are designed for motorsport applications.  Imagine trying to put a McLaren Mercedes F1 2.4 V8 engine under the bonnet of a Golf, or any road car.  You'd soon get mighty p!ssed off with its 4,000rpm tick-over speed - and having to rev the nads of it at 18,000 rpm to make the power.!!

I haven't just bought a product off a retailer.

But in all fairness, it is often the 'retailer' (especially when they are a 'specialist retailer') who has far greater knowledge of how products fair in the 'real world' use on public highways, interspersed with the occasional track day! 

If you just use DS2500s all round, then you might actually make the bias worse - simply due to the compound of the DS2500.

....Oh dear! Rear DS2500's have just arrived yesterday in the post. Please send me a get well soon card to the local Nurburgring hospital.

I'm going to try them out. Wish me luck!

Hopefully, the ESP system should still keep the car in check.