Rear Brake Pad Upgrades....

[Hurdy]

Luckily I now have a couple of guys locally who can help me out with OEM stuff fairly cheap and this should pay dividends with getting stuff swiftly and at *cough* cost

[Teutonic_Tamer]

....

I have it on good authority (AP Racing) that the Golf GTI does about 85% of its braking on the front wheels and consequently most big brake upgrades are front kits.

Oh, boy, you really do keep going on about that utter BS, from AP.  As I have repeatly stated, the GTI, along with most road cars do NOT have an extreme bias like that.  The Golf Mk5 platform cars are running around a 60:40 brake bias - and this is very EASY to prove!

For normal road use it's considered fine to leave the rear brakes as oem, but for trackday use it's advisable to at least upgrade your rear pads.

Nope, if you 'upgrade' the fronts, then the rears should also be upgraded, to maintain the balance.  If you don't upgrade the rears, the rear end will become un-nervingly twitchy under heavy braking, in anything other than an arrow-straight direction, on billiard table smooth and level tarmac.  And both you, and others have described this very situation.

If you don't, you may experience fade on them quite quickly and without fully realising.

That simply PROOVES just how hard the rear brakes are trying to work!!!!!!  And it also proves that the rear bias is CONSIDERABLY more than the rubbish AP are spouting!

Unless you want it as eye-candy you don't really need to change the rear discs on the Mk5 GTI to something grooved and/or drilled - For the 15% work they do the plain discs are quite sufficient.

Nope, if you upgrade your fronts with 'bigger' discs, you really need enlarge the rear discs by the same relevent amount - to cope with the 40%, not 15% the rears have to deal with.


And you have completely failed to address the issue of the rear brakes working when the brake pedal isn't even pressed!

[Teutonic_Tamer]

never had a problem with them on track and don't really see the point . braided hoses will help tho

How do braided hoses improve brake efficiency?  They do NOT.  Just another 'snake oil' product.  Braided hoses arn't even used in MotoGP, with their mighty carbon brakes, braking from 230mph!

[Teutonic_Tamer]

never had a problem with them on track and don't really see the point . braided hoses will help tho

....Weeeell, I'm inclined to take AP Racing's advice.

Perhaps adding braided hoses to the rear may also help but I won't bother with that until my next brake fluid change and also until speaking with AP and VWR again.

I remember asking T_T (Sean) about braided hoses in the past. He said that the OEM hoses are banded internally anyway and that they are more than up to the job.

Correct.  Braided hoses are only really usefull on rally cars, to prevent the hoses being cut from flying rocks and the likes.

[RedRobin]

^^^^

Hey, T_T!! Helloooo!! I think my post was done here before we had our reasoned and calm convo about the same subject on the other forum.

[Teutonic_Tamer]

if the number was 85/15 then the car would feel absolutely awful to drive with excessive wear put on the front suspension to alleviate the massive dive that it would generate.

Agreed.  If it did have an 85:15 bias, everytime you braked hard, the car would try and stand on its nose.  But it doesn't.  The Golf5 rear suspension has been designed with quite agressive 'anti-dive' geometry - an NEEDS quite a large rearwards brake bias.  This is why Golf5s are fairly pitch 'neutral' when braking hard.

Whilst I appreciate the advice came from AP (who sell brakes...front brakes.....) I would be sceptical that its actualy that bad in reality, sometimes generic flippant remarks come out with no real substance......

I fully agree!  AP have NEVER backed up this statement! 

If the bias was indeed as bad as that the first thing on my shopping list would be a huge rear brake kit IMHO

Exactly, couldn't agree more! 

Braking is about balance - 85/15 sound right to you???

Not at all correct, by a long margin! 

[Teutonic_Tamer]

My AP Big Brake Kit was fitted by their Senior Engineer at Coventry with myself present. At that time in 2006, I asked him whether he thought it was worth also fitting their AP brakes to the rear and he said no, saying that about 85% of braking on the Mk5 Golf was done by the front brakes and the power of the front AP's would 'do the job'.

The 85% value has been mentioned by him again since 2006 in our conversations and also yesterday when I specifically asked for his advice about what would be best to do now that I occasionally track (Nurburgring).

If AP are still standing by this bias rate, perhaps you can ask them to provide individual wheel braking effect readings from a rolling brake tester.  But I honestly bet they wont be able to!

[QD MBE]

As I have said, the car feels spot on with the FULL S3 upgrade, very well balanced front and rear braking.  You can feel the rears working and for the money, I would rather have a system that was designed by the manufacturer to work on a similarly sized platform such as the S3.

The front may not be as 'Eye-candy' as AP, Tarox, or Brembo, but the system works very well.  It is all about function for me.  That is why I think the Audi S3 looks a far better car that the pictures of the golf R20.

But as always each to their own.
 

[Teutonic_Tamer]

robin 85/15 would drive crap and thats the sort of split I would expect from a ford fiesta with rear drums.....

And that would usually be with the assistance of a relatively 'dumb' pressure limiting valve in the rear hydraulic circuits.

Front end dive is not a good trait - wherever possible 60/40's /////  70/30 is the figure normally aspired to

Agreed, and on modern cars with anti-dive rear suspension setups, they can often run closer to 55:45 front to rear.

And I don't know if you are aware, the new Renault Laguna has larger REAR brakes than it does up front, and that is a front engine, front wheel drive car.  The rears really do play a massive part not only in traditional 'braking', but also in terms of vehicle stabilty, when controled by ESP systems.

Dont know whether its an installation issue but the 2500 compund has been getting a bit of a slating recently over on uk-mkivs, the pad of choice over there at the moment seems to be the pagid blues

Ferodo went through some very serious quality issues in the 1980s and early 90s!  Anyway, are these Pagid Blues the same as Pagid RS pads? 

[Teutonic_Tamer]

Just thinking aloud, but both the oem R32 and S3 rear brakes will surely have been designed to work on 'driven' rear wheels (be it Haldex or quattro).

Not really.  When the brake pedal is pressed, the Haldex automatically disengages the drive to the rear wheels.  Haldex only sends drive to the rears during acceleration, and then only after the fronts have lost traction.  So that thought, whilst perfectly reasonable, is not technically correct! 

Does this suggest that fitting them on the rear of the FWD Mk5 GTI may be overkill?

Nope! 

[xxx_mojo_xxx]

TT, what would you suggest to complement (i.e. rear brakes) the 360mm 6 pot front brakes I will be getting installed in a couple of weeks time?

[RedRobin]

^^^^
I've said most of what I have to say on this subject on the other forum - I can't be arsed to drag it all up again. Likewise I wouldn't expect AP to be arsed to dig up info for a forum - You can see why most companies don't want to get involved in forum discussions and when they do it rarely lasts for very long.

All any of us can ever do is post info which we believe to be to the best of our knowledge - Sometimes it's spot on and sometimes it turns out to be bollox, no matter who we are.

Whichever brand of whatever mod we choose, we are each going to believe it's the best because it's what we chose for ourselves and it's also natural to justify our decisions to ourselves.

stokeballoon is very happy with his setup and I'm happy with mine.

[/end of]

[Teutonic_Tamer]

In my opinion i would just stick some decent pads in the back, front wheel drive cars shouldnt use much rear braking... when your trying to do everything through the front wheels the last thing you want to do it to make the back too stable!

In a mid engine car it is possible to have more rear braking... because thats where the weight is!
For front engined front wheel drive its alwase going to stand on the nose when braking, no matter what suspension setup you have... so the front wheels have the most amount of grip to put the braking force through!!

What utter nonsence! 

at the end of the day when VWR (or any touring car team) build a car if there was an advantage to fitting huge rear brakes on a front wheel drive car dont you think they would use it?

Erm - that is because a RACING CAR is a massively different beast ot a road car! 

[Teutonic_Tamer]

Guys, whilst this is all good discussion - I can't help feel confused. 

I have a big brake kit arriving any time this week.  Should I also look at upgrading my rear pads, or go for the plunge and upgrade the discs as well?

To maintain car stability, you really need to be looking at larger rears too. 

[Teutonic_Tamer]

Guys, whilst this is all good discussion - I can't help feel confused. 

I have a big brake kit arriving any time this week.  Should I also look at upgrading my rear pads, or go for the plunge and upgrade the discs as well?

....Personally I would get to know your front big brake kit first and then later think about your rears.

I'd have to strongly dispute that.  What if he lost the rear round a corner whilst braking - which could be highly likely if you just go for 'bigger' fronts!