Mk4 256mm Rear Brake Upgrade Reviews

Dave 20vT

Active Member
Mar 15, 2010
29
0
Stevenage
Hello all,

I am currently running an Ibiza FR TDI with stage 1 upgrades, as well as running the Audi 312mm front brake setup. I am thinking about fitting the Skoda Octavia VRS rear brake setup with the 256mm vented disc / bigger caliper setup.

Before I decide whether to upgrade or not, I was after some reviews from other forum members who have already made the change, as to just how much a difference they think it makes to the cars braking performance, and to any handling changes under heavy braking.

My reason for wanting the brake upgrade is that I look to do 4 - 5 trackdays a year, as opposed to just fast road use.

My current setup is EBC yellowstuff front and rear pads with Motul RBF600 fluid, and extra venting on the front brakes. I know alot of people on this forum and others are critical of the EBC pads, but having done 3 trackdays this year as well as about 4000 miles on the road, I have found them to be capable of strong and consistant stops when at temperature.

Any positive / negative (or no different) feed back on the rear upgrades welcome!
 
Feb 26, 2009
5,275
1
Wolverhampton
I realise this may not be the comparison you want, but my Toledo V5 runs the 312mm / 256mm brake set up, and even for such a heavy car I find the braking ability far exceeds my driving ability! Even on 'only' greenstuff pads it takes a while before I'm in trouble, maybe 2 or 3 70mph to stationary panic brakes before they go off.

Of course, I don't know how much of that is down to the rears, I think the general rule is about 20% of dry braking comes from the rear?
 

mgrays

Active Member
Dec 9, 2006
371
18
Aberdeen
Seeing as the rear discs seize up on standard Cupras .. they are not doing anything. I might be tempted to start with an adjustable rear pressure valve so that you can turn up the rear braking when past the valve setting. This will not do anything at 20-30% braking but it should allow you to increase rear braking above those levels.

Tricky bit is that you definitely do not want to lock your rear brakes as then you basically spin as you lose the stability given by the rear tyres .. so the manufacturers will always make the rears do relatively little. With the adjustable pressure valve you can run nearer the limit when over 20-30% braking. If you want to get more braking from rear below that 20-30% threshold then you need bigger rear brakes but not too much or you will get them to lock up and hence spin.

Rear brake valves usually are open to the rear until a certain pressure (knee point).. then they reduce the pressure to say 80% of that supplied to the fronts. This allows for weight transfer as if you are braking hard the load pitches onto the front wheels .. hence need less braking at the rear. If you put on stiffer springs then less load transfer occurs and hence you can get more rear braking; hence fitting an adjustable valve. Not actually checked what an Ibiza has mind.. maybe the valve is in the ABS..
 
Apr 13, 2011
1,971
1
hull
But rear brakes don't really do much. I have found that the standerd set up on my Cupra is fine an perfectly fit for perpose Even on a track
 

Dave 20vT

Active Member
Mar 15, 2010
29
0
Stevenage
Cheers for the replies. Regarding one of the replies, I just run standard discs front and rear, as I have found the biggest difference to the braking performance has been to buy decent pads and quality brake fluid.

I have been told by a few people that the grooved discs in particular have a detrimental effect on pads, I appreciate that all pads will wear down with time, and as above, the pads/fluid are where the gains are made (when obviously keeping the same size disc etc).

From the replies so far, I think I will retain the standard size rear brakes and look to improve pads in due course, to either the Ferodo DS2500 or even Ds3000. I ran the DS2500 pads on a Clio 172 Cup a few years ago and these were very impressive, particularly on track.
 

R1ch85

1/4mile - 13.935 @ 100.54
Nov 9, 2006
1,675
0
Bristol
I've found no real difference in performance since changing mine, but then, I haven't had a chance to test them properly on a track yet. They do however, fill the wheel a little more and don't look quite so puny. They also haven't rusted like the solid 232's did.
 

mgrays

Active Member
Dec 9, 2006
371
18
Aberdeen
Cheers for the replies. Regarding one of the replies, I just run standard discs front and rear, as I have found the biggest difference to the braking performance has been to buy decent pads and quality brake fluid.

I have been told by a few people that the grooved discs in particular have a detrimental effect on pads, I appreciate that all pads will wear down with time, and as above, the pads/fluid are where the gains are made (when obviously keeping the same size disc etc).

From the replies so far, I think I will retain the standard size rear brakes and look to improve pads in due course, to either the Ferodo DS2500 or even Ds3000. I ran the DS2500 pads on a Clio 172 Cup a few years ago and these were very impressive, particularly on track.

You can get better material for discs.. e.g. Brembo make their own grey chilled cast iron discs.
Likewise grooving will allow for more aggressive pad application (theory is that it lets the vapourised pad material to escape, and of course helps clean disc of water in rain); it will cause more rapid pad wear. Drilling does similar but if not done right will allow cracks to appear so grooving is better.
Better material like DS2500 can have higher coefficent of friction than standard stuff.. and support higher temperatures but the trade off is usually in dust creation and/or poor cold performance (i.e. you need to warm up your brakes and the first stop of the day leaves you worried.. but second one is OK).
.. so all those will help get better/grippier rear brakes.

Adjustable valve may help on longer brakes as you can push more braking balance to the rear

After that you need to increase the effective diameter of the rear discs; i.e bigger discs. Note I say effective.. there is possibility to get a little by changing the shape of the pads so they are narrower (that is what lots do now for rear discs to make them self cleaning.. sadly VAG have not learn this lesson). .. and then note the need to ensure your rear brakes NEVER lock up..we.. note I think we have EBD (electronic brake distribution) which ties in with traction control to make your brakes effectively work on each wheel at 101% slip (guessing that means we have 4 channel ABS then) but that will have "limits" for the maximum difference from factory.. so it may start to reduce braking ability if it sees too much braking on the rear; no idea how large that tolerance is!
 

hoggy a

Newbie
Mar 24, 2005
92
0
my son is running the 312mm set up on his ibiza fr which is running about 190bhp,brembo discs and mintex pads with standard rear set up,hes also changed the brake fluid to some sort of racing AP racing i think and his brakes are spot on,in all fairness the rears will be a waste of time me thinks
 
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James 1.8 fr

Active Member
May 6, 2016
10
0
Thanks for reply just picked up carriers calipers and discs today will my normal hoses fit if so do I have everything I need pads obviously thanks