Has anyone done this?

It seems fairly staright forward using the exsisting caliper and carrier, just going to make a braket

Although another route i might go down is hav a bracket made for the original to use as a handbrake only and then use the exsisting maounting points for the Carerra rear calipers i have!

Just not sure what way to go yet?

I know what id rather do lol

I know Audi 300mm S4 discs can fit if you re PCD them! but i dont want to go that route plus ive got a few porsche and VRs calipers and discs in the garage and i thought id use them!

I'd be slightly concerned about locking the rear wheels (braking causing weight transfer away from the rear, making it lighter) if you had to brake hard, dunno whether it would be to the point of being dangerous though?

Why do you want to do this anyway? The brakes don't really do that much on the octy, and putting 312's is likely to make the wheels lock up.

Why do you want to do this anyway? The brakes don't really do that much on the octy, and putting 312's is likely to make the wheels lock up.

NOPE!

If you look up the togue figure and how a 312mm disc will change the bias it wont be an issue plus im not going to use a bigger caliper just move it out with the standard, or fit carerra rears with are smaller pistons so eiether way it will be no issue

The older VAG platform cars are underbraked on the rear and if you compare a mk4 chassis car with say something like a BMW or Mercedes then yourll see what i mean.

I know there will be some smart arse out there that will come back with something like the back brakes only do about 30% of the braking anyway!

Yeah true but its not that simple!

Basicallly is down to the mechanical bias on the car and weight transfer

There will be no issues with these brake set ups on the car and a believe that there are a few companies in the uk that make a 300mm + brake conversion for the rear of a mk4!

You could put Porsche Cayenne 6 pots on the front and 997 Turbo rears and have no issues what so ever, hell you could even go PCCB if you had the money and youd have one hell of a set of brakes!!!

I understand what your concerns are and that an RS only has 7x17 wheels and braking traction is easy at the best of times but ive got Porsche wheels on mine so once again, no issue!

All this and i only wanted to know if it had been done before!? before i do some calculations and a trail fittment!

Do it and find out ...It'd be interesting.

If it was worth it tho, im sure skoda and hundreds of other car manafacturers would of used large disks on the rear of average saloon/hatchback cars heh heh

Do it and find out ...It'd be interesting.

If it was worth it tho, im sure skoda and hundreds of other car manafacturers would of used large disks on the rear of average saloon/hatchback cars heh heh

Most do! lol

Like i said look at BMW Merc Audi even the new VWs like the Passat and the Golf R32 have big rear discs and the new Superb has 310mm on the rear!

The size of the rear brakes won't cause locking up, and 312mm is far from the largest rear brakes fitted various mk.4's out there.

I've seen the compbrake 330mm rear rotor/bell and caliper setup on a few.

The size of the rear brakes won't cause locking up, and 312mm is far from the largest rear brakes fitted various mk.4's out there.

I've seen the compbrake 330mm rear rotor/bell and caliper setup on a few.

My point exactly

Take a look at the K Sport brakes on The R36 Golf Unit18 is building, not sure on disc size but 8 pots at the front, four pots at rear. Discs are easy 350+mm front and rear.

Spacing the caliper out further from the centre will increase the performance, even with the same pad and caliper.

Take a look at the K Sport brakes on The R36 Golf Unit18 is building, not sure on disc size but 8 pots at the front, four pots at rear. Discs are easy 350+mm front and rear.

Spacing the caliper out further from the centre will increase the performance, even with the same pad and caliper.

Yeah moving the caliper out creates more torque, braking force

Hmm.... Interesting stuff. I understand the part about moving the caliper further out increases braking effort. That is why 312 discs are better than the 288's even though the pad area is the same. Means the pad has to travel further in one revolution.

Now that you mention it, was looking at Jags with the old man the other day and the XKR has massive front discs and the rears are just as big too.

Hmm.... Interesting stuff. I understand the part about moving the caliper further out increases braking effort. That is why 312 discs are better than the 288's even though the pad area is the same. Means the pad has to travel further in one revolution.

Now that you mention it, was looking at Jags with the old man the other day and the XKR has massive front discs and the rears are just as big too.

Most of the new BMW's are the same massive discs at the front with the same size, almost! at the rear just with a lesser pad surface area

Going to mock up a bracket today and see how it looks!

Pointless and not needed.

You could make the brakes unbalanced.

So you've noticed that BMW and Mercedes have bigger rear discs. Did you not think that being rear wheel drive might be the reason for that, then? Changing the rears to that degree without uprating the fronts has got bad news written all over it. At least you're using the original calipers though so hopefully the change won't be too drastic.

Edited 11 July, 201114 yr by demonufo

A little knowledge is dangerous!

Used to work on Group A BMW's so im fully up to spec on brakes!!!!!!!!

Just wish people who dont know what they are talking about would just stop putting pointless opinions in!

Edited 11 July, 201114 yr by dannyboy759

What size front brakes are you running.

What size front brakes are you running.

312mm with Porsche Carerra Calipers

Whys that?

312mm with Porsche Carerra Calipers

Whys that?

Just wondered, still seems daft to fit the same size rear brakes

Just one question, if the back brakes dont do alot why would you want to do it, just seems a waste of money,

Plus i thought the point of asking a question was to get peoples point of view not to fire them down in flames because there not clued up ex rally car mechanics

Plus he shouldn't be so quick with the assumptions anyway, let alone be

downright rude about it. Aside from all that crap, the one thing that hasn't been taken into consideration is the extra heat the larger disc effectively passing through the pads much faster. Fade may well end up being a big issue with what are pretty fade prone brakes to start with. Standard pads are an almost definite no-no with heavy prolonged use.

I wasnt been rude people make assumptions based on a little knowledge

I wasnt trying to upset anyone and for that ill say sorry now!

IMHO the back of an Octavia has always been very skitish and to be honest could do with more braking

The cost isnt going to be that much as ive got a spare set of 312 discs in the garage and i can fabricate a braket to move the exsisting calper out, so the cost to me will be next to nothing.

I understand all your points about braking force and heat but to negate that it will be a bigger disc therefore stay cooler!

And the brakes arent going to work any harder, just be the nature of the sioze of the disc it will provide more torgue.

I mean why does the R32 have 330 upfront and, is it 288mm at the rear?

I know its four wheel drive but to be fair thats not got a lot to do with it.

It will work fine, ive done some calculations and im confident that it will work great

If not nothing ventured nothing gained! lol

Will try a mock up this week and see how it looks and the fabricate some brackets and give it a go and come back and let you guys know how it works, or doesnt!!! lol

Take it from someone who HAS done this bigger rear disc conversion....

Bigger rears do make a difference, but nothing that makes the ride dangerous.

330mm rears do require big discs up front..

I ran 335mm up front with AP 6 pots for several months with 330mm rears using OEM calipers with no problems.

360mm fronts and 330mm rears work just nice....trust me!

Steve

I wasnt been rude people make assumptions based on a little knowledge

I wasnt trying to upset anyone and for that ill say sorry now!

IMHO the back of an Octavia has always been very skitish and to be honest could do with more braking

The cost isnt going to be that much as ive got a spare set of 312 discs in the garage and i can fabricate a braket to move the exsisting calper out, so the cost to me will be next to nothing.

I understand all your points about braking force and heat but to negate that it will be a bigger disc therefore stay cooler!

And the brakes arent going to work any harder, just be the nature of the sioze of the disc it will provide more torgue.

I mean why does the R32 have 330 upfront and, is it 288mm at the rear?

I know its four wheel drive but to be fair thats not got a lot to do with it.

It will work fine, ive done some calculations and im confident that it will work great

If not nothing ventured nothing gained! lol

Will try a mock up this week and see how it looks and the fabricate some brackets and give it a go and come back and let you guys know how it works, or doesnt!!! lol

Who knows. this may be the next big Briskoda mod!

The thing is like Steevie said they work fine as i thought they will!

Its only a matter of making a flat H shapedbracket and drilling and tapping it to move the caliper out

Well the main thing here is, for those that can, this isn't a difficult thing to try and is easily reversible. On the up side (in a big way) at least you'll be getting rid of those flimsy disc guards.