R32 rear brake upgrade project

[dsm1983]

Didn't think this was going to be a project, so to speak. But when the brakes arrived, I realized it was going to require more work than just slapping 'em on...
The paint on the calipers was flaking and bubbling all over, so here they are:
1) after a little bit of sanding, 2) being painted with high-heat caliper paint from Pepboys, 3) finished product, 4) slotted rear rotors that go with them.
Final product will consist of the aforementioned parts along with stock GTI front brakes & pads combined with slotted rotors, Mintex Red Box pads for the rear, stainless steel brake lines, and super blue racing brake fluid.
Standby for more pics in the next couple of weeks. :thumbsup:

 

[roastpuff]

Looking good! The new paint looks nice. How come they were red initially and not blue?

 

[AERO]

Keep the updates coming. I'm wanting to do the same upgrade.

I was thinking R32 had blue brakes too???

How much larger are they, and are they single of dual piston?

Let us know how they feel when you get them on. Are you going to put your stock front brakes in the back?

 

[dsm1983]

I picked these up second hand. They were probably initially ordered from ECS or DBC without the blue powdercoating.
From the ECS website: "Converts the standard rear OEM VW/Audi 232x9mm non-vented brake system to the Audi TT/ VW 337 256x20mm vented system." Someone with more technical knowledge, please chime in to clarify what those numbers are referring to. lol
Still single piston. Rotor size is increased from 286mm to 310mm.

 

[2010GTI4me]

Very interesting... can't wait to see how they turn out!

 

[jmblur1]

no front brake upgrade? thats where most of your braking is going to come from, adding better braking to the rear might upset the brake balance.

 

[dsm1983]

no front brake upgrade? thats where most of your braking is going to come from, adding better braking to the rear might upset the brake balance.

Interesting that you say that. I've always heard the contrary (that our cars utilize mostly rear braking).

 

[absoluteczech]

vw's tend to have slightly more rear brake bias. most people will see the back pads wearing out before the front.

 

[2010GTI4me]

Interesting that you say that. I've always heard the contrary (that our cars utilize mostly rear braking).

vw's tend to have slightly more rear brake bias. most people will see the back pads wearing out before the front.

x3 on that, helps with stability under hard braking i believe.

 

[AERO]

I find this rear braking idea hard to believe, but I suppose it is possible. When you brake, most of the vehicles weight shifts to the front wheels, and its much more efficient to do a vast majority of the braking with the fronts.

If VW uses an unsually high rear brake bias, it might explain the poor braking on the stock GTI. I was planning on starting a thread on this subject, but I am very disappointed in the stock brakes. I have considered doing a full R32 brake conversion, but I fear that I still won't be satisfied. My problem in that you are very limited by the size of brakes you can run with 17inch wheels as I have.

 

[dsm1983]

I find this rear braking idea hard to believe, but I suppose it is possible. When you brake, most of the vehicles weight shifts to the front wheels, and its much more efficient to do a vast majority of the braking with the fronts.

If VW uses an unsually high rear brake bias, it might explain the poor braking on the stock GTI. I was planning on starting a thread on this subject, but I am very disappointed in the stock brakes. I have considered doing a full R32 brake conversion, but I fear that I still won't be satisfied. My problem in that you are very limited by the size of brakes you can run with 17inch wheels as I have.

Trust me, I see exactly where you're coming from. But the first time I ever heard about our cars using more rear braking, it was from a very reputable source.
The reasoning behind them being designed this way was that it causes less nose dive under heavy braking. Which makes sense.
And just so everyone's aware, eventually I'll probably go with larger brakes up front, along with a two piece rotor.

 

[gti_loki]

Mild bias helps trail braking and rotation on corner entry.

A heavy rear brake bias is very dangerous. While cornering, if you attempt to brake, the rear will lose traction too easily causing snap oversteer, not the nice gentle kind we all love. Even in a straight line a heavy rear bias will cause the car to squirm.

 

[Aonarch]

Mild bias helps trail braking and rotation on corner entry.

A heavy rear brake bias is very dangerous. While cornering, if you attempt to brake, the rear will lose traction too easily causing snap oversteer, not the nice gentle kind we all love. Even in a straight line a heavy rear bias will cause the car to squirm.

Dead on.

 

[roastpuff]

Mild bias helps trail braking and rotation on corner entry.

A heavy rear brake bias is very dangerous. While cornering, if you attempt to brake, the rear will lose traction too easily causing snap oversteer, not the nice gentle kind we all love. Even in a straight line a heavy rear bias will cause the car to squirm.

x3.

What Loki said. If you have heavy rear bias on a front-wheel drive car with most of it's weight on the front axle, you are not using your full braking capability.

I did some bias calculations with the stock GTI brake system, and look what it came up with:

67/33 bias in the stock system. For light braking, I can see the system using more rear brake than the front, like you would with a bicycle when slowing gradually. When stopping hard, you're going to have more weight shift to the front, and the front brakes do most of the hard work.

 

[dsm1983]

roastpuff,
that's cool. Thanks for the calculations. But you did it using the stock rear brake system size. Can you do it using the R32 size?