Brake upgrade help

Brian H

Zorg Expert (I)
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E36/7 3.0i - E85 Z4///M
I would like to upgrade the brakes on my Z and having been down this route before (and failed) I would like to understand what impact any possible upgrade will have. There seems to be plenty of people that throw BBK on 1.9s - 2.8s but doing this must affect the braking bias, front to rear!

Facts I know:-

I have a 2 port master cylinder (DSC) and the ports are as follows:-

  • Port 1 = 23.81mm diameter
    Port 2 = 20.64mm diameter

There are two lengths listed for the master cylinder, these are as follows:-

  • Length 1 = 35.9mm
    Length 2 = 116.4mm

Port 1 is for the front brake circuit and port 2 is for the rear brake circuit.

My brake calipers have the following Pistons:-

  • front caliper single 54mm diameter piston
    Rear caliper single 36mm diameter piston

My front disc sizes are 300mmx22mm

I have tried the following:-

E46 330ci front brake calipers and carriers with 325mm brake discs, these fit perfectly but the brake bias is not right, the calipers for the E46 have single 57mm Pistons.

Porsche 4 pot brake calipers and carrier, these would need some fettling to make physically fit and spacers on the front of the car so this is not an option.

Over to you gurus, how do I calculate the following:-

Relationship between the piston size in the brake master cylinder and the caliper piston size?
Current brake bias? I've tried to do this and got the figures to front 57% and rear 43% but not sure.

What are your thoughts :)
 

t-tony

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E89 Z4 23i Auto
That would be my thoughts too, an adjustable bias would surely give you a range of options Brian?

Tony.
 
Z

zedonist

Guest
The key to the upgrade of 325mm upgrade us to upgrade the master cylinder to the one off the M3, this is the same for the Porsche caliper upgrade, other than that is as said above which was done on the mk2 escorts and fit a bias valve.
 

Brian H

Zorg Expert (I)
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British Zeds
Scottish Zeds
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Model of Z
E36/7 3.0i - E85 Z4///M
In the rally school all the mk2 have adjustable brake bias they seem easy to fit ?
That would be my thoughts too, an adjustable bias would surely give you a range of options Brian?

Tony.

Thanks guys for the suggestion, does having dual lines (i.e. Separate front and rear) on the zed complicate this? I know the DSC system looks for a certain pressure on the sensors located on the master cylinder so this may be a limiting factor if fitting a valve.

The key to the upgrade of 325mm upgrade us to upgrade the master cylinder to the one off the M3, this is the same for the Porsche caliper upgrade, other than that is as said above which was done on the mk2 escorts and fit a bias valve.
Thanks Rich, I have looked in to other master cylinders with the DCS ports, the E46 has one as does the S54 Z3M. If I change the master cylinder I need to know what size pistons I need.

http://www.apracing.com/products/road_car_upgrades/factory_big_brake_kits/bmw/z3_applications.aspx

Have a chat with these guys Brian, I've worked with them in the past, very knowledgeable
Perfect, I'll give them a call, surely I'm not the first to try this.
 

Brian H

Zorg Expert (I)
Supporter
British Zeds
Scottish Zeds
Joined
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Points
205
Location
Killin
Model of Z
E36/7 3.0i - E85 Z4///M
Spoke to APRacing today, kits are specifically made to order and they said that the calipers were matched to the master cylinder so no issues there, only problem is is the price of the kit...........


£1550.00ex VAT :wideyed::wideyed::wideyed::wideyed:
 
Z

zedonist

Guest
That's the price of racing Brian, how much better would they perform over stock, and could you keep the ASC?
 
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