Front or rear brake bias adjustment?

[Frank818]

In the manual, if there is no mistake, they say to connect the brake proportioning valve with the FRONT brakes, which will increase or decrease front bias and won't change anything for the rear.

This is quite odd, I and my mech have never seen the adjustment done to the front brakes, it's always the rear, cuz the weight transfer on braking makes the rear lighter, requiring less brakes.

Is there a reason for that?
Is it cuz there is way too much brake up front?
What if someone uses the OEM standard brakes, vs OEM Brembo brakes, vs Wilwood 12/12.2", vs Wilwood 13"? Do we still need to connect the valve to the front brakes?

[Bob_n_Cincy]

In the manual, if there is no mistake, they say to connect the brake proportioning valve with the FRONT brakes, which will increase or decrease front bias and won't change anything for the rear.

This is quite odd, I and my mech have never seen the adjustment done to the front brakes, it's always the rear, cuz the weight transfer on braking makes the rear lighter, requiring less brakes.

Is there a reason for that?
Is it cuz there is way too much brake up front?
What if someone uses the OEM standard brakes, vs OEM Brembo brakes, vs Wilwood 12/12.2", vs Wilwood 13"? Do we still need to connect the valve to the front brakes?

Hi Frank
On all the braking packages above there is twice the clamping force on the front calipers. This is what is needed on most front engine cars.
The mid engine 818 doesn't need twice as much in front. So the Proportioning valve reduce the front brakes so you have closer to a balance clamping force front and back.
Bob

[Frank818]

Good old Bob to the rescue! :)

Makes a lot of sense, the kits are designed for a front engine and now we moved it in the back but we didn't install a kit especially for the 818 or for MR cars, so we need to reduce front. Ok I see why!

tnx!

[Hindsight]

http://thefactoryfiveforum.com/archive/index.php/t-13543.html

I found that discussion a while back and there is a lot of good info there. Don't feel bad.... prop valves are normally only in the rear so it is confusing. All the vw ones I am used to working with are in the rear and adjustable via suspension load in the rear.

[Frank818]

Yes good catch Hindsight, it explains it. We don't see that very often, but then again we don't buy very often a car that uses parts of another car that has the engine in the opposite location. :)