2 replies to this topic

[Daniel Watkin]

Hello,

 

I'm converting my Mini Sprite to run 10" wheels and and I need to install 7.5" discs on the front. I'm aware this will alter the brake bias of the car and make the rear end prone to locking up. I have a brake servo and a green tag master cylinder, with a FAM7821 PDWA valve. 

 

What is the best way to go about correcting the brake bias? I've considered removing the PDWA altogether and running direct from the master cylinder to the brakes, with a 1/2"

 cylinder on the rear drums. Is that a suitable option?

 

Many thanks

Dan

 

[Ethel]

I doubt it's a pdwa, but the FAM7821 brake proportioning valve. It's only a name but it'll save confusion & potentially buying the wrong parts.

 

I don't think you'll need to do anything. 7.5 & 8.4 calipers are almost identical in piston diameter. Smaller rear cylinders may reduce locking up, but variations axle weight & driving style will be bigger factors.

 

If your car is prone to locking up the rear it would make more sense to look at the suspension first, especially rear springs, to improve the tyre loading rather than reduce the braking.

[Spider]

If you fit 5/8" Rear Wheel Cylinders, that'll be fine with the set up you have.