engine and drivetrain RHD Brake Hydraulics

[tomorrowcalling]

Hi,

I've been trying to get my head around how the twin remote booster setup works in RHD cars, specifically how the front/rear bias works.

Tracing the lines it appears that one booster operates the rear and one set of pistons in the front, the booster operates the remaining pistons in the front.

I assume that the pressure to the rear is lower as is usual from drum brakes.

Questions

Do both boosters have the same ratio? - they look the same and there doesn't appear to be a pressure reducer.

Do both outlets of the master cylinder produce equal pressures?.

Background

I'm building another 2002 rally car, my current car has a twin master cylinder setup with Volvo front calipers, E30 rear calipers and no boosters, it works well but has fairly high pedal pressure.

The new car will be for my wife and daughter so I was wanting to run boosters, with Volvo fronts and 320 drum rears. I was hoping to be able to adjust the bias hydraulically with a bias valve but of course you need to remove any fixed valve first....

I was also planning on remounting the boosters in the back to give more room in the engine bay but have a dedicated booster for the front & back to reduce the amount of plumbing required. I strongly suspect that will require changing to a twin master setup to get bias right.

[bingbong]

I believe the pressure differential is in the master cylinder. I have upgraded the front brakes on my car as I used to have the rears lock before the fronts and it was very scary at points! Its also possible that the boosters have different internals but I'm not sure.

[NickVyse]

both servos are the same, a bugger to find in working order, very expensive new and a bit hit and miss when having refurbed.