Power brakes to manua brakes;l master cylinder sizing question

[Zanie]

I am finally making some headway on my Vega project. Its getting & LS1 & T56 for the go. For the stop; I am running 2002 Blazer (s10) four wheel disc brakes; the iron Dual piston calipers up front and aluminum single piston (PBR style) calipers in the rear. The wheel portion of the brakes is easy, because I am using the blazer spindles and the entire 8.5 inch disc brake rear end. So it will all be genuine GM at the wheels
The blazer had power brakes with a 1 inch bore master cylinder and ABS. I'm ace-ing the ABS because its a 3 channel system and more complicated than I have any time to even imagine tackling.

I'm not running the power booster in order to keep things simple. I plan to run an adjustable prop valve in the rear line.

Since my little Vega wagon is so much lighter than the 2 wheel drive blazer, should I just try the factory 1 inch master and see how things feel?
Or should a go with a 7/8 bore?

I expect ther to be trial and error, but looking for guidance for the jump off point.

Thanks!

[andrewb70]

I am finally making some headway on my Vega project. Its getting & LS1 & T56 for the go. For the stop; I am running 2002 Blazer (s10) four wheel disc brakes; the iron Dual piston calipers up front and aluminum single piston (PBR style) calipers in the rear. The wheel portion of the brakes is easy, because I am using the blazer spindles and the entire 8.5 inch disc brake rear end. So it will all be genuine GM at the wheels
The blazer had power brakes with a 1 inch bore master cylinder and ABS. I'm ace-ing the ABS because its a 3 channel system and more complicated than I have any time to even imagine tackling.

I'm not running the power booster in order to keep things simple. I plan to run an adjustable prop valve in the rear line.

Since my little Vega wagon is so much lighter than the 2 wheel drive blazer, should I just try the factory 1 inch master and see how things feel?
Or should a go with a 7/8 bore?

I expect ther to be trial and error, but looking for guidance for the jump off point.

Thanks!

Dan,

The factory 1" bore MC probably has a shallow hole in the back of the piston and for that reason is not suited to be used in a manual set-up. I would first try a 15/16" bore MC that has a deep hole and positive push rod retention. Try Raybestos PN MC39946, or equivalent.

Do you know the pedal ratio?

Andrew

[Skip Fix]

One of the most fun cars I had driving growing up was my parent's 70 Vega Wagon! Good for dates with the seat folded down:)

Did it have power or manual brakes originally?