Brake Booster SV

[Barry]

Tom,

On my series 3, I'm restoring, I got a .750 Wilwood girling style master cylinder and a VB 5" lockheed booster kit. Will this combination work well.
Ive rebuilt the front and rear brake system with original parts.

There is no way to be sure without knowing the specific booster hydraulic ratio's, but I suspect that pedal effort with the combination of a 0.750" master cylinder and a 5" Lockheed booster will be about 20% higher than with the combination of a 0.875" master cylinder and a 7" Girling booster.

 

[Tom H]

I think Barry has it about right. I think that combination will work ok.

Tom

 

[beamertwo]

Can someone tell me the bore size on the original Alpine servos?

 

[Barry]

Can someone tell me the bore size on the original Alpine servos?

Which bore and which servo? There were multiple versions of "the original Alpine servos" and all vacuum assisted remote brake boosters have multiple "bores" and / or bore sizes.

In any case, the bore sizes of vacuum assisted remote brake boosters are not important; what is important is the hydraulic pressure ratio (aka, boost ratio). The information I have seen for suitable Girling and Lockheed "boosters" lists various ratios ranging from about 1.6:1 to 2.4:1.

 

[puff4]

The bore in Girling boosters is a 3-step bore.

 

[beamertwo]

Ok, what I really want to know is if the servo is not of an appropriate type, will it make the pedal travel longer?

 

[Barry]

Ok, what I really want to know is if the servo is not of an appropriate type, will it make the pedal travel longer?

"... not of an appropriate type ..." covers way too much ground and I am not going down that rabbit hole.

Typical 5" or 7" Girling or Lockheed vacuum powered brake boosters (aka, servos) intended for lightweight vehicles such as British sports cars do not change the pedal travel, they change (reduce) the pedal effort.