Possible to replace brake booster with master cylinder in place?

[Arlo911]

Long story short, the brake booster on my fathers' SC doesn't work.
I found a replacement, but wanted to know if it's possible to replace it while leaving the master cylinder in place, so I don't have to bleed the brakes.

[jlynch1960]

I asked this question a few years back and didn't get a definitive answer - the sense seemed to be that it would probably work.

Before you go to the trouble, check to see if the problem is in fact with the booster - it's a pretty robust part and rarely fails. I thought mine was cooked, but it turns out the vacuum line was damaged. Disconnect the line where it enters the trunk and check to see if you're drawing vacuum.

[Arlo911]

Yes I tried that and I have vacuum there...
At first I thought it was because of the bremtek brakes, but since I've fitted standard SC brakes there's still no change.

[gazzerr]

Also check the brake pedal itself. Mine was binding and I wasn't getting the full travel. Very hard pedal. I was pretty convinced it was the booster but it wasn't.

[emac]

Nope

Ernie

[timmy2]

How old are the rubber brake lines?

[Arlo911]

Brake lines are new, calipers are new, brake fluid is fresh. I'll try and see where I end

[Dan J]

You can swap the booster and master as a unit You will have to bleed the brakes

[Arlo911]

Quick update:

-Turns out I had a vacuum leak at the hard line that comes out of the transmission tunnel, there was a chunk of metal missing, go figure... So before you change out your booster, check for vacuum leaks where you least expect them

-BUT: I learned it IS possible to replace the brake booster without having to bleed the brakes.

[T77911S]

that's what I was going to suggest.
pull a vacuum on the booster and see if it holds.
if it does, connect it back up, then pull a vacuum on the line back at the engine bay,

this is a good check to do anyway as you can have a vacuum leak, the booster still works but it will effect the engine.