Excessive pedal travel when braking after installing a 9" Servo & 22mm Master Cylinder to a 1.5 GL.

Referring to the guide on this site, I recently upgraded the braking system on my Golf 1.5 GL by installing a refurbished 9" Brake Servo and a new Meyle 22mm master cylinder.

I fitted the pressure switches on both the rear brake lines using "T" pieces and a short pipe connections to maintain the original rear brake light operation.

With all the expectations for an improved system, I find that the firm pedal is far to low before effective braking commences, I was hoping for something better than my original system. i.e. touch the pedal to begin braking.

Yes, I can stop, it looks to me that I should not have cut off the 10mm from the 9" servo input shaft.I have googled a bit, it seems that I am not the only one with the issue but I could not find any solution to correct it.I have bled the full system, longest to shortest pipe length, 3 times with a pressure bleeder.

I confirmed the vacuum function of the 9" Servo before and after the upgrade. i.e. Hold the pedal down and start the engine to feel the assistance.

I have checked the rear brakes, no excessive slack, new drums were fitted and worked well with the original servo and master cylinder before this upgrade.

There is a large movement of the brake pedal before any pressure is applied to the front discs (original solid discs still in place). Quite scary.

The brake bar across the car cannot be adjusted at the moment, it is very difficult to undo the nuts in situ. I might have to take it off to free and adjust the connections.

Some thoughts, Are there other 22mm Master Cylinders with different external dimensions?

Is there an air gap internally between the servo internals and the master cylinder input shaft when the brakes are not in use?

If so should I refit the original larger 16V bellcrank connection, plus drill a hole for the heavy duty spring?

Any thoughts and a solution would really be much appreciated.








 

Taken from my project:

It's been a while since by last post working hard in addressing my low pedal braking issue following my 9" vacuum servo and 22mm master cylinder upgrade installation.

I decided to take the brake bar off, remove the connections and lock nuts, and cut additional threads on both ends using left and right hand cutting dies.

I fitted some heatshrink at both ends of the brake bar before assembly to allow subtle rotation by hand to set the height of the brake pedal.

In hindsight, I found that the most effective adjustment was at the servo by undoing / extending the length of the input servo rod. If I did this job again, I would not cut the full 10mm from the servo threaded connection, i.e. just enough to allow access for the heavy brake spring at the bell crank.

Though not completely the same as the previous brake pedal position, it works. So much so, I  booked it into my local garage to check the whole system for leaks and MOT brake tests which it passed.

I have been out a few times now with no issues.