Girling 70 Brake Master

[Morris McKinnon]

What size seals are needed for single line masters? PTH was fitted with a Girling 70 master but when I was restoring her I fitted a similar one but the bore size is different. I want to fit back the original one but don't know the seal size. Are they 5/8 as I see that stamped on the cylinder or does it mean something else?
cheers guys.

[david painter]

5/8 is likely to be the bore size in imperial fractions decimal inches is 0.625 very common brake master cylinder bore size and is approximately 16mm in metric
Dave

[MarinaCoupe]

The Mk1 ally bodied servo M/Cs were 0.75" according to my parts book, not sure about the 'tin can' type. The Ford Escort used the 0.70" version of the same master cylinder, but without the servo. Burton Power stock the kit here http://www.burtonpower.com/girling-mast ... p2102.html

[Morris McKinnon]

ok, cheers guys. My 71 saloon has no servo and the Girling 75 master is different (servo fitting) so It looks like the 0.625 seals are needed then. Cheers Chris, forgot about Burton ..I've ordered a 0.625 kit from them.

[Morris McKinnon]

Right then, seals arrived today and perfect weather for such a job. Opened the bonnet on PTH to see she already has the Girling 70 fitted! I must have done that job a while back as I was convinced she had the Lockheed 'tin can' master and can't for the life of me remember fitting the 70 back anyway, the 0.625 seals I ordered fit the 5/8 master I had in the kitchen, the Girling 70 actually takes the 17.5 seals... which I already had! so now I have two fully working masters with different bore sizes. Oh well, shows how little I open that bonnet. Not sure if that's a sign of reliability or neglect!

Need to get a new union made now as the ports are different sizes, want to see how the brakes feel with the 5/8 bore. Pedal should feel lighter but if it feels weird I'll stick the 70 back.

[david painter]

You will have slightly longer brake pedal travel but more responsive brakes. As brake pressure is inversely proportional to master cylinder bore size.
Dave

[Morris McKinnon]

When it comes to drum brakes, better response is preferable. I can get used to longer pedal travel.