Master cylinders

[Gary Whitaker]

Hi all,
Are all brake and clutch cylinders the same internally?
I am replacing the seals in the clutch master cylinder. The seals were very swollen as you can see from the photo. I thought they had given me the wrong seal kit especially the small one that fits on the thin rod.
Could someone please explain how these work. I understand the large seal as it pushes the fluid down the bore, but what does the small seal do that fits on the spring rod as it doesn't seem to touch anything. I think it's some form of slow return valve but it's just a guess.
Any advice would be much appreciated.
Regards
Gary

[John A. Ross]

Gary

Yes its a small valve, just makes sure the fluid can move free into the cylinder when needed and does not head back up to the resevoir instead of doing its job. Its actually the little seal that does most of the work.

Clutch and slave are the same except when a servo is fitted and the bore size on the brake one jumps 0.625 to 0.700

Not a bad explanation here on the working of the small seal

I have not rebuilt a master cylinder for a long time as I can get new ones for the same price as some Girling repair kits.

Normally I would fit these for replacement of the master cylinder MOTAMEC 0.625

The price is OK and never had a problem, something I cannot say about Willwood at £40. But same comment is true of any brand on a few onlione sites, anything can be copied, if it is super cheap, most likely is !

You are lucky you can skim the bores as thats my main reason I always replace than fit seal kits other than cost.

There are 3 types of cylinder. Dave identified them HERE

Dave Lane ae all the rebuild kits the same Dave ? I would assume so.

- John

[Dave Lane]

Gary




Dave Lane ae all the rebuild kits the same Dave ? I would assume so.

- John

I believe so , the internals didnt change as such , just the casting