FAG Brake Master Cylinder

[Inka’d02]

So I purchased a tii master cylinder on ebay. I'm upgrading from a stock master due to a Volvo BBK. It was suppose to be an ATE but an FAG showed up in a generic box. The part number on the side of the cylinder is S5339 9A2. Its about .150" bigger in diameter.Can anyone confirm this one is correct before I spend the time installing it?

Thanks,

Andrew

[allbim]

Have you tried the Volvo BBK with the original MC? It should work just fine.

The larger MC will require more pedal force.

[Inka’d02]

Pedal travel is further and spongier; do you know if this is a tii master?

[allbim]

I don't know about your P.N. According to the manual (blue book), the diameter of the regular MC is 20.64 mm (.8125"). The diameter of the TI and tii is 23.81 mm (.937"). The difference is 3.17 mm or .125".

I have the same brake conversion you have and the pedal is firm, with possibly a bit more travel. You might try bleeding the system once more. Good luck.

[Hans]

measured where?

[Inka’d02]

the OD of the body measure at the front

[Hans]

I wouldn't rely on that measurement. BMW used several suppliers for the same cyls. The only way to confirm (unless someone can verify your casting numbers) is to measure the bore diameter. If memory serves, you can see the end of the bore if you peel back the rubber bellows on pedal end. Use vernier calipers.

[allbim]

measured where?

The bore diameter, of course.

[Hans]

compare that with dimensions on Realoem.

[TobyB]

Don't sweat it. FAG makes good parts, and I've run Volvo calipers on

all of our cars with the stock master- it's not particularly spongy.

And the bore's the only thing that matters- the OD will vary between manufactures.

In fact, some may make the OD intentionally big to be able to bore different

sized parts out of the same casting. Thus, don't count on casting

numbers to tell you everything, either.

hth

t