My '95 spec'd Rover Sprite is leaking brake fluid from the rear-right drum and I suspect that it's the rear brake wheel cylinder. Before I start tearing down the rear wheel brake cylinder, I would like to know the exact part number or size for the brake cylinders. I checked several online sites and these wheel cylinders comes in different sizes. I could not believe that they have at least 5 different sizes (3/4", 11/16", 5/8", 9/16", 1/2")!

 

I haven't done brakes on mine... yet. But it looks like you could tear down the cylinder and run a brake hone through it to smoothe out the cylinder wall. Maybe the seal is in good enough shape that it can reseat to the now-smoothe wall. If not, my quick look at Minimania lists brake cylinders at about $30. Not bad. Measure yours while its out and order one the same size.

FWIW.

 

They can be rebuilt if not scored or pitted. New seals are a MUST. But, new cylinders are pretty inexpensive. Identify your car to the supplier and they will send you the right ones. BTW, if one rear is bad, how about the other? Not far behind, imho.

 

Thanks for the inputs. The plan is to replace both wheel cylinders with new ones so that I don't have to worry about rebuilding or replacing them again in the short term.

I was told that 11/16" should work for my car but I didn't get the impression that they are absolutely sure that that is the correct part number. I guess I need to tear it down and measure just to make sure I get the right part.

btw, 11/16" wheel cylinders are priced at $50 ea. vs. $25 for 3/4". Any thoughts on why it is twice the cost when they are almost the same size?

 

Sizes are matched to system design, master cylinder, front brakes, proportioning valve, etc. Don't create issues where there are none. A regular Mini parts dealer like Minimania, Seven Enterprises or Heritage Garage can tell you exactly what you need based on identifying your correct year and system.

 

I work with 7 Enterprises, and they have never sent me the wrong part. I replaced my rear brake cylinders a couple of months ago, but I cannot remember what size they were - but the price was very reasonable.

Nik