Lifespan of a clutch master cylinder

Jefco said:
Does resleeving not include new seals?
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It should, but the actual sleeve inside the cylinder bore won't improve the quality of the seal itself. So if the seals themselves are failing (as I suspect) then it will still be an issue regardless of the sleeve.

Elsewhere I suggested trying to find better quality seals to use in all of these cylinders. If that is possible then the combination of the improved seal and improved cylinder bore ('resleeved') would be the best answer.

Why do I suspect the seals are an issue? Because new masters (never exposed to fluids or moisture) are failing while sitting on the shelf. That is a seal issue, not a cylinder bore issue.
 
Does anyone dismantle a new cylinder to check the inside surface, or condition of the seals, before installation? I resurfaced my 850's cylinder with a split rod, scotchbrite pad, and Aerokroil, bought new seals (Maybe from Mikemo, it was at the dealer in Oakland) and was good to go.
Are the new seals really that bad?
Or is it cheap materials in the cylinder?
 
The Issue has a lot to do with the clutch or brake not seeing regular use. When the systems are left to sit for weeks the seals have a much harder life than if they are in regular use. What can happen is the seals effectively stick to the bore in position and there is no lubrication provided by the brake fluid because of no movement. Then when the clutch or brake is used it takes the outer most layer of the seals off with the movement. I am not talking about ripping huge chunks off the seals but microscopic amounts at the edges. Its worth remembering that the brake fluid does double duty as the hydraulic pressure medium and seal lubricant.
 
Jefco said:
Are the new seals really that bad?
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I'm sure not all of them are. It likely depends on the particular manufacturer of the specific seal being used in any cylinder. My opinion is the majority of the current supply of affordable aftermarket master/slave cylinders (i.e. sold by most common vendors) may not have the best quality of seal inside. If you search by the part number for the seal itself you will find it is offered by many different manufacturers. Some of which are well known, very reputable brands that should offer a decent quality product. Those companies are seal makers, not cylinder makers, so they don't offer a complete assembly with their seals inside. And those are not likely the seals being used to build the supply of cylinders from other companies.

I purchased some rebuild kits made by one of the better seal brands (in my opinion). The intent is to use the seal in a new cylinder made by someone else. No idea if it will make a significant difference, especially if the cylinder bore is also partly at fault for the common problems. Hopefully it will help though. As I stated earlier, the ideal solution might be to get a cylinder sleeved, then use a quality seal in it.
 
JKIDD said:
My question is, how long do these typically last? It was maybe 1000 miles ago.
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First, I tip my cap to you for having done the MC replacement inside the car. You are a braver man than I, and apparently have a back that doesn't mind spending hours being wrung over the door sill.

Second, the lifespan of a MC is a matter of time and use. It's probably better off being used than sitting at rest. You can collect a lot of answers from members here about their experiences with how long an MC lasted, but I think the most accurate answer is that nobody really knows. The originals seem to last for ages. Most of the MCs I replaced appeared to be OE. The replacements never seem to last as long as the originals.
 
Soooooo, I received my replacement MWB master & went to start the job, but now there was no fluid leaking.... Then I remembered, I soaked the clutch pedal assy with penetrant last fall to try to quiet the squeak when I depressed the clutch pedal. I did wipe up the excess at the time. Maybe the car sitting out in the sun on an 85 degree day thinned out a little penetrant & caused a single drip.... Either that or its just weeping very slowly & hasn't overflowed the boot again... Time will tell. Good news, no clutch cylinder replacement for me today!
 
JKIDD said:
Soooooo, I received my replacement MWB master & went to start the job, but now there was no fluid leaking.... Then I remembered, I soaked the clutch pedal assy with penetrant last fall to try to quiet the squeak when I depressed the clutch pedal. I did wipe up the excess at the time. Maybe the car sitting out in the sun on an 85 degree day thinned out a little penetrant & caused a single drip.... Either that or its just weeping very slowly & hasn't overflowed the boot again... Time will tell. Good news, no clutch cylinder replacement for me today!
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That may just be denial, but I'll go along. :p:D
 
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