Slave Cylinder Thoughts
 

Here are some bits from a slave cylinder rebuild project. Check out the bore which to the naked eye looks shiny and smooth. Next shots shows the failed seal (see where it leaked?) next to the rebuild kit parts. The rebuild kit uses an anodized aluminum piston instead of a ferrous slug.

But look at the seals. The rebuild kit version is heftier and firmer. Look at the OD vicinity. I wonder if the service life will improve. The seal that failed is quite thin and flexible.

On the bore finish…I will flex-hone the bore. This provides a superior finish compared to regular honing. It leaves little folded metal and very smooth peaks. The valleys will still be there to retain fluid (which the seal people feel is very important). If the bore is too smooth, the seal moves across too dry of a surface which degrades seal life expectancy.

That rebuild kit is the one that I have used before. That said, O'Reilley Auto now carries slaves in stock in town for $19.94. Makes me wonder if it is even worth spending the 15 minutes to rebuild. I've done four now so it's no biggie.

Things like slave cylinders and front hubs are items every Miata enthusiast should have "in stock".

But many receive low lifespans out of the lower priced options. The slave I showed is under warranty. So a new one is available for free. However the present one only lasted a year while the OE version lasted over 10. I would not expect the replacement cheap SC to last 10 years.

You could just keep loading in cheapies. Or do things like load in ubergrease into your front wheel bearings. Or redo your slave cylinder for a higher life expectancy. Between the stronger seal and a more seal friendly bore hone it should be possible to have better than OE slave cylinder life. You can do this with higher quality seals and five minutes with a flex-hone.

Are the factory ones pricey?

Not really. It's the hassle and inconvenience factor. You can also get rebuild kits for 4 dollars. I like to have bulletproof parts. Since there are different seals that will work along with more seal-friendly honing techniques it begs the question.

perhaps your rebuild kit should include this:

https://www.miataturbo.net/attachmen...ine=1313777680

What??! No remote bleed?

BTW…research has shown that Mazda themselves came out with a slightly larger seal for the slave cylinders. The larger seal in the Dorman kit I showed makes more sense now. It's slightly larger in diameter and the OD flap is about 3 times thicker than the "lite" variation. It is noticeably harder to load into the bore than the wimpier version for instance. The same bits are used on some other Mazdas and even some Fords.

I'll see if I can find a cross reference for the actual rubber seal itself. Usually the boot, piston, and spring survive fairly well. I bet they are dirt cheap, like 12 cents.

I might try this out for 10 bux…dual seals baby!

I'm the guy who always takes a spare slave cylinder and timing belt to the track with him...every time.