Fabrik8

Brake fluid doesn't need to be replaced based on mileage, it needs to be replaced based on service life. Time and mileage aren't the same thing for hygroscopic fluids. So if your 30k miles happens to line up with the service life of the fluid, that's fine. But if you drive a lot more (or drive a lot less) during the service life of the brake fluid, you'll be replacing the fluid a more frequently (or less frequently) than recommended.

marlinspike

Would this (the dimples) bother you? It's one on the one side of this one caliper. I'm not even sure what that metal piece is for.

Fabrik8

Looks like someone had to coax it in place a little more than usual. I'm assuming that metal piece is probably a separate retaining cap for a seal underneath, or an integral part of the seal itself (as part of a co-molded seal). Actually, the recessed flats on either side would probably mean that the metal piece turns with a spanner. Maybe the metal piece screws over top of a seal. That piece isn't attached to the piston I assume?

marlinspike

As far as I can tell, all the metal piece does is cover the dust boot (that "seal" is actually a dustboot, even if you took it off it's not like fluid would go anywhere). The metal piece is a press fit, and it isn't attached to the piston but it does move with it (the dustboot expands and contracts with the piston, and that metal piece moves with it)

Fabrik8

Oh. Probably a heat shield for the boot, or just a cap to make it easier to install. Either way I wouldn't worry at all about the dimples.

marlinspike

What amazes me is that MB was putting 2 piston calipers on these cars, while today pretty much anything other than an M or AMG from BMW/MB gets a 1 piston floating design.

BTW, you might be onto something by saying it's a heatshield - the rear calipers don't have them, and not needing them because there's less heat there would explain that.

marlinspike

The thing that gets me is MB said to change the fluid every year, the company that makes the fluid says every 2 years (factory fill was the ATE Dot 4 fluid) and the fluid I use says every 3 years (ATE Super Blue). I figure I split the difference by doing every 2.

White Devil

I generally do mine based on mileage rather than time, which is every 30,000 miles, which is pretty typical...

http://www.trustmymechanic.com/brake_fluid_change.htm

http://www.aa1car.com/library/bfluid.htm

TiredToyotaDrvr

or 2 years, whichever comes first

Fabrik8

I'm assuming MB is saying every year because they can't guarantee that people will use the factory fluid and will instead maybe use DOT3 (which has a 1year change interval).