Lately I've begun to suspect that my rear brakes are not functioning at 100%. Here's why. After I wash the car I always get a light coating of rust on the rotors. The rust usually gets cleared away after you apply the brakes a few times. However, this has not been happening on the rear rotors recently. The rust takes forever (well, at least a couple hundred miles of driving) before it's mostly cleared. This applies to both rear rotors. The front rotors don't have this problem. This leads me to believe there's a possible problem with the rear brakes, although I can't say I perceive a significant difference in the overall effectiveness of the brakes when applied in normal driving.
Does anyone have some suggestions (other than taking it back to the dealer) on what I might look for in the way of a possible malfunction?
My car sits during the week and only gets driven on the weekends if the weather is nice. I've noticed the same thing, it takes forever to clear the rear rotors if they're rusty after a wash.
I've even tried driving backwards and stomping on the brakes to no avail. I'd figured by that going backwards and stopping, I'd put more weight on the rear brakes to scrub them off. Oh well, it's been like this from day one so I'm not too worried.
Hope someone with more experience can explain why this happens with the rear rotors.
This is a very common problem.
We see it on cars as far back as 993's. Mostly on the inside, rather than the outer edge of the discs and always the rears.
Early type Boxsters seem to get it the worst (in our experience).
There does not appear to be a simple or cost effective solution to this problem other than simple advice.
*Always take the car for a quick run after washing to dry the discs
*Try not to put the car away when wet
*Use the car as much as possible (best advice of all
)
Generally its cars that dont get used as much, the show cars & trailer queens, that have the worst reliability issues.
+1 On the 3 tips above!!!
Also try not to get the discs wet when you are washing the car i.e. Don't hose the wheels. I always have washed the rims by hand on our current and previous Porsche's and have yet to have this problem.
More driving is better. And a brisk drive after a wash is a good idea.
That being said, the front brakes to most of the work, so casual driving isn't going to bite down hard enough to eat the rust accumulated from wash and sit practices.
I tend to blast onto an on ramp and then stand on my brakes to slow down enough to match the speed of the traffic on the road way. Or some such effort to get the rears to do their part. That keeps my rotors clean.
Some good thoughts here. The thing that has me wondering, though, is that this problem only started this winter. I never really had a rust problem on the rear rotors before that. I wonder whether the cold temperatures have something to do with it. Perhaps the water doesn't evaporate from the rotor surfaces as quickly as when it's warm, so more rust sets in while they remain wet.
I use a leaf blower on the rotors during washing to keep the rust from accumulating. It has made a big difference for me.
I usually wash the wheels first and use the blower on the rotors. I use the blower again on the rotors and add the rest of the car following that part of my exterior cleaning.
Just use the brakes harder. 1-2 threshold braking runs from 60-70mph down to 20mph should clean 'em up just fine. And mess up your pretty clean wheels again!
As least for me, I've tried all that and the marks remain. Oh well. I'm pretty close to the ocean (2 miles) so maybe the salt in the air has something to do with it since I keep it outdoors.
A few years ago, I had to replaced all 4 rotors on a brand new Audi after 2 years and about 13,000 miles due to the rotors rusting so badly the metal was flaking off like pastry. The mechanic had never seen anything like it. I hope that doesn't happen with the Cayman rotors!
