SL350 - Changing Rear Disks and Pads

[davecw000]

Just replaced rear disks and pads on the SL350 – now the brakes come on ok, but stay on and don’t release.


Have taken wheels off and callipers can be freed very easily so they not sticking. Anything I can do to resolve or is this a garage fix now via STAR?


When I changed the above, I did first disconnect the rear battery, so didn’t expect any issues.

 

[television]

Re the rear brakes, on the 230 the rear slides must be cleaned where the slots sit, some times the rear pads need the paint cleaning off. The 2 pins must be cleaned and all should be well.

 

[bembo449]

when fitting any brakes you should check the pads are easy to get in and out before rebuilding them , any tightness may / will cause them to stick , if yours are locking out then the pads must have been very tight fitting indeed

 

[davecw000]

hi thanks for the reply.....
But, no, pads were not tight when fitting, caliper appeared (and do) move easily enough.. called Indy he not come accross this either, so booked in on Tuesday to see if any fault codes, however, plan to disassemble over the weekend and see if wear, rust on pistons which may be stopping the brakes from easing off, although strange both sides doing the same, so my money now on a SBC issue...

 

[Wighty]

Is your brake fluid reservoir totally full now you have put new thicker pads in .????

 

[davecw000]

Not totally full no, but did notice it was above the max level, still lots of room in the reservoir for fluid. Thin I will dismantle clean lube and rebuilt thanks...

 

[star]

My money is the calipers are at fault. As the pistons are further back in the caliper, they can stick slightly.

 

[davecw000]

Will report back over the weekend... Hopefully, as you all suggest it's just a bit of cleaning and lube, and still got the fronts to do....

 

[Steve@Avantgarde]

We have this issue on SL, S Class and CL callipers quite a bit.

The piston is interference fit and due to corrosion build up on the lip edge prevents the pistons returning.

 

[davecw000]

Thank you the info, advice etc, have taken pistons out as far as I dare, pulled back rubber and all looks good, but as you suggest if rust round the bottom edge of the piston then it will need to come out , or at least out further to see it... Did notice that the brakes do release slightly so able to turn wheel all be it with difficulty. So positing appears to be going back in but not enough. So perhaps strengthen the rust on piston edge. Any way of refurbishing calapers DIY or does this have to go to my Indy... Any way of clamping down brake hose, so only losing a little fluid any loss can be replimished by ensuring enough in the reservoir?... Thanks again

 

[davecw000]

Someone also mentioned the brake sensor, Bobby replace with new, would this case any issues?

 

[television]

Brake pads sensors are good if all OK, once split /broke they cost a £5. You do need to clean well all channel wells so they all move easily.

 

[television]

 

[John Laidlaw]

I recognise that wheel!
Sensors are about 7 quid from MB now, hardly a fortune !

 

[television]

I recognise that wheel!
Sensors are about 7 quid from MB now, hardly a fortune !

They are quite good

 

[John Laidlaw]

Stunning Malcolm I thought nicer than I have on the 63 now!

 

[crippo2]

Funny this has come up just now.
I am about to replace my rear discs & pads on the SL350. My garage says that on the last 2 SBC mercs they have done, the rears stuck on after disc/pad replacement. They say the reason is that the pistons are made of a composite material, which tends to go oval on the bit exposed between caliper & pad back plate.
New pads obviously push the piston back into the caliper, but the ovality causes the piston to fail to retract properly once pressure is released.
true? urban legend? fairy tale? - Others may well know better/different.
all I can say is that over the last 12 months, across the entire MB network, there have only been 7 rear calipers which fit the SL350 (& maybe others) sold. - at approx £190 a side

crippo2

 

[flowrider]

Look like WSP Italy wheels, very nice indeed

 

[television]

Funny this has come up just now.
I am about to replace my rear discs & pads on the SL350. My garage says that on the last 2 SBC mercs they have done, the rears stuck on after disc/pad replacement. They say the reason is that the pistons are made of a composite material, which tends to go oval on the bit exposed between caliper & pad back plate.
New pads obviously push the piston back into the caliper, but the ovality causes the piston to fail to retract properly once pressure is released.
true? urban legend? fairy tale? - Others may well know better/different.
all I can say is that over the last 12 months, across the entire MB network, there have only been 7 rear calipers which fit the SL350 (& maybe others) sold. - at approx £190 a side

crippo2

I have never had to change a wheel, only mainly had known wheels that I always had. Now down only to one spare set.

 

[John Laidlaw]

Look like WSP Italy wheels, very nice indeed

Is right....