I have just attempted first time,to replace new front disk pads on 89'560SL. The first pad I removed (A) was worn down to almost touching the sensor. Now here's the odd thing....the inside pad (B) was only 40% worn down?? when I attempted to insert a new pad into (A) I could not get it into place....the pistons would not withdraw enough (no how). The inside... (B) was no problem. So what I had to do was place the 40% worn one back into (A) and the new pad into (B) Could anyone explain why they did not wear down evenly in the first place ? and what could be the problem with the piston not fully withdrawing?
I checked all the other brakes and the pads were all showing about 40 % worn.
So I just had the one worn pad. Your thoughts or experiences would be greatly appreciated.

__________________
Share your knowledge. It's a way to achieve immortality.
Dalai Lama.

probably your rotors (discs) are uneven. Did you ever have them grinded before?

it quite possibly is caused by a stiff piston seal not allowing the 'worn' pad to retract. I suggest you rebuild at least the ueven wear caliper.

You need to replace the calipers with rebuilt units + replace all flex hoses + flush the brake fluid.

Brake:
Brake:



Have a great day.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

I have only had the car 1 year so do not know if the rotor was ever ground.
To 'rebuild' a rotor, can that be done by myself or is it a professional job?
I will look into all your inputs and proceed accordingly. Thanks again, you've been a great help and much appreciated.

__________________
Share your knowledge. It's a way to achieve immortality.
Dalai Lama.

Read what Arthur Dalton had to say in the following thread B4 forking out $$$ for new Calipers:

Calipers dragging

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

read here before that MB rotors are not supposed to be ground, but replaced when they wear beyond specific thickness.

Thanks all.........your info was well inderstood and now will be applied.

__________________
Share your knowledge. It's a way to achieve immortality.
Dalai Lama.

a bit.

the pad that is worn is doing all the work. the other side of the caliper is sticking and not working its share. so minimum replacing that caliper with a rebuilt. some folks recommend never replacing one caliper. i dont see how this is related to the hoses but if they are original it wont hurt to replace them.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I thought that might be the case also......but all the other pads were worn down to the same degree...about 40%. Only this one pad was down to the sensor?
Strange, eh?

__________________
Share your knowledge. It's a way to achieve immortality.
Dalai Lama.

it is admittadly strange.

another odd possibility is that the other pads were all changed and the pad for that location was lost and not replaced.

does it pull? it should pull to the opposite side that the faulty pad is on.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

no, there is not a hint a a pull. All seems to be normal? as suggested, it might be that an earlier brake job ( before I owned the car) had 1 pad short and therefore might explain the oddity. Time will tell I guess. Thanks again all.

__________________
Share your knowledge. It's a way to achieve immortality.
Dalai Lama.

Replace the caliper and the hose, and flush the brake system.

One side of the caliper is stuck, and also the hose should be replaced.

Have seen the hoses clogg inside and not allow proper fluid dispersal.

I would replace both fronts to do it right also both hoses.
that was the policy at both dealerships I worked for.

If it were my vehicle, I would also check to see if the rears will compress too, and if not do the same on the rears.

What's more important , money or safety?

You do not want to go cheap on brakes on theese older cars, sometimes just compressing the calipers will roll the seals in your master cyllinder and cause another problem.