What brand of pads have they installed? Some of the cheap ones, the ones that biker trash Jesse James promotes, will not seat correct and cause the rotors to overheat and warp in no time at all.

You don't have a set of KleenWheels on the fronts, do ya? Could be another contributing factor.

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Chas

Had a 380SL, 450SL, 380SEL, 420SEL, 500SEL

Got a Euro 500SEC right now.

Thanks for the replies. I have reviewed all in detail.

To reply to the previous posts:

I have replaced the guide mounts shown in WBain's post, twice since I owned the car, and this is not the same symptoms as when they fail. And to add life to them, I suggest ensuring the boot is sealing properly keeping dirt out the this part.

The pads are Pagid brand. Prior were ATE.

There are no kleen wheels installed.

Last night I went by the shop. The mechanic was walking back from the brake shop across the street, with my freshly turned front rotors in hand. These were new 50 miles ago. The shop supervisor was confident this was the problem, and he assured me he will put everything together in the morning and call me after test driving the car. I instructed him to put the original caliper back on the car, and put everything back where it was when he started. I intend to go get my keys and get the car out of the shop today, and get it away from him.

I will update when I get the car back. I am leaning toward caliper or brkae lines maybe? I have experienced a caliper sticking due to a collapsed brake line on another car. Perhaps this is the case here?

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1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)

If one guide rod mount has failed, it will allow the guide rod to move rearward in the bushing. This will allow the lower control arm to move rearward when the brakes are applied.

This will cause the vehicle to pull toward the side of the failed guide rod mount, AFAIK.

Please correct me if I am mistaken.

I just spoke to the shop supervisor.

He reports the problem is fixed, as it was the rotors. He also reports I need two new calipers and rotors to ensure the problem does not return. He is generously offering rebuilt calipers, (to save me money), at a price of $175 each, and rotors at $75 each. No mention of hoses. I believe the price of a caliper rebuild kit is about $15 each, and the rotors are maybe $50 each.

I am getting my car back this afternoon, and I am leaning toward rebuilding the calipers, replacing the hoses in the front. That will take me personally about 2 hours, tops, based on experience. I rebuilt the drivers caliper about 2 years ago, but will do it again to make sure.

I will be glad to get my car in my garage, I will sleep better to night.

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1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)

You are correct, sir.

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

Is there any opinion as to how a functioning caliper can "damage" the rotor?
If one of the pistons in the caliper is hanging, and the opposite piston is doing all the stopping, I would think you would get a pull to the opposite side because the caliper is not gripping properly.

I would also think that there would be some irregular wear on the pads that are on the side with the bad caliper. However, since the pads are new, you cannot check this.

Do you recall the thickness of the pads when they were first changed? Regular wear pattern on all pads?

The rotors are about $50.00 each. I have located a rebuild facility for calipers that charges about $90. each (for the SDL). Let me know if you choose not to rebuild them yourself.

If you do rebuild them yourself, please post whether any of the four pistons are not moving properly in their bores (you will have difficulty extracting them).

His idea of the mechanism where the caliper could damage the rotor is for the piston to remain extended, and not retract after braking. This would keep the pads in contact with the rotors, causing overheating and warping. It actually sounds reasonable to me.

I did not notice any uneven wear on the pads when I replaced them. I will post something next weekend regarding the condition of the pistons, but only on the front wheels.

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1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)

Well, the pistons do not actually "retract". They lightly contact the rotor at all times, and, when pressure is added to the caliper, they are forced against the rotor.

Jack up the front of the vehicle. Take the wheels off. Step on the brake pedal firmly and release. Rotate the rotors by hand. If they spin with light contact between the pads and the rotor, his idea is incorrect.

If they will not spin by hand, then the piston is binding in the bore and the pad will overheat the rotor. However, in this condition, when you drive the vehicle you should feel a slight pull to the side with the faulty piston when you take your foot off the brake.

BTW, brake hoses can cause this exact same problem. So, if one of the rotors will not rotate, crack the bleeder screw and let the pressure off the caliper. If the rotor will now rotate, the brake hose is the culprit.