Author Topic: Brake trouble on newly installed front discs and callipers - help!  (Read 3700 times)

Ollie

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My trusted mechanic at one of our local Mercedes dealerships replaced the 250SL's front discs and callipers this spring. Driving back from the dealership to my home, the brakes suddenly became soft and I could push the pedal almost to the metal. I stopped, the car was taken back to the dealer on a flatbed trailer. By the time it was unloaded, the brakes working fine again. They kept the Pagoda and the service manager (an older German man, familiar with these cars) test drove the car a few times and could not find any problem. I drove the car home a week later and drove it quite regularly during the summer. No similar issues came up, but the brakes lack the same bite I was used to on the old set. Last weekend , the same problem came up again. The service manager suggests that I may want to replace the brake booster, but there was no issue prior to the replacement, so I am hesitant. Any ideas would be appreciated.

Benz Dr.

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #1 on: September 30, 2016, 04:11:56 »
This could be one of those cases where it happened after you had it in for repair and something happened right after that which may not be related to the repair you had done. However it could be.

Generally, but not always, when a brake booster fails you won't be able to stop the car. Full brake pedal pressure won't give you much.

 However, this sounds a lot more like a failing master cylinder. If it hasn't been changed I would do that right away. Don't drive it until you get this fixed!  You've been lucky so far.............
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

Shvegel

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #2 on: September 30, 2016, 04:31:37 »
Failing master cylinder or wet brake fluid that was heated by the new pads on rough rotors.  As for the overall feel that the car isn't stopping as well and I will say in advance this probably doesn't apply here as the work was done at a Mercedes dealer but sometimes people install "High Performance" brake pads in place of the stock pads.  Most ceramic or metallic pads need to be hot before they work even close to well.  My father in law wanted to upgrade the brakes in his 911 because it "didn't stop worth a darn".  I installed factory pads and the problem was solved.  Sometimes parts get put on back order and things like brake pads might be bought from a local auto parts store.  If you know the mechanic who worked on your car it might be worth asking.

Benz Dr.

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #3 on: September 30, 2016, 19:05:10 »
Any time the pedal goes to the floor it's either a major leak or a failed master cylinder. Any time you can't stop the car, it's more likely one of the problems already discussed.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

su8pack1

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #4 on: September 30, 2016, 21:26:32 »
I would replace the master cylinder as others have said above.
1969 280SL
1984 300CD
1987 190E 2.6
1988 190D 2.5

Ollie

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #5 on: October 01, 2016, 02:54:04 »
Thanks all. Master cylinder will be replaced ASAP. I will report back. Is an original still available from MB?

Shvegel

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #6 on: October 01, 2016, 05:06:15 »
The Original supplier to Mercedes is almost certainly Ate.  Ate Master cylinders are readily available. If you do a Google search of "Ate Master cylinder Mercedes W113 you will find a picture and you will see a little sort of raised Ate logo on the casting.  Compare this to yours.
« Last Edit: October 01, 2016, 05:16:25 by Shvegel »

kampala

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #7 on: October 01, 2016, 06:13:26 »
Since your car is a 250sl, you will need to make sure to get the correct Master Cylinder depending on your car being an EARLY 250 or a LATE 250.  There was a change in type of Master Cylinder during the 250 production.   
250sl - later - manual
280sl - 1971 - Auto - LSD

Ollie

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Re: Brake trouble on newly installed front discs and callipers - help!
« Reply #8 on: October 03, 2016, 15:08:41 »
Thanks Kampala, you are correct. Mine is an early 250 SL, a 67 North American model with no side marker lights.