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Author Topic: Brake problems..  (Read 89 times)

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Offline twigren

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  • Posts: 70
  • Exterior Color: Black
  • Interior color: Beige / Brown
  • Location: Sweden, Skåne
  • Year_Model: 1951
Brake problems..
« on: May 08, 2020, 03:12:52 PM »
Had the most strange problems occuring on back brakes.
Everyting is renovated is renovated into bits and pieaces.
All brakes are working fine, at least what I was aware of.
However, when driving I can hear  one of the back brakes lock (however I determine which one, as it change over time..).

Decided to look into details, and was so surprised.
Master cylinder has been renovated once, with bushings repleced and cylinder reconed etc. Its as close to OEM it can ever be. The same with the brake cylinders. They are all renovated with coning, new bushings and things are really OK.
Nevertheless, when bleeding the brake fluid I discover a VERY strange behaviour.
The brake cylindrer is pressed out, but when preassure is gone it is still there.
Brake springa are obviusly not able to return the brakes!!??

I have (almost...) gone crazy and put apart all cylinders, went through all bushings, checking for leaks, bleediing all brakes (several times, and again..) but havent found any proböems.

Until NOW!

Obviously the rubber brake hose has ”melted”, as rubber does over long time.
The inside diameter should normally be 0.5mm (free level),  but in my case it was more or less zero!!!!
The brake flyuid (with enormous preassure downwards..) managed to het out, but was’nt returning after preassure was released.
I cut the rubber line and found out this. Look at the photos.

This week I bought new lines, and suddenly my back breakes are working!!!
Thomas Wigren
Mercedes-Benz 170S, 1951

Offline Scott Montoney

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  • 1952 - 220 Cab B
  • Exterior Color: Black
  • Interior color: Red
  • Location: Mason,Ohio USA
  • VIN #: 187.013.04370/52
  • Year_Model: '52 220 Cab B
Re: Brake problems..
« Reply #1 on: May 10, 2020, 08:52:54 PM »
Thank you for the information.  Yes, the rubber hoses can cause problems.
Do you happen to know how old the bad rubber hoses are? 
I'm just curious, and it may make others consider checking their lines very carefully.
I don't know if there is a recommended replacement cycle.
"Gertrude" a.k.a. "Troidl"
1952 - 220 Cabriolet B