Pagoda SL Group

W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: lurtch on April 11, 2009, 03:32:01

Title: - - a very curious brake malfunction (long post)
Post by: lurtch on April 11, 2009, 03:32:01
Hello to All, 

Last year while on a driving event in the mountains with the local MBCA chapter, I experienced a case of "caliper lock-up". Entering a turn aggressively I hit brakes firmly to maintain control, but the inside rear wheel  locked up and I found myself in a scary little drift toward  the roadside gully. At the time I attributed it to the wet road surface. That wheel was  logically carrying the lightest load because of weight shift during the inertia of the turn.

Only recently when I noticed that I could no longer roll the car back out of the garage easily, did it dawn on me that the right rear caliper was not releasing completely. Many of us who have been messing around with cars since our teens know that after many years of use ( or , more correctly in my case, non-use )  a brake piston will eventually begin to corrode in the bore area behind the seal.


After pulling the wheel I noticed severe dis-coloration on the rotor and there were some small shards of metal  imbedded into the leading edge of the inside brake pad. Investigating this further, I realized that the spring that anchors the emergency brake shoe to the backing plate had somehow failed, then migrated out of the drum area and gotten lodged in next to the rotor. The additional drag from the fouled pad and the heat build-up from the extra friction served to make a BAD situation worse. 

Now on to the FIX:  Since the shoe set was  out of position inside the drum it took more than a few whacks of the dead-blow hammer and the longest prybar I own to dislodge the rotor/drum. The local MB dealer is getting me the retention springs, while the rotors and calipers are quickly and easily available over the web. The fix is underway.

Hope this never happens to any of you - -   Comments?

Regards, Larry in CA

Title: Re: - - a very curious brake malfunction (long post)
Post by: Dash808 on April 11, 2009, 04:08:48
I guess you can chalk it up to experience and be glad you're not in the ditch! 
Sounds like you have it under control.
Title: Re: - - a very curious brake malfunction (long post)
Post by: SteveK on April 11, 2009, 05:28:24
Larry, good post and I like the pictures.  When I started working on my car I read somwhere that the rear brakes almost never need servicing.   It just goes to show that after 40+ years of use even simple springs can fail from fatquie.  This will get me to take a look and see what gives inside those rear drums.  Probably a pretty cheap deal to replace the springs and shoes before something fails. 
Title: Re: - - a very curious brake malfunction (long post)
Post by: Bob G ✝︎ on April 14, 2009, 06:12:26
Larry :
Please take lots of photos and documentation on the rear brake shoes for the hand brake. I
my self need to service my brakes and have never  removed the brake rotor or caliber to check the
rear hand brake shoes lining,I think it would be a good experience if you could document the process
you are doing at hand.

Thank You
Bob Geco
1968 280SL
Title: Re: - - a very curious brake malfunction (long post)
Post by: johnd on April 17, 2009, 19:57:17
I would do the flex lines at the same time.  Those can look perfect, but degrade inside and cause problems.  Picked up the gf at the airport once, and she noticed I was a bit dirty.  I explained that I got dirty putting out the fire.  The fire caused when the '65 Vette's line closed up and superheated everything back there . . .