230SL Brake Problem
 

I had my 230SL out for the first time in a couple of months. The brakes felt funny. They work stop the car fine except that it feels like they do not release when pressure on the pedal is released (brake drag). After releasing pedal pressure, I could feel the brake pedal "connect" with the brake mechanism when the pedal was part way depressed. After driving a little, the brake mechanism would fully retract. Repeated braking did not change how it felt.

I am not sure if you could follow this description (kind of like the sound effects on "Click & Clack"). The question is what needs replacing? The master cylinder is about a year old and the brake booster is original. The fluid is DOT 4 and it was flushed about six months ago.

My guess is the brake booster. Has anyone rebuilt one? Is it rebuild able? A replacement is $425 ($493 in the Fast Lane), any leeds on a "more economical" source?

Hi Jim,

The booster can't hold or apply pressure. All they do when they fail is leak air. That would cause the car's idle to change when the brakes are applied.

See if the brakes are dragging and try to isolate the problem by holding your hand near the wheels one at a time. Any wheel with dragging brakes will be significantly hotter than the others. I would suspect a collapsed brake hose before anything else. If the wheels all feel the same heat-wise, check the pivot assembly that the pedal attaches to. Those can bind from non-use.

Regards,
Randy D.

Jim,
If you suspect the master cylinder / booster is sticking, try repeating the condition and then cracking the brake lines loose at the master cylinder. If the brakes 'unlock' then it's not the brake hoses.
I had the vacuum booster fail on my 1972 220.
It would hold pressure to the brakes with increasing force as the car warmed up, to the point where the car would hardly move! In my case, this was accompanied by gradual loss of brake boost as the car warmed up. A salvage yard booster finally fixed the problem.
Hope this helps.
Happy motoring, Mark

Most definitely hoses
 

Jim,

Check the date code on the hoses. If they're more than 5 years old, replace them. If the little bits of metal up on the body connection for the hoses are too corroded, replace them too.

-CTH

Jim, in case you do need to have the booster rebuilt, I got the following source from Paul Russell and Company - Power Brake Exchange, 260 Phelan Avenue, San Jose, CA 95112, (408) 292-1305. They quoted me $188.00 to rebuild my booster with a 2-3 day turn around. I ended up getting a new booster from S&S Imports at a similar price, so I got the new one. I still have my old unit if that might be of any use. I changed mine out for a lack of boost, but it didn't lock or drag the brakes.

Thanks for all of the good information. I tried Randy's (and Arthur's offline) thoughts first and sprayed some penetrating oil into the two swivel joints between the firewall and the booster. The symptom went away. I am not so cavalier as to say that the problem is solved but no symptoms is a major step in that direction. If the symptom reappears, I will explore further.

Final status report. The symptom re-occurred. I removed the brake booster and discovered the problem. The pivot at on the bottom of the aluminum booster frame for the arm that transfers the brake pedal pressure to the booster was badly corroded and the arm would not pivot freely. I removed the pivot pin, cleaned the pin and frame and the brakes now work and feel super. Again, thanks guys for you help.

Deja Vue
 

Hi Jim,
Glad you figured it out. Trust me...I've seen it all before.
Regards,
Randy D.

230sl brakes not releasing
 

http://www.peachparts.com/shopforum/...cons/icon7.gif 230sl brakes not releasing
My 230sl has had a problem of the brakes not releasing after pressing on the pedal even though the pedal appeared, (control rod - no!) to return to normal position. :( I had to hit the pedal again to get it to release. I replaced the front calipers, flex lines, pads, master cylinder, adjusted rear brakes, and adjusted parking brake, all to no change. :( Finally after leaving the brakes in the locked position I pulled off the vacuum line off the booster and the brake actuating arm retracted. :book: My problem - brake booster even though it held vacuum. I took it out -easy, 7 bolts total. Carefully moved the master cylinder away w/o removing brake lines. Had it rebuilt by Power Brake Exchange, 260 Phelan Avenue, San Jose, CA 95112, (408) 292-1305, in 2 hours while I waited for 182.00! Brakes work great now.:):) :)

Leo .... It is amazinig how much experience is cataloged in these threads. Thanks for posting your problem/solution. We all keep learning.

Jim

Don't forget to lube the pin. Personally, I wouldn't try to take the booster apart because there is a big spring inside under some serious compression. In my recent brake class at NVCC, the instructor said he took one apart and one half flew across the room and and narrowly missed his head. You really need a special jig, plus the two halves are crimped together.

BTW, I'm in the process of fixing my 220S front suspension. I saw your spring video, very good.

Waren ....I am amazed at how many people have found the brake video. When I gave the presentation, I was not aware that he was going to make a video. It was an excellent "car guy" weekend.