1986 300SDL Brakes Driving Me Insane - Page 2 - PeachParts Mercedes-Benz Forum

gehunter · #16 02-08-2013, 06:46 PM

Thanks for everyone's input

As it turns out, i installed the rear calipers on upside down and backwards. As an added bonus, I kinked the rear brake lines, and killed the master cylinder with all of that pumping. And as a cherry on top, the left rear caliper was the wrong type (close enough it "looked right" on first inspection, but wrong enough to bung it all up).

DOH!

I'm going to create a video post on my 300SDL blog detailing the correct procedures and pitfalls, so other noobs like me out there can learn from this debacle.

Never thought this would apply...
"The fault dear Brutus lies not in the stars but in ourselves"

Wanted this to work out, but I feel like such a yutz.

ah-kay · #17 02-08-2013, 07:39 PM

Quote:

Originally Posted by gehunter

As it turns out, i installed the rear calipers on upside down and backwards. As an added bonus, I kinked the rear brake lines, and killed the master cylinder with all of that pumping.

How could it happen? To err is human but one can mitigate the risks by replacing one caliper at a time. Compare the new one with the old one then there should be no issue. Brake is serious DIY work. I am glad that you sort it all out.

barry12345 · #18 02-08-2013, 08:18 PM

Well now that you are totally over the edge.

It really is not that bad. The master was probably very old to start with. Make sure to get any fluid out of the brake booster if the back seal in the master cylinder let go. The brake system with periodic flushing will probably now go years without attention other than pads when they wear down.

Some years ago there were kits available with the installation tool. I would rekit my mercedes master cylinders if the bore was still good in them and no rust. I should have purchased even more of those kits because they were withdrawn from sale for liability issues. Although there may stil be some out there as the rebuilders are obviously still getting them.

I paid about 10.00 per kit and never had a moments difficulty. Actually that is about all the rebuilders do as well. Your master cylinder is a stepped bore and if damaged I would toss the core and imagine they do as well.

DC is the washington area in general? So you may have corrosion issues there. I live in an even more salted area.

Take some fuel line or simular small tubing that fits over the bleeders on the calipers. Cut it into short lengths a little longer than the bleeders protrude from the calipers. Apply grease to the bleeders. Slide the snug rubber tube over each one and jam a little more grease in the top. They will never seize and it will always be easier dealing with them in the future.

The average bleeder screw here if unmolested for quite a time. I have to heat up around it very hot with oxy/acy and cool down rapidly three times before even considering trying to loosen it. Other wise it will usually break off for sure. I adopted a lot of practices or figured them out for myself.

Once you do one car I found I just automatically do every one of ours over the years. These minor basically free things to do and there are many around a car generally cost nothing but help out yourself if you keep the car long term or perhaps the next guy afflicted with it.

I am so far over the hill myself I even grease the metal brake and fuel lines. Only takes a brush and a litle grease. Extends their serviceable life substantially.

pawoSD · #19 02-08-2013, 08:37 PM

I've had an original W126 master cylinder fail by pumping less than 10 times to do minor bleeding of a single caliper....so don't feel bad. They are not all that expensive, and are pretty easy to replace.

Make sure there's no fluid inside the booster too....

I looked at the pic of your car on your blog page, thats a nice looking SDL!