DIY tune-up for the original MB calipers...
 

Those who have read my recent threads know that I have had a few problems with my rear brakes and that I am just about to do the bleeding, change the rear brake pads and look into the parking brake shoes to make sure everything is all right there.
It seems my car has the original rear calipers and, since both of them (L and R) have been using the internal pads more than the external, my intention was initially to change calipers with new ones... But, after seeing what they go for, right now I can't spend $300 on ATE/Bendix calipers alone... so I am looking into ways I could possibly "condition" them (bring them back to life, so to speak). I am not even sure something is inherently wrong with them... it would be absurd to spend $300 without first trying whatever else that can be possibly done... How do I go about it? Also, when I disconnect them from the hoses in order to take them apart, what's the best way to prevent the brake fluid from coming out?

Thanks,
Rino

Yikes!

You are in uncharted territory. Stop before you cost yourself some serious money.

Do not attempt to take the calipers apart. If they aren't stuck, or leaking then leave them alone. You may want to change the rubber brake hoses. If they are originals then definitely change them. However, be advised, that you need some tools for this type project.

You need a can of the proper brake fluid ( Do not use Silicone Fluid). You need to know to take precautions about getting fluid on the paint. You need to know how to bleed your brakes. You need a flare nut wrench for the brake bleeder nipples. You need some tubing. A pressure bleeder, like Motive Products, would be very helpful.

You may need a service manual to explain some of the procedures. Like how to back off the parking brake in order to remove the rear disks.

It's all not very complicated, the second time you do it. The first time will require some patience.

Good Luck,

Steve

I seem to remember a rebuild kit that was available, but it required a special tool and some expertise...

If both rear brakes are wearing the pads out unevenly, then I'd be leaning toward contaminated brake fluid, not only would I bleed the brakes, but I would do a brake system flush if the fluid in your reservoir is anything other than transparent.

I spoze you could plug up the brake line when you remove it, but you have to bleed it after you put the caliper back on so why not let it drain into a small bottle?



ps. I got a junkyard caliper and rotor for $20

If the caliper is screwed, I thought, I would have to replace it anyway... I am actually saving money by trying to re-condition it...
I have to change the brake fluid anyway... I thought to use the following method, which it is also great for pinpointing any problems with the brake lines (as just described in a recent thread today):

Originally Posted by larry perkins
For the brake bleeder nipples, doesn't it take just a 8 or 10mm normal wrench?
Regarding the tubing needed, can someone advise what type and size I should get? It would be much appreciated... As stated above, I won't need the pressure bleeder. How do you back off the parking brake in order to remove the rear disks? I do not have the service manual, just the Haynes... I thought the info I needed was covered already in some of my other threads on this subject and that the procedure was not at all complicated....

Thanks,
Rino

Yes, both rear brakes are wearing the pads out unevenly with the exact same pattern (much more wear on the inside pads). Contaminated brake fluid is very likely, since I never changed it in two years, and God only knows when it was last changed. The fluid in the reservoir IS transparent, but you need to understand that I have added fresh fluid several times during these past two years (since owning the car), even though I checked for leaks and there are none.

I would appreciate someone (who has actually done it) to explain to me specifically how to go about it and exactly what specialized tools are needed...
I have no problems draining the whole fluid from the system first and then disconnecting the rear calipers. My only question in this regard is: once I put the calipers back, will refilling the MC reservoir and using the procedure illustrated by Perkins (see preceding post in this thread) extract all air from the brake line and calipers and work as it is supposed to?

Another reason for disconnecting the calipers, IMHO, is to get rid of the old fluid/gunk that is likely to have accumulated in the calipers throughout the years... but once that is done, what's the correct procedure for reconnecting the calipers in a way that eliminates any air inside them? (I know, redundant question...)

Thoroughly explanatory answers would be very much appreciated...

Rino

Given that the calipers are 28 years old, I wouldn't even try to restore them.

I'd buy new ones.

As for stopping air getting in, just crimp the brake hose, put your new caliper on, attach the hose to the new caliper, and pump new fluid through until any air has been evacuated.

What they are referring to is a "brake caliper rebuild". You can purchase a kit and rebuild the calipers yourself. But, it's a difficult procedure and getting the pistons into, and out of, the bores is quite a task. You'll need an air compressor and a rig to block one of the bores (when the first piston is ejected). Furthermore, you need to be able to evaluate the piston for any rust or damage and toss the entire caliper if you find any that cannot be polished out.

Finally, the front calipers have heat shields that are very difficult to install without the proper tool.

If you've never even removed a brake caliper from the vehicle, I'd urge you to reconsider the task of rebuilding the calipers. It's not for beginners.

Yes, the calipers are 28 years old, it is true. At the same time, though, the car has relatively very low mileage on it and these 28-year-old calipers have worked faithfully and flawlessly for the past two years... Isn't it worth it to give it a try when the other only prospect is to buy new ATE/Bendix calipers which will damage my wallet with minus $300? (this is a bad time for me doing that...)

I have to change the brake fluid anyway, and someone else suggested to drain all the fluid first, since I would have to get rid of it anyway later, so that's why I asked that question...

Thanks,
Rino

Yes, but what are the chances of my finding two matching calipers and rotors in a junkyard that supposedly work all right... I already have those in my car, though they are old, and I know them to be in good working order as they have flawlessly worked for the past two years....

Rino

I wasn't really thinking in terms of "brake caliper rebuild..." I thought I would disconnect the calipers, get the old fluid/gunk out by compressing/extending the pistons a few times, lubricating the things at the same time with new brake fluid...
that's all... You are right, I am a beginner... who is just trying to find out from you experts around here what it is that I can do intelligently and within my reach under these circumstances...
Again, I have no evidence of anything being specifically wrong with the calipers that I have now installed. As someone else has pointed out, it could be just a matter of old, contaminated fluid... and if that were the case, it would be a great sigh of relief for me.

Thanks,
Rino

Yes, you are a beginner, and we are telling you, based on your questions, that rebuilding brake calipers is beyond your skill level and beyond you existing tools. I suspect that many of us would do the following based on your description. New Rear rotors, new calipers, new brake lines, new fluid, and new pads.

Remember, the braking system is a big safety issue. Do it wrong and die, or kill someone in a wreck.

Cars don't last forever. They require maintenance. They often times require spending money for parts.

Steve

I disagree....... I rebuilt 3 of the calipers on my car when I did the brakes, within 4 months of buying the car. I'd never even touched brakes before.. My family always has left brakes to the dealer because they believed it to be a "specialty" job....... I was the first in the family to attempt myself (too much a cheapskate to farm it out) and rebuilt three calipers with just simple shop tools. I also learned a secret to removing both caliper pistons with an air compressor too. The only reason I didn't rebuild 4 of the calipers is I broke a piston on the first caliper trying to forcefully extract the piston with channel locks! :stupid: I learned the error of my ways and didn't do that again! I bought a rebuilt unit at AutoZone for $75 + core charge and found this tip.

: To remove both pistons with a shop air compressor, place two strips of lathe board inside the caliper where the brake disc would go. This will not allow either piston to come out of the caliper as they will still be partially seated. Then press both pistons back in all the way. Do this several times as it will loosen the pistons up. Then remove the lathe board and using your fingers, you should be able to remove one piston and then the other very simply. I installed the pistons and the heatshields on the front carefully with channel locks and have been driving on these brakes for over 25000 miles with no problems and no leaks.

So, no, it's not a simple idiot proof job, but I recommend trying it before forking over the dough for new calipers. Plus, if he totally screws em up, he can go to Autozone and get rebuilds (my store had mine in 1 day) and they will even accept his damaged caliper(s) as an acceptable core!

The only way contaminated fluid will affect your brake system as you say it is, is if the water in the fluid has cause a piston to rust. If that is the case, your caliper WILL need to be replaced with a rebuilt one...... :(

THERE WE GO! Thanks a lot, Matt!!! And as you can see, Steve, though I AM a beginner, not all of you are telling me the same thing. Twenty years in the self-publishing industry have taught me that after asking 29 experts to do something, and having them tell me it can't be done, if you don't give up and keep asking someone different, in a different way, they will come up with a way to do it and even teach you how to do it... And I am specifically referring to a particular instance that happened to me about ten years ago... 29 experts said no, it can't be done... the 30th person said, oh yeah, here's how to do it, and taught me how, and I was able to do it successfully. That was one of the greatest business lessons I learned in my entire life... and a very profitable one for me. The case here is not as extreme: a couple of people advised against it, then along came Matt and told us how he did it...

Which is completely beside the point anyway... As I have already stated in one of my earlier posts in this thread, I am not thinking in terms of "brake caliper rebuild..." I did not want to go that far, realizing I do not have the proper tools anyway... I just wanted a way to move around the pistons a bit and lubricate them and see what happens... And Larry Perkins, from the other thread, has provided the solution I was looking for... Should that fail, I'll probably go for a couple of $60 rebuilts... Here is what Perkins had to say:
Thanks everybody for enlightening me with your concepts and expertise...

Rino

Sure, but two calipers in exactly the same way and at the same time?
Please refer to my last post... Should that not work I'll go for the rebuilt ones...

Thanks!
Rino