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

I haven't had to do my rear brakes yet but I have rebuilt calipers on other cars and the biggest thing is just take your time and don't force things. Calipers are usually supposed to float so they stay centered and if your brakes are wearing on one side more than the other I would suspect that the caliper is sticking on it's slide pins and not floating. I would check this first to be sure they are not rusted in place. I have not looked at the rears so its possible they are not supposed to float and if that is the case then this does not apply.

theres a junkyard in jessup MD that always has 5-10 w123s and they crush their cars regularly, so theres lots of fresh meat. I found a good RR caliper and rotor on the 2nd car I looked @...

hardest part was breaking the rusty lug bolts free.

Update:
 

I did the fluid change this morning, using the method suggested by Larry Perkins: it worked like a charm on all wheels, so it means no problems with the brake lines. I first emptied both sections of the master cyl reservoir and filled it with new fluid, then did the wheel sequence as he suggested. At first the dripping was slow (gunky stuff came out) on each wheel, then faster as the liquid cleared. It took about 1 hour to do the complete process.

I took out the old pads and was about to move the cyls in the calipers around, as suggested by Larry... but noticed that the rubber rings from the calipers (the ones that push on the pads) were worn out unevenly on both rear calipers... this causes the pads to push against the rotors at an angle, therefore wearing the pads at an angle... So these calipers either need to be rebuilt or I need to get a different pair...

What's your take guys, does it make sense to get my calipers rebuilt locally (by some local professionals) OR should I just dispose of them and go ahead and get a different rebuilt pair? Throwing away the ones I have to get a rebuilt pair seems a big waste to me: why not having mine rebuilt? And it should save me some money too... What do you think of it?

Thanks,
Rino

Don't they usually ask for the cores with calipers?

I have no idea... I was planning to get them from a place online... I called them on the phone, they told me the price and availability... there was no mention of cores... By "cores" do you mean to return the old ones in exchange for the rebuilt ones?
I am very new to this, so please explain...

Rino

what you describe is a floating caliper. on a 123 the calipers are fixed and so have cylinders on both sides of the disc and the caliper is fixed, whith no floating on the pins. and no pins.

tom w

By "core" I mean a unit where the casing is not cracked of something really FUBARed on it. That way they can take the piston out and rebuild it. Now if your piston is cracked or broken, they might consider that a bad core. Like when I get a reman trans. I have to send them my old broken trans. HOWEVER, if the case were cracked, you are SOL. They will take the internal parts and put new clutch packs and clean it out, etc, etc. So, Lets say I get a trans for $4000. They will tack on another $1000 in a core charge. My Visa Bill just became $5000. When I send them back the old trans and they find it in suitable condition, they will credit me the $1000. Same with an engine. If the crank is cracked or the block broken, they deduct what they think it is worth from the core charge they tacked on. That way, you return them something they can use. Otherwise, if you trashed the trans, engine, alternator or whatever, they will have nothing to rebuild.

Got it... I checked the seller's website again, and they do have a $10 core charge on that item... What I don't understand is, it's going to take at least that amount to ship the old caliper to Pennsylvania... and who is going to pay for the shipping? You know what I mean... Heck, I'll find out tomorrow.

Thanks,
Rino

I'm replying to that guy right now. If you go to the bathroom and look in the mirror, you will see him too. :D :silly:

OK, first off, you can get a rebuilt caliper at AutoZone for $75 with warranty and you can physically hand them your old caliper across the counter for covering your core charge, thus no shipping cost.

Second, you said that the "rings" that push on the pads are worn unevenly and causing your pads to push crooked? That is BAD as that means that your pistons have rotated. The pistons are SUPPOSED to not touch the pad in a perfect "O" shape, more of a "C" shape with the open part pointed straight away from the body of the caliper.... This is to keep water from pooling inside the piston seating surface.....

But, it's no big deal, as you can rebuild the calipers as I did, and like I mentioned previously, I would recommend trying as doing it may save you some serious dough and even if you mess it up, they will still be good as cores when you buy your rebuilts.

Oh, where are you located? If you live near Southern MI, I'd be happy to help you rebuild em.....

No special tools or experience need to rebuild the calipers. It's just not worth the time and effort to do it.

I rebuilt the front calipers of my TD. I'd rather pay for already rebuilt replacements than do it again.

Well, whether it's worth it or not depends on how broke you are!!

Rebuild kit: ~$13 each vs $75 each. = $244 savings...........

That'll buy ya some power mods!! :D

rino
 

were the pads worn down to the metal? if so you may be all right with a new set of pads,there isnt much stroke on the cylinder piston, you may have a usable caliber,did you see any evidence of leaking brake fluid?
larry perkins

Thanks for the info. Do you know if the 126's are similar?

You see, that's exactly my point... it doesn't make any sense that they (who operate as online-only - no stores) refund you $20 for returning a couple of calipers (core) that are going to cost you about the same to ship... (even more, if you want to include the cost for the packing and the waste of time involved).

Rino

Also available at Kragen (I just checked) for about that prize... good suggestion, thanks.

Yes, that's correct... (your "Second" paragraph)

Man, I wish I had the tools to try that, I'd do it right away... I have no air compressor (how do I push the pistons out without it?) I'd love to save some serious dough, and as a matter of fact it is ridiculous to me to have to spend all this money for a pair of calipers (I paid $1,100 for the whole car) Do you know of a way to attempt that without the need for workshop tools (air compressor, etc.)?

Thanks,
Rino

I wish... you are a the type of guy who is not found around here... I am in So. California... everyone is fakey and flakey around here... you can count on no one to give you a hand when you need one... and I am not that type of guy... I think one of these days I'm gonna move to someplace where people are more real...

Rino

You must have different sources than I... I've seen those kits around (and on the net) for $29.95... Which makes me kind of uneasy about taking the risk of a DIY caliper repair (if unsuccessful, there goes another 30 bucks down the drain...)

Rino

The pads were worn unevenly, the thinnest side down to about 3mm (thank God not yet worn down to the metal, which would have damaged the rotor...) with the less worn-out side measuring about 6-7mm on the same pad. After pulling them all out, I realized that all the pads have that pattern (and not as I stated before that the inner ones were worn out more than the outer ones). What varies is, for instance, the inside pad being consumed more on its bottom part while the outside pad in the same caliper shows more wearing in the upper part...

There was evidence of leaking brake fluid only in the form of slight rings of rust in the shims, which tells me that the fluid that escaped must have been sort of watery for some time... (I changed the whole fluid in the system this morning)

What do you mean, I may have usable calipers? If I install new pads in these ones (which I was about to do this morning), the damaged (uneven) rubber pushing on them will cause the pads to be pushed again at an angle against the rotor... I don't know how safe or desirable that can be...

Thanks,
Rino

Identical actually. interchangeable even...if you swap the rotors too.
well, there is more space between the pistons to make room for the vented rotors...
John

It just hit me, Larry, is it possible that it is the rotors on both sides to be positioned at an angle to the calipers and therefore to the pads? I have no idea if this makes any sense at all, but it would explain that pattern (inside pad worn out in the opposite way as outside pad in the same caliper) on both the RL and RR sides of the vehicle... And if conceivable, what is it that could make it so?

Rino

your mounting points could be bent. this could happen if the car hit something that impacted the caliper.

or if a ham hand jacked the car up maybe by the caliper.

but if not too severe i would probably live with it. it will be very difficult to repair.

probably the only practical thing is to replace the spindle/ hub carrier.

i am not sure if i have named the part correctly.

tom w

How about the fact that the sway bar link's lower mount is destroyed on the right side... so basically the car has only one SBL connected on the left side. Could this cause that? Meaning... when I fix the sway bar links, will that also fix the tilted rotor/caliper angle and therefore take care of the caliper problem? If that were the case, I'd just need to fix the SBLs and introduce new brake pads and I would be set... God, I hope so...

Rino

Where were you quoted $300?

About $150 each x 2 = $300...

I remember seeing several places with about that price (for new) on ATE and Bendix.

Rino

Wonderful tutorial on DIY caliper rebuilding for the beginner
 

You can find it right here (I just found it and am happy to share it), with accurate descriptions and plenty of self-explanatory images:

http://www.astrosafari.com/cgi-bin/ikonboard.cgi?act=ST;f=6;t=19210

It is not specific to our calipers, but the principle and steps are nearly identical...
It shows you how the right mental attitude and a little creativity can take you a long way...
I would definitely do it if I had an air compressor and accessories at this time.

Caliper rebuilding is really easy, even for a beginner, when someone who has done it is willing to share their know-how and help others, as the guy who wrote this tutorial demonstrates. And I suspect the same is true for every fix imaginable relating to our old MB diesels. All we need is people with a true desire to help one another in this forum...

Rino

You've offered a reference for a floating caliper with a single piston and no heat shields. The rebuild of the floating caliper is a walk in the park as compared to what you have on the Mercedes.

For all others reading this post, rebuilding M/B calipers is not easy, even when someone has done it many times. It's a tedius and frustrating job, usually made worse without the proper tools.

I've done it several times and will probably purchase the front calipers completely rebuilt if I do it again. The rears are somewhat easier without having to deal with the heat shield.

OK, thanks for the clarification... So doing it with our calipers is a bit more complicated. There have been others in this forum saying that they have DIYed their caliper rebuilding for their MBs and that it is not at all complicated... Maybe it is to some and not to others... My point, though, was to commend the good intentions of someone like the guy who took all the time to write that tutorial with a genuine desire to help others and to say that that type of mental attitude is also a very precious asset in a forum like this one.

Rino

The only person stating that it was "not complicated" was Matt.

However, if you understand and read his post, he never even needed to rebuild those calipers because the pistons were easily moveable within the bores. He extracted them with his fingers.

The typical caliper rebuild is done when on piston is frozen in the bore and you cannot remove it..........even with 125 psi..........from a shop air compressor.

Matt makes no mention of this issue and it requires some careful planning and thought........and time.........to free the piston. Even after it's removed, the condition of the piston is in question due to corrosion and all of you work may have been for naught if there is any corrosion on the piston that cannot be polished away.

Installing the pistons back into the bores with a standard C-clamp is extremely difficult because of the shape of the caliper. There is no solid surface to park the jaw of the clamp and it tends to apply pressure off center on the piston. This can cause the piston to bind in the bore and refuse to fully seat.

Matt makes no mention of the heat shields which must be pressed onto the piston and sit at least .004" below to top of the piston face. This is effectively impossible without the proper tool, and, anyone who tells you that they did it properly without the tool doesn't understand the specification.

Matt also makes no mention of the precise 20 degree angle between the piston and the bore that is required per the specification. In reality, you have no tool to measure this angle and can only estimate it.

Trust me when I tell you that it's a long and tedius process and when you are finished it's still not done to the specifications of a proper rebuild house.

As you can see for yourself, "complicated" is a relative term. I consider glow plug replacement on a 606 Turbo engine to be fairly straightforward at this time and schedule myself to do it ever 2 years. However you may think it is over your head.

Personally, if I haven't done it before, I wouldn't. An exception to that is if I have a qualified tech or someone who has done it before do it for me first and let me learn later or one of them standing by in case I get something FUBARed. Now, GPs, who cares? What is the worst thing that happens? The car doesn't start? That is optional. Stopping, well, that is mandatory. So, once again, do you feel lucky? Well, do ya, punk?

This is a link to the caliper repair kit for the front Bendix caliper for my 82 SD.... http://catalog.eautopartscatalog.com/buymb/022406/quote.jsp?header=http://www.***************/header.txt&footer=http://www.***************/footer.txt&partner=buymb&year=1982&product=N1050-30632&application=000047560&clientid=buymbparts&cookieid=20I155P2O2150ISTY1&baseurl=http://www.***************/

Your car should be about the same price. That kit does 1 caliper.... So you'd need two kits..... Maybe the other's you've seen online are a set, for both calipers? That'd be about right price-wise.....

But, what you're saying about the funny wear pattern....... I think Tom W is right, you've got something else going on.........

OK, Brian, thanks for further clarifying... I do appreciate it... I am here to learn, therefore I ask questions, and am thankful to you guys who take the time to answer them. So it does appear like a very complicated endeavor, better left to professionals... (hopefully, no one else will come up and say it is an easy thing and confuse things further by so doing)

Thanks,
Rino

Ease of operation is always different among different people. What is easy for you may be very difficult for me and vice versa.

Not really. At first a simple oil change seemed like over my head... until I did it. Then came the transmission fluid... the diff fluid changes... Now brakes - I thought I could never do it by myself... but I have done it after receiving proper guidance.
So, I've learned the lesson: I am a fast learner... show me how to do it, and I'll do it.

You realize what you just said is a catch-22 type of thing: with that attitudinal approach there will never be a first time. Sometimes it pays off to be a bit adventurous... gather as much information as possible about something, then go ahead and do it...

Should I now be expecting a .44 mag slug coming my way any time soon? Or more precisely a .44 special slug... I hear he used .44 specials in his S&W mod. 29 .44 mag...

[I do understand your safety concerns, by the way...]

Rino