My roommate's 1991 W126 350SDL needs a brake job. Due to the convenience and low cost, he bought a set of remanufactured calipers by BrakeBest at the "O" Auto Parts. His car has Bendix on the front and ATE on the rear, but I like ATE better, so we ordered in ATE calipers front and rear. The calipers that came in actually looked really good.

Unfortunately, we found that the new ceramic pad set he got wouldn't fit between the front calipers and rotors. It turns out they only sell the ceramic pads in 17.5mm thickness and the ATE calipers only fit 15mm pads. Darn. I thought about trying to grind a couple mm off of each pad, but that's a pain to do each time and then there will be issues if they are not perfectly flat. So, we returned the ATE calipers and ordered in Bendix calipers.

The front right Bendix caliper, pads, and rotor fit together perfectly. Awesome. But, the pistons and heat shields in the front left Bendix caliper looked different than the right side ones--like they are cheaper quality. Odd. I did a test fit and the pads wouldn't fit between it and the rotor. I pressed the pistons in as far as they could go and was able to force fit the pads in, but the rotor would not turn.

It looks like on that front left Bendix caliper, that they rebuilt it with pistons that are too tall so you can't use the 17.5mm Bendix pads--you have to use the 15mm ATE ones. The caliper on the left is the one with the pistons that are too tall, while the one on the right is correct.


It gets better! The pins provided in the hardware kit were way too long. The pin at bottom is from the left side caliper, and the top one is from the right side caliper.


When fully seated, the clip isn't even in the bore, so the pins would just fall out. But, the right side caliper that was good had the correct length pins.


I wasn't going to have that, so I ordered in another front left Bendix caliper. The parts store ordered in 2 of them by accident. BOTH of them were rebuilt with pistons that are too tall AND had pins that were too long. But the good thing I can say about them is that the bleeder screws weren't as puny as the on the previous set.

I was inspecting the Bendix rear calipers and the hardware set that came with them was really cheap. The spring wires that hold in the pads were bent out of shape and kept catching on the pad shims. One side came with silver pins and gold springs, while the other side came with gold pins and silver springs. One side had a large bleeder screw and the other side had a small one--both different threads. I decided that I didn't like the Bendix rear calipers and returned them for ATE rear calipers since the pad thickness doesn't matter on the rear.

The ATE rear calipers that came in were not the ones I had returned a few days earlier. One of them was missing the hardware kit. So, I ordered in two more rear calipers. One of them was also missing the hardware kit, and the other was a new casting that looked to be of atrocious quality. But, I was able to come up with a decent set of 2 out of those 4--although the rebuilder ground off the "step" that aids in anti-squeal from the end of all the pistons.

I ordered in another front left and right Bendix caliper in the hopes that the left one would be a good one, and that if not, hopefully the right side would be good so I could pop out the pistons and use them in the left side one. They should arrive today.

In the meantime, I went to "A" Zone and ordered in a set of Bendix front, and ATE rear calipers remanufactured by Duralast to see what they are like. Both the rear calipers were missing the hardware kits and I brought this up. The employee said that if I go onto their website, it will say if they come with hardware or not. I said, "I did, and it said YES, but these are missing it." Not that it mattered as I am content with the ATE rear calipers we have now.

But, I inspected the Bendix front calipers and both of them had pistons that were too tall so the pads wouldn't fit, the same cheap-looking heat shields, and both hardware kits had pins that were too long! Unreal! So I had "A" Zone refund my credit card. But they only refunded me for 3 calipers and 1 core. So, I had to go back and get that corrected. The employee said that I should try Summit Racing.

So, I take it that now when you buy remanufactured Bendix calipers, you can only use ATE pads? But then they also come with pins that are too long and will fall out, so it seems like a big mess-up. This is costing me a lot of time and frustration and reminds me why I spend the extra money to get parts from more reputable sources for the car I own.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

Another example of poor quality control.
The rebuilder used ATE rebuild kits on Bendix calipers.
They put ATE pistons and ATE heatshields in the Bendix calipers... that's why the Bendix pads don't fit.

For any rebuilt parts I need, I now source from my independent mechanic.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

I am familiar with what has happened here. They used an ATE style piston on the Bendix body as Alec stated.

Here some pics. Bendix piston on left and ATE piston on the right.



My hunch is during these mass rebuilding, people not familiar, mix up these pistons. (on a side note, Calilper Halves get mixed up all the time with earlier w126 vented and w123 non-vented rotor calipers.)

Or they choose the pistons that look best. I have found the Bendix piston coatings do not provide the best rust protection and ATE versions almost always look really good. So to save time, they choose the piston with less work to do not knowing what the consequences are.

I would of stuck with ATE (my favorite version) and get the correct pads. But what I've seen in the wrecking yards with 2nd Gen w126, Bendix is most prevalent and ATE are rare. So searching for the correct pads might be a bit painful. But not as painful of what you're going through right now.

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1983 123.133 California
- GreaseCar Veg System

Well, that explains it, although the pistons that were in the ATE calipers we had before look like the ones that are supposed to go in the Bendix calipers. Maybe I can get those back and swap out pistons. Haha.

I still don't understand why the pins are too long, though. Probably a miscalculation of some sort.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

I'm about to start the rebuild process on the calipers on the 1991 560SEL. Your post confirms to me that perhaps it is better to rebuild the ORIGINAL calipers rather than risk auto parts store CRAP.

Yes. At this point I'd rather rebuild the originals, but they are still on the car and my roommate doesn't want the car to be down for more than a weekend while I'm rebuilding calipers (the brake job would realistically take a weekend). But I suppose we could replace the wheel bearings, rotors, pads, and parking brake shoes while not messing with the calipers one weekend, and then remove the calipers and rebuild, paint, and reinstall the next weekend--though he wants plenty of time for the paint to dry before we would reinstall them.

For my personal car, I bought brand new ATE calipers and the ceramic pads fit, even though I think they were the 17.5mm thick ones. They worked right the first time.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

I have been around and around with some chain store rebuilds, luckily calipers are not one of these items.

In any event, if you choose to rebuild, please document it for us.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

The Fronts can be done one weekend and the rears on another weekend being that front and rear can be bleed seperaterly.

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84 300D, 82 Volvo 244Gl Diesel

The poor quality of rebuilt calipers is one of the reasons to get the locally instead of having to deal with shipping back and forth and trying to get a warranty honored.

Also when was the last time the Brake Hoses were changed?

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84 300D, 82 Volvo 244Gl Diesel

Good to know that the fronts and rears can be bled separately. The brake hoses are original and those are going to be replaced as well.

Yesterday "O" Auto Parts only got in a right front caliper. Same issues of wrong pistons and pins that are too long. They didn't get in another front left caliper and don't know what happened as it was ordered, but they are going to order another.

At this point I think it's scour for a decent front left from another supplier.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

Do you have Pep Boys in Phoenix? As bad as I talk about them, I have installed two new ATE calipers from them in my 1981 300SD and have had no problem after a couple of years. As I remember they were not expensive - something like $75 each.

I now live in Surprise, about 30 minutes northwest of Phoenix, but there is a Pep Boys about 15 minutes away from me. Both front calipers would take a week to order in and use the same stock photo as O'Reilly Auto Parts and Auto Zone, so it's probably the same rebuilder.

I have a NAPA close by and might order from them to see what arrives. They come with a black coating (which burns off, or is it actual caliper paint?--my roommate wants his calipers painted with red caliper paint) so it may be a different rebuilder than the other guys.

There is also a Carquest, but their website is awful and you can't look up anything. But I may try them. There is an Advance Auto Parts right by the house according to Google Maps, but their website doesn't list any parts and I'm not sure if they are more of a distribution center than a walk-in store?

I forgot to mention that as good as the rear calipers seem to be, one has a pinhole in the boot from when the snap ring was installed--and one side has snap rings to hold in the boots, while the boots on the other side caliper hold themselves in by the inner lip.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

Advance Auto bought out Carquest, which owned WorldPac. Now they arenboth under the same umbrella of Advanced. Both Advanced and Carquest should have access to higher quality rebuilders from the WorldPac side.

But I would stay with O'Reilly's and make them find the correct left rebuild.


.

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1983 123.133 California
- GreaseCar Veg System

Update: It would take a week for NAPA to get the calipers and I would have to pay non-refundable freight if they weren't right. Carquest can only get the front left caliper (which is fine), but they want twice as much as everywhere else plus a $40 core charge plus non-refundable freight, and it would be a week out. It would also be Cardone, which is probably the same rebuilder as O'Reilly and Auto Zone.

I stopped at O'Reilly and swapped out the puny front bleeder screws on the front calipers I have with the bigger ones that came on the two left fronts (with wrong pistons and hardware) that they ordered in a few days ago. So at least I have two decent bleeder screws.

I had them order in a pair of ATE fronts. We originally ordered ATEs for the car but they wouldn't work with the 17.5mm brake pads. But, they had the same pistons and heat shields that the one correct Bendix caliper has. So, they were probably rebuilt with Bendix pistons.

I am planning on getting those ATE calipers and swapping out the pistons from them and putting them into the Bendix calipers so that each caliper has the correct pistons and heat shields. I really hope this works because this is incredibly frustrating. If not, we might as well use ATE calipers since there is no benefit to using Bendix calipers if the thicker Bendix pads don't fit and they at least had proper hardware and the pistons and heat shields matched from side to side.

The other O'Reilly nearby might have gotten in that other front left caliper by now, so I'll check by there later today to see if it's correct.

P.S. I love seeing the auto parts store employees cringe or make snarky comments when they realize the parts are for a Mercedes--because they are voodoo, you know.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

This thread has made me increasingly happy that I purchased rebuild kits for the 1991 560SEL's calipers rather than new calipers from the Autocrap store.