Author Topic: Brake Shoe Adjustment Problem - 230 SL (Read 5944 times)

rjmarco · « **on:** September 25, 2023, 21:07:58 »

Background: I recently had new brake shoes and springs installed along with a pair of reused brake drums that were in good condition. This was done by my trusted mechanic (old school and very knowledgeable) with whom I've worked for over 10 years.

Problem: While on the lift, the left rear wheel can be spun freely while the right rear wheel does not and has some apparent rubbing/binding. I am told that there are adjustment bolts on the rear wheel backplates that adjust the position of the brake shoes. The backplate is shown as part no. 1 on the attached drawing. The left side adjustment bolts are working but the right side bolts do not. I've been advised look for a replacement backplate and to refrain from using the car as a daily driver with concern for friction and overheating of the aluminum drum. Of course, new backplates are NLA so I am looking for a salvage part.

Question: Has anyone experienced anything similar and how was it resolved?

Thanks much!!

dirkbalter · « **Reply #1 on:** September 25, 2023, 22:11:45 »

I think the adjusters in the backing plate are just (rusted) stuck.
I would try to soak them (WD40 or better) for a while and get them to move again before you buy new backing plates. Mine were quiet tight as well and it took a bit of rocking back and forth together with lubricant to get them moving.
Its easier with the brake shoes and mechanisms removed when you do that.

rjmarco · « **Reply #2 on:** September 25, 2023, 22:51:31 »

Dirk,

Thanks much for the suggestion and will give this look.

Rich

rwmastel · « **Reply #3 on:** September 26, 2023, 03:20:38 »

Many people say WD40 is not techically a penetrating lubricant. Everyone has their favorite. I prefer Liquid Wrench or PB Blaster.

ja17 · « **Reply #4 on:** September 26, 2023, 05:13:00 »

The 19mm bolt heads with the slot, are the adjuster bolts on back of the backing plate. Use a 19mm 1/2" drive socket and breaker bar to get them working, after dousing with penetrant. There are two on each rear baking plate.

rjmarco · « **Reply #5 on:** September 26, 2023, 12:23:53 »

Thank you, Joe and Rodd. Rich

Pawel66 · « **Reply #6 on:** September 26, 2023, 13:02:10 »

It does not look like you need it, but in case of catastrophe you have one backplate here: https://www.niemoeller.de/en/w113/w113/B042/422/1

rjmarco · « **Reply #7 on:** September 26, 2023, 13:31:52 »

Pawel,

This is a great reference and glad to have it in my back pocket in case it's needed.

Thanks much,

Rich

dirkbalter · « **Reply #8 on:** September 26, 2023, 14:21:03 »

Rich,
Looking at the picture of the used one from Niemoeller, the adjusters likely need some work as well.

rjmarco · « **Reply #9 on:** September 26, 2023, 15:58:19 »

Latest info: my mechanic tells me that the adjustment bolts turn but do not move the brake shoes as needed. I have found a US source for a salvage backplate. To my amazement, the MBZ Classics Center had the gaskets that go with the backplate.

dirkbalter · « **Reply #10 on:** September 26, 2023, 17:11:47 »

Rich,
Looks like you got it under control.
However and without questioning you mechanic, it would be interesting to know what exactly causes the non movement of the brake pads.

rjmarco · « **Reply #11 on:** September 26, 2023, 17:15:55 »

Agree, Dirk.

I wondering about that, too. Rich

rjmarco · « **Reply #12 on:** October 08, 2023, 15:41:10 »

Here is an update. I expect to get a salvage backplate for the right rear brake and we'll reattempt adjusting the brake shoe-to-drum clearance. In researching this further, I cam across a useful youtube video which includes the function of the back plate screws for the 230 SL and older generation brakes.

Regards,

Rich

https://youtu.be/-0ZIN7gG-7U?si=ojMyASrMO811D6y3

ja17 · « **Reply #13 on:** October 08, 2023, 19:53:45 »

Yes the slotted bolt should have an eccentric shaped washer on the shoe side of the backing plate. When the slotted bolt is turned, the eccentric washer moves the brake shoe.

rjmarco · « **Reply #14 on:** October 08, 2023, 21:02:22 »

Thanks, Joe.

I should find out this week whether I have the problem licked.

Rich

rjmarco · « **Reply #15 on:** October 08, 2023, 21:08:21 »

Joe,

Here are two photos that illustrate your comment on the eccentric shaped washer.

Rich

dirkbalter · « **Reply #16 on:** October 09, 2023, 00:21:26 »

Quote from: rjmarco on October 08, 2023, 15:41:10

Here is an update. I expect to get a salvage backplate for the right rear brake and we'll reattempt adjusting the brake shoe-to-drum clearance. In researching this further, I cam across a useful youtube video which includes the function of the back plate screws for the 230 SL and older generation brakes.

Regards,

Rich

https://youtu.be/-0ZIN7gG-7U?si=ojMyASrMO811D6y3

Unless the very early 230is are different, the video is not for a 230 SL.

ja17 · « **Reply #17 on:** October 09, 2023, 01:19:59 »

Thanks Rich, you can clearly see in your photo, how the eccentric washers "spiral outward" to move the shoes out. The front adjuster should be turned counter-clockwise to adjust and the rear adjuster should be moved clock-wise to adjust. Notice that these units are not meant to ever be removed from the back plate.

rjmarco · « **Reply #18 on:** October 09, 2023, 02:28:00 »

Dirk and Joe,

Very helpful info.

Thanks,

Rich

rjmarco · « **Reply #19 on:** October 14, 2023, 01:09:12 »

Just want to follow-up on all the helpful notes and let you all know how things turned out.

I was able to get a salvage right rear backing plate from Bud's Benz plus two replacement gaskets from the Classics Center. These were installed and we were able to adjust the brake shoe/brake drum clearance as needed to make the right rear wheel freely turn when on the lift.

What I think must have been the original backing plate on my car showed that the eccentric adjusting washers had clearly been worn down and made ineffective from past use.

This ended up requiring a lot of disassemble/reassemble work by my trusted mechanic. I am glad to have another restoration issue behind me.

Regards,

Rich

Cees Klumper · « **Reply #20 on:** October 14, 2023, 03:17:41 »

Perhaps the old plate can be repaired/salvaged by making new excentric washers from heavy gauge steel and welding them onto the slotted bolts.since they are NLA and apparently can wear out.

rjmarco · « **Reply #21 on:** October 14, 2023, 12:38:07 »

Good thought, Cees. Thank you.

ja17 · « **Reply #22 on:** October 16, 2023, 04:56:19 »

They don't wear. Most likely someone modified them. Mercedes finback sedans of the era, shared the same brake plate most likely. Check to see if the first three #s for the part is "110" or "111" if so, the search for used parts should be much easier. If it is not "113" it will be easier to find used and much less expensive. In fact I probably have a dozen out back!

rjmarco · « **Reply #23 on:** October 16, 2023, 12:07:22 »

Very helpful. Thanks, Joe.

Pawel66 · « **Reply #24 on:** October 16, 2023, 12:30:07 »

I checked the part as per ja17 advice. It is important as it is vastly broadening your search.

Part numbers are:
A 110 420 30 17 for left plate and 31 17 for the right plate.

They were used on W110, W111 and W113.

For W110 - 110 000, 110 001, 110 002, 110 003, 110 004, 110 005, 110 011, 110 012, 110 013, 110 014, 110 015 and 110 016.

For W111 - 111 010, 111 012, 111 014, 111 021, 111 023.

A good place to decode those numbers is Niemoeller catalogue: https://www.niemoeller.de/en/catalog-d

You will see which designation meant which car.

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Author Topic: Brake Shoe Adjustment Problem - 230 SL (Read 5944 times)