I am doing a brake job on my 1980 w116 300SD, all four wheels.

There appears to be some sort of rotted-away sheet metal shim on the old pads.

The front Mintex pads came with no shims, but the rear pads did, 4 of them.

My question is, are they required to be installed if the new pads fit well, or do they serve some other function and would need to install them?

Thanks in advance.

If I remember correctly, they are anti squeal shims and not mandatory.

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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

Correct; they are not required. Usually you spray the brake pad with no-squeak spray, let it dry and then stick the shim to it. However it is not hard to cut a new shim from a piece of tin with shears; I have done this before and it works fine.

Yes, they are necessary on the front brakes. They are heat shields and they protect the piston rubber boots from sparks under heavy braking and also prevent the pistons from rotating (i.e. keeps the cut-out on the piston face in correct position). Under extreme braking the boots can ignite or melt. They are pressed into the bores of the pistons and usually it is only necessary to straighten them out when fitting new pads.

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Beagle

Ok, so it sounds like its recommended to put them on, had a hard enough time getting the new pads in alone but dont want to take the easy route when working with brakes.

Couple of side questions on the subject.......

1. When working on the front pads, I was taking off the top retaining bolt pin and it shot off, could no longer find it. I have looked at a few auto repair shops and nobody carries them. Any advice where to get them? I only need a single pin.

2. The rotors are ok but what are the symptoms that the calipers needing replacement? The installed calipers seem to work fine but I dont know what to look for to determine if they are still good.

Thanks

If MB felt there was a good enough reason to put them on in the first place, its probably a good idea to put them back on.

I should probably get some of those shim things.. I didn't notice any on my first brake job and I did that a while ago

I bow to Beagle's post.

Beagle - not sure how the completely flat shim can prevent the piston from turning. Have never looked closely for a cut out on the piston. Need to look at my brakes; not sure I replaced all the shims each time I replaced the pads. Did you get this info from a manual and are you sure it is correct?

I think we are talking about 2 different things here.

the ones I believe that Beagle is referring are actually a ring (shield) pressed onto the piston of the caliper. I had purchased remans, the first pair did not have this ring, they did not last long(5 weeks) the second pair had this ring, and they are good 8 months later.

then there are the anti-squeal shims, which are a flat piece of thin steel glued to the backside of the pad.

You should be able to order in a front brake hardware kit and get all the pins. I have one I'd give ya if your close. or the dealership couldn't want too much if your near one.

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1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.

The shields should not be completely flat. They are bent up at 90° on the inside edge to sit against the disc pad inner side to prevent turning (see scetch). You may often find that they have been flattened out when new pads have been pushed in too far. I find that the easiest fix is to use a thin screwdriver to bend the shield back against the inside edge of the pad after the new pads and retaining pins are in.
I had to replace pins once and the only sure-fire place of finding them was a workshop that specializes in reconditioning brake calipers. The calipers themselves should never need replacing. It is only the pistons and seals that wear out. Pistons are chrome plated and if discs are worn and out of parallel the pistons tip and this can peel the chrome. New pistons are available from MB ($$$) or a Brake recon. workshop($). As long as you have no sign of leakage you should be OK.

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Beagle

As far as the retainer pins go I bought a full set for the fronts and rears from this place. I needed one of the springs and the dealer wanted $25 each so this is a good deal.
http://www.oreillyauto.com/EW3/HomePage.do

The thin sheet metal shim is, as others have said, for anti squeal. I always put them in.

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1983 300SD
200000miles

Thanks guys for the replies.

About the pins, thanks for the idea about going to the dealership. I try to avoid the dealership so hard that I forgot I can probably find a small hard to find part there forgot thats even an option lol.

About the calipers, thanks for that diagram. There was mention that as long as there are no leaks I should be fine. When I took the old pads out, there was some goo on them (on the backs of the pads), but was more of a thick sticky substance than brake fluid, so I assume that is not brake fluid.

But I hate to assume, so would love feedback

The sticky substance would be the no-squeak spray. My spray is blue and very sticky.

There is no reason to take a simple job like brakes to a dealership or shop. The average DIYer should be able to do all 4 brakes in less than 30minutes if there are no problems encountered. MB's brake pads are about the easiest in the history of all cars to change.

Remove wheel.
Punch out two pins and take out anti-rattle clip.
Remove pads.
Compress pistons.
Install new pads.
Install pins and anti-rattle clip.
Install wheel.

retainer pins? just buy the kit for the front and rear brakes that also comes with the retainer spring for the fronts and rear