Changed brakes and still squeeks - PeachParts Mercedes-Benz Forum

turbozeke418 · #1 09-20-2013, 12:14 AM

I have 1980 300TD and have been redoing my front brakes little by little. On my right front side, I replaced the rotors, loaded calipers and replaced the brake hose (that was the original problem and just did the rest). Now everything is new and I hear a squeaking coming from that wheel. Any idea on what would be squeeking and why? The old rusted out brakes and rotor that barely worked (locked up when it did) never squeaked a bit. The car does it just rolling at idle. Not when just the brakes are a pressed.

Stretch · #2 09-20-2013, 12:20 AM

Is the brake shield rubbing?

Did you fit a new calliper?

Can't Know · #3 09-20-2013, 12:47 AM

Did you use the mb brake paste (lubricant)?

Properly applied (!) that usually takes care of it. You can also apply the red or blue goo to the pad backing plate.

cooljjay · #4 09-20-2013, 01:28 AM

Agreed, make sure you used the shims that came with the pads or the anti squeak...brake quite what ever you want to call it grease.....don't need the genuine made from virgin tears Mercedes stuff.....the 99 cent package by the cash register will work....

turbozeke418 · #5 09-20-2013, 01:44 AM

Nope didn't put any grease on since they were loaded calipers. I didn't think I needed to.

cooljjay · #6 09-20-2013, 02:17 AM

Had to Google loaded calipers....never heard that saying...,

Supposedly it means the calipers come with all hardware and pads....so you would still need to buy grease and apply it to the back of the pads.....to quite the squeak.....unless a plastic shim came with the pad, that you unstuck and stuck to the back....aka sticker.....

If it doesn't stop, with grease....it may pay to get some nicer OEM type pads...

MBeige · #7 09-20-2013, 02:25 AM

Quote:

Originally Posted by turbozeke418

I have 1980 300TD and have been redoing my front brakes little by little. On my right front side, I replaced the rotors, loaded calipers and replaced the brake hose (that was the original problem and just did the rest). Now everything is new and I hear a squeaking coming from that wheel. Any idea on what would be squeeking and why? The old rusted out brakes and rotor that barely worked (locked up when it did) never squeaked a bit. The car does it just rolling at idle. Not when just the brakes are a pressed.

The bolded part of your original description tells me it's a bearing issue, when it squeaks when the vehicle is rolling, and the brakes are not applied.

cooljjay · #8 09-20-2013, 02:26 AM

Quote:

Originally Posted by MBeige

The bolded part of your original description tells me it's a bearing issue, when it squeaks when the vehicle is rolling, and the brakes are not applied.

Ooopppssss I missed that.....

turbozeke418 · #9 09-20-2013, 03:40 AM

That would make sense I suppose. I just regreased the current bearings.

barry12345 · #10 09-20-2013, 08:01 AM

I would jack up the wheel and turn it by hand. Being that close in proximity might help you locate the offender. If not and the squeak is still present remove the wheel and try gain. You can eliminate or blame the pad to rotor contact by backing the pads off the rotor a little. If you are not sure you set up the front bearings properly check the end play.

turbozeke418 · #11 09-20-2013, 08:11 AM

Awesome idea... Thanks.

Zacharias · #12 09-20-2013, 10:15 AM

How did you do the final tightening of the locking bolt? By feel or with a dial gauge indicator?

I overtightened mine the first time I did it, but I would call the sound I got more of a howl than a squeak.

Can't Know · #13 09-20-2013, 11:54 AM

A brake-related squeak while rolling that goes away when the brakes are applied is almost always a pad-vs-rotor issue. What you're hearing (assuming it's not a bent dust shield) is a harmonic that results from the pad just barely kissing the rotor, much like you can make a crystal wine glass "ring" by wiping a partially-wetted finger around the rim. (If your wheel bearing is so dried out that it is squeaking, then you have another issue entirely, and since the OP says he re-packed them, that's not an issue anyway.)

The MB paste (lubricant) isn't made with tears from a virgin, but it differs from the .99 packet stuff in a few ways. One, it is thick and stays where it is put, particularly as it gets hot. Two, it doesn't attract as much dirt and dust as do other brake lubricants. Three, it seems to be more resistant to age, heat and water and thus usually lasts the life of the pads, whereas other brake lubes may have to be reapplied. The packets are not much more than the .99 packets at autozone, and one packet does one axle set, so why quibble over pocket change?

Also, brake lubricants shouldn't be just spread across the back of the pad. Rather, they are to be applied to the edges of the backing plate to lubricate against any metal-to-metal contact. If you need to, after you clean up the caliper then test fit the pad to see where it contacts the caliper. Then apply the brake paste in all such contact places. Note that a thin film is all that's required (and a thin film may be applied on the back of the plate anyplace that it contacts the caliper or piston, though these are not really movement points). If you have guide pins and notches or holes in the pad backing plate then the lube/paste should be applied here as well.

There are also anti-harmonic products, such as the red and blue gel/goo I referenced. These are indeed designed to go on the back of the pad backing plate.

The idea of these products is that they cushion against, disrupt and absorb harmonic noises.

Lastly, if your replacement pads don't come with shims, but there are shims on the pads you're removing, read the literature that comes with your new pads to see if you should re-use the old shims. Some manufacturers glue a thin shim right to the back of their pads, often rubberized (again, fighting harmonics). If you try to use your old shims with such new pads, you will end up defeating yourself rather than squeaks, and the loss of clearance may mean you have heavy brake scrub, perhaps so much that you cannot even turn the wheel by hand.

Good luck.

The Gears · #14 09-20-2013, 02:06 PM

This problem drove me nuts for a year. When applying the brakes initially always a squeal and a groan at a crawl. I tried all kinds of backing pastes and grease where the backing bottom edge rests on the caliper. Nothing worked for long.
The final fix.
I placed a 10 thou. brass shim strip between the caliper and the bottom edge of the pad. The shim was cut to the width of the space for the pad to insert into the caliper and a 1/2" bent over at each end to keep it in place.
I thought that the space allowed in the caliper was Just a few thou. to long allowing the pad to move up and down in the caliper sort of a grab and let go action. Reducing the space stopped this movement and the squeal on application. Try it, the shim cost a buck at a hobby shop or industrial supply shop.