Brake squeal

[Pomorza]

Hey mates

 

So about a year ago I redid my rear brakes, replaced all the hardware, drums and shoes with new parts. This past week my rear brake started sqeaking when coming to a stop. Wasn't bad at first but now it sounds awful. I took the drum off and inspected the shoes but all looks find. The drum itself did seem like it had grooves in it - I'm assuming from braking. Any ideas on what this could be? It sounds terrifying whien coming to a stop, to the point where it sounds like its metal on metal.

 

Thanks

Jan

[Zed Head]

Are the parts moving correctly?  1976 has the sliding wheel cylinder.  It has to move freely.

[Chickenman]

Can you take some picture of the shoes, drums and overall brake setup. We may be able to tell more that way. A picture says a thousand words.

 

Drums should not have any significant grooves worn in them. " Significant " is subjective, so that's why the request for pictures.

 

FWIW, brake dust in drum brakes accumulates with use and can cause noise. But usually not a " Metal to Metal " grinding sound.

 

 

[Pomorza]

Chickenman

 

I'm going out of town next week so I won't have pictures until sometime after I get back. I saw nothing out of the ordinary when I took the passenger's side drum off other than those grooves in the drum. They aren't deep but you can feel them if you slide your finger across. There's an ungodly amount of brake dust when I take these off, it always has been this way it seems. I've never owned a vehicle with drums so I'm not sure if that's normal or not.

Off topic question. Should your RPM go up when you pump the brakes or is this a sign of a failing (failed) brake booster?

 

Thanks mates

Jan

[Hodgimus-maximus]

Does the squealing happen all the time or does it get worse the more the brakes are used?

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[Zed Head]

 

Off topic question. Should your RPM go up when you pump the brakes or is this a sign of a failing (failed) brake booster?

 

That's a sign of a failed booster.  They seem to be hard to find these days, so good luck.  

 

Brake dust is worn shoe material.  A lot of dust means a lot of wear.  Are you sure the shoes are still okay?

[Pomorza]

Zed Head

 

The shoes are a year old and have 10k on them. There's plenty of material on them. Other than being a bit glazed I don't see any issues with the shoes. 

 

@hodgium-maximus

 

The squealing only occurs when I use the brakes and only really at slower speeds (coming to a stop for example). It does get louder the more I use the brakes.

 

Jan

[Hodgimus-maximus]

Well my thinking was since you had a grove in your drum that it was heating the gas causing the sequel either way you should see about having them turned or buying new drums. Also check to make sure that you breaks are properly greased

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[Chickenman]

Zed Head

 

The shoes are a year old and have 10k on them. There's plenty of material on them. Other than being a bit glazed I don't see any issues with the shoes. 

 

@hodgium-maximus

 

The squealing only occurs when I use the brakes and only really at slower speeds (coming to a stop for example). It does get louder the more I use the brakes.

 

Jan

Unfortunately, brake shoe quality has taken a big dive since the banning of Asbestos. Asbestos was the perfect material for brake shoes ( and clutch discs ) due to it's thermal and friction properties. It was the " Just right " bowl of porridge.

 

Since the banning of asbestos, brake shoe manufacturers have had to go to other materials to act as a " filler ". The result being that some filler materials ( such as Kevlar ) are too hard and result in noise and excessive wear on the drums. Shoes with carbon as a binder, create a lot of dust and again can be noisy. It's getting very hard to find quality brake shoes for Vinatge cars these days.

 

You can still get custom shoes made, usually by specialty manufacturers for Trucking and Industrial use. But the places are not as plentiful as they once were and sizes may be limited. If you can find a good semi-metallic lining for your shoes, that may be one way to go.

 

https://www.google.ca/search?q=Custom+brake+shoe+relining&ie=utf-8&oe=utf-8&gws_rd=cr&ei=_XE6VsHUAcaqogSRgKnoAQ

 

BTW.. the glazing on the shoes and dust will have to be removed. The dust can cause a lot of noise and can be very abrasive. You may have to machine the drums depending on the severity of grooving. Unfortunately, with today's brake shoe materials, it is common for the dust accumulation and drum grooving to return in fairly short order. Easily in 10K miles.

 

It may be time to consider a disc brake conversion....

Edited November 4, 2015 by Chickenman

[Mark Maras]

 May or may not be related to Zs, When my Subaru brakes start getting noisy, I can quiet them with a thorough cleaning using compressed air. Lot's of dust buildup. I don't ever remember a brake squeal problem in my original Z. I agree with Chickenman, new compounds seem to be prone to squealing.