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What can cause drum brakes to squeal?
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D4B



Joined: 28 Dec 2010
Posts: 2092
Location: Hampshire UK

PostPosted: Fri Sep 09, 2016 5:41 pm    Post subject: What can cause drum brakes to squeal? Reply with quote

I rebuilt my Land Rover series 3 drum brakes with many new parts prior to the MOT test in May, and to start with performed as they should without so much as a peep.....

Gradually they began to squeak during braking, and this has since turned into loud squealing every time the brake is applied. I have dismantled and dusted them down, reassembled and adjusted, but still they squeal!

Any suggestions very welcome.

Thanks Steve
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kevin2306



Joined: 01 Jul 2013
Posts: 1331
Location: nr Llangollen, north wales

PostPosted: Fri Sep 09, 2016 7:49 pm    Post subject: Reply with quote

Have the shoes overheated and become glazed perhaps?

Kev
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D4B



Joined: 28 Dec 2010
Posts: 2092
Location: Hampshire UK

PostPosted: Fri Sep 09, 2016 9:15 pm    Post subject: Reply with quote

Hi Kev, thanks for your prompt reply.

No there was no sign of glazing over, besides, i wire brushed them off before refitting the drums, also there are chamfers at ends of the linings.
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jp928



Joined: 07 Jun 2016
Posts: 247
Location: Australia

PostPosted: Sat Sep 10, 2016 2:58 am    Post subject: Reply with quote

Are there signs of the lining to drum contact not covering the the lining completely? Were the relined shoes radiused to the drum ? This involves running the shoes over a grinder so the linings have the exact same radius curved face as the drum. Should be done to suit each individual drum.

jp 26 Rover 9
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D4B



Joined: 28 Dec 2010
Posts: 2092
Location: Hampshire UK

PostPosted: Sat Sep 10, 2016 9:59 am    Post subject: Reply with quote

jp928 wrote:
Are there signs of the lining to drum contact not covering the the lining completely? Were the relined shoes radiused to the drum ? This involves running the shoes over a grinder so the linings have the exact same radius curved face as the drum. Should be done to suit each individual drum.

jp 26 Rover 9


Hi JP, no i didn't do that, and you could be onto something there, but you may need to explain the process to me in more detail..... Confused
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Peter_L



Joined: 10 Apr 2008
Posts: 2349
Location: New Brunswick. Canada.

PostPosted: Sat Sep 10, 2016 1:06 pm    Post subject: Reply with quote

It can be caused by having the wrong design shoe. i.e leading and trailing design compatible with the cylinder and pivot points.
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jp928



Joined: 07 Jun 2016
Posts: 247
Location: Australia

PostPosted: Sat Sep 10, 2016 1:15 pm    Post subject: Reply with quote

When shoes are relined, assuming the new linings are exactly the same thickness as the originals, and the drums are still same diameter as new, all should be well. If the linings are different or the drums machined, the shoes need grinding. The drum dia is measured and a special machine set to that diameter, and each shoe (for that drum) is mounted and run past a grinding wheel so the effective radius of the shoe matches the drum exactly.
All the brakes on my car have been relined and machined before my time, so I may be confronted with the same issue.
This link may help
http://www.autoandindustrial.co.uk/index.php?webpage=radius-grinding

Note the bit at the end about shoes anchored at one end with a cam at the other needing special attention in this regard.
jp 26 Rover 9
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D4B



Joined: 28 Dec 2010
Posts: 2092
Location: Hampshire UK

PostPosted: Sun Sep 11, 2016 2:13 pm    Post subject: Reply with quote

Thanks jp, as new brake drums are just 13.50 each, i might try a pair of those next......
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D4B



Joined: 28 Dec 2010
Posts: 2092
Location: Hampshire UK

PostPosted: Sat Sep 17, 2016 1:53 pm    Post subject: Reply with quote

D4B wrote:
Hi Kev, thanks for your prompt reply.

No there was no sign of glazing over, besides, i wire brushed them off before refitting the drums, also there are chamfers at ends of the linings.


There WAS signs of glazing over, no doubt caused by the drum not matching the shoes profile as per JP's suggestion.......
New brake drums installed this morning, shoes de glazed,
and all is quiet now thank goodness!

Thanks all for your advice Cool Cool

Steve
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kevin2306



Joined: 01 Jul 2013
Posts: 1331
Location: nr Llangollen, north wales

PostPosted: Sat Sep 17, 2016 8:57 pm    Post subject: Reply with quote

Glad you are sorted Steve,
Nothing worse than noisy brakes.

Kev
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BigJohn



Joined: 01 Jan 2011
Posts: 908
Location: Nr. Lancaster

PostPosted: Sat Sep 17, 2016 9:56 pm    Post subject: Reply with quote

Oh I don't know, I'd take noisy brakes over no brakes.
(sorry couldn't resist, I'll get my coat) Laughing
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