Odd wear on brake pads

[robb4100]

My brakes often squeal and when I checked them out I found this circular wear pattern on the back of the brake pads. Does anyone have an idea of how to stop this wear and stop the squealing.
http://yfrog.com/kjipd0j
Thanks Robb

[robb4100]

Here is the picture without having to go to the link

[john.p.clegg]

Robb

Anti-squeal shims ?

John

elan-f15/the-danger-reading-the-archives-t13364.html

[UAB807F]

Hi Robb,

Do you have the stainless shims fitted, like in this sketch ? I think they are required to stop the pads rattling about & were at one time called "anti-squeal" shims.



Brian

Edited to add - by the time I'd found a picture, I was already too late.....

[robertverhey]

More likely the piston itself surely?

[AHM]

You will need the shims - notice that they are directional and only shim half of the piston.

Simon

[robb4100]

Thanks Brian,

No I do not have the shims fitted. Do you know where they can be purchased in the US?

Also I tried the Thin aluminum sticky shims that fit over the entire back of the pad. This caused the brakes to be engaged at all times- the piston did not retract far enough. Is this symptom of a different problem. The pads only have 1K miles on them so I assume that there is not enough wear on them to allow both the full back shim and new pads.

robb

[UAB807F]

No I do not have the shims fitted. Do you know where they can be purchased in the US?

Also I tried the Thin aluminum sticky shims that fit over the entire back of the pad. This caused the brakes to be engaged at all times- the piston did not retract far enough. Is this symptom of a different problem. The pads only have 1K miles on them so I assume that there is not enough wear on them to allow both the full back shim and new pads.

Hi Robb,
The shims are fairly standard items and nothing "Lotus special" so you might be able to buy them at your local parts store but they are also listed by RD Enterprises. They are very thin stainless steel, probably 0.020"-0.030" or so, certainly not much more and are easily sent by post if you can't get locally. They are fitted to lots of British cars using the same sized caliper, eg Triumph spitfires, heralds, gt6, etc.

The second issue I don't know about, I guess it's how thick the Aluminium shims are. Normally even with new pads there is still a slight clearance - I presume the pistons are free to move in & out ?
Brian

[ardee_selby]

FWIW...if RD are out of stock...

http://www.theautopartsshop.com/auto+ca ... -shim.html

[robb4100]

I got some shims from RD but they did not have the space for the piston cut out. Was I supposed to cut them out? or is there a different set of shims?

Robb

[patrics]

Hi Robb,
The picture doesn't look right but might be a trick of the light.

Is that a big hole in the backplate?

Regards
Steve

[robb4100]

Steve,

I see what you mean- yes it is an optical illusion there is not a hole in the back but there is a round circle the size of the piston that is worn into the gold colored backing on the pad. there are linear wear marks from the vibration.