I have a set of Cooper S disc brakes on my car and the pad shims are rusty and worn through in some parts. The question I have is are they required and if so can you still buy them somewhere?
Pete

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A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

G'Day Pete,
I was told that the new (non asbestos) pads do not require the shims and have ditched them with no problems. Originally my disk pistons had a step so that there was a portion of the circumference that was not in contact with the disk pads, but the last lot I put in were a full circle and thats when the noises started. The metal bits you have are supposed to be anti squeal shims but with the new material pads mine did the opposite, hence why I went looking for an answer.

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Over 1,000,000Km, but now my retirement restoration project

Some pads now have a plasticky coating on the back to stop squeal, others (EBC) suggest you smear the steel back of pads lightly with copper grease (anti-seize).
I run EBC pads- both Greenstuff and Blackstuff, no probs without shims.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks for the info.
Pete

_________________
A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Are they anti squeal or anti rattle shims???
My 1965 Mini parts book calls them anti rattle shims, my 1971 Clubman parts book calls them anti squeal shims!
From what I can remember the shims were NOT flat but had a small curvature which tends to suggest they were anti rattle shims.

Deluxe_68,
The shims used to come with the genuine Lockheed pad sets along with the galvanised split pin retainers. Haven't bought any for ages but the last ones I did buy only had the pads. Nothing else.
(I'm still using the original shims.)

Circus Maximus,
The caliper pistons should have the cut out as this is designed to make sure the pads wear evenly. The idea is to reduce the pressure on the leading edge of the pad to prevent it self energising. Similar effect to a leading brake shoe which tends to drag itself onto the drum or disc in this case.
Some after market pistons don't have the cutout. Does it really make any difference? If your pads are not wearing evenly then this is probably the cause.
The original shims also had a slit in each edge where the piston recess begins.

Hope this helps
RonR

Ron,
Last 2 sets of pistons I bought, both SS and chrome ones have no cutout.
I agree with your synopsis, but pads still seem to wear OK.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

G'Day Ron,
Even with the original stepped pistons I have never had wear that was exactly even, the inside pad and outside pads had different amounts of material remaining. As well the thickness of pad material from top to bottom was different, but in all cases the difference was probably less than 1 mm. The "new" ones seem to be pretty much the same. I agree they should at least include the split pins with new pads.
The biggest difference to braking effect though is to have the rear drums adjusted correctly both for drag and grab, so both sides have equal effect (otherwise you might as well be driving a "bobcat" - skid steering). Try slowing yourself down using the handbrake and see if the car wants to swing left or right.
I put new oversize shoes in my rear drums yesterday then spent 1/2 hour setting them up and going for trial runs around the neighbourhood. Not only is it important to set the adjusters on the rears but you have to get the tension on the handbrake cables even as well. When done properly I have a hard (non spongy) pedal and the car pulls up dead straight and really well. If during your testing a rear wheel should lock up, back off the adjuster. When all four wheels are at peak efficiency you will really feel the difference in G force.

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Over 1,000,000Km, but now my retirement restoration project

nah bugga that nothing like the back end coming loose .....
ask kevs son he shat bricks when i jumped on the brakes on granny
makka

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Anonymous moderation means the agro that is built up towards the mods isn't aimed at an individual (fewer "Makk" attacks). Less stress for mods means less moderator "retirements".

Circus Maximus,
I was refering to tapered wear on individual pads pad rather than differences between the inner and outer pads. Some BMC cars, if I remember correctly, Morris 1300 or 1500 cars, had tapered thickness pads to even out the wear over the life of the pads.
On Minis the inside pads are more exposed to road rubbish/crap compared to the outer pads which are protected by the wheel so the inner pads will wear at a faster rate.
I agree that correctly adjusted rear brakes along with a proper working handbrake are essential for balanced brake effect.

Hi Kevin,
Interested to hear that the piston cutout doesn't seem to make much difference to the pad wear pattern. I've never tried pistons without the cutout. Whenever offered I have always refused to buy them.
More modern cars with single caliper pistons seem to be able to do without cutouts in the pistons. They generally have pads with a bevelled leading (and trailing) edge along with flexible rubber mounting pins for the sliding caliper bits. I guess this compensates for the self energising effect. Well that's my thinking.
Interested in your thoughts on this.

Regards
RonR

I've mentioned this before....talking to a mature Mini racer (code for he was there in the 1960s) he went into great detail about the need to have the pads apply equal force over its friction area on the disk surface.....

The fella reckoned that the standard caliper geometry was one of the biggest impediments to good brakes....under racing conditions....very uneven wear can result and whilst swapping pads around can share the wear it dosent fix it.....he worked up a modification that cured this problem and gave him brakes he was very pleased with...

I don't know if he is willing to describe what he did in more detail....but I will ask next time we meet.

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"Show me the Mini!"

Ron, the tapered 1300/1500 pads you mentioned were used in weird single piston calipers that pivoted from the bottom.
Pads were triangle (or trapezoid?) section when new, one pad thick at top the other thick at bottom. Caliper sat on a 15*? angle with new pads in.
When worn out the pads were parallel and tha caliper axis horizontal.
Weird, but they did work. I ran a 1300 auto for 4 or 5 years.

re the S pistons I was told by Karcraft they were the dreaded NLA.
Can get flat ended now in chrome or SS, that is all.
I was prepared to grind a step on them, but both sets I'm using (1 of each type) on both cars work OK.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hi Kevin,
NLA. That word Mini owners don't like to hear. Oh well I guess we just have to make do with what's available and modify if possible and necessary. At least they are still available.
Hopefully I won't be needing any caliper pistons in the foreseable future.

9YaTh
The equal force thing is why the pistons have the cutouts, but from others experience it doesn't seem to matter for road use. Track use is an entirely different situation. If you can find out what the caliper mods were I think we would all be interested.
Thanks for your info

Regards
RonR

G'Day Ron,
Agreed definately wear difference top to bottom. I will measure mine next time I change them, just out of curiosity if nothing else.
The emphasis on the rear brakes was for the benefit of other readers.
If I might ask a question, why don't slotted rotors shred pads?

9y, I to would be interested to know.

Dino.

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Over 1,000,000Km, but now my retirement restoration project

Don't hold your breath guys...it will be a couple of months before I see him again. I vaguely remember it being to do with locating the piston on the pad....to stop the piston "wobblying" and to make it bear its force more in the centre of the pad.....I'm on it

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"Show me the Mini!"