500 Strada front brakes.........

[TimClarke]

New pads and discs from Mdina fitted.

They all went in really easily and seem identical to the ones that they replaced.

Odd thing though.

There seems to be virtually no clearance between the discs and the edges of the caliper body on the sides where the pads are fixed (the inner sides) and I think the disc my be skimming the body of the caliper.

This can't be right surely?

What's odd is that i think that maybe this was happening with the old discs as all the wear and tear is on the inner sides of the disc with them.

I can't see anything wrong with the fitting but maybe there's a spacer missing somewhere?

Any ideas anyone?

Tim

[morini_tom]

On my k1 (same setup as the 500 essentially) I used shims betweeen the caliper and fork to ensure an even clearance each side of pad and disc. m10x16mm in thicknesses from 0.1 to 0.5mm are easily available.

[3potjohn]

I just looked hard at my twin brakes on the K1 and yea the inner face is very close. It’s only taken me since 2007 to notice.
Inners are .7 and .5 mm, but the outside gaps are nearer 1.3mm.
No damage to discs- yet.

[TimClarke]

Interesting!

I'll have a look and a think

[MickeyMoto]

I just looked hard at my twin brakes on the K1 and yea the inner face is very close. It’s only taken me since 2097 to notice.
Inners are .7 and .5 mm, but the outside gaps are nearer 1.3mm.
No damage to discs- yet.

Good to see motorcycles aren't banned this century!

[3potjohn]

I blame the sun- cannot see to type. Fixed now ta. I expect it is nearly dark up there…

[MickeyMoto]

Due to global warming, the perma frost here should be clear by 2097 so I can get the bike out!

[TimClarke]

I just looked hard at my twin brakes on the K1 and yea the inner face is very close. It’s only taken me since 2007 to notice.
Inners are .7 and .5 mm, but the outside gaps are nearer 1.3mm.
No damage to discs- yet.

Well, I fanally worked it out.

What the issue is that the pads i bought from M dina fit perfectly and are the ones that were in the bike when i bought it. Trouble is the fixed ones (on the inside of the discs) fit almost flush with the body of the caliper in that is virtually no pad sticking out. Makes me wonder if there's supposed to be some sort of spacer behind the pad?? Or the pads are the wrong ones??

[morini_tom]

They aren’t floating calipers- there are pistons on both sides so there is no fixed pad… Are you sure the piston in that side isn’t sticking and therefore not pushing the pad out?

Some of the available seal kits are very tight in the caliper and can cause the pistons to stick, so even if they’ve had a rebuild don’t assume both sides are equally free without visually checking.

[TimClarke]

Oh blimey yes, I'd better check again!

But even so, even if a piston is all the way in (pushed back as far as it should go) surely the pads should protrude out from the caliper body a bit and not be flush with it?

[TimClarke]

They aren’t floating calipers- there are pistons on both sides so there is no fixed pad… Are you sure the piston in that side isn’t sticking and therefore not pushing the pad out?

Some of the available seal kits are very tight in the caliper and can cause the pistons to stick, so even if they’ve had a rebuild don’t assume both sides are equally free without visually checking.

Thanks to all for the tips earlier on at the Ace, much appreciated. It seems both inner pistons had stuck (all the way in) which would completely explain disc wear on the inner facings as they are pushed against the caliper and also the low speed brake judder.

I've taken the calipers off and split them, you can see evidence of disc/caliper contact.

The next task is to unstick the stuck pistons and I would appreciate any tips as to how to do that!!

Thank you.

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[TimClarke]

This looks like it might work - maybe add some penetrating oil as well?

https://www.youtube.com/watch?v=HZ1SLCHR8EI

[TimClarke]

I am frustrated with the calipers. I thought the brakes would be the easy bit which is why I left them til last!

Anyway, where i'm at is that the pistons are sticky and 2 of them are stuck in.

I've tried to get them out and I can rotate them but not remove them although one of them is half out.

I've spent hours on it and much as I enjoy the satisfaction of fixing a problem i sometimes reach a point where I'd rather pay someone else to do it.

If i could just go and buy some replacement calipers i think i would but failing that does anyone know anyone who does a caliper rebuild service please.

Tim

[MickeyMoto]

Compressed air of the nipple, try rigging a bicycle pump. You will need to reassemble first.

Have you tried heat?

Soaking in penetrating oil?

[Arthur Farrow]

I bought a VERY cheap Chinese master cylinder and used paraffin as a medium (brake fluid would be messy) to move the pistons out on the bench...simply put the master cylinder in a vice and pumped. Worked great

Not the first time I've made this comment