Fiat Coupe Club UK

Rear brake caliper-shims; between what & what?

Posted By: dante giacosa

Rear brake caliper-shims; between what & what? - 10/08/2018 20:20

Help me out here, team- I'm having a senior moment

We are just about to refit the back brakes on our project car, and I'm damned if I can work out where the caliper-shims go.

The bolts for the calipers pass clean through the brake disc backing plates & hub-carriers from the rear, to thread into the calipers themselves from behind.
Do the caliper-shims fit between these two parts ?

I had it in my mind that they were under bolt heads- but that's not right is it??

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Posted By: DaveG

Re: Rear brake caliper-shims; between what & what? - 10/08/2018 21:33

It tells you which way in the workshop manual IIRC. If not, just pull Simon's rear brakes apart and have a look wink
Posted By: Edinburgh

Re: Rear brake caliper-shims; between what & what? - 10/08/2018 21:46

Originally Posted By DaveG
If not, just pull Simon's rear brakes apart and have a look wink


Splutter....er well, "what a good idea" laugh


idea Or Paul's.....
Posted By: french_coupe

Re: Rear brake caliper-shims; between what & what? - 11/08/2018 06:48

Just done mine. It goes on the bolts as a washer would do. Does that make sense?
Posted By: dante giacosa

Re: Rear brake caliper-shims; between what & what? - 11/08/2018 08:03

Hey French-

So; it’s like a combination washer for both bolts (obviously) which fits under the bolt heads..? (Behind the hub carrier)

I had in mind that it might be a spacer, between the caliper and hub.

I went through the manual but it wasn’t massively helpful
Posted By: DaveG

Re: Rear brake caliper-shims; between what & what? - 11/08/2018 10:29

The manual say "During re-fitting, remember to fit the shim between the bolts and mounting bracket"
Posted By: french_coupe

Re: Rear brake caliper-shims; between what & what? - 11/08/2018 11:06

Yes that is correct Dante.
Posted By: dante giacosa

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 04:59

Thanks team-

As improbable as it seemed at the time; you are of course exactly right.

Interestingly, there was a subtle clash in the most obvious alternative orientation.

They are on now- Thankyou for your help...
Posted By: dante giacosa

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 07:42

yep-

it was a bit sticky there for a few minutes, I can tell you- we further were confused by these brake pads, which didn't seem to fit 'so well' in the rear callipers...

It all went together though...

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Posted By: neil_r

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 08:09

Why did they not fit well?

Are the pad springs placed in the hole in the caliper? Should they not be within the caliper to take up the play?
Posted By: DaveG

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 10:15

Yes the "tips" of those spring things on the pads are supposed to push up against the inside of the caliper, either side of the "hole" so that the pads are pushed in towards the centre. It looks likely that you've bent one or more or of the "tips" to fit through the hole?
Posted By: dante giacosa

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 12:20

oh crap

yes- that's exactly what we did.

so they are just supposed to push back from either side of the slot; rather than bite into the slot..?

what a fool.

after everything else we've overcome!

We'll correct that tonight...

it didn't look to me like the pads would sit in position with those springs just 'sat on'. they're didn't seem to be a 'right' place for them to go..
will they not just fall-out; against the centre of the brake disc..?

what would hold them in, then..?

thanks for your feedback
Posted By: neil_r

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 12:34

The profile of the backing plates (the steps for a better description) hold them radially in the caliper bracket. As you push the caliper over the pad springs, this secures the pads on the bracket. The caliper and piston hold the pads either side of the disc.

The only other thing you have to remember is to get the little post on the inner pad to sit between the piston indentations so that the handbrake ratchet is locked. Otherwise, even if the piston does not rotate, the pressure on the pad is very uneven and brake force is reduced. Don't ask me how I know smile
Posted By: dante giacosa

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 13:35

I think I'm going to have to see this in situ later on-

yes; we matched the little post into an indentation on the piston; thank you

I could see it wouldn't turn with action of the handbrake- but will it turn with convention hydraulic actuation..?

Thanks for that Neil...
Posted By: neil_r

Re: Rear brake caliper-shims; between what & what? - 13/08/2018 14:10

As soon as you take the caliper off, you will see how the pad cannot move any closer to the disc hub now that you are looking for it smile

The hydraulic side is independent of the pistons rotational position. They just need to go in and out. Front pistons don't need to be lock smile

The rachet mechanism of the handbrake needs the piston to stay put so that the ratchet can screw against the the piston as the pad wears.
Posted By: dante giacosa

Re: Rear brake caliper-shims; between what & what? - 14/08/2018 07:13

thanks Neil & Dave;

we nailed it last night; one of our team is an ambidextrous virtuoso, who was able to produce a result, when all others had failed...

afterwards; we got the arch-liner back in again...

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