Rear caliper slider pin diameter?

Technical Area Wheels, Tyres & Brakes
1

We had the calipers on our 1990 Eunos completely refurbished by Big Redd but I’m wondering if they fitted the wrong slider pins on the rear calipers because there is a lot of play and the carriers rattle over bumps. Anyone know what diameter they should be please? http://www.ethancollingridge.com/MX5/diary/2019/07/index.php

It’s the top pin that sits inside a socket (filled with grease) and not the one that you undo to separate the caliper parts.

2

Video of the play here: https://youtu.be/wmLL328ohyg

3

Hi Rob,
Not sure if you have sorted this yet.
Pin
If this the pin in question then my spare is 11.98mm.in diameter.
Hope this is helpful.
Dave

4

Thanks. That’s what I measured them to be. There still seems to be a lot of slack though :frowning: I’m not sure why this would be the case.

5

Hi, just a few thoughts.
If the pin is the correct size then presumably the hole is too large, have you measured it at all?
Were the calipers fitted to the car prior to overhaul, were they loose then?
If not I think I would consult Big Redd for their thoughts.
The only other solution I can think of is to machine up slightly larger replacement pins.
Good luck and please post solution.
Dave

6

These were on the car before and were fine. The brake parts were stripped and painted, so I don’t know why they are loose now.

7

Interestingly, this eBay listing shows the sliders inside are 13.5mm and this sounds more likely.

I think I can see the problem now. The sliders were installed incorrectly by Big Redd and need to be swapped over :frowning:

8

I swapped the sliders over today and the problem is solved. Not more clattering over rough surfaces. How they managed to put them together wrong I don’t know but all fixed now.

9

Hi, I am intrigued if the pins are different diameters how could the larger pin be fitted into the smaller hole?
Dave

10

The slider that is not enclosed in a ‘cup’ runs through a rubber bush and they had squeezed it through this. It was very tight but it did fit.

11

So they’d put the slider with the hexagon head in the top position and the slider with the Allen key head in the lower position?

12

Yes. The allen key head slider is fatter (13.5mm) and sits inside the cup. The hex head one is 12mm in diameter and goes through the rubber bush.