Brake caliper not clearing disc.....

[AndyB57]

I've rebuilt the various bits and pieces I've been checking over. Everything has gone back together as it should but the brake caliper is not centering over the new disc I've fitted. The wheel revolves but the outer face of the disc just rubs the caliper.

Can anybody share a screen shot of the parts list for the front axle setup please as I wonder if I'm missing a washer/bush?

Thanks!

[George 350]

Hi Andy,

If you go to http://www.habukt.de/morini/list.html you can download the parts book.
For your query you will need tavola 19A and 19B, but I fear it isn't going to help you much.

Question 1: Have you painted or powder coated the wheel? If so, was the disc mounting face masked off?
Question 2: Is the new disc thicker than the old?
Question 3: Is the offset the same? Easy to check by putting both discs on a flat surface, one outer face down, the other outer face up, put them close together and with a ruler across the mounting face of one disc, it should just 'scrape' the running surface of the other disc.
For what it is worth, some people have fitted the disc(s) meant for a Ducati Pantah, but my understanding is that the offset is slightly more than the Grimeca Morini ones, so this may be your issue.

Hopefully this will steer you in the right direction.
Regards,
George

[mbmm350s]

Hi Andy,

Brand new disk from Mdina Italia?
As per Georges reply question 3.
I found that the offset was slightly out compared to the original, no big deal I shimmed the axle spacer to centre the disk in the caliper.

Hope that helps.
Mark

[Glennh]

Is your replacement disc an original Grimeca part or a non OEM part such as EBC?

I recently changed my old Grimeca disc for an EBC semi floating item. The EBC item’s spec relating to hub diameter, fixing bolt hole pitch Circle diameter we’re all fine. However, the disc was marginally thicker and the disc off-set slightly greater. This had the effect of moving the disc rotor centreline outboard to the extent there was no clearance with the caliper.
Some fettling of the caliper lower mounting lug and revised upper mounting spacer cured the problem.
The pads needed modifying so the little “ears” cleared the disc rotor bobbins.
It was worth the effort as braking performance is massively enhanced.

[AndyB57]

Thanks both, will take a look again at both discs, make sure hub face is clean, etc.

Appreciate your help!

[Ming]

...no big deal I shimmed the axle spacer to centre the disk in the caliper...

I have shimmed the caliper on mine. If nothing else it means you can ensure the disc is accurately centred in the caliper.

[mbmm350s]

Hi Ming,

I have shimmed the caliper on mine. If nothing else it means you can ensure the disc is accurately centred in the caliper.

I couldn't do that in my case as that would require grinding the lower caliper mount on the fork leg or the caliper itself as the disk was too far out.
I preferred a reversible fix.
your method is also reversible if the disk was too far in.
The key is to ensure the disk is vertical in the caliper and central whatever method is used.
Cheers Mark

[AndyB57]

That would be the same for me - shimming the caliper would increase interference.

[EVguru]

Wheel position in the forks is set by the bearing spacer.

[AndyB57]

Paul - the bearing spacer is in place but to center the caliper when the axle is secured I need to use a 0.5mm shim too.

[EVguru]

Paul - the bearing spacer is in place but to center the caliper when the axle is secured I need to use a 0.5mm shim too.

A damaged, modified, or incorrect spacer, or debris between the spacer and the bearing, or between the spacer and the fork leg can throw off the offset.

The ex NLM race bike had a crappy home made spacer and both discs were rubbing.
https://youtu.be/RFN61qZ5fW4

[mbmm350s]

Hi Paul.
I replaced an original Grimeca disk bought myself brand new in 1993 with an NLM supplied non OEM disk recently.
The original disk was bang centre. The new disk offset was out about 1mm.
I had to make a shim to make the bearing spacer longer to shift the wheel over.
Cheers Mark

[Exmoor beast]

I had a similar problem, when braking I could hear a slow tick from front brake, one per revolution of wheel. Turns out the front wheel has Been laced with thicker gauge spokes and would only just clear the back of the calliper, when braking the flex imposed just pushed calliper to strike a spoke, albeit slightly. I shimmed the disc out .5mm and gave the Chanel through the calliper more clearance then I could centralise the calliper with adequate clearance all round. The problem nowawadays is multiple error caused by pattern discs/spokes/ pads etc , never straightforward!