Brake caliper not clearing disc.....

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AndyB57
Posts: 84
Joined: 01 May 2019 20:25
Location: Ilfracombe UK

Brake caliper not clearing disc.....

Post by 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
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Joined: 16 Jun 2007 09:43
Location: Northampton

Re: Brake caliper not clearing disc.....

Post by 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
George
350 sport 1978, 350 Strada 1978
650 Norton 1967, 650 Kawasaki 1977 and 650 Enfield 2019
mbmm350s
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Location: Berkshire UK

Re: Brake caliper not clearing disc.....

Post by 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
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Location: West sussex

Re: Brake caliper not clearing disc.....

Post by 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
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Location: Ilfracombe UK

Re: Brake caliper not clearing disc.....

Post by AndyB57 »

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

Appreciate your help!
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Ming
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Re: Brake caliper not clearing disc.....

Post by Ming »

mbmm350s wrote:...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
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Re: Brake caliper not clearing disc.....

Post by 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
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Location: Ilfracombe UK

Re: Brake caliper not clearing disc.....

Post by AndyB57 »

That would be the same for me - shimming the caliper would increase interference.
EVguru
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Re: Brake caliper not clearing disc.....

Post by EVguru »

Wheel position in the forks is set by the bearing spacer.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
AndyB57
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Joined: 01 May 2019 20:25
Location: Ilfracombe UK

Re: Brake caliper not clearing disc.....

Post by 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
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Re: Brake caliper not clearing disc.....

Post by EVguru »

AndyB57 wrote: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
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
mbmm350s
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Re: Brake caliper not clearing disc.....

Post by 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
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Re: Brake caliper not clearing disc.....

Post by 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!
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