Norvil 14" floating disc replacement

pdl999 · Apr 16, 2014

My bike has this disc and I always thought there was some run-out (braking judder). I recently upgraded the master cylinder using the AN kit and now I am sure there is bad brake judder!!
The disc has quite noticeable run-out and needs replacing.

The thing is I am a Norvil hater to the extent that I really don't want to have to give them £231 for a new disc. Can anyone suggest an alternative? The issue with changing to a 12" disc is that mine has a front mudguard (fender) that fits the caliper bracket so I don't want a solution that means I have to change the mudguard.

thanks

David

pete.v · Apr 16, 2014

Many of us find that the bottom/rear fender brace to be redundant. When I took my second mudguard brace off for the RGM kit, I put button headed screws in the fender to mend the holes. Looks just fine.
This may open up options for you.

Although I have made some changes recently, the lack of the brace seems to be a non issue for me. These fenders are quite robust and could probably do fine with no extra bracing at all.

kiwi · Apr 16, 2014

If you are experiencing brake judder

before replacing the rotor I would look at the bobbins and make sure they are not either excessively worn or tight on the rotor / carrier not allowing the disc to float

your disc is a floating type and it should be free to move on the anodised bobbins without excessive play ,

when the bobbins get worn they do judder / rattle under braking load

might be worth removing the disc from the carrier and checking for run out if you do not have a perfectly flat surface use a sheet of glass

I think new bobbins can still be sourced as they are used on most Japanese front discs ( some OEM are swaged but there are aftermarket ones with C clips around which are easily replaceable )

Seeley920 · Apr 16, 2014

http://www.bikehps.com/isr/isr_brake_discs.html

pdl999 · Apr 16, 2014

Pete
That's a useful idea. I could actually cut and remove the lower bracket on the disc side only, inside the back of the mudguard where it doesn't show.
Kiwi
The bobbins are held with circlips and they all feel tight. My crude method for checking run out was to take out the pads and spin the wheel, resting my thumb on the fork leg and feeling the run out. There is a very noticeable kink in one place. My guess is changing the bobbins won't fix that, but I'm prepared to be proved wrong!

David

Nortiboy · Apr 16, 2014

kiwi said:
If you are experiencing brake judder

Bobbins tight on the rotor / carrier not allowing the disc to float

quote]

Very common cause of "run-out"

Fast Eddie · Apr 16, 2014

pdl999 said:
My bike has this disc and I always thought there was some run-out (braking judder). I recently upgraded the master cylinder using the AN kit and now I am sure there is bad brake judder!!
The disc has quite noticeable run-out and needs replacing.

The thing is I am a Norvil hater to the extent that I really don't want to have to give them £231 for a new disc. Can anyone suggest an alternative? The issue with changing to a 12" disc is that mine has a front mudguard (fender) that fits the caliper bracket so I don't want a solution that means I have to change the mudguard.

thanks

David

Go to a RGM disc and caliper mount and use a kinked mudguard stay from Holland Norton Works, they're shown about half way down this page: http://www.hollandnortonworks.eu/?lang=EN&page=10 actually, I've got a new one surplus to requirements if you're interested.

daveh · Apr 16, 2014

pdl999 said:
Pete
That's a useful idea. I could actually cut and remove the lower bracket on the disc side only, inside the back of the mudguard where it doesn't show.
Kiwi
The bobbins are held with circlips and they all feel tight. My crude method for checking run out was to take out the pads and spin the wheel, resting my thumb on the fork leg and feeling the run out. There is a very noticeable kink in one place. My guess is changing the bobbins won't fix that, but I'm prepared to be proved wrong!

David

Your rotor could indeed be out of true but I would agree with Kiwi - remove the bobbins and check the rotor on plate glass.

I had the same symptoms as you with a floating disc (on another bike). I replaced the rotor and the judder was still there. It turned out the carrier was slightly out of true. I have also witnessed a wheel hub slightly out of true with reference to the wheel spindle, which allowed an otherwise perfectly flat disc to wobble slightly. Unlikely but still worth checking. Let us know how you get on.

Dave

ntst8 · Apr 17, 2014

I have a Norvil 13" disc with not a lot of miles on it and not too happy with its wear.
I would have thought that the rotor internal diameter would be a neat fit on the carrier external diameter but there is around 1mm slop.
Now that the bobbins have worn the whole thing rattles and clangs while in motion.
I don't get any judder while braking though so the suggestions regarding out of true sound to be on the mark.
Fortunately there is a gent locally who makes rotors so i plan to get one made to fit.

pdl999 · Apr 17, 2014

Thanks for all you input gents. I took it apart this morning. I was struggling to think of a large enough piece of plate glass to use and then realised it was right in front of me in the kitchen.

Ronnie (the dog) said I was taking a big risk doing this in the kitchen but he kept guard for me.
The rotor is definatly not flat. I tried it several ways round just in case my table isn't flat but got the same result.
So I feel an RGM order coming on.

Thanks for the offer of the stay FastEddie, I might just take you up on that.

cheers

David

kiwi · Apr 17, 2014

David

Ronnie looks a little worried in the photo ( did you curse when you found it was not flat ) or was the wife stood behind you with the rolling pin

good luck sourcing a replacement and don't forget to check the new one is free to float on the bobbins this could be the route cause of your troubles

pdl999 · Apr 17, 2014

Kiwi
Ronnie has good reason to be worried. Our vet, who knows he doesn't need to sugar-coat things with us, says he is a "knackered old dog" and that he could keel over at any time!
Thanks for the tip re the bobbins on the new one, I'll be sure to check them first. The 12" RGM disc is on order. I never did much like the look of that huge 14" disc anyway. I'll post some pictures of the end result, hopefully next week some time.

David

Matt Spencer · Apr 17, 2014

" Just checking the tables not warped , with this flat piece of steel , dear . "

grandpaul · Apr 17, 2014

Going from a 14" to a 12" disc will require re-alignment of the caliper to keep the pads in contact with the braking area...

JimC · Apr 17, 2014

A new caliper adapter plate is easily fabricated to bring the caliper into alignment. It you fab a new adapter you won't even have to change the length of the fender stay.

pdl999 · Apr 26, 2014

The new 12" RGM disc is fitted. To me, it looks much more "right" on the Commando that the Norvil 14" both in its size and its styling. Its a shame though that RGM's disc bracket is universal and has slotted mounting holes for the caliper.

For the mudguard stay, I simply cut off the disc side. So it still has support on the lower left and I don't think anyone would ever notice the right side is missing.
There was one snag. When the set up was first fitted, the in-board disc pad just fouled the disc bobbin clips. The cure was to rotate all the clips 180 deg. The new brake hose was sourced from HEL who make anything you need from a simple on-line menu. Mine was a mere £19.95 delivered.

I just need it to stop raining now so I can try it out!

David

Norvil 14" floating disc replacement

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