12" Floating disc

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johnny Lagdon

johnny Lagdon

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I have a "Norvil" 12" floating disc and carrier paired with a lockheed caliper. The disc rattles on the bobbins and with the front brake on you can actually rock the bike back and forth...Norvil/fairspares recommend replacing the bobbins with a new set for about 40 quid + thrust washers... My disc is noticably worn and has a bit of runout.
A new disc is 135GBP + postage to Aust
Anyone know what is the minimum thickness I can have it ground to?
Cheers
Johnny
 
The RGM 12" floating disc & carrier complete is about the same price as replacing the "Norvil" disc and bobbins from Les Emery's emporium. I know there has been plenty of discussion before my time, but which way to go?
Cheers
Johnny
 
It is not just the bobbins that wear down the semicircular location in the alloy disc carrier also loses its shape and becomes elongated. If you remove a bobbin you should be able to see the wear on both parts. Older discs are 1/4" thick (when new) but those now sold by Norvil are thinner by about 0.040" (which makes them the same thickness as most commonly used modern discs). So check your thickness on an unused area before ordering replacement parts.
I have the thicker type 13" disc an found this out when i ordered a new centre carrier and bobbins plus the weavey washers. They explained they had changed the disc thickness meaning the carrier and bobbins would not fit and they refunded my money with not problem once i returned the parts but im in England an phone and postage is much cheaper than for you if your in Australia.
If your disc needs grinding an the bobbin location area is reduced in thickness this will affect its fit on the carrier depending on amount removed.
I fitted the weavey washers and this has helped my disc for the time being and braking is not affected by the increase in play as yet. But i think by the time you (or me when the time comes) have messed about with centre and bobbins it may be not much more to simply replace the whole disc (i will have to anyway as parts for my older style are not available).
 
toppy said:
It is not just the bobbins that wear down the semicircular location in the alloy disc carrier also loses its shape and becomes elongated. If you remove a bobbin you should be able to see the wear on both parts. Older discs are 1/4" thick (when new) but those now sold by Norvil are thinner by about 0.040" (which makes them the same thickness as most commonly used modern discs). So check your thickness on an unused area before ordering replacement parts.
I have the thicker type 13" disc an found this out when i ordered a new centre carrier and bobbins plus the weavey washers. They explained they had changed the disc thickness meaning the carrier and bobbins would not fit and they refunded my money with not problem once i returned the parts but im in England an phone and postage is much cheaper than for you if your in Australia.
If your disc needs grinding an the bobbin location area is reduced in thickness this will affect its fit on the carrier depending on amount removed.
I fitted the weavey washers and this has helped my disc for the time being and braking is not affected by the increase in play as yet. But i think by the time you (or me when the time comes) have messed about with centre and bobbins it may be not much more to simply replace the whole disc (i will have to anyway as parts for my older style are not available).
Click to expand...
Thanks Toppy,
i am just checking with them now as I bought the original disc & carrier in 2010
Cheers
Johnny
 
toppy wrote;
It is not just the bobbins that wear down the semicircular location in the alloy disc carrier also loses its shape and becomes elongated.
Click to expand...
I fitted the weavey washers and this has helped my disc for the time being and braking is not affected by the increase in play as yet. But i think by the time you (or me when the time comes) have messed about with centre and bobbins it may be not much more to simply replace the whole disc
Click to expand...

I've had two of Les Emery's discs and I consider them to be very poor quality, as on my mk3 the rear disc became loose on it's bobbins in under 3,000 miles and the front at approx 6,000 miles, but as toppy says, the carrier becomes elongated and so replacing just the bobbins is (was for me) a waste of money. At the time, I sent my rear disc back to Les for evaluation, and it came back with new bobbins fitted, a £40 plus bill and a note in the box saying something to the effect of "Bobbins replaced, this is a service item on a Ducati," and nothing else. This rear disc did less than 500 miles before rattling away / being loose again as the carrier which hadn't been replaced had elongated holes.
If it was me, I'd either get a different disc set up or if you want to stay with L Em's products at the very least a new carrier and bobbins or a complete disc.
 
It is wise to never ride the bike if the front brake is dodgy. I think the front hub in my bike is off a CB750 Honda and I use two smaller rigidly mounted discs off a Suzuki. I found a second Lockheed AP calliper. The callipers are mounted on a couple of plates each side, and powered from the master cylinder designed for a single disc. I use the old style asbestos pads and the discs are hi-speed steel, not chrome plated. The brake is excellent. I previously tried a single disc rigidly mounted, but couldn't get enough stopping power for road racing. You can only go as fast as the front brake will allow you.
 
Thanks, I think I am gonna replace the whole disc/carrier.
the RGM ones are a little thicker (5.74mm as against the les Em one 5mm) and consequently a bit more unsprung weight..
Anyone have experience of the RGM 12" floating setup? I would go the one Maddass sells but its more than i can fit with the PR slider and lockheed caliper.
 
I went with Mick Hemmings (now AN) proddy racer front brake. It's 11.5 inches of floating disc with the new slider and Lockheed (AP) caliper. Not a cheap setup, but a very worthwhile mod. Stops well and looks the business.
 
johnny Lagdon said:
Thanks, I think I am gonna replace the whole disc/carrier.
the RGM ones are a little thicker (5.74mm as against the les Em one 5mm) and consequently a bit more unsprung weight..
Anyone have experience of the RGM 12" floating setup? I would go the one Maddass sells but its more than i can fit with the PR slider and lockheed caliper.
Click to expand...

I've been using RGM 12" floating discs for years in conjunction with an AP alloy caliper, yes they are good (haven't had to replace a worn out one) but in my opinion they still need to be used with a sleeved down master cylinder or a different master/cyl. One of my winter projects is changing to a Magura master cylinder from Venhill.
sam
 
The MOST important thing when choosing brake components is the size of the master cylinder in relation to the caliper. The piston area of the caliper should be approximately 27 times that of the piston area of the master cylinder. In most cases the master is sized to the caliper, rather than the other way around. The biggest problem with the Norton disc brake is the master cylinder is way oversized, resulting in very little "leverage" to squeeze the caliper. The brand, whether Brembo, Magura, Lockheed or Grimeca is not that important. Hose material, rotor size and mount all make a difference, but none as near effective as caliper to master cylinder ratio. ~27:1 and you'll be happy.

See Vintage Brake: http://www.vintagebrake.com/mastercylinder.htm
 
Concerning original caliper and 12" disc, I posted this thread a year ago on what i did. The Norton disc was almost 5 pounds, the Kawa disc was less than 1 pound.
This was in conjunction with sleeving my m/c to 1/2" diameter.
The performance of this combination is as good as a modern day bike. You can see a preview in my avatar.
ugrade-brake-lockheed-plus-ninja-t22556.html?hilit=ninja

Jaydee
 
Thanks, I didn't mention that I am already using a 13mm sleeved master cylinder and s/s braided line...
 
johnny Lagdon said:
Thanks, I didn't mention that I am already using a 13mm sleeved master cylinder and s/s braided line...
Click to expand...
13mm is probably on the large size for most calipers. Bigger is not better, in this case.
 
JimC said:
johnny Lagdon said:
Thanks, I didn't mention that I am already using a 13mm sleeved master cylinder and s/s braided line...
Click to expand...
13mm is probably on the large size for most calipers. Bigger is not better, in this case.
Click to expand...


OEM Mk3 uses a 5/8" (16mm) m/c, so a 13mm will be quite an improvement. Mine is 1/2" (12.7mm), so close enough. Agree, smaller is better. I tried a 11mm before I went to 1/2", too much.

Jaydee
 
disc & caliper, 13mm master cylinder
 

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I have this front brake on My new MK111. And a matching MC. Handlebar brake lever was outside of my physical reach , so I filed down the fulcrum point where it hits the piston so now can at least reach it. Don't know anything about it. :? Should I silicone grease these bobbins and elliptical plate to prevent the wear you speak of ? :?:
 
If you file down the point of the lever where it contacts the piston you will alter the position/ stroke of the piston and could render it inefective.
grease near disc/pad does not sound like a good idea so be very sparing...
My thoughts, but I am NOT the fount of all knowledge, more like only a little bit of knowledge nicked from other people!
 
a lot of truth in what you say there Johnny, same as fitting different levers from different suppliers can give the same negative result.
Don
 
Don, you dont happen to make 12" floating disc?
From what I have seen, your products are way better than most...
 
mine are 320mm but dont have the same offset as the Norton disc but have stainless carrier which wont flog out like the alloy ones
Don
 
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