Seeley - Norvil Front Hub Dual disc spoke-caliper clearance

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springer

springer

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Hi to all
Continuing my Seeley Norton Project , i ve been facing a quite difficult problem. I am wondering if someone has nun into something similar or has to suggest any solution.
I am running (or trying to run) a Minnovation Seeley fork yoke (7 3/8 center width) , Ceriani replica GP35 forks and a Norvil dual disc Hub with two Norvil 11.5'' semi floaing discs with AP Lockheed racing calipers. Setup is similar to the NYC NORTON front ends apart from the Ceriani forks.
At first the Hub with discs would not pass through the bottom of the forks, later a little machinning of the disc carriers for about 2 mm each made that possible. However now the problem is that if mounted , the disc calipers intefere with the wheel spokes. I need at least 3 mm each side clearance to be ok.
On Solution I ve thought is to lace wheel only with spokes that run from the inner side of the Hub flange but i am not sure how to do it and what kind of spokes i will need because certainly the ones i have do not fit that way. Anybody with an idea how to do that? and if it is possible and safe for the wheel rigidity.
Another was to remove some material from the rear of the caliper but don t thing it ll be safe if i remove as much as i need . Not possible
Another to de- press the 3 piece hub and narrow it but dangerous for the hub to press it on again and may affect the rigidity of the wheel.
Any others?
 
What's the difference in the OD between the ceriani and norton fork lowers?
 
springer said:
Hi to all
Continuing my Seeley Norton Project , i ve been facing a quite difficult problem. I am wondering if someone has nun into something similar or has to suggest any solution.
I am running (or trying to run) a Minnovation Seeley fork yoke (7 3/8 center width) , Ceriani replica GP35 forks and a Norvil dual disc Hub with two Norvil 11.5'' semi floaing discs with AP Lockheed racing calipers. Setup is similar to the NYC NORTON front ends apart from the Ceriani forks.
At first the Hub with discs would not pass through the bottom of the forks, later a little machinning of the disc carriers for about 2 mm each made that possible. However now the problem is that if mounted , the disc calipers intefere with the wheel spokes. I need at least 3 mm each side clearance to be ok.
On Solution I ve thought is to lace wheel only with spokes that run from the inner side of the Hub flange but i am not sure how to do it and what kind of spokes i will need because certainly the ones i have do not fit that way. Anybody with an idea how to do that? and if it is possible and safe for the wheel rigidity.
Another was to remove some material from the rear of the caliper but don t thing it ll be safe if i remove as much as i need . Not possible
Another to de- press the 3 piece hub and narrow it but dangerous for the hub to press it on again and may affect the rigidity of the wheel.
Any others?
Click to expand...
springer, if you could post some pictures it would make it easier to see the issue and advise, but I'm pretty sure you could shave 3mm off the calipers (presumably just off the bottom corner of the piston chamber) without any danger.

Cheers,

cliffa.
 
acadian said:
What's the difference in the OD between the ceriani and norton fork lowers?
Click to expand...
I am not sure about the Norton and i dont have now the measurement now of the Ceriani, i can post that tomorrow. I am sure NYC Norton have theirs (Norvil hub with Norton forks) modified someway but dont know exactly how.
 
kommando said:
Your other options are

1. Take 3mm off the inside of the fork legs risking compromising strength.

2. Yokes with an extra 6mm over the 7 3/8"

3. Alternative hub 6mm narrower, RGM do a hub for twin discs which might be narrower.

https://www.rgmnorton.co.uk/buy/com...td-discs-our-12-disc-complete-with-b_2715.htm

Honda CB750 hubs are narrow and can be adapted for twin discs.
Click to expand...

1 cant be done, the lower-lower fork s screwed on and will compromise strength
2 Yes i know custom ordered very expensive
3 might be an option

Thanks
 
cliffa said:
springer, if you could post some pictures it would make it easier to see the issue and advise, but I'm pretty sure you could shave 3mm off the calipers (presumably just off the bottom corner of the piston chamber) without any danger.

Cheers,

cliffa.
Click to expand...
Thanks , i dont have all parts with me now , i will try maybe tomorrow. Here are pictures of the rear of the calipers. 3mm i think are not possible, the bolts will not fit then.
Seeley - Norvil Front Hub Dual disc spoke-caliper clearance
Seeley - Norvil Front Hub Dual disc spoke-caliper clearance
 
kommando said:
Your other options are

1. Take 3mm off the inside of the fork legs risking compromising strength.

2. Yokes with an extra 6mm over the 7 3/8"

3. Alternative hub 6mm narrower, RGM do a hub for twin discs which might be narrower.

https://www.rgmnorton.co.uk/buy/com...td-discs-our-12-disc-complete-with-b_2715.htm

Honda CB750 hubs are narrow and can be adapted for twin discs.
Click to expand...
I agree with the cb 750 hubs I had fitted several ,last one on my seeley with 180mm between centre fork yokes , plus a spacer between disc and hub .....another on a cdo with 7"3/8 norton yokes, and another cdo with BMW K100/K75 yokes (like Matchless /Martyn did ) with yamaha R6 43mm stanchions , cheap hubs and you can take out the ribs to get a proper look .....
 
marinatlas said:
I agree with the cb 750 hubs I had fitted several ,last one on my seeley with 180mm between centre fork yokes , plus a spacer between disc and hub .....another on a cdo with 7"3/8 norton yokes, and another cdo with BMW K100/K75 yokes (like Matchless /Martyn did ) with yamaha R6 43mm stanchions , cheap hubs and you can take out the ribs to get a proper look .....
Click to expand...
Does the CB 750 hub fits the Norvil carriers and discs? which cb 750 hub is it exactly? It is a good idea, or else maybe i will try to modify my hub narrow it ,since i already have it . That is one option but has to be done carefully because it is a 3 piece interference fit. We have to de-press it with heat , modify it and then re press it together again with the same orientation of the spoke holes.
 
No the CB750 hub has to be adapted with disc carrier plates, one thicker than the other as the hub is offset. It was originally for a single disc with a Speedo drive on the other side but the 6 holes for the disc are full width. Will post some pics tomorrow. You will also need to sort the axle size out.
 
There's certainly a few ways to go with this kind of thing:

1) Swap to cast wheels to get more room for the caliper you already have.

2) Find low profile calipers and you'll have to make custom bracket adapters to position them properly.

3) Custom yokes that have a wider spacing between the forks.

Personally, I have the cast wheel conversion on my commando. It's not cheap to do after all is said and done. I had to make an offset bracket for the caliper to accomodate the larger diameter disc that fit the hub I chose. I also used a circular spacer to move the disc outward about .1875" . I had to swap the wheel bearings to match inner diameter of the bearing to the norton axle diameter and lastly, cut custom spacers to center the hub...

If I was you, I would explore the use of alternative calipers. There's a lot of multipot calipers out there from older bikes that would have more clearance than the calipers you have pictured. I would look for a bike from the 80's which had a dual disc front. I would bet they would have a narrower caliper than most bikes by design in order to fit the dual disc front end of the donor bike.

There's a ton of used parts on craigslist and ebay. It's not that hard to search for potential donor bikes.

I used this site to search for donor bikes for my project.

https://www.motorcyclespecs.co.za/index.htm
 
Last edited:
o0norton0o said:
There's certainly a few ways to go with this kind of thing:

1) Swap to cast wheels to get more room for the caliper you already have.

2) Find low profile calipers and you'll have to make custom bracket adapters to position them properly.

3) Custom yokes that have a wider spacing between the forks.

Personally, I have the cast wheel conversion on my commando. It's not cheap to do after all is said and done. I had to make an offset bracket for the larger diameter disc that fit the hub, and use a circular spacer to move the disc outward about .1875" . I also had to swap the wheel bearings to match the norton axle diameter and cut custom spacers to center the hub...

If I was you, I would explore the alternative calipers. There's a lot of multipot calipers out there from older bikes that would have more clearance than the calipers you have pictured. I would look for a bike from the 80's with a dual disc front. I would bet they would have a narrower caliper than most...
Click to expand...

Well thanks, the caliper swap is not an option, nor the cast wheels. Calipers are NOS Lockheed of the era and there is a certain racing bike and look i am trying to achieve. I think i may go with modifying the hub or ordering a wider fork yoke if i don t find any other solution.
 
Hi Springer
Sorry to hear your news!
Yes, 7 3/8 yokes Norvil/Seeley forks & the disc bobbins rub on the legs. I locked mine down & had to file a notch in the legs for clearance. Les at Norvil told me they all do that.
The Ceriani fork legs are much wider & because of how they are constructed you can't slim them down much.
Options
contact Les at Norvil the man who makes the hubs might be able to alter a set for you. Maybe Minovation? Dick Hunt?
Alternative hubs. Lots of people use the Honda hub, definitely slimmer.
I will measure my hubs tomorrow.
I have a Norvil hub in the garage also
an Italian 6 bolt twin disc hub & a Rob North hub again 6 bolt. Carriers probably will need making.
Hate spending money & coming unstuck on a build.
All the best Chris
 
Springer
Sod all that.
I have an original Seeley hub three piece construction.
Not sure if it's in the garage.
Health wise I am not allowed out at all during the lockdown.
If it's out there I will post it to you & you can machine it & rebuild your wheel.
You may need longer spokes.
Post your hub back to me.
Chris
 
Chris said:
Springer
Sod all that.
I have an original Seeley hub three piece construction.
Not sure if it's in the garage.
Health wise I am not allowed out at all during the lockdown.
If it's out there I will post it to you & you can machine it & rebuild your wheel.
You may need longer spokes.
Post your hub back to me.
Chris
Click to expand...
Thanks Chris for taking the time to write, i will post tomorrow with more info about the hub and more. Spokes are not a problem. Last solution will be a new custom fork yoke from minnovation . Calipers are NOS AP 2195 original so will be definitely on the bike. Discs and carriers are also origina 11.5 Norvil from Mick Hemmings , would like to use them too .Could modify Hub maybe. Write tomorrow, thanks
 
I came across that problem on my avatar bike, Kenny Dreer's original 952 monoshock prototype. I used ZX6 forks and brakes with a VR880 hub which Buchanan's laced to an Excel rim. It has MAYBE 2mm clearance between the spokes and calipers! I din't even think of this beforehand, I just got lucky. (I'm wondering how close they get under the stresses of high speed cornering?)
 
springer said:
At first the Hub with discs would not pass through the bottom of the forks, later a little machinning of the disc carriers for about 2 mm each made that possible. However now the problem is that if mounted , the disc calipers intefere with the wheel spokes. I need at least 3 mm each side clearance to be ok.
Click to expand...
Call Buchanan's and see if they have a lacing solution. I'll bet they do.
 
2 CB750 hubs both identical but 1 up and 1 down, 40 spokes and 2 flat disc mounting surfaces even if they are offset slightly.

Seeley - Norvil Front Hub Dual disc spoke-caliper clearance


Seeley - Norvil Front Hub Dual disc spoke-caliper clearance


Distance between 2 disc mounting surfaces

Seeley - Norvil Front Hub Dual disc spoke-caliper clearance


Overall

Seeley - Norvil Front Hub Dual disc spoke-caliper clearance
 
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