Fork seal holders

You really need a thread gauge to check that they match. The original seal holders were always chrome-plated so I wouldn't expect a lack of fit. The NavigatorI bought from a former NOC member seems to have a problem -both seal holders are not fully screwed in. I understand that the fork lower legs (sliders)were replaced with new ones (Phew - expensive!) within the last 2 years so they must be the Commando type as that's the only sliders that have been made for many years. I was wondering if the thread was different? The bike is a runner so I haven't dismantled the forks yet - they ain't broke!

I'll be interested to see what your findings are as I was going to buy new seals from the NOC shop too!

Cheers, Lionel

Steve, can you do us all a favour and measure the precise length of thread on the newseal holders you bought from NOC?(Nearest 0.5mm or 1/32") It sounds like they may have been made incorrectly or for a different fork? The seals on my Navi are old ones I think, so I don't think it can be over-long threads that make it protrude - but it might be. When I can dig them out I'll check the old holders from my 1959 Dommie. They are definitely all-original and are for short roadholders. If the thread length is the same as the new ones then that shouldn't be the prob - if they're not then that IS the prob.

In my first posting I meant I was going to buy seal holders of course - not just seals.

Cheers, Lionel

Previously wrote:

I am trying to fit a new set of seal holders to my Navigator short Roadholders. The thread on the seal holder seems to be slightly too large to screw into the fork legs. I'm guessing that the plating is causing the problem. Any ideas on how to proceed? Incidentally the seal holders are from the NOC shop.

Steve kilbey

With just a quick bit of research I found that Andover Norton still make the seal holders. (actually called "Main tube lock ring with cup" by Nortons) The old part number was 50117 - new No. is 06-0350 "DESCRIPTION: FRK SLIDER EXT"N 030453/030454". It's listed at £19 (each!). I haven't found a pic of it though so I don't know if it's the type with peg holes in, like the originals. Norvil's prices start at an eye-watering £26.76 each! RGM lists it at £28.60! (no photo). "Yer pays yer money and yer makes yer choice!"

I would be interested to know other peoples experience with the different versions avalable - i.e. NOC's item compared with Norvil and Andover Norton's. Do they all have a lack-of-fit problem?

Steve, I would strongly recommend that you don't butcher the new ones but send them back for a refund and try another make first. Or buy one from Norvil and check its measurements against the one you have before returning it. You could even ask them to give you the exact measurements, rather than buy one and then have to return it if it didn't fit! A keen company with good customer service would not mind doing that! Hopefully NOC should be able to tell us where there's are sourced from. I need two pairs - one for the Dommie and one for the Navi but I want themn to fit properly! Failing that, I might just have to polish off the old rust and get them rechromed instead.

Good luck, Lionel

Previously wrote:

Previously wrote:

Steve, can you do us all a favour and measure the precise length of thread on the newseal holders you bought from NOC?(Nearest 0.5mm or 1/32") It sounds like they may have been made incorrectly or for a different fork? The seals on my Navi are old ones I think, so I don't think it can be over-long threads that make it protrude - but it might be. When I can dig them out I'll check the old holders from my 1959 Dommie. They are definitely all-original and are for short roadholders. If the thread length is the same as the new ones then that shouldn't be the prob - if they're not then that IS the prob.

In my first posting I meant I was going to buy seal holders of course - not just seals.

Cheers, Lionel

Ok where to start, firstly the facts, The thread is 20TPI, measured using a thread gauge. The outside diameter is 1.984 inch. This diameter is very close (within 0.002") of the original seal holder thread.

I'm not one of those who considers a problem for long before taking action. I stayed on at work this evening and set about a cure. Firstly undercutting the thread at the shoulder to remove the small unthreaded portion and the radius. The holders would never seat without doing this (or removing the first 2 threads in the fork tube).

Comparing the original thread length with the new I would say it was around 3/16" longer, not any more!.

The issue appears to be with the thread root diameter, like its been cut with a blunt tool. Using a 60degree cutting tool I have corrected this. Not helping all of this is the fact that the fork tube thread tapers inward further into the tube.

I now have a pair of holders that fit the tubes and the only thing left to do is make some spacers to bridge the gap between seal and holder so the seal is clamped.

Blimey! They ARE a long way off original sizing! To be honest they are "not fit for purpose" as far as Trading Standards go and it needs looking into by the spares team. 3/16" over length is a tremendous amount in engineering terms! I wonder what the maker used as a pattern? The wrong thread form too? It's not enough just to have the right pitch, as you know toowell. It's a good job you have workshop facilities you could alter them with. Most people don't have them - I haven't! With this problem I would have no choice but to return them for a refund. I assume your spacers would need to go inside the leg tube against the seals themselves? What a palaver! AND there's a taper in the fork leg threads? Couldn't get much worse then?

Good luck, Lionel

Previously wrote:

Previously wrote:

Took me 2 1/2 hours of work to get this far!. The spacers will indeed sit on top of the seals and be clamped by the seal holder when fully screwed in. I am going to make them from white high density nylon to avoid any rust issues. I afraid I'm a bit impatient when I see an issue like his has been, that and the factit was holding up the rebuild. Christmas with pneumonia took a week out of the build time.

Thanks for all the comments and suggestions.

Steve Kilbey

Crikey! Pneumonia too? You poor sod! Just looking for sympathy eh? Well you've certainly got it from me mate! You're a hero messing about with parts that should fit "out of the box"! It looks like I'll be going elsewhere for my replacements - probably Andover Norton as I've dealt with Nick before when they used to be in Southampton. He's a very understanding chap! I'd rather pay more for something that fits!

Good ideausing 'virgin nylon' as spacers.

Cheers,

Lionel

Previously wrote:

Previously wrote:

Previously wrote:

Steve, can you do us all a favour and measure the precise length of thread on the newseal holders you bought from NOC?(Nearest 0.5mm or 1/32") It sounds like they may have been made incorrectly or for a different fork? The seals on my Navi are old ones I think, so I don't think it can be over-long threads that make it protrude - but it might be. When I can dig them out I'll check the old holders from my 1959 Dommie. They are definitely all-original and are for short roadholders. If the thread length is the same as the new ones then that shouldn't be the prob - if they're not then that IS the prob.

In my first posting I meant I was going to buy seal holders of course - not just seals.

Cheers, Lionel

Ok where to start, firstly the facts, The thread is 20TPI, measured using a thread gauge. The outside diameter is 1.984 inch. This diameter is very close (within 0.002") of the original seal holder thread.

I'm not one of those who considers a problem for long before taking action. I stayed on at work this evening and set about a cure. Firstly undercutting the thread at the shoulder to remove the small unthreaded portion and the radius. The holders would never seat without doing this (or removing the first 2 threads in the fork tube).

Comparing the original thread length with the new I would say it was around 3/16" longer, not any more!.

The issue appears to be with the thread root diameter, like its been cut with a blunt tool. Using a 60degree cutting tool I have corrected this. Not helping all of this is the fact that the fork tube thread tapers inward further into the tube.

I now have a pair of holders that fit the tubes and the only thing left to do is make some spacers to bridge the gap between seal and holder so the seal is clamped.

Just an update, I have now assembled the fork legs together with the nylon spacers and new seals. I was still not fully happy with the way the seal holders were seating on the top of the tubes. The photo shows the solution I have used. Between the holder and the tubes I have trapped a ring of brass, rolled from plain brazing rod and solder joined. The brass has been polished and laquered. The joint is un-noticable bur for the picky I have positioned these to be nearest the mudguard. Hope you like the result, I do.

Steve

Well I like it Steve! A band of gold eh? What a lot of trouble to have to go to just because the seal holders were made incorrectly. I'm not impressed with that. I'm not quite sure how this all affects the geometry of the forks though. It makes them longer doesn't it? There might be a knock-on effect because of that. I suppose it has pushed the sliders slightly further down the stanchion tubes so that it will 'bottom out' (or is it 'top out' ?) a touch earlier?

Cheers, Lionel

Steve Kilbey previously wrote on Wed Jan 26th 2011. 21.56hrs:

>The geometry will remain the same as the seals, and therefore the bushes underneath remain in the same position, the only difference will be the position of the seal holders in relation to the lower yoke. I have checked, with the springs removed, that the seal holders will not 'bottom out' on the lower yoke. I know the wheel spindle is still the correct distance from the lower yoke as I measured this before the strip down, just in case!

Thanks for your comments,

Steve<

Nice going, Steve!

Paul