New stanchions, bushings and seals but they leak... any suggestions?

gpzkat said:
it seems to me if it leaks out the top just sitting there with 1 oz too much oil, I'm not going to have a good seal in use either.
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Absolutely.
It may help if you can tell if the leak is coming from the sealing lip of the seal or the outer. If its the outer the gasket that fits below the seal might be damaged or the slider sleeve nut needs a good tighten.
 
Generally the most common cause of leak is bad lips on a seal. Either from wear or from assembly. On modern forks use of plastic wrap and adequate lubrication will be used on assembly to keep the lips. Sometimes dirt can be removed from a leaking seal with a thin metal strap without taking the fork apart.
Worn, pitted, bent or oval stanchions can leak. (Experienced most of it)
Overfilling of fork oil can cause leaks. (Had that on a Velo last week, which has a very low tech seal)
Then there is the seal outside leak which has been discussed in previous posts. Not mentioned is the thread tolerances. A tight fitting thread don't leak noticeable. A worn or poorly made thread do leak more.
Then we have all the leaks from bottom end of the sliders. Drain plug leaks, damper fitting washers, on some marques with sliders built from a number of parts soft or hard soldered or welded where joints can leak. Yes the Velo forks are soft soldered!
 
Mike40M said:
Generally the most common cause of leak is bad lips on a seal. Either from wear or from assembly. On modern forks use of plastic wrap and adequate lubrication will be used on assembly to keep the lips. Sometimes dirt can be removed from a leaking seal with a thin metal strap without taking the fork apart.
Worn, pitted, bent or oval stanchions can leak. (Experienced most of it)
Overfilling of fork oil can cause leaks. (Had that on a Velo last week, which has a very low tech seal)
Then there is the seal outside leak which has been discussed in previous posts. Not mentioned is the thread tolerances. A tight fitting thread don't leak noticeable. A worn or poorly made thread do leak more.
Then we have all the leaks from bottom end of the sliders. Drain plug leaks, damper fitting washers, on some marques with sliders built from a number of parts soft or hard soldered or welded where joints can leak. Yes the Velo forks are soft soldered!
Click to expand...
Thanks, I am not sure what thread is being referred to, could you explain?
 
gpzkat said:
A bit frustrated, I've rebuilt many forks but never Norton - they are the N15CS Roadholders with lowers from disc brake Commando. Just sitting there they leak past the seals overnight - no need to even compress them.

Any help greatly appreciated ~Tom
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I can think of a potential cause. Your forks are unloaded, right? So damper pistons are in their upper position. If you filled oil and immediately closed the top nuts, there may an occurence of air being compressed inside the long dampers, preventing the oil to enter, and causing the oil level between damper and slider to rise to a very high level. Now, if you jog your forks, the lower bush will force most of this oil up and trying to overcome the seal. Some will eventually seep past the seal. I am not saying your seal is all good, and maybe roughness of your stanchions is too coarse as well. However, I'd try to vent the forks for 24 hours by leaving top nuts unscrewed. Hopefully this will allow the long dampers to fill up internally. If the slider seals still leak, I'd check stanchions for permissible roughness and/or try a fresh pair of seals.

- Knut
 
gpzkat said:
Given that inside, the slider and damper mechanism is identical between the Commando and N15CS Roadholders,
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Wrong. If you fitted the proper length fork stanchions for the N15, you need the long dampers also, which are different to those for the Commando.

-Knut
 
gortnipper said:
5oz/150ml per leg for Commando
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Tom, you have overfilled your forks. The 1964 service manual by F. W. Neill specifies 5 oz / 146 ccm for the Matchless roadsters equipped with Roadholder forks and internal springs, which I suppose you have.

- Knut
 
mdt-son said:
Tom, you have overfilled your forks. The 1964 service manual by F. W. Neill specifies 5 oz / 146 ccm for the Matchless roadsters equipped with Roadholder forks and internal springs, which I suppose you have.

- Knut
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OK I have arrived at that conclusion too and corrected the oil level. Correct about the damper tube, my mistake.
 
Have not used these so can't speak from experience, but years ago I read a recommendation and purchased Ariete ARI fork oil seals. (I got ARI.003T for my 75 850 MKIII). Again, this was years ago but might be an option.
 
Did you check the condition of the surface that the OD of the seals fits into? If it has screwdriver gouges up the bore there, oil can leak out. Bit of non-hardening gasket sealer on the OD of the seals helps.
I have just had the same problem with an old Honda 350 Four in the shed. Seals leaking prodigiously while just sitting there. Forks have not been touched in at least 30 years and leaking started after moving the bike around in the shed for the first time in years. Must have had rust on the stanchions from standing and ripped up the seals. But the oil seems to find its way uphill and out just sitting there. Capillary action perhaps?
 
Not sure if it helps much , but I recently fixed a leaking fork seal on my older E-Bike. New seals are not available . So I lifted the dust boots , cleaned out some hardened crud and then sprayed with a product called Rubber Care . It softens up rubbers . Changed the fork oil too . This worked and no more leakage whatsoever . Ride on .
 
It was overfilled and isn't leaking now. I am only able to 'test' in garage by grabbing brakes and plunging the suspension and it has not leaked anything, and the action seems great. My bike is just about ready to fire up after its decades long residence in a bunch of boxes, but there's been a delay with some paint work on a reproduction side cover/battery box that I got. I left the oil tank with the painter so he can properly match it. He called yesterday and said it won't be long, early January target. Can't wait.
 
gpzkat said:
It was overfilled and isn't leaking now. I am only able to 'test' in garage by grabbing brakes and plunging the suspension and it has not leaked anything, and the action seems great. My bike is just about ready to fire up after its decades long residence in a bunch of boxes, but there's been a delay with some paint work on a reproduction side cover/battery box that I got. I left the oil tank with the painter so he can properly match it. He called yesterday and said it won't be long, early January target. Can't wait.
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Just in time for winter ! Enjoy .
 
Nobody puts them in DRY ?

Do they !

rubber lube , pre oil & suchlike . Overdry they could burn out before they do their thing .
 
Yeah the over filled oil trick and nowhere else to go except from the seal, glad you got to the bottom of this and such an easy fix and thanks for letting us know that you fixed the problem so many leave and we never know if they fix their problem or not as in this case a big jump from July to last Saturday.
 
ashman said:
Yeah the over filled oil trick and nowhere else to go except from the seal, glad you got to the bottom of this and such an easy fix and thanks for letting us know that you fixed the problem so many leave and we never know if they fix their problem or not as in this case a big jump from July to last Saturday.
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No worries, yeah a lot going on in my life, many changes. Moved from Southern CA to northern WA. Of course I trailered my Norton up here. Before that I sold my '73 Honda CB750, '79 Suzuki GS1000E, '82 GS1100 Mr. Turbo Bonneville racer (on BringaTrailer) and '54 Willys Wagon. I have my priorities straight!
 
gpzkat said:
No worries, yeah a lot going on in my life, many changes. Moved from Southern CA to northern WA. Of course I trailered my Norton up here. Before that I sold my '73 Honda CB750, '79 Suzuki GS1000E, '82 GS1100 Mr. Turbo Bonneville racer (on BringaTrailer) and '54 Willys Wagon. I have my priorities straight!
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Ya surely do .
 
Torontonian said:
Ya surely do .
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Going off grid here but we are all motorheads here so WTH.... lately as I patiently wait for the Norton parts so I can finish I have been working on some smaller bikes for some pals: A '67 Vespa 150 Sprint and a '75 Honda ST90 'Trailsport' (which I now want!). The Vespa is cheesy with lots of Vietnam add-ons and was a nightmare to re-wire. They changed colors at will with scraps of wire it seems. 6V converted to 12V for no good reason except some LED running lights. But I got electrics all fixed. I worry about the rest of the bike's integrity, but have looked at it pretty well and it seems decent. The Honda on the other hand is like jewelry, just easy to figure out and get rolling, starts first kick etc. But honestly I like the Vespa too, I'd just strip it down to solo seat and no racks etc, as none of that stuff was stock.

New stanchions, bushings and seals but they leak... any suggestions?


New stanchions, bushings and seals but they leak... any suggestions?
 

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