Author Topic: Fitting fork seals  (Read 291 times)

Offline Russ

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Fitting fork seals
« on: 08.08. 2020 10:41 »
Ok guys simple question, for those who know.  Mine is 1951 A10.
How do I fit the seals to my fork inner tubes? Do I fit them first from the bottom, before the bushes, or are the fitted last from the top?
Not sure if they are designed to go over the wider section of the inner tube where it is clamped in the bottom yoke. Without knowing, and unable to find a definitive answer, I assumed the seals were inserted in the seal holders and screwed into place from the top after the clip was inserted.
Cheers Russ
1951 A10 Plunger.
Australia

Online chaterlea25

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Re: Fitting fork seals
« Reply #1 on: 08.08. 2020 14:24 »
Hi Russ,
Fit the seals to the chrome holders, lip down, a big socket or round  alloy piece
To push them home,
Slide them up from the bottom of the stanchions, then  circlips and any shims needed, then top bush,  btm bush washer and nut...
It is a good idea to trial fit the top bush and circlip to the slider as a first off job in order to see if any shims are  needed to keep the bushes tight. Thin shims will break up in use so it's better to machine the top lip of the bush until a thicker shim will fit..

John
1961 Super Rocket
1963 RGS (ongoing)

Offline Russ

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Re: Fitting fork seals
« Reply #2 on: 08.08. 2020 14:43 »
Thanks John.  Excellent explanation, now I have my head around it.
Appreciated Russ
1951 A10 Plunger.
Australia

Online Angus

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Re: Fitting fork seals
« Reply #3 on: 08.08. 2020 15:12 »
Can they not be fitted from the top as I have new seals and stainless holders to fit and was hoping not the strip the rest of the fork legs from the sliders. Always assuming I get get the old holders off  *fight*
1961 A7 since 1976
1960 A10 Gold Flash Super Profile Bike
1958 Matchless G80 Project
1952 Norton Model 7 Plunger
1950 T100

Online Black Sheep

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Re: Fitting fork seals
« Reply #4 on: 08.08. 2020 20:29 »
No. Won't go from top downwards.
2 twins, 2 singles, lots of sheep

Offline Russ

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Re: Fitting fork seals
« Reply #5 on: 09.08. 2020 00:54 »
Thin shims will break up in use so it's better to machine the top lip of the bush until a thicker shim will fit..

OK but what is a thin shim as opposed to a thicker shim?
Russ
1951 A10 Plunger.
Australia

Online Peter in Aus

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Re: Fitting fork seals
« Reply #6 on: 09.08. 2020 01:49 »
I slide mine down from the top, sounds a bit butchers but I have always don that and have not had any trouble, just lube the shaft first and work it down slowly. But that me! *fight* *beer*
Peter   

Busselton West Australia
49 A7 longstroke
58 A10  SA

Online Greybeard

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Re: Fitting fork seals
« Reply #7 on: 09.08. 2020 09:02 »
... just lube the shaft first and work it down slowly.
Ooh you are awful!  ;)

Online JulianS

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Re: Fitting fork seals
« Reply #8 on: 09.08. 2020 09:59 »
The difference between the smooth machined working diameter at the bottom of the shaft and the comparitively rough machined top part is around 3 mm where is swells around the bottom yoke position.

If you try from the top the probable outcome will be a stretched seal with damaged working surface due to the rough machining.

Just tried with parts from my bits and pieces and cannot do it from the top.

 

Offline Swarfcut

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Re: Fitting fork seals
« Reply #9 on: 09.08. 2020 10:47 »
 Russ  Here's an easy way.

 Make sure all is ready for assembly, shims chosen as necessary, all internals nice and clean and lightly lubricated. The shim thickness bridges any gap between the top of the top bush and the underside of the circlip. A gap will allow the bush to move up and down in the slider. It's not a super critical part, at a push make your own from any hard easily worked material, even ABS or polypropylene.

    Assemble the bare stanchion into the yokes and tighten the lower yoke clamp bolt. Feed the new oilseal holders, with the seals fitted, on from the bottom, followed by the circlip, shims as required and top bush. Add the lower bush, washer and nut, and tighten the nut with the leg held firmly by the yoke clamp. Then all off again to add the slider, locate the circlip and tighten down the oilseal holder.

 The next stage involves adding the spring, and passing the extended stanchion up through the lower yoke and fork shroud.  You will need some way of pulling the stanchion from the top. The pesky little devil invariably wants to slide down just when its almost home.

 Proven methods include the official workshop tool, a fork top nut turned down with a length of bar tacked on, or like most backyard fixes, a length of wooden dowel or broom handle screwed into the top of the stanchion.

 A later part from an A65  from 1966 can be used as a circlip cum shim assembly. It is a collapsible spacer, a cheap tin can pressing. Part number 68 5134. Described as a Top Bush Widget, to add confusion for want of a simple description.  Here in the UK, Drags have excellent stock levels, and at £10 each........

 Swarfy.


Online chaterlea25

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Re: Fitting fork seals
« Reply #10 on: 09.08. 2020 15:28 »
Hi Russ,
I would go with a minimum thickness of 10 thou, I prefer to use 15 or 20 thou

John
1961 Super Rocket
1963 RGS (ongoing)

Offline Russ

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Re: Fitting fork seals
« Reply #11 on: 10.08. 2020 14:47 »
Thanks guys for that helpful info.  Job now done with 20 thou shims.
Cheers Russ
1951 A10 Plunger.
Australia