Front fork, cannot remove stanchion from yoke

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Front fork, cannot remove stanchion from yoke

Postby tippi11 » Fri May 17, 2019 5:34 pm

Hello there,
I am currently struggling with my telescopic front fork (1 1/4", 56-on): even with a hammer (and a piece of wood) applied to the loosened top bolt, the pinch bolt loosened on the lower yoke and the clamp slightly spreaded, I am unable to get the fork leg/stanchion off the yoke(s). I have no information regarding the "history" of the fork; it is suspected that the previous owner may have done something wrong or applied extrem forces when assembling things ...
Any hints/experience are very much appreciated - thank you, Peter

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Re: Front fork, cannot remove stanchion from yoke

Postby ajscomboman » Fri May 17, 2019 5:53 pm

Take out the Allen pinch screw and belt a steel wedge into the slot in the bottom yoke. Unscrew the top dome nut very slightly, say 1/8" inch or 2-3mm and spray everything insight with penetrating oil leave it to soak over night. Heat the top crown and bottom yolk with a hot air gun and then belt the dome nut with a hide mallet and eventually it should break the rusty grip.

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Re: Front fork, cannot remove stanchion from yoke

Postby 56G80S » Fri May 17, 2019 5:58 pm

I could be well off the mark but if you have only loosened the top bolt then the damper rod is still attached to the underside of the cap bolt?

If you are intending refurbishing then it wouldn't hurt to apply some freeing liquid, like Plus Gas, leaving it.

Applying heat.

If the cap bolts are to be replaced you might make up the puller tool (that you'll need for re-assembly anyway) from a scrap bolt (do a Search) using some threaded rod and use this fully inserted into the threads at the top of the fork tubes and strike that with the hammer. Easy to damage the threads if bolt only partly inserted.

Others will make alternative suggestions. I'm sure there have been other threads on this. The Search function is the magnifying glass near the top of the screen beneath "Adverts".

Johnny B

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Re: Front fork, cannot remove stanchion from yoke

Postby Mick D » Fri May 17, 2019 6:35 pm

Hi

I had a similar situation on my current restoration, under the advice from others I tapped the upper yoke upwards with a club hammer and a copper drift, I was surprised how easily the stanchions freed themselves. Tapping upwards uses the inertia of the fork leg to free them whereas hitting the dome nut is fighting the leg inertia.

Regards Mick

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Re: Front fork, cannot remove stanchion from yoke

Postby tippi11 » Sun May 19, 2019 8:37 am

I followed your instructions (ajscomboman) except using a hot air gun, because the yokes and cover tubes are painted. No success so far - the whole thing feels and behave like a solid block, no skid/movement of any kind. When I left my garage yesterday I heard the yokes and stanchion talking to each other and laughing about my hammer and wedge technique. Do you think hot air is the way to go, last chance? As it stands today, I tend to cut the upper yoke in pieces to clear off the top area of the stanchion. Or do you have any other genious idea? Thank you very much, regards Peter

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Re: Front fork, cannot remove stanchion from yoke

Postby Mick D » Sun May 19, 2019 8:51 am

tippi11 wrote:Or do you have any other genious idea?


You could try my suggestion :roll:

Heat, beating down and this didn't work:

Fork Pulling.png


But beating upwards did

Regards Mick
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Re: Front fork, cannot remove stanchion from yoke

Postby ajscomboman » Sun May 19, 2019 10:17 am

Mick D wrote:
tippi11 wrote:Or do you have any other genious idea?


You could try my suggestion :roll:

Heat, beating down and this didn't work:

Fork Pulling.png


But beating upwards did

Regards Mick



But if the shrouds and everything else is in place Mick you can't do that with the puller, which is why I suggested the other way. To be fair The wedge method has never failed on all the forks I've had to pull apart. If they're that stuck, and I've had some that have almost grown together yet still come apart, I'd now be inclined to suggest that the complete top crown is removed from the bike with the bottom yolk left on the fork legs and then stripped that way as opposed to trying to remove individual legs. At least it's the ideal opportunity to inspect the steering head completely and regrease the races and bearings.

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Re: Front fork, cannot remove stanchion from yoke

Postby Mick D » Sun May 19, 2019 10:22 am

Hi Rob

Read my post - I'm not suggesting to use a hydraulic puller, merely stating that my use of one didn't succeed where knocking upwards did

ajscomboman wrote:I'd now be inclined to suggest that the complete top crown is removed


Yep - that's what knocking up will achieve

Regards Mick

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Re: Front fork, cannot remove stanchion from yoke

Postby tippi11 » Sun May 19, 2019 3:02 pm

Rob, you state: "... suggest that the complete top crown is removed ...". Removal of the top crown is part of my problem since the stanchions stick in the top crown bores like welded, I have already loosened the large hex on top (normally used for steering head adjustment) to minimise possible mechanical stress between stanchions, yoke bores and steering head bearings. As I said earlier, I have no information who assembled this fork or mounted it to the bike, surprisingly it is not a rusty basket case. It looks clean, yokes and cover tubes are painted, head bearing adj was ok etc. it is a miracle. Thank you, Peter

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Re: Front fork, cannot remove stanchion from yoke

Postby ajscomboman » Sun May 19, 2019 4:50 pm

I used to have a split clamp tool, bit like a twin conrod that'd bolt around the fork tube. On tourers it's possible to pull down the spring top cover and slide in the tool bolting it up real tight! I then slid a pole over the end and applied rotating force to the tool to break the joint in both the top and bottom yolk. It's only possible to use this method on standard springs and CSR's. For forks with sidecar springs in it's impossible. You also have to have the hands of a gorilla (I'm blessed in that area) and mate to insert the tool whilst you're swearing at pulling against the spring pressure whilst holding the shroud. If that method fails then I'm at a loss as personally I've never ever run across a top crown that's been that tight! The lower yolks on the other hand I've seen grown together but still managed to break apart! I can only think of fabricating a puller using a pulling tool in each leg and another attached to the stem similar to Micks idea.

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