Fork yokes - on-the-wonk!

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Re: Fork yokes - on-the-wonk!

Postby clive » Wed Jan 13, 2021 10:03 pm

I dont understand the problem. My route would be to firstly assemble the fork crown and top yolk with all the bearings. Once this is in place and roughly tightened up. Then fit one stanchion. If you dont have a fork puller then the ratchet strap method may help, and you are only trying to pull one stanchion into a fixed fork crown and top yolk with the headlight ears etc in between. Repeat this with the other stanchion.
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Re: Fork yokes - on-the-wonk!

Postby DavidHulse » Wed Jan 13, 2021 10:16 pm

Thanks for prompt reply Clive. I foresee a problem with your solution as, without a puller, I can't get hold of the stanchions to pull them up inside the top shrouds.

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Re: Fork yokes - on-the-wonk!

Postby clive » Thu Jan 14, 2021 9:00 am

David Save yourself hours of frustration and get a universal fork puller. Listed by Surbeys AMC Classic spares at present. Alternatively make your own with an old top bolt with the flange turned off and some studding. A section member even managed by screwing an old broom handle into the stanchion before I could lend him mine during lockdown number one.
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Re: Fork yokes - on-the-wonk!

Postby Mick D » Thu Jan 14, 2021 9:23 am

Hi

It does sound like your lower yoke may be distorted, remove the stanchions covers etc. and place a straight edge across the bottom surface of the lower yoke to check.

If this doesn't reveal the issue I'd assemble the yokes as Clive says and fit the stanchions without covers and springs, you'll then be able to take comparative measurements to identify the issue.

While you're doing this the postie will have time to deliver the dedicated tooling that you really need to buy, make or borrow.

Regards Mick

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Re: Fork yokes - on-the-wonk!

Postby DavidHulse » Thu Jan 14, 2021 2:20 pm

Thanks guys. I've made a puller this morning so I'm now in the process of getting the legs out again, with higher confidence about the eventual reassembly. Interestingly, the right leg came out easily, but the left one is being very stubborn, I'm just going back to the garage to have another go! Will keep you posted. Dave.

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Re: Fork yokes - on-the-wonk!

Postby DavidHulse » Thu Jan 14, 2021 4:10 pm

Here's an update. Got the left leg out ok. Measured the distance between top yoke and fork crown and it's definitely 2.5 to 3 mm larger on the left than on the right, Taken the yoke off to check bearings all correct and reassembled but difference between sides is unchanged. Fork crown appears to be flat, tested top and bottom with a straight edge, so I'm assuming the whole thing must be crooked on the stem, rather than bent on one side. Now I'm wondering what's the best way to straighten it. I haven't got a spare stanchion but I have got a large, long cold chisel that fits through the fork crown holes. Should I try levering it with that, or would it be better to put the crown in a vice with a suitable spacer and try to bend the left side upwards?

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Re: Fork yokes - on-the-wonk!

Postby Mick D » Thu Jan 14, 2021 4:40 pm

Hi

You need to identify where the distortion is:

Rest the bottom yoke on a flat surface - is the column vertical?

Fit the top yoke to the column - is the top yoke parallel to the bottom?

Regards Mick

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Re: Fork yokes - on-the-wonk!

Postby DavidHulse » Thu Jan 14, 2021 6:42 pm

I've just come in from the garage and I've already done the first part above. As far as I can tell, the column is not vertical. I used a set square with the thick part flat on the bottom yoke machined surface and it looks to be about 2mm out of true at the top of the blade (I've tested it on both sides). I haven't tried the top yoke to see if it's parallel but I'm guessing it won't be. I will do that tomorrow. The next big question is what can I do to straighten it?

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Re: Fork yokes - on-the-wonk!

Postby clive » Fri Jan 15, 2021 4:29 pm

The column comes out of the crown. tap it down first so that it comes out far enough to remove the circlip then bash it back the other way (with a suitable drift of course). Some heat may help make things easier but I have done it cold and 35 years later it is still no problem. With the column out you can see if that is distorted or if it is where it fits into the crown that is the problem. Rolling the column on a flat surface will soon show if it is bent, and if it is I assume Mick will have an idea how to straighten it which is more professional than putting it in a vice and using a bit of scaffold pole as a lever!
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Re: Fork yokes - on-the-wonk!

Postby Mick D » Fri Jan 15, 2021 5:41 pm

Hi

I'd be very surprised if the column was distorted, it's supported at both ends by the races in use.

Assuming the covers etc. are all of similar dimensions I'd be tempted to assemble the yokes in the headstock and using studding, washers and nuts in place of the stanchions, see if you can correct the distortion.

Regards Mick

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