VH500 broken sprocket mounting lug

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PeteL
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VH500 broken sprocket mounting lug

Postby PeteL » Sat Jul 18, 2020 9:19 am

Preparing to get the rear wheel of my '52 plunger VH500 rebuilt, scrubbing the hub clean ready to paint before the wheel build, I was dismayed when half of one of the ten lugs on the sprocket mounting flange dropped off. It has broken across the threded bolt hole.
I know that as there are 10 bolts holding the sprocket, the looss of one may not be a big deal, but it seems stupid to go ahead rebuilding the wheel on a hub with this damage.
Its the "fixed"type of hub, not the "QD". If anybody has a usable hub to spare, fixed or QD, it would be the easy way around the problem.

Another option of course is to get it built up with weld and machined to the original shape, redrilled and tapped.
I have a good arc welder and a fair bit of experience but I have never welded cast iron before. With the right, hi nickle content rods, it ought to be a relatively simple pocess of filling in what remains of the threaded hole and building up the area around it with a series of small welds and developing minimal heat build up.

While I quite like the idea of having a go, it probably makes better sense to take it to somebody who is properly capable of doing it. So I'll ask around, but I would be glad if anybody can recommend a place, preferably somewhere in south west UK.

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Paul_Linden
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Re: VH500 broken sprocket mounting lug

Postby Paul_Linden » Sat Jul 18, 2020 12:22 pm

These people are in Bridgewater, Somerset - https://hamlinsengineering.co.uk/
I highly recommend them from the work they have done for me on two different square four engines.
Ariel Square 4 mk2, Ariel Square 4 mk3 (yes, really), Ariel Colt, Matchless G12, BSA C12. Room for one more......

PeteL
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Re: VH500 broken sprocket mounting lug

Postby PeteL » Sat Jul 18, 2020 1:23 pm

Thanks.
I know them, they have been very helpful and knowlegable. I was thinking they might be able to tackle it, but wasn't sure if they would do the welding.
I'll pop over there on Monday.

nevhunter
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Re: VH500 broken sprocket mounting lug

Postby nevhunter » Sun Jul 19, 2020 5:08 am

When welding most iron you will get hard spots at the edge of the weld, making any recut of threads etc difficult. Nickel bronze is the best for this job as an oxy torch is less fierce heat of a localised nature. It's also stronger than the existing metal. Those threads have to be very accurately spaced to align with a good sprocket. Preheat and cool down carefully and there should be close to no distortion. Skim the drum on a set of bearings to ensure no out of round exists. It may have had some to start with. (Most do) Nev

PeteL
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Re: VH500 broken sprocket mounting lug

Postby PeteL » Sun Jul 19, 2020 7:17 am

Thanks Nev.
That makes me realise it would be daft to have a go at it myself. Hamlins are really good and should know what they are about, but your info will enable me to ask the appropriate questons.
Its a very good drum, nearly zero wear and dead round, at the moment so I don't want to spoil it.

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Paul_Linden
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Re: VH500 broken sprocket mounting lug

Postby Paul_Linden » Sun Jul 19, 2020 9:12 am

Do check the other lugs before any welding work.
Ariel Square 4 mk2, Ariel Square 4 mk3 (yes, really), Ariel Colt, Matchless G12, BSA C12. Room for one more......


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