TR5mx Fork/Steering Stem

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TR5mx Fork/Steering Stem

Post by johnu »

So sitting on my tr5 I could tell that something was awry with the forks. With the bars straight the wheel points slightly to the left. Loosened all of the triple clamp (yoke) bolts and tweeked it to more of less straight but still not quite right. Unassembled forks, triples and found that the stem is bent :cry: I have absolutely no idea how this could occur on this very stout piece. Are new stems still available? Right now I am even tempted to look for another set of forks, this stuff bugs the heck out of me.
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Re: TR5mx Fork/Steering Stem

Post by mlb50 »

That can be straightened. Take to an engineering shop and ask that they cold work it. No heat. Should be able to press that true in 5 minutes.
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Re: TR5mx Fork/Steering Stem

Post by minetymenace »

Failing that, Mark Cook will make you one (might have one in stock), but he is the other side of the pond and all that entails....
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Re: TR5mx Fork/Steering Stem

Post by johnu »

mlb50 wrote: Wed Sep 30, 2020 6:20 am That can be straightened. Take to an engineering shop and ask that they cold work it. No heat. Should be able to press that true in 5 minutes.
That's a good call but I just looked at the stem again and it is bent at the bottom as well so it looks like I'll just replace it.
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Got an email in to PES regarding a new stem. I assume the old one just presses out of the yoke. Also do I need to heat the yoke at all before pressing out the stem?
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Re: TR5mx Fork/Steering Stem

Post by BasilF »

Its threaded both ends, a course thread into the bottom yolk and a fine thread into the bearing adjusted nut. Heating the bottom yolk will certainly help if it is tight.
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Thanks Basil, it came out easy. About the only thing that has been easy on this build so far :mrgreen:
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Stem is a right mess, bent both ends and bearing surfaces worn. Not sure how it could be this bent! I would make a new one myself but I don't have the screw cutting gears that I need for my lathe.
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Stem is a right mess, bent both ends and bearing surfaces worn. Not sure how it could be this bent! I would make a new one myself but I don't have the screw cutting gears that I need for my lathe.
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Re: TR5mx Fork/Steering Stem

Post by SteveS »

Hi johnu

Last time I needed one I couldn't source one anywhere at a sensible price so a friend made one up from 3/4" solid mild steel bar. It was fairly simple to thread the end that goes through the bottom yoke 3/4" UNC. The thread at the top varies between early and late models:

early models - 3/4” UNF (16tpi) - stem top nut 97-4029, steering stem 97-4116
late models - 3/4" UNF thread form (24tpi) - stem top nut 97-4317, steering stem 97-4319

It would be helpful if you could post details of the overall length of the stem and how far the thread is cut at each end for future reference :smile:
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Steve, here are the dimensions of of my stem. I think I will just buy a couple of dies and make the stem from 3/4" precision ground bar. I'm going to try to bore the middle out but that's a lot of drilling! It will be easier to get the 3/4 x 16 unf die so I'll probably do that then buy the earlier top nut. I dimensioned it in imperial as that's what it would have been originally.
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Re: TR5mx Fork/Steering Stem

Post by robtg »

You can get 4130 tubing the size in your drawing from Aircraft spruce By the foot.

https://www.aircraftspruce.com/
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Thank you Rob, that is a big help :thumb Just ordered a piece :razz:
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Re: TR5mx Fork/Steering Stem

Post by beesa71 »

And that nice fella ‘stainoifless’ on EBay sells a stainless steel stem top nut in the early version ie the coarse thread. They will ship worldwide.

It is cheaper to buy it, and the other listed items, through direct contact via this wonderful forum. As you would expect.

Regards to all OIF’ers.

Paul.

PS; if you haven’t realised it ‘stainoifless’ is my pal and I.
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Got started on the stem today. My cheap Chinese 3/4-10 die did a pretty good job! Still waiting for the 3/4-16 die to arrive.
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Re: TR5mx Fork/Steering Stem

Post by johnu »

Done!
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Re: TR5mx Fork/Steering Stem

Post by Keefe »

Nice
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