KTM forks on your Airhead! Group Buy Two

are the clamps ready yet?
Can you supply only the clamps?

Guy,

This sounds good. Do you advise adding more threading and length on the nut?

I would suggest you pick material as you would probably know best. I have no idea and trust your expertise.

Cheers

-C

I read up on the stem issue on the other thread. It looks like the old nut from KTM had 20mm of threads and then used a ~3mm washer leaving ~17mm of engagement. The replacement nut has 12mm of thread height but only 8mm of engagement because of the wide thread relief at the bottom. Either one is fine for a KTM, but apparently the different bearing taper of the BMW bearings requires significantly more torque than the KTM stem/nut were designed to take.

I don't know if this is really a huge problem, as I could only find one instance of it happening. Never-the-less, it seems like a good idea to address the issue at this time. I have cancelled the order for the KTM stems and have placed an order for 7075 stock to machine them from scratch. I will maximize the thread engagement on both the nut and the stem.

Since the parts are being machined from scratch, maybe it would be a good idea to copy the thread pitch of the BMW stem bolt so torque values would remain the same for the BMW bearings? This might eliminate some confusion regarding setup. Does anyone know offhand what the thread pitch is on the BMW P/N 31 42 1457859 "Screw" used on the '87-'91 R100GS?

Hey all!!! My main issue, and it took me quite a long time to realize it....but my top bearing would never fully seat in the race without an awful lot of force on the little alum. bolt from KTM. I had it turned down, and apparantly it still was not enough, and grenaded the stem threads in the process...... I had another triple lying around that I pressed the stem out of. I had access to a lathe, by the myford was too small for the stem, and none of the chucks would fit it. I began thinking that I'm a bone head, and need a steel stem. My friend Terry is a machinist and works in a rather extensive shop at UGA. I left him with the stem along with a bearing, and asked it be turned down for a press fit. He also exteneded the threads in the stem to except a 50mm bolt.! I apologize for not letting Guy know, I really thought it was me and didn't see a reason to bother him with it. I now realize I may be the only one that has actually ridden extensivley with the 2nd gen set up. I'm sure mine was an anomoly, but perhaps the stems need to be turned down a hair more. Mine was at 28.04mm....I think I had Terry turn it down just under 28...27.98 IIRC.

I never produced the steel stem as I only had 2 interested parties, and I don't have the cash right now. But they still can be made.

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Thanks for chiming in! Hopefully Guy know what to do moving forward

Guy, i am happy to pay a bit more for a better setup and use as much of the thread as possible. Athough similar to what has already been mentioned, i have no idea about these things so will go with your best judgment. Also did you manage to find out what the pitch is or should i find someone with that part to measure for us?

Posted a thread to figure out the thread pitch etc. We got one reply so far.

The thread size is 28mm x 1.5mm.

http://www.advrider.com/forums/showthread.php?t=894921

Thanks for the info Jenna!


Thanks C-Dub for the info on the nut as well. The KTM bolt uses the same pitch, though smaller diameter. I have decided to stick with the KTM size/pitch for uniformity, but add length similar to the original version. This way those that have the previous set of triples can use the upgraded nut as well.

Now for the bearing/stem fit....does anyone have a stem bearing set they can send me? I would like to verify some dimensions to see if any changes are necessary as Jenna suggests.

Thanks Clay Spinner, I think we'll be OK with the original pricing. The only difference might be the bolt as it was pretty reasonable through KTM.

I'll have mine apart soon, I can't take the bearing off of the bottom of the stem though. What parts exactly do you need?

any news

Just wondering how the fabrication of a new nut thing is going?

kinda quiet in here

how's it coming along?

Bump

+1

What is the hold up? Several months ago I think you mentioned they were on the CNC machine ready to go made, does anyone have contact info for Guy? It's been over a year at this point

I'm still here. The clamps are about half done, all perimeter machining is done the slit work is all that is left.

I sincerely apologize it is taking so long, I hate being behind on things and it wears on me. My machines have been spinning around the clock and tight deadlines have left me with no extra machine time. If I had known this year would be like this I would not have taken this project on.

I will finish them up as soon as I can. We are not working this weekend, so I will come in and give them a whirl over the weekend...hopefully I can make some good progress.

The stem/nut issue is resolved, the material is here. I will get on them as soon as the triples go out to anodize. Lathe time is not as jam packed as the mills.

For anyone who is tired of waiting, I can send your deposit check back, they are sitting here in the file. I am doubting that I will do this again however, so if you want the clamps....hang on a little while longer, I will get them done.

Thanks,
Guy

Thanks Guy for the update.....
kinda..maybe..sorta..figured you were/are overloaded with other work...

Keep us posted

G.

Guy,

do you have a sense of when you are going to be able to finish this up?


thx

I know I'm late a party that's been going on for awhile, but if there is a triple available at the end let me know.
2WT

Finally caught up, and as of yesterday I am back on this project....hopefully to the end. I'll keep you posted.

Thank you all for your patience,
Guy