Knurling/shim stock/spacers

Questions and comments about converting to beefier forks..
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stringburner
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Knurling/shim stock/spacers

Post by stringburner »

Just a couple of questions concerning the top clamp:

I know nothing about machining, but I see posts where some of you guys have the stem knurled. Wouldn't it be easier to knurl the hole in the top clamp and end up w/ the same fitment, since the clamp material is softer than the stem? Or is that why the stem must be knurled, because the knurling wouldn't hold up in the top clamp because the material is too soft? Or is knurling something that can only be done on an OD situation, and not an ID scenario? So, the solution is either knurling, or shim stock, or having a spacer sleeve fabbed up.

I gather the height of the top clamp can be adjusted by shims (washers) either under or over the top clamp, to give the desired clearance for the protruding stem from the handlebars, and to keep you from running out of threads on the stem. I understand that, if it's correct. I'm thinking w/ the washers in one place or the other, you will have more room for fork height adjustment, but that may not be right. Perhaps it doesn't matter....but in my mind, it seems the lower the top clamp, the more room you have to slide the longer KX forks up to compensate for the slightly longer length, and get you back to the original ride height....the more I think about it the more confusing it becomes.

Other than that, after having the KDX stem pressed on the USD lower clamp, it's a straight forward procedure, right? Or, pretty much all of the issues have to do w/ the top clamp. We are using our original stem and bearings, so everything else isn't an issue. If any of this sounds incorrect, please correct me.
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Post by Colorado Mike »

Knurling takes metal and raises it up for a friction fit for a part to be pressed in. If you did that on a part meant to be removable like the top clamp, you'd be screwed.
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Post by stringburner »

Ok, I see. In SOME instances, the lower clamp needed to be knurled for the proper tolerances from ID of the clamps stem hole, to the OD of the KDX stem. I don't think the set-up i'm getting has this problem. He used calipers and determined the lower part of my stem is the same size as his lower bearings inner diameter...So I think that means the lower clamp hole is also the same...I think....hopefully. :shock:

Otherwise, the top clamp could be knurled to pick up the slack between the larger hole and the KDX stem (as long as it wasn't knurled to the point of being too snug), or you could use shim stock, or have a spacer made....
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Post by canyncarvr »

In a word..no.


Re:'He used calipers and determined the lower part of my stem is the same size as his lower bearings inner diameter..'

That has exactly nothing to do with how the stem fits into the clamp.


Re: 'So I think that means the lower clamp hole is also the same...I think....hopefully.'

Which is to say, 'No.' Not at all related.

Re: 'Wouldn't it be easier to knurl the hole in the top clamp'

As CM has said...(sorta), 'Don't do that!'

It's the BOTTOM clamp that may be knurled. Or the stem, either one. In any case, the fit is SO loose from stem to TOP clamp, you couldn't knurl it enough to make it tight. That's where some use shimstock. I had a spacer made and pressed INTO the top clamp so I wouldn't have to worry about it. You don't want it tight at that spot anyway. Slip fit!! NOT tight!!


This is a repeat of a lot of stuff already noted here..but..I wouldn't want to go looking for all of it..

It is not critical that the stem-lower clamp fit be perfect. It being pressed in is NOT where any 'strength' of anything comes from. Assemble it with the Loctite product intended for cylinderical interference fit and you will be fine. That product is shown/noted in my gallery if you don't have it already.

Don't forget the clip on the stem. Leave THAT out, and you have a problem!!

Re:'it seems the lower the top clamp, the more room you have to slide the longer KX forks up to compensate for the slightly longer length,'

In another word (the same word), 'No.'

Consider: You have it assembled, but need to nudge the forks up 1/2" to get it 'right'. But...the forks are already hitting the handlebars!! What's going to fix that? The top clamp higher or lower?

The answer is 'higher'.

As you said..put it together such that you have room to put the top nut on, WITH enough threads. That will give you the maximum amount of movement needed to 'level' the bike.

Check that level before you START the process so you know where to get back TO!!


Re: 'Other than that, after having the KDX stem pressed on the USD lower clamp, it's a straight forward procedure, right? Or, pretty much all of the issues have to do w/ the top clamp. We are using our original stem and bearings, so everything else isn't an issue. If any of this sounds incorrect, please correct me. '

With the exception of 'pretty much all of the issues' part (because the fitment of the stem to the bottom clamp is somewhat of an issue), immediately following are all the things that need to be corrected with that statement:

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Post by stringburner »

Well, I'm just as confused as can be, but I left my bottom clamp/stem at the shop awhile ago to have it pressed into the RMZ lower clamp. He seemed to know what he was doing (he pointed out the keeper clip and all that), so i'm sure he will know if something isn't right. He spent alot of time talking to me about it, what to do about the slop in the top clamp (I think its 30 or 40 thousands difference), etc. Then i'll bring all the stuff home and see what I got to work w/, and go from there. The steering stops may be a concern as they are a bit different than the stock set-up. I can figure something out there. I'm gonna look up the front wheel size on the RMZ to see if I can put my tire on that rim, even though the stock tires are likely crap. Thanks for the reply CC. I guess the worst that could happen is for it to fold up like a deck of cards when i'm wot. :mrgreen:
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Post by canyncarvr »

If you have further questions, ask. Maybe one at a time would be good.

No need to be confused about any of it. Most answers, though, will be based on a KX/KYB swap..not on an RM. I don't know to what extent they are the same OR different.

No reason to assume your KDX caliper will bolt to a set of RM forks, while bolting the caliper to a KX fork is fine....stuff like that.

When you talk about knurling the top clamp...I get kind'a worried..... .030-.040" is a lot of space.

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Post by stringburner »

It's easy to become confused reading through all the material here relating to the swap. I though it was knurling or using a spacer/shim stock to tighten up the slop in the top clamp. Obviously not. From what the fella at the shop i'm dealing w/ said, it's the stem that would have to be knurled anyway, you can't knurl inside the hole. And as far as I know, i'm getting everything from the stem forward, including the m/c, brake lever, caliper, wheel, rotor, etc., so if I can get the clamps to fit my stem (he said no problem), then it should work (no caliper mounting issues to deal w/). I imagine there will be some catches along the way, but it's like that pretty much whatever I do. I'm guessing the springs will be too stiff for me also. I'll deal w/ that after I get everything fitted.
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Post by canyncarvr »

Re: '..knurling OR using a spacer/shim...'

It IS spacer/shim...it is NOT knurling. And..'tighten up' is a phrase that's cause for concern..because that fit CANNOT be tight. The top clamp has to SLIP to the stem.

Consider: That connection IS press fit tight. When you put the top nut on and tighten IT, what's going to happen?

Nothing that is supposed to happen!

As long as the clamps will fit the stem/frame connection, you will be OK.

Consider: (Exaggerated to make a point) If your bottom clamp is 2" thick, the stem isn't going to be LONG enough to extend THROUGH the stem tube to be able to fit the TOP CLAMP to.

Who makes the RM fork? Any REAL dirtbiker would know I guess...which maybe is why I don't.

What's the diameter of the things? 46? 48? Bigger?

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Post by stringburner »

I understand now that knurling is NOT for the top clamp. :grin: I understand it's not a press fit. When I sit it on the stem, i've noticed there is a small amount of play, and understand the top clamp doesn't mount rigidly to the stem like the lower clamp, which is pressed on and has a clip. He measured a whole bunch of stuff and determined that it would fly is about all I know. Maybe it won't. I'm gonna call or go over in the next few days and see what he's come up w/. I don't think either of the clamps is remarkably thicker or thinner than the KDX's pieces, but again that remains to be seen. He's turning his RMZ450 into a drag bike w/ mountain bike inverted forks (yes, bicycle forks!) :shock: He raced the RMZ in GNCC races, but he seems to like all things dirt, so this is his latest project, and I get the forks if they will work on my machine. He had a custom washer/spacer made for his mountain bike forks, where the spacer would fit down in his top clamp to pick up the slack, then the top part would be the proper thickness for the head nut washer. He wants me to do something similar. Kind of a "T" type spacer/washer. He was a Kawasaki tech for 11 years, so I'm assuming (bad ideer I know) he knows what's going on.

The forks are 47mm Showas.

Thanks for taking time out of your day to clarify stuff for me AGAIN. I did understand the top clamp wasn't a press fit. We were just getting confused in the translation.
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Post by strider80 »

You are on the right track, here is my "T" spacer I think you described.

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Post by motorider200 »

I will admit the the little machined spacer is pretty nice but I was on a budget so here is what I used as a spacer

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Post by strider80 »

I would have done that too if I did not have the luxury of machine shop access at work. :grin:
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Post by stringburner »

Strider, that is pretty much exactly like what he showed me he had made. I guess you would call it a step washer(?). I was thinking it was the other way around, where the wider step would be up and under the head nut, but I see now your way is the way it willl be to provide the proper spacing/clearance. I guess it depends on the parts used too what spacing will be needed. It's pretty hard to think this through in your head. Nice setup you have there.
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Post by strider80 »

Thanks!

I was confused too before I started the swap. If you get the stems swapped, then install the stem and lower triple on the bike, it will become more apparent what kind of a spacer/shim you need in the top triple.

My spacer could have gone either way, I don't really think it matters if the step part goes up or down. My rational is that moving the top triple higher allows the forks to be clamped a bit higher....not that it really matters.
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Post by stringburner »

Foots, you have a Bazooki fork set-up on your KDX? Nice spacer btw. :grin:
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Post by bradf »

Strider, you did do it right and it might matter! If the spacer was swapped the top clamp would be 3/8" lower and it would limit just how high you could effectively raise the fork tubes for handling purposes. Your way, the right way, gives an additional 3/8" space for the tubes.
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Post by canyncarvr »

Those 2-way spacers are indeed very nice. 2-way meaning they not only space the KDX stem to the top clamp hole..but space the top clamp UP.

My 1-way spacer (stem to clamp hole) gets around the shimstock fit..and I had no idea how much of the 2- spacer I'd need.

I settled for hi-tech washers!

foots: You made an aluminum stem? Or the pic is just OF the stem that came out of the suzuki?

I'm envious of you guys that know HOW to, have the ABILITY to AND have the equipment to 'make' metal stuff.

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