KX/KDX STEM SWAP, PRESSING INFO PLEASE!

Questions and comments about converting to beefier forks..
Post Reply
gertie6car
Member
Posts: 132
Joined: 05:05 am May 17 2008
Country:
Location: sunny surrey uk

KX/KDX STEM SWAP, PRESSING INFO PLEASE!

Post by gertie6car »

Hi Guys,

sorry for all the posts asking for info but I would rather ask questions than do something and get it wrong! please bear with me a little longer!!

ok I have a hydraulic press and need to swap the stem from my kdx to the KX lower triple tree. I have read various posts and am going to have a go myself.

What I would like to know is which way to press the old stems out , is it pushing the long length through the tree or is it pushing the stem out from the underside of the clamp?

When pressing the KDX stem into the KX lower tree should I turn the tree upside down, lower the stem through threaded end first and push the last inch or so into the tree or should I place the tree up the right way and just push the stem in?

I am going to heat the tree up before pushing out the stems (even if the stem heats up as well the thermal expansion of ally is greater than steel so should ease things). When I am pressing the KDX stem into the KX tree I am going to heat up the tree and chill down the stem in the freezer to make life as easy as possible.

Any suggestions before I start would be appreciated! I really don't want to trash either the stem or the triple tree!

I have read something somewhere but cannot find it again and I am sure there is a right way and wrong way?!


Thanks in advance

Gert
User avatar
canyncarvr
Gold Member
Gold Member
Posts: 6943
Joined: 01:07 pm Nov 05 2004
Country: US
Location: The Mythical State of Jefferson

Post by canyncarvr »

Re: 'What I would like to know is which way to press the old stems out , is it pushing the long length through the tree or is it pushing the stem out from the underside of the clamp? '

The former.

There is a clip on the stem..press it down and out..the long length through the clamp.

Re: 'When pressing the KDX stem into the KX lower tree should I turn the tree upside down, lower the stem through threaded end first and push the last inch or so into the tree or should I place the tree up the right way and just push the stem in?'

1. I didn't do mine myself.
2. If I understand your question (which seems perfectly clear to me), what's the difference?

Depending on how your press is setup, the direction of press will determine what you are 'holding' and what you are 'pressing'. My $.02..support the clamp, press the stem. Doing it the other way 'round won't let the stem 'center' in the hole. I understand your statement in both cases to be pressing on the stem itself, just the direction of press changes..which doesn't matter. The 'other way 'round' I refer to (which you MIGHT mean) would involve holding the stem and pressing the clamp onto it. IMO, that's not right.

You may find the KDX stem will not press into the KX clamp with sufficient force..it will be too loose. That's why some applications (depending on your clamp and it's condition) call for knurling of either the stem or the clamp.

I'm not a machinist..but there are common measurements for press fits for different metals. Steel on steel of course being different than steel on aluminum.

Consider using a Permatex/Loctite product that is specifically designed for the press fit of objects with specific fit measurements.

You are familiar with those?

Like this..

Note it's stated for use up to a .005" fit. That's pretty sloppy, a fit that should be knurled, seems to me.

Or:
this.

Looks like:

Image

..in the Loctite brand.
Last edited by canyncarvr on 02:17 pm Nov 17 2008, edited 4 times in total.

Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis

bike profile: !clicky!
gertie6car
Member
Posts: 132
Joined: 05:05 am May 17 2008
Country:
Location: sunny surrey uk

Post by gertie6car »

Hi CC,

thanks for the comments, I appreciate your help!

ok so the pressing out is sorted long stem through the clamp, do i do both the KDX and KX stem the same way? I guess so.

Now for the pressing in part. I think you are saying fitting the stem is the reverse of removal, am I correct? I will support the triple tree and push the stem trough, a close look at the kx stem shows it has a slight taper slightly increasing the diameter at the lower end. I need to check the kdx one, if that is the same it should self centre as I push it through.

I will measure the diameters of the KDX stem and the KX triple tree hole and make a call on whether or not I need to knurl or can use loctite. I have read the threads on these subjects and am ok on that front.

Thanks once again for taking the time to post, I appreciate it.

I hope the weather is better with you than it is here (south of london)! its dark at 3.45 pm and wet and miserable! But all the better for working in the garage and finishing this project! Cannot wait to ride it!

Cheers Gert
User avatar
canyncarvr
Gold Member
Gold Member
Posts: 6943
Joined: 01:07 pm Nov 05 2004
Country: US
Location: The Mythical State of Jefferson

Post by canyncarvr »

I messed around with the first post a good bit getting links, pics and stuff. It might have changed from when you first read it.

Re: 'ok so the pressing out is sorted long stem through the clamp, do i do both the KDX and KX stem the same way? I guess so.'

You guess correctly. DO make sure there is NO ROLL PIN in your KDX bottom clamp, through the stem. I think this was said already, but some KDXs (overseas SR types) have pins like that. Obviously, such a stem is not going to be pressed out in ANY fashion.

Re: 'I think you are saying fitting the stem is the reverse of removal, am I correct?'

Absolutely...as long as it was removed in the correct direction! :wink: If you did attempt removal in the wrong direction, you now have a broken bottom clamp, so the how-to assembly part of the process is moot, 'eh?

Like: place the bottom clamp upside down on your press support (the part that doesn't move). Drop the stem into the upside down clamp, threads first. Place your arbor tool on the bottom of the stem (it's facing up..you can see the clip), move the press down to press the stem into the clamp until the clip seats. You can see where the clip fits when you have the two pieces apart.

You're a good bit farther north than here. 50ºN latitude is south of Britain (England..U.K. ...sorry... about being I'm sure wrong about that somewheres) and north of the US/Canada border. Still, it's dark way too early here, although I'm sure not as wet.

Wibby posted some pics of riding here last weekend in the 'Ride Pic' forum. See the sun? See the blue sky? :lol:

Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis

bike profile: !clicky!
allergic2death
Member
Posts: 9
Joined: 12:35 pm Oct 27 2008
Country:

Post by allergic2death »

It is so easy to do yourself. I just through it on my 12 ton press not even 5 minutes ago and it took only four pulls of the handle and it popped right out. I woud not even mess with heating it up it was a snap.
gertie6car
Member
Posts: 132
Joined: 05:05 am May 17 2008
Country:
Location: sunny surrey uk

Post by gertie6car »

Hi guys,

thanks for the comments!

Great pics not seen blue sky here for some time! Will be in houston 3rd week december Houston so will see some blue sky then and in singapore 1st week december and that will be hot hot hot! Both business but cannot wait!

So at the risk of being controversial what do you think of the presedent elect?!

cheers gert!!

ps did you support the triple tree in any way or just push the stem out?
User avatar
canyncarvr
Gold Member
Gold Member
Posts: 6943
Joined: 01:07 pm Nov 05 2004
Country: US
Location: The Mythical State of Jefferson

Post by canyncarvr »

>|<>QBB<
allergic2death wrote:It is so easy to do yourself. I just through it on my 12 ton press not even 5 minutes ago and it took only four pulls of the handle and it popped right out. I woud not even mess with heating it up it was a snap.
Something to consider...they are not all that easy. The experience of one with a simple time of it does not equate to the realities of some situations. There are those that have used presses a lot bigger'n 12T, and when the assembly let loose, it 'snapped' with enough force to take off a limb or two..had such happened to be in the way.

A recent swap posted here required force enough to damage the threads on the stem.

Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis

bike profile: !clicky!
allergic2death
Member
Posts: 9
Joined: 12:35 pm Oct 27 2008
Country:

Post by allergic2death »

Yeah but you dont know if you dont try.
User avatar
canyncarvr
Gold Member
Gold Member
Posts: 6943
Joined: 01:07 pm Nov 05 2004
Country: US
Location: The Mythical State of Jefferson

Post by canyncarvr »

Nope. You don't.

And..if you try in an unprepared fashion, having no clue of the possibilities.... maybe you die.

If God gave you a brain, use it.

If he didn't (re: So at the risk of being controversial what do you think of the presedent elect?!), God bless your president-elect (come December-15) anyway.

Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis

bike profile: !clicky!
gertie6car
Member
Posts: 132
Joined: 05:05 am May 17 2008
Country:
Location: sunny surrey uk

Post by gertie6car »

Hi Guys,

after all the help I thought you would appreciate an update! Well I have pressed out both stems, the newer KX 2000 stem came out with just over 4 tons pressure, with the lower bearing in place and without any heat being applied. The older KDX stem took some shifting, held 10 tons no problem with no signs of shifting so I applied heat (paint stripping hot air gun) to the stem and lower triple tree, put it back into the press and it shifted at just over 7 tons. To say I was pleased was an under statement!

The original KDX stem is a sliding fit in the KX lower tree, just like it is described in many of the posts on here. Measurement shows the stem is approximately 0.004" smaller in diameter than the hole in the lower tree. That 0.002" radial clearance makes a very big difference to the fit!!

I am tempted to use the loctite CC recommended and drill and insert a roll pin through the tree into the stem as added insurance. What do you think? I will machine up a top hat spacer to take up the slack created by the thinner KX lower tree.

Thanks for your help while I have been doing this, it is appreciated, I know I say that alot but I like to say thanks! I dont think I would have done this with out the input of you guys :supz:

Cheers Gert
allergic2death
Member
Posts: 9
Joined: 12:35 pm Oct 27 2008
Country:

Post by allergic2death »

Good Job! I pressed out the kdx stem this morning and it was a bit harder than the kx stem. It took about ten minutes of heating with a torch before it popped.

What year kdx do you have?
gertie6car
Member
Posts: 132
Joined: 05:05 am May 17 2008
Country:
Location: sunny surrey uk

Post by gertie6car »

Hi allergic2death!

it is a 1990, completely rebuilt the engine, frame repainted, rad re built, etc etc, soon to have KX 125 yr 2000 front end!

Should be good fun to ride!!
User avatar
canyncarvr
Gold Member
Gold Member
Posts: 6943
Joined: 01:07 pm Nov 05 2004
Country: US
Location: The Mythical State of Jefferson

Post by canyncarvr »

after all the help I thought you would appreciate an update! Well I have pressed out both stems, the newer KX 2000 stem came out with just over 4 tons pressure, with the lower bearing in place and without any heat being applied.

:hmm:
Huh?

You cannot remove a stem, cannot have it come out... 'with the lower bearing in place'...unless you took it out the wrong way!!!

In which case, at the very least the clamp it came out of is now useless (without some work done to it anyway).

This is a 'lost in translation' moment, hhmmm?

You mean you pressed the stem out without taking the bearing off first? That's the generally approved way to replace the bearing in the first place, yanno. You press the stem out of the clamp which removes the bearing from the stem in the process.

..most don't do it like that 'cuz they don't have a suitable press.


.002" is well within the spec of the above noted 'stickum' products.


I wouldn't bother with a pin..but that isn't based on anything other than personal preference and point of view. Once the stem is in the clamp, it's not going anywhere. The clip is going to keep it from migrating up through the clamp and the whole mess is held together fairly well with some pretty big tubes clamped on either side to both clamps.

If you're a machinist type (seems you are) then you would likely drill the holes in the clamp and stem separately. I would think that if you drilled the hole after the two parts were mated, when the drill bit got through the soft clamp and hit the h-a-r-d round steel stem, it would waller (don't bother looking that word up..you won't find it) around a bit. Then you would end up with a too big hole in the soft stuff (the clamp) which would make the whole process kind of a waste of time.

The 'top hat' spacer is a good idea, seems to me. I had one made 'cuz I didn't want to mess with shim material..and I wanted everything to line up the way it should..with the stem going through properly sized holes with the same centerline.

A btw...but when you put your new bearing on the stem, DO support the STEM as you press it on. Generally the stem will be somewhat recessed into the clamp, so merely supporting the clamp will put the pressure you use to seat the bearing on the stem/clamp fit.

That's mechanics 101...but I like stating (and restating) the obvious....'cuz it's the obvious that so obviously gets overlooked.

...obviously!

Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis

bike profile: !clicky!
gertie6car
Member
Posts: 132
Joined: 05:05 am May 17 2008
Country:
Location: sunny surrey uk

Post by gertie6car »

Hey CC how you doing?

thanks for the post. I took the stems out as advised, older one just took more persuading! its all clear when you haver done it!! I did take some pics thought they might be usefull.

I ordered the locktite stuff yesterday along with new bearings, should get it all back together for the weekend, still waiting on the FMF muffler I bought in the states a week of so ago, then its hi the trail!!

I think I will pass on the roll pin idea!

thanks for the input! its still dark andf still raining here!!!!

Cheers Gert
Post Reply