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Old 04-30-2012, 06:40 AM   #541
hardwaregrrl
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So I just had a thought and took out my caliper. My stem is too large at the top. I'm getting 28 and the I'd of the bearing is 27mm. The reason I mucked up my threads is I had to beat the snot out of the stem to get it to release. And I know that's not right. Off to the machine shop where I'll get accurate measurements.
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Old 04-30-2012, 08:43 AM   #542
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Quote:
Originally Posted by hardwaregrrl View Post
So I just had a thought and took out my caliper. My stem is too large at the top. I'm getting 28 and the I'd of the bearing is 27mm.
The standard head bearings for the gs are 52 x 28 x 16.5 mm (or 16mm.. )

So, your stem is correct!

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Old 04-30-2012, 10:06 AM   #543
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Originally Posted by redboots View Post
The standard head bearings for the gs are 52 x 28 x 16.5 mm (or 16mm.. )

So, your stem is correct!

Cheers,
John
Actually it's not. The whole reason I could not seat the top bearing race is because my stem is just a bit too large. The machinist agreed but I forgot to ask him to write the measurement down. He has a new set of bearings to compare. Just a bit of buffing should be enough but it is definatly too large.



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Old 04-30-2012, 10:08 AM   #544
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Originally Posted by hardwaregrrl View Post
Actually it's not. The whole reason I could not seat the top bearing race is because my stem is just a bit too large. The machinist agreed but I forgot to ask him to write the measurement down. He has a new set of bearings to compare. Just a bit of buffing should be enough but it is definatly too large.

Is this an HPMGuy stem? What did the OD measur out at? IIRC mine was just a few thou over 28mm.... something like 28.12 or 28.08
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your bike is suitably dirty. Well done.
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Old 04-30-2012, 10:13 AM   #545
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Originally Posted by SOLO LOBO View Post
Is this an HPMGuy stem? What did the OD measur out at? IIRC mine was just a few thou over 28mm.... something like .12
Updated with pics
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Old 04-30-2012, 11:17 AM   #546
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Updated with pics

10 thou's of an inch larger... what is the correct size for an interference fit I wonder, versus a tight but sliding fit?
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Old 04-30-2012, 01:09 PM   #547
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10 thou's of an inch larger... what is the correct size for an interference fit I wonder, versus a tight but sliding fit?
I think its tighter than that. Sliding fit is what you get on your axle.
If it slides it will rock/wobble.
I have to use a mallet to get the top bearing off my shaft but it winds down OK with the adjuster nut... which you don't have

John
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Old 04-30-2012, 01:21 PM   #548
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I think its tighter than that. Sliding fit is what you get on your axle.
If it slides it will rock/wobble.
I have to use a mallet to get the top bearing off my shaft but it winds down OK with the adjuster nut... which you don't have

John
You lucky bastard!!! I still fantisize about pressin the KTM stem out and putting the DR one in. But then I'd have to change out my races, and Beater has my welder....and I paid for the stem....but it is seriously too large. I'm telling you it took me at least 20 mins to remove the stem with bottom clap. That bearing wouldn't let go, and I remember it was a real pain to get on even after spending the nite in the freezer. SOLO, if you had no problem sliding the top bearing on , I wouldn't worry. I'm just special I guess??
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Old 04-30-2012, 01:40 PM   #549
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Well, to get the stock BMW stem out of the stock top bearing did take some malletation, and I am sure I used a bit of force putting the new bits together... I dn't remember any real right though.

So, what is the KTM torque value for that top nut, because I am sure I all well beyond it and need to set it back to whatever is right
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Old 04-30-2012, 01:51 PM   #550
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Originally Posted by SOLO LOBO View Post
Well, to get the stock BMW stem out of the stock top bearing did take some malletation, and I am sure I used a bit of force putting the new bits together... I dn't remember any real right though.

So, what is the KTM torque value for that top nut, because I am sure I all well beyond it and need to set it back to whatever is right
KTM manual calls for 12nm And they call it the 27.

And since I had my panties up in a wad, I have to apologize to my helpers that were here for the install. I jumped to conclusions, but I will stand by the proper way to set the bearings. Do not tighten that blind nut (27)! I'm falling back on the stem being too large which really caused all of the problems. That bottom bearing probably would've been fine if I was able to get the top bearing to seat all the way. The bike has always been fine on road, but the last 2 weekends of hard, off road riding, really loosened them up.

hardwaregrrl screwed with this post 04-30-2012 at 02:04 PM
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Old 04-30-2012, 02:42 PM   #551
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I think its tighter than that. Sliding fit is what you get on your axle.
If it slides it will rock/wobble.
now I am worried about my stem, because having pondered overnight, rocking/wobbling seems to have been what happened to cause the step which wouldn't allow my top bearing down any further- and then I had to remove this step (more material) to get the bearing over the ridge. If we are splitting hairs again, I think my stem/bearing fit is now closer to sliding than interference- there is interference still, but with the top clamp off and the upper bearing pushed down into the race, there is barely enough interference to hold the stem in the headtube- if I bump the bike it will suddenly slide out. I'll guess we'll see if this happens again.

I still don't get what happened to mine- nor what may have been seatiing while torquing the blind nut up to dangerous heights. I hammered that lower bearing down with a perfect driver and a BFH- it notably 'rang' differently once it got to bottom and wouldn't move any further. Not having a bearing seal below it I could see there was no gap- the races were old and already seated in the headtube- the top bearing was at that point freely sliding.

Quote:
So, what is the KTM torque value for that top nut, because I am sure I all well beyond it and need to set it back to whatever is right
I suppose we are somewhat in unchartered seas here. After what mine has done with very few KMs, I'd be pulling your stem and checking it out if I was you. If you feel like you have too much torque on that nut but your steering isn't tightening up then there is something wrong (well there was something wrong with mine, and mine now actually tightens with that nut and doesn't require much force to do it).

By the way, don't worry about the adjuster Jenna, I superglued my adjuster into the needle extension. I even stuffed it up the first time, didn't push it in quick enough and it glued in halfway. Damn solid it was and it took some heat to remove it. Now it is glued in all the way and until it gets some more heat I don't think it will be moving anywhere. I used some 'two part' loctite superglue- primer and glue.

I've been wrong before and I will be again, but for the moment, I'll stick my neck out again and stand by having to tighten that nut a little bit (not much, maybe 5 ft-lb or so as you tap it, a bit tighter at first until the steering stiffens a tad, and then back it off till it feels right if your bearing is actually sliding down the stem like mine wasn't). I have actually been reading about preload on tapered roller bearings- not exactly black and white stuff. Given that we are unlikely to experience any thermal expansion anywhere here during use, I think we need to set it exactly where we want it. A little too tight and you may develop a wobble while riding (slowly for me)- you'l know. Too loose and the bearings (or your stem like mine) won't last too long. A lot too tight, maybe bearing failure like Jenna's but I find it hard to believe the bike didn't feel obviously wrong if the bearing was that tight. My wild guesswork and assumption is there was a combination of bearing damage in there somehow that causes a roller to bind or something.
A lot of tapered roller wheel bearings are described as being seated properly by torquing up 'as hard as you can', to seat properly and squeeze out grease and are then backed off unti they spin well with no play. The act of tightening them itself shouldn't harm a sound bearing as long as you loosen it off to the desired preload for use. I also think there would be a safe level of preload for these bearings that would produce very unpleasant steering characteristics, hence why I think something else must have occurred.
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Old 04-30-2012, 02:48 PM   #552
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I just put a big socket on mine and tightened until I had the typical BMW pre-load where the bars fall slowly to the steering lock.

If I had to guess, it took somewhere arounf 30-40 ftlbs to get there. I'm going to back the nut off and re-torque to something more reasonable.

That said, I wouldn't be suprised if the pre-load stays where it is now. Fingers crossed at least.
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your bike is suitably dirty. Well done.
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Old 04-30-2012, 04:02 PM   #553
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Sorry Hans!! As you were posting, I was disassembling.



No way to really measure it. My needle was also apart and was visabley bent at the tip. But you'd have to roll it to see....

new one on the bottom.



Here's the spring and no markings what so ever??!!!



And since I'm waiting on my stem....



New needle and on the fly adjusters!!! Well, I just did the rebound side tonight. And I made a fucking mess!!!
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Old 04-30-2012, 04:15 PM   #554
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Not that I am a suspension expert, but your spring looks like it is progressively wound and not dual-rate.

But that is based on the thought that dual rate would involve having two different coil diameters, not just increasing spacing of the windings.
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Old 04-30-2012, 11:27 PM   #555
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Ok, not to muddy the waters but hopefully as a help, this is the page from my 250excf manual.
As you can see, it says to tighten the stem nut to 10nm and also to loctite the stem pinch bolt.


Happy spannering.
The sun is shining here this morning after 14 straight days of rain so I'm out for a road test on mine ... too wet for any tracks on this tank though

Cheers,
John
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