Stem bearing issue?

[showtime586]

A few weeks back, I had to replace the upper and lower stem bearings in my RM. These have the integrated seal built into the bearing. Anyway, I have done this task a few different times on various bikes, but the front end on the RM keeps getting loose and requires retightening. I confess that I don't use a torque wrench on the spanner nut, but I didn't on any of the other bearing jobs either. This one is becoming a pain. Is there some kind of issue with these bearings, or is the torque value that crucial?. Any insight is much appreciated.

 

[RM_guy]

I haven’t had any trouble with mine. I don't know what process you use but here's what I do when reassembling it.

1) Before the top triple clamp goes on I snug up the nut on the top bearing so there is a slight amount of drag on the bearings.

2) Put the top triple clamp on and DO NOT tighten the top pinch bolts on the fork tubes.

3) Tighten the large hex nut. I don't use a torque wrench here either but be careful because I have also stripped out the threads on the stem ($300+ at Suzuki or $90 at Emig Racing to replace). Make sure it is tight.

4) With the front wheel off the ground, see how smooth the bearing action is. It should flop to one side under it's own weight but not be loose. It's hard to tell if it's too loose so I usually error toward the tight side.

5) You will have to readjust the first nut a few times to get it right.

6) After you get the tension right go ahead and tighten the upper pinch bolts.

In cases where it looks like the nut loosened up I believe it was either because it wasn't tight to begin with (it's hard to tell sometimes) or the upper pinch bolts were tight while the nuts were being tightened and the top triple clamp wasn't down against the first nut when the top nut was tightened.

 

[showtime586]

Thanks for the reply. The first time I assembled it without the tubes in place. It felt good, but apparantly it was not.
The second time, I left the tubes on, but I did not loosen the top clamp pinch bolts, but it appeared to get tight.
I am afraid I will need to tear it down as I am hearing what sounds like some popping coming from a new bottom bearing...... :bang:

 

[RM_guy]

Yeah, you really need to assemble it with the tubes in place. The extra leverage you get with the tubes makes a big difference when checking the snugness.

 

[showtime586]

That sounds very realistic and I will do it that way when I put it back together. I am curious as to why my thumper never experienced this issue since I did that bike the wrong way too. I guess I got lucky. thanks for the info.

 

[showtime586]

RM_Guy,
The lower bearing is spinning on the stem. When I removed the old bearing, I nicked the stem and buffed the burr down with a file. I guess I took off too much of the metal. It felt snug when I pressed the new bearing on, but it sure is spinning now. I guess I could "peen" the bottom part of the stem to see if that will snug the bearing up. Any ideas?

 

[RM_guy]

Sometimes you can upset the metal under a bearing to get it to be tighter but eventualy the raised sections will get pushed back down and you will be back where you started. If its not too loose you can use some retaining compound to fix it. Loctite has a full line of products http://www.loctite.com/int_henkel/loctite_us/index.cfm?&pageid=19&layout=3

 

[showtime586]

Looking up the stem was how I uncovered that I had been had as I have explained in the "general forum".
When I saw how the 02 stem looked, I knew I had something that was older. Fortunately, the bike is not on the nation wide stolen list. I am still waiting for the seller to contact me.