Bearings on MotoLite
Had a rough one yesterday.
I had a complete set of replacement bearings sitting in my toolbox from years ago. This weekend I decided to go ahead and replace all my bearings whether they needed it or not. Although I've been riding my ML since 2005, I live in sunny California, and figured they were probably fine. Sure enough, the rocker pivots were toast - all of them severly pitted or outright frozen. Replacing these was actually pretty easy.
Then I moved on to the main pivot bearings. Okay, so I've never done this before, but I was working with a friend that had; albeit on a different frame. That gave me the confidence to try this, but it was an absolute disaster. I ended up gouging the crap out of the main pivot bores since the old bearings (which were fine by the way) were in there so damn tightly. I now realize I should have soaked everything in WD-40 prior, and been a little less ham-fisted with the hammer/pin. I did drift pin (12, 3, 6, 9), but not as carefully as I should have. Anyway, I got them out eventually, used a ultra-fine rat-tail file to mitigate the burrs I created, and then seated the new bearings. I ended up having to put the new bearings in the freezer to get them to go in flush - nice trick if you haven't tried it. Despite being new and smooth, once in the frame the bearings felt a little notchy. I'm guessing the pressure on the races causes this - right? After hours of trying and a nice sunburn to show for my efforts, I got all four new bearings in... ummm I mean three new bearings and an old one since I blew one of the new ones up when I had to tap it out because I forgot to replace the aluminum spacer .
Okay, so all the bearing fit perfectly flush, are tightly pressed, and secure. The pivot pin slid in smoothly and snugly as before. The swingarm moves up and down easily. There is absoultely no detectiable play in the swingarm. Did I f@ck up my frame?
One more thing, I noticed after, but I'm not sure if it was like this before; if I yank on the rear tire while holding on to the frame I can get a slight clunk. I'm pretty sure that I've narrowed it down to the non-driveside horst pivot. I can actually pull the tire so it will pop a little, and then place my hand on each pivot and push the wheel the other way so it pops back into place. As I do this I can feel the non-drive horst interface move just slightly. I had something similar on another bike, and it turned out the bushing axles were a fraction of a mm too long. But, I'm also worried that maybe I somehow messed with the frame's tolerances and now it's manifesting itself in this way.
Last edited by dulyebr; 03-28-2009 at 02:24 PM.
Originally Posted by dulyebr
The only thing I can say about the 1st half of your post is that I had SERIOUS difficulties trying to get the bearings back into the main pivot on my Ti Motolite. INSANELY tight tolerances. I ended up sending the frame off to RedBarn to have Chad finish it up.
On the rear end knocking: I had the same thing and it was indeed the CS-ST pivot. I took it apart, cleaned, lubed, reassembled, torqued, and no more knock. Could be that you just need to retorque it or maybe you have a bushing that's going south. But I highly doubt your knock has anything to do with the main pivot...
Good luck man...
Originally Posted by simplton
Yea, just somewhat paranoid. Was difficult seeing the frame being potentally wrecked by my own hands like that.
I did re-torque everything. The bushings are brand new as I recently replaced the seat-stays with the carbon version. Titus included new bushings and bushing axles in the new stays. I have an extra set of bushing hardware, so I'll just start with the easier stuff and go from there. I wish I'd done the push/pull-wheel-test before making the changes yesterday.
I also replaced my 2005 XT crank bearing cups with spankin' new 2007 XTR cups. I'm really keen to see how much of a performance increase there is. I would have to imagine given how thrashed my rocker bearings were I'll notice some meaningful improvement.
Dude, sounds like you've done to your ML what I've wanted to for a long time... New rear end, new rockers, etc... Did you also get the hydroformed chain stays? Please report back with your impressions on the upgrade.
just got back from the garage. So it appears that the clunk is fixed (knock wood).
I noticed that the pivot in question (non-driveside horst) slid away from the chainstays much easier than the driveside. I also noticed that where all the other plastic bushings were scuffed and dirty, one wasn't. I tapped out the clean one, and replaced it with an extra bushing I had. Greased it up and went to screw it back together, but same thing -- the clevis interface slid together too easily. I was thinking I may have an out of spec seatstay. I went ahead and replaced the other (inside) non-driveside bushing and this time it was definitely more snug when I inserted the seatstay. It was not quite as tight as the other one, but it was tight. Went ahead put everything back together; gave the rear wheel the push/pull test, and this time she was solid as a tank -- no clunk or pop. Nice!
I actually have the old "free-ride" lowers from before, which I think I prefer to the newer lighter ones. My orignials were the ultra narrow chainstays that could barely fit a 2.1. I took Chris's offer way back to replace it at cost, and then took the extra effort to have it anodized. I was worried about breaking my aluminum seatstays as it seemed to be a design flaw. I found a bro-deal on the carbon stays and took it. After inspecting the original seatstays I could feel a crack right at the weld, where they always break. The carbon stays are *really* sweet; no regrets at all.
yea, I'll report back after I have a ride. One thing I've noticed lately is that I have a hard time keeping the rear tire from locking up and skidding while I'm braking. I'm wondering if this could be from the frozen bearings not allowing for the suspension to be fully active.
Last edited by dulyebr; 03-27-2009 at 06:15 PM.
Today was the 1st chance I've had to ride the MotoLite since I replaced the bearings. I noticed the suspension was smoother through its travel. It was not a big difference, but it was there. The biggest benefit was that the bike had better traction while braking, i.e. it was harder to accidently skid the rear tire.
My XT cranks (previous generation) felt really smooth and friction-free from the new XTR bearing cups. Anyone know if the XTR bearings are better than the XT? I know the replacement XTR cups are more expensive, but that doesn't mean much.
Overall, I'm really glad I made the effort to change the bearings out. The MotoLite is a fine riding machine, and now my old 2005 is riding like new; hell, better than new...