Steering stem removal and replacement

[seinwave]

Hi all!

With the warmer weather and a little more riding, the smokification of my oil mentioned in a previous post has calmed down enough to be kicked down the road to winter.

Now I have a new problem: the front end seems to be getting mighty squirrelly, and I swear it's due to some notchiness.

I'm going to do some more diagnostics, but I think that the 1200 mile road trip I did a month ago finally did in the (potentially four decade old) steering bearings. I'm preparing for that medium-sized job; this thread will be a series of questions I come across in the process of preparation.

The first one - can I remove the *upper* bearing and bearing races with a bicycle-style puller (the kind that looks like Elmer Fudd's gun after he's tried to fire it with a carrot in the muzzle)? It seems the lower bearing and faces come out with a reasonably gentle application of a mallet on a length of pipe or similar, and J really don't think I can stomach $200 for a single purpose tool I will hopefully only use once or twice per bike.

The second one - are there any special tools it's worth buying for this job?

I'll probably ask for confirmation of what bearings I'm looking for once I get to that stage.

[salty_monk]

Yes is the answer to that question... you just need the right size. There was a guy on here making the tool at one point but I don't know what happened to him.

[Rob S.]

Your wobble might be caused by swing arm bearings (or bushings).

[seinwave]

I'm fairly sure I've isolated the problem to the front (less sure about yet pessimisticly leaning towards specifically the steering bearings), but I'll give the rear a shake before I jack the front up.

[KiwiAlfa156]

What model bike is it? What condition are the tires?

[dgates1]

There was a recent thread where someone changed fork oil and forgot to tighten the drain screw.. so lost all the oil in one fork. He was reporting wobbling about 25-30 mph. Might be worth a look to check your fork oil levels.

[seinwave]

I'll know pretty soon if that's the case, but I doubt it. This is a worsening of symptoms that have been at the "barely noticeable" level up until recently. Or maybe I just have a higher standard after putting a few thousand miles into the bike and getting over the euphoria of it not exploding.

It'd be really nice if one fork was just lower on oil than the other though.

I might as well *describe* what the symptoms are. Diagnosis is conjecture until I get the bike jacked up.

- Feels like the front "jumps" or "bump steers" a little at low speed, especially over rougher terrain (gravel, anything with bumps). When I paid a little more attention, it feels like the little micro movements you make to steer in these cases are moving the front around as normal
.. until it finds a notch (roughly in the same place every time) and takes more force to get out of it.
- When coming to a stop, the front seems to tuck a little to the left at the last moment (hard to distinguish from front brake action, or the shaftiness of the bike, but it does feel like it's coming "from" the handlebars).
- Taking turns at speed, it feels like the bike - or specifically the handlebars - "want to" turn more into the turn than I'm used to; it feels like I have to press a little against the direction they want to go to hold an angle, rather than just holding them where I want. This might just be in my head, but it does feel like there's a place the steering "wants to go" beyond where I'm putting it (also notchlike behavior) on either side.

I had previously noticed a less-well-defined looseness in handling. The lower pinch bolts turned out to be loose, and tightening them to spec felt like it rectified the problem. These issues were slight enough that I can't say if they were along the same lines of my current problems.

The above symptoms do make me think the bearings could be replaced. There's other possible causes: the tires reaching their useful lifespan, the fork tubes getting a little twisted, something up with the front brakes, and the fork oil thing. But it's the steering bearings that would be the most difficult and novel to rectify. Everything else I've either done before or have the tools and knowledge to learn how.

[KiwiAlfa156]

Well, replacing the bearings won't hurt anything and if it is them you've solved your problems and if not you will have eliminated a suspect. It may just need retensioning. Tapered roller bearings are pretty robust -unless the grease is gone and then corrosion pitting can ruin them.

You asked about special tools worth buying, I have one of these for setting the steering stem torque. When (from memory) you fit the new bearings you torque up the stem, rock it back and forth to seat them then back off the stem a ¼ turn. The procedure is in the manual.

[Grimly]

Steering bearings are a consumable. Replace them.

[seinwave]

tldr: Checked. Didn't see the classical signs of worn bearings (though some concerning quirks did emerge). Even though the front-end adjustment appeared to be precisely correct, I ran back through it and seemed to alleviate symptoms. Still ordered what I need to change the bearing.

I finally found a piece of wood in the alley to use as a lift chock and got the front end in the air today. Try as I might to yank the forks around, I found none of the linear slop I've been told indicates bad bearings. I also couldn't find a single hint of notchiness. It also appeared that the bearing torque was perfectly set - a little push to either end sent the forks falling to the stop but not bouncing off of it.

Finding the wood has been a big enough chore that I figured I should make the most of the airtime. I loosened the lower pinch bolts and the top nut, and once I created a suitable tool* I played with the steering bearing torque. I noticed that while I could easily get the adjustment right with the pinchbolts loosened, tightening them back up would throw it off (usually to the loose side). In the end I think the adjustment ended up ever so slightly looser than previous - there is still a near-imperceptible bump off the stops when you let the handlebars "fall", but I feel like I'm pretty close to maximally-tight and I'd be loathe to force any more tightness into the nut.

I got it out for a road test and found things vastly improved. At first I thought the bike was now pulling the front to the *right* when stopping, but I quickly realized that was me still correcting for the fall to the left. I also thought there might be an extremely slight 'weave' under ~30 mph, but when I went looking for it I couldn't find. If it is there, it'd indicate I'm still a little tight on the adjustment.

Even though things are alright for now, I'm still a little suspicious of the bearings. This was a pretty sudden and extreme worsening of symptoms, and if it were normal falling-out-of-adjustment I'd expect to have shaken itself too loose, not somehow ended up too tight. I ordered what I'll need for the bearings, and if I have some downtime I'll make an afternoon of it.

* To enlighten those who follow in my footsteps: the preload wrench provided with Hagon's single-damping-adjustable shocks fits perfectly into the steering stem slotted nut with a little bit of careful filing on the outermost edge - and is still snug enough in the shocks to adjust preload with.

[salty_monk]

Did you inspect the bearings? When you loosened it off & messed with it & then tightened you may well have moved the bearing relative to the race so now you're on a "fresh" bit (because the bearing doesn't fully rotate).
My guess is your bearing is rusty or breaking down.

[seinwave]

That's what I meant - I suspect that while they're not totally shot, they're entering the right-hand side of the bathtub curve, where they degrade in strange and unpredictable ways.

I don't see much point in inspecting the bearings since it seems getting to the inspection point is about 75% of the bother of just replacing them.

[first timer]

You can also replace the steering stem bearing with tapered bearings if they are not already, the taper bearings will really clean up steering input if you were running ball bearings.