Steering Issue -- Opinions please

jodog

jodog

Joined
Jan 27, 2012
Messages
590
Location
Minnesota
Bike
2012 ST 1300
2025 Miles
008700
I have a bridgestone BT45 rear tire mounted on the front. I am not seeking an opinion of whether I will die in a fiery crash as a result. These tires last a LONG time and usually before the tread wears down the cupping becomes so bad that the handling is for crap. This usually occurs at 26-28K miles.

On a recent long trip the front tended to want to go into a tank slapper whenever I took both hands off the bars. Normally the BT45 is very stable at any speed. My assumption (yeah, I know) was that the cupping had reached it's critical point and it was time to tire swap. As I was removing the tire I noticed a flat spot in the steering at "dead center" or straight ahead. Moving the tire right or left slightly and the tire would return to it's straight on position.

I used to have this issue on bicycles and it required new bearings and races to correct. I've never had head bearings fail or behave badly on an ST before so I am in unfamiliar territory.

My question is whether this is normal, whether it can create the tank slapper phenomenon, or is it just a tire issue? Opinions?

MoBob
 
Regardless a fork that self-centers at rest indicates bearing replacement. It’s been loose long enough the balls or rollers have hammered dents in the races.

You didn’t say what speed or if acceleration /deceleration is happening when it starts.
 
dduelin said:
Regardless a fork that self-centers at rest indicates bearing replacement. It’s been loose long enough the balls or rollers have hammered dents in the races.

You didn’t say what speed or if acceleration /deceleration is happening when it starts.
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I don't notice it at slow speeds. Doesn't happen all the time, but did seem worse the worse the road surface. Accel/decel don't seem to matter.
 
When my steering bearings needed replacement I didn’t notice any problem that couldn’t be explained without common deceleration hands-off wobble due to worn or cupped tire. When I removed the wheel for that that’s when I noticed the fork self centering. The mass of the wheel masked it until then. When exposed, the races clearly showed dents where the balls rested against the races in straight ahead orientation where it spends most of time going down the road. The bike had 96,000 miles so it wasn’t unexpected. The OEM bearings are caged balls, I replaced with tapered roller bearings, still good 85,000 miles later.
 
dduelin said:
When my steering bearings needed replacement I didn’t notice any problem that couldn’t be explained without common deceleration hands-off wobble due to worn or cupped tire. When I removed the wheel for that that’s when I noticed the fork self centering. The mass of the wheel masked it until then. When exposed, the races clearly showed dents where the balls rested against the races in straight ahead orientation where it spends most of time going down the road. The bike had 96,000 miles so it wasn’t unexpected. The OEM bearings are caged balls, I replaced with tapered roller bearings, still good 85,000 miles later.
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Where did you source the bearings. Do you have a part number.
 
I’ve done the bearings in each ST…not hard to do (just time consuming) with the proper tools. I bought the Motion pro race remover that worked well and was able to partially press in (and finish by tapping in with a hammer) the races. According to the Mike Martin pages, torque them to 20 ft-lbs, then loosen, then hand tighten to just past hand tight, and that setting has worked well for me. It’s All Balls # 22-1020 and they sell them on eBay (allballsracing.com has them as out of stock right now, but I’m sure someone has a set for purchase online). Those and a new set of tires will likely make the bike feel like new.
 
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