Strange Steering After Head Bearing Change! WTF????

[SilentG]

Hi guys n gals

Today I had my steering head bearings changed. I didn't get them fitted by a proper bike garage but by a friend of a friend who is a qualified bike mechanic.
Anyway, I bought the bearings myself, tapered (pyramid parts ones) correct size etc. So after going and picking my baby up, the guy asked me to take it for a spin to see if I thought it felt ok. Tootled off down the road and virtually as soon as I set off there was a weird swaying in the steering going off.
Might sound a bit odd but it was like something was off balance. As I am no mechanic I don't really know the technical term for it but it didn't do it prior to having the bearings done. By the way the old bearings were really f**ked, one ball bearing had totally disintegrated on the top race.
Quick u-turn and went back to the mechanic. He seemed a little befuddled of the problem but endeavoured to check all the bolts, nuts etc, which were all tight. Took it for another little spin to see if that was any better and to no avail... same as before, no better no worse so I took it back.
This time he looked at the position of the stancions, which obviously had to be the same either side, me noticed that one was ever so slightly higher than the other. The grooves on each one that are about 2mm off the top are apparently supposed to be lined up to the yoke top. He altered one of them but stil to me seems a fraction off kilter. So off I popped once again for a test run.
Same as before, it is really noticable when doing upto 40mph, which on UK roads is pretty much all you are allowed to do. Anything over 40mph is less noticable.
I took it back once again and he said its possible because they are new bearings and may need bedding in and if they are no better to come back later on in the week.

Right, ramble over. Has anyone got any ideas of what could be causing this weird swaying of the steering? Or is the fraction between both stancions to blame or could it be purely the bearings that need bedding in?

This is really doing my head in, with only one days riding under my belt since having them done my arms are killing with having to compensate the sway which is also making me NOT enjoy riding... seriously I can't be doing with this as its putting me off.

There must be someone who can shed light on this predicament :/

Thanks for reading guys n gals

 

[OneTrack]

Well, my 1st piece of advice is PARK THE BIKE. Don't ride it until you get it sorted.
Regardless of what you say that your friend is a "qualified bike mechanic", I'd get it to a proper bike shop and let them check it over....It sounds to me like there's something really, really wrong with the front end.

 

[wrlomas]

Ditto, park it and figure it out.

 

[Erci]

There really can only be 2 issues with head bearings from *feel* perspective:

1. Bearing play. The easy way to check this is to have a friend straddle the bike and just stand over it, to prevent it from tipping over. Now approach the bike from the front, grab the handlebar using underhand grip, squeeze the brake lever with your right thumb and give it a good pull towards yourself...you can do this few times in a row. There should be no play.

2. (I am guessing this is the issue) The bearings are too tight. If you straddle the bike and turn the bar lock to lock, does it turn smoothly and very freely? If there's any *drag* bearings are either overtightened or are not seated properly and the bike will definitely not ride right.

 

[Wolfman]

2. (I am guessing this is the issue) The bearings are too tight. If you straddle the bike and turn the bar lock to lock, does it turn smoothly and very freely? If there's any *drag* bearings are either overtightened or are not seated properly and the bike will definitely not ride right.

My thoughts as well....

:thumbup:

 

[SilentG]

i dont suppose any of you guys know of a website or something that i can find out the sizes for the bearings to my bike. i went to see the mechanic again and he said its possible i was sent the wrong parts. fishy but hey, its been known to happen.

 

[jtarkany]

1. park it
2. check it as Erci suggested
3. Bottom Bearing Part#: 93399-99932-00 : Top Bearing Part#: 93399-99931-00 (Refer to parts catalog here for Part numbers and diagrams: My Yamaha Prompt - Parts Catalog)
4. Stearing Head Bearing Installation Process:
- Clean all parts thouroughly and pack your bearings
- Slide your bottom steering seal down over the bottom race, it should be sitting on top of the bottom triple
- Slip your bottom bearing onto the bottom race (be sure it is not upside down)
- Install your bottom triple and steering tube with the bearing and dust cover onto your frame
- Slide the small washer plate into place
- Slip your top bearing into place (again be sure it is not upside down)
- Slide your top race into place
- Put the ball race cover into place
- Next in order: Nut, Washer Plate, Nut, Special Washer (2 tabs hanging down)
- Torque the whole assembly down to 52 ft/lbs (to seat the bearings)
- Back the nuts off and re-torque to 13 ft/lbs
- Install the top clamp
- Install the top clamp washer plate
- Put on the crown nut and torque to 80 ft/lbs
- Install your fork tubes and be sure that they are even on both sides (Don't eyeball it, measure it)
- Check the play again as Erci suggested

You should be good to go. If not, take it to an authorized Yamaha Mechanic. Good Luck :thumbup:

 

[SilentG]

thanks for the run down. the parts number in particular is puzzling me slightly. the bearings i received do not have a code on them, they just have the sizes of the bearings ie 30x55x17 that kind of thing (not sure of the exact size as the box has been left at the mechanics)

 

[jtarkany]

thanks for the run down. the parts number in particular is puzzling me slightly. the bearings i received do not have a code on them, they just have the sizes of the bearings ie 30x55x17 that kind of thing (not sure of the exact size as the box has been left at the mechanics)

Sorry, I don't know the sizes, however, if you contact a Yamaha Service Department they might be able to give you some insight.

 

[FuriousGeorge]

My bet would also be that they are a little too tight. My bearings were getting loose on my old Suzuki so I relubed and tightened them. I got them just a little too tight. The bike was just spooky trying to ride it in a straight line. It would feel like it was rapidly going back and forth instead of straight. Loosened them up just a little bit and everything was back to normal.