Wobble part II - now in turns

[JPaganel]

So, after installing the RPM brace and replacing rear bearings my straight line wobble at some speeds has disappeared.

Now, however, I have a pretty consistent wobble in low speed (30 mph and under) turns. The fork bearings seem solid, I can't detect any wiggle.

Tire pressure? Tire wear? Something else?

[FJ_Hooligan]

Do you have too much preload on the steering head bearings?

[Pat Conlon]

Tire pressure? Tire wear? Something else?

Both Possible, especially with a cupped front tire.

Hooligan has a good point. With the front tire up in the air, take your top triple off and check the torque on the steering neck bearings. Too tight is not good.

Check your front wheel bearings. You already did your back bearings, so chances are your front also needs replacement.

Also, check your rear wheel alignment.

[andyoutandabout]

Everytime my front end has felt funny, it's been cured with new rubber.
(snigger)

[JPaganel]

Both Possible, especially with a cupped front tire.

Tire is less than a month old. Don't think it can get cupped in that short of a time.

Hooligan has a good point. With the front tire up in the air, take your top triple off and check the torque on the steering neck bearings. Too tight is not good.

Haven't tried that. However, I have tried to move and wiggle the fork and wheel, everything is smooth, with no detectable looseness.

Check your front wheel bearings. You already did your back bearings, so chances are your front also needs replacement.

I checked when I put the tire on. Smooth, seals in place, no detectable wiggle.

Also, check your rear wheel alignment.

When I put the wheel back on after doing the bearings I used a marked piece of wire to set the adjuster bolts the same. Do I need to do something different?

[Pat Conlon]

From Home Depot I bought 2 pieces of 3/4 x 3/4 tube steel, 8' long. I attach one end of the tubes with squeeze clamps on each side of the lower face of my back tire, now with at the front wheel pointed straight, the tubes extend forward along the face of the front wheel, you can easily see and measure the offset angle of the rear wheel in relation to the front. Adjust the rear tire accordingly so that the front wheel left side and right side measurements (measured distance between the front rim and steel tubes) are the same.

You can do it with string or wire but I like the straight steel tubes better.

Do the flop test on your neck bearings. With the front tire off the ground, center your handlebars. Now give the bars a very slight push to one side or another, the forks should easily fall to the side (either side) with a small bounce when the bottom triple contacts the steering stop.
To get the proper torque to the steering stem nuts is tricky, you need a special tool on your torque wrench to set it according to the workshop manual. What I do is hand tighten the first nut (base nut) snug, then tighten by turning the nut (only) 1/4 turn using a hammer and dowel, gently tapping the nut to rotate it.
Be careful when you tighten the backup nut (lock nut) so that you don't further tighten the base nut.

Cheers. Pat

[ribbert]

From Home Depot I bought 2 pieces of 3/4 x 3/4 tube steel, 8' long. I attach one end of the tubes with squeeze clamps on each side of the lower face of my back tire, now with at the front wheel pointed straight, the tubes extend forward along the face of the front wheel, you can easily see and measure the offset angle of the rear wheel in relation to the front. Adjust the rear tire accordingly so that the front wheel left side and right side measurements (measured distance between the front rim and steel tubes) are the same.

Cheers. Pat

Pat, I take it you do, but didn't mention, the measurements need to be the same at the front AND the back of the front wheel.

Noel

[Pat Conlon]

Yes, thank you Noel, you are correct.

[JPaganel]

Tire pressure it was. The new tire was 15 psi low. Gr.

The valve stem looks a little suspect. I'm thinking when I got the new tire put on they didn't replace it.

[andyb]

Or they did what I did the last time I changed a tire....

Turns out using a small phillips screwdriver to just compress the valve and let air out normally works well, but you can fractionally tweak it a pinch and once it's bent it'll never hold air properly.  $2 worth of the proper tool and stole the stem from my old 16" FJ rear wheel. 

[fintip]

I was going to say tire pressure, I'm using a NOS front tire at the moment that I got for free that slowly loses air pressure--a month after installation, started getting a wobble. Assumed for a week that it was my declining rear tire. Turns out my front tire was sloooooowly going flat. Didn't realize until it was ridiculous. Aired up, fine again.

One of those face palm moments. Had to experience it once to know, but now I'll know forever, probably.