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Wobble part II - now in turns

Started by JPaganel, July 21, 2013, 09:42:37 AM

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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?
1993 FJ1200 ABS

1984 FJ600, up on blocks

1986 FJ1200, flaming wreck, repaired and sold
1986 FJ1200, repaired, ridden, sold


I don't want a pickle
I just want to ride my motorcicle

FJ_Hooligan

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

Pat Conlon

Quote from: JPaganel on July 21, 2013, 09:42:37 AM
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.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

andyoutandabout

Everytime my front end has felt funny, it's been cured with new rubber.
(snigger)
life without a bike is just life

JPaganel

Quote from: Pat Conlon on July 21, 2013, 11:57:31 AM
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.

Quote from: Pat Conlon on July 21, 2013, 11:57:31 AM
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.

Quote from: Pat Conlon on July 21, 2013, 11:57:31 AM
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.

Quote from: Pat Conlon on July 21, 2013, 11:57:31 AM
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?
1993 FJ1200 ABS

1984 FJ600, up on blocks

1986 FJ1200, flaming wreck, repaired and sold
1986 FJ1200, repaired, ridden, sold


I don't want a pickle
I just want to ride my motorcicle

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
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

ribbert

Quote from: Pat Conlon on July 21, 2013, 03:00:00 PM
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
"Tell a wise man something he doesn't know and he'll thank you, tell a fool something he doesn't know and he'll abuse you"

Pat Conlon

Yes, thank you Noel, you are correct.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

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.
1993 FJ1200 ABS

1984 FJ600, up on blocks

1986 FJ1200, flaming wreck, repaired and sold
1986 FJ1200, repaired, ridden, sold


I don't want a pickle
I just want to ride my motorcicle

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.
fjowners.wikidot.com

Not everyone understands what a completely rational process this maintenance of a motorcycle is. They think it's some kind of a knack or some kind of affinity for machines in operation. They are right, but the knack is almost purely a process of reason.
-ZAMM

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