Violent wobble in front end (updated)

[macmac]

Cj, I really doubt you really fixed the problem, but have reduced it to nil.. By snugging the bearings you removed the ability for harmonics to get started.

That is almost as good as a real fix. I think the problem is trail. I know that is a problem on crotch rockets and due to trail being too steep, and where tank slappers happen while a rider has both hands on the bars.

Usually the harmonics are set up by slowing down.

A tire rolling seems to be one thing, but if you mark a spot on a tire the rollong becomes more like 'm', as each spot appears to be different then.

This has been a on going problem since motorcycle.

[kudzufarmer]

Originally Posted by cactusjack

I seriously doubt this condition is brake-related at all. If it only happened when the front or rear brakes were applied, then perhaps. It's either the steering head bearings or possibly an out of round or unbalanced tire or wheel. FWIW, I had the problem with both lead balance weights and dyna beads, made no difference. I'd put a new tire on the front, and the problem would disappear for awhile, then come right back. The only thing that eliminated the problem completely was adjusting the steering head bearings.

I fought this problem for over 30,000 miles.

thanks Scott....I guess I will break down at some point and actually pull the front end completly off the bike and put in new bearings since it will be out anyway...I will just have to psych myself up to do it. jus didn't want to go that far by myself....in the meantime I will keep my hands on the bars while slowing down...appreciate the help...thank you too MAC and everyone else who has offered suggestions or Ideas.....that is one thing I like about a forum like this

[blowndodge]

Mac, I thought trail was the horizontal distance from where the steering axis (straight line running down the forks) intersects the ground to where the front wheel (tire) actually touches the ground?

On a Nomad this is rather large distance? this would promote slower steering but more stability and resistance to wobbles than a shorter distance or less trail?

Nomad's have 32 degrees of rake and about 6" of trail. This dimension would equate to a better handling (at high speed) than a rice rocket with 23 degrees of rake and 2.5" of trail that most of them have??

Your trying to confuse BD right? ;)

[kudzufarmer]

For information.....this is the direct wording from the pdf version of the 1600 nomad manual that is on the Kawanow sight.

page 14- 13 of the PDF

Tighten the stem nut to 78 N·m (8.0 kgf·m, 58 ft·lb) of
torque. (To tighten the steering stem nut to the specified
torque, hook the wrench on the stem nut, and pull the
wrench at the hole by 440 N (45.0 kg, 99 lb) force in the
direction shown.)

the 43 inch lbs seems to be reffering to the cap on top of the steering stem rather than the bearing nut

[macmac]

BD , Naw you on track, but never the less this wobble has gotta come from a harmonic, and added to by engine vibs, shakin the frame, plus the rear suspention, the ft suspention and is enacted on slowing down with no human damper.

Don't expect me to get it right, when for 100 years many engineers can't get it right.

I don't know which vib is setting this up, so I consider them all having a part.

The way I see it this doe not happen with a locked throttle, and it happens less with properly snugged up bearings which become dampers.

I have no idea which change should be made, but it isn't likey you or I could come up with that change.

I see no way we can change these angles in any meaningful way. We could add on a raked triple tree maybe, but that is almost never a good idea, even on would be choppers.

It is a Nomad problem, or it wouldn't be typical for about all of us..

[macmac]

Originally Posted by kudzufarmer

For information.....this is the direct wording from the pdf version of the 1600 nomad manual that is on the Kawanow sight.

Tighten the stem nut to 78 N·m (8.0 kgf·m, 58 ft·lb) of
torque. (To tighten the steering stem nut to the specified
torque, hook the wrench on the stem nut, and pull the
wrench at the hole by 440 N (45.0 kg, 99 lb) force in the
direction shown.)

Geeze.... None of that matches my book.

Page 14-3

Item 5 Steering stem head nut N-m 88 kgf-m 9.0 ft-lb 65
(this is the one you can see top most and hexagon)

Item 6 Steering stem nut N-m 4.9 kgf-m 0.05 43 INCH Pounds
(This one is the 4 slot nut under the one you can see and this is total schlock.)

Your settings are way too tight, my book is way too loose...

[blowndodge]

When in doubt "CHOOSE TIGHT!"

[macmac]

NO! "the 43 inch lbs seems to be reffering to the cap on top of the steering stem rather than the bearing nut."

The top Item 5 Steering stem head nut should be tighter than the 4 slot, but that 4 slot is not at any 43 inch pounds or 58 ft·lb either.

AND AND AND the 99 foot pounds again is another error.... way too tight.

[macmac]

OK BD if you say so, but at 58 foot pounds he better be going dead straight most of the time or leaning as counter steer isn't gonna happen...

That might work in Cali, but I doubt it will in Tn...Ky or where ever kudzu grows in the USA.

That boy's got some wicked tight curves in his roads as my best guess..

Ya know that road outta Yosemiti to oakhurst, but way up high? Well about every single road he has is like that one.

[kudzufarmer]

Originally Posted by macmac

NO! "the 43 inch lbs seems to be reffering to the cap on top of the steering stem rather than the bearing nut."

The top Item 5 Steering stem head nut should be tighter than the 4 slot, but that 4 slot is not at any 43 inch pounds or 58 ft·lb either.

AND AND AND the 99 foot pounds again is another error.... way too tight.

I don't know so i trust your judgement MAC, but I think the 99 foot pounds is the force on the handle of the bearing nut wrench rather than the torque on the nut.....i

[kudzufarmer]

here is the wording on page 2-30 on adjusting steering...if the steering is adjusted so that the wheel holds steady at any point in the turn arc.....is it too tight?


Steering System
Steering Play Inspection •Check steering as follows.

Use the jack [A], the attachment jack [B] under the frame
pipe ribs [C], and a commercially available jack [D] under
the engine [E] to lift the front wheel [F] OFF the ground
until the rear wheel [G] touches the ground.

Special Tools - Jack: 57001-1238
Attachment Jack: 57001-1398

With the front wheel pointing straight ahead, alternately
tap each end of the handlebar. The front wheel should
swing fully right and left from the force of gravity until the
fork hits the stop.
If the wheel binds or catches before the stop, the steering
is too tight.

[macmac]

The force on the handle is equal to the other end.. Unless the wrench is a lot longer than I think it is... I expect that wrench is no longer than about 8 inches long..

If it is 2 feet long well you get some gain in leverage.. I have never seen a spanner hook wrench much longer than 8 inches... For that matter I haven't seen one with a 1/2 square drive either.

The top nut I agree with at 65 ft lbs, but no way do I agree with 43 inch pounds, or any 58 foot pounds...

Somewhere between 18 ft lbs and 28 ft lbs is about right for the slotted nut... And at that it is a matter of some judgement. In that case i wouldn't use a torque wrench a bit, not unless I could determine the stretch or crush, in this case pre load by other means.

And you can. You can custom pre load this easy, a little too tight is ok to a point, it will make the steering sluggish. too loose and you get the wobbles..

With that ft end off the ground, you can knock it around and tighten more to knock it around more a few times till you have it as sluggish as you like.

The idea iis to take up all the slack, and still be able to push the bars over with a fair amount of ease.. And so it will return as the bike comes back up to be straight.

Somehow I don't think you will want to pull the bars to get back up straight.

[Yellow Jacket]

Originally Posted by kudzufarmer

For information.....this is the direct wording from the pdf version of the 1600 nomad manual that is on the Kawanow sight.

page 14- 13 of the PDF

Tighten the stem nut to 78 N·m (8.0 kgf·m, 58 ft·lb) of
torque. (To tighten the steering stem nut to the specified
torque, hook the wrench on the stem nut, and pull the
wrench at the hole by 440 N (45.0 kg, 99 lb) force in the
direction shown.)

the 43 inch lbs seems to be reffering to the cap on top of the steering stem rather than the bearing nut

Page 14-13 is giving the procedure for installing new races and bearings. The procedure actually reads as follows:

Settle the bearings in place as follows:
Tighten the stem nut to 78 N·m (8.0 kgf·m, 58 ft·lb) of
torque. (To tighten the steering stem nut to the specified
torque, hook the wrench on the stem nut, and pull the
wrench at the hole by 440 N (45.0 kg, 99 lb) force in the
direction shown.)

The procedure continues on page 14-14 as follows:

Check that there is no play and the steering stem turns smoothly without rattles. If not, the steering stem bearings may be damaged.
Remove the stem nut.
Install the O-rings and adjust the steering (see Steering Play Adjustment in the Periodic Maintenance chapter.)
Torque - Steering Stem Nut: 4.9 N-m (0.50 kgf-m, 43 in-lb)

As the procedure states, the 58 ft-lb is to settle the new races and bearings (take up any slack). The 43 in-lb is the final torque setting for the stem nut.

This is the setting that most of us think is way too little.

[macmac]

I have that same page atleast... It says the 65 ft lbs i agree with at the hex top nut...

It is WRONG lower on the page giving 43 inch pounds...

It is right about the touch mostly... You want the forks free enough to return with out pulling...

We are a post apart here, as i was talkin' from what I know above and just confirmed what the book says here... I wasn't in the book in section 2 and had no idea that was there...

[kudzufarmer]

Originally Posted by Yellow Jacket

Page 14-13 is giving the procedure for installing new races and bearings. The procedure actually reads as follows:

Settle the bearings in place as follows:
Tighten the stem nut to 78 N·m (8.0 kgf·m, 58 ft·lb) of
torque. (To tighten the steering stem nut to the specified
torque, hook the wrench on the stem nut, and pull the
wrench at the hole by 440 N (45.0 kg, 99 lb) force in the
direction shown.)

The procedure continues on page 14-14 as follows:

Check that there is no play and the steering stem turns smoothly without rattles. If not, the steering stem bearings may be damaged.
Remove the stem nut.
Install the O-rings and adjust the steering (see Steering Play Adjustment in the Periodic Maintenance chapter.)
Torque - Steering Stem Nut: 4.9 N-m (0.50 kgf-m, 43 in-lb)

As the procedure states, the 58 ft-lb is to settle the new races and bearings (take up any slack). The 43 in-lb is the final torque setting for the stem nut.

This is the setting that most of us think is way too little.

OK thanks...I am just trying to understand it