1992 Low Speed Steering Wobble

[jgotko]

Guys - Was going about 25mph and went over a small bump and front end began to wobble. What could be possible cause? I verified everything is tight.

I tried to check the air in the Forks and read nothing. I think the air fill valve is no good as I didn't get any air out when trying to exhaust and could get any air in when trying to fill. :bang head:

Could no air or low air in the forks cause this? With the bike on center stand I can physically compress the forks about 4" with a good push. Is this normal. I go at about 180lbs. My manual says standard 5.7psi (0.39 Bar) / Maximum 14psi (0.96 Bar). I ride alone, what is a good/proper air pressure? What are they refering to in the book as "Bar"?

:ummm: Thanks...J

 

[clintard]

sounds like your fork seals are completely shot and not holding air whatsoever. As for the wobble it could be a bad steering head bearing or low front tire pressure. i dont think bad fork seals would cause low speed wobble but what do i know

Set your bike up on the centerstand and let the bars fall to one side and then the other. I will bet that the steering head bearings are too loose as has been said already.

The bars should take a slight push to start movement and then should fall and stop on the bottom. If they bounce (or if they won't stay halfway down when setting them there) the bearings are too loose.

It's a very common problem as many don't know how to set the right. Too tight and you won't be able to keep going in a straight line without constantly correcting the steering. Too loost and you can't take your hands off.

Sean Morley

 

[jgotko]

Thanks Clintard - You think I can pull/screw the air stem valve off the fork for further inspection? My 92 has one fill point for both forks. It looks like it may just screw in/out. If fork seals were bad would there be some oil coming out somewhere? I'll check steering head bearings when I get home from work...J

 

[shawn kloker]

The air could be leaking out of the orings in the piece that has the shrader valve on it.There are 2 in each side.Could even be the valve itself.If you are not seeing fork oil the seals are probably ok.As long as there is oil in them?Should be changed every year or 2 anyway.

I run no air with racetech 1.0 rate springs,20 wt. oil,2 inch lowering blocks.Thicker oil slows the forks down.Less diving and climbing.

Sounds to me like your bearings are in bad shape.Must really be loose to wobble at that low of a speed.I would watch out for a tank slapper at high speed with this bike.I recommend taking the front end off and inspecting the bearings and races.At the very least they need greased,at the worst they need replaced.Watch for the races to look stop signed instead of round.

The front end will weave if too tight not wobble at low speed.I prefer to have mine adjusted right to where it starts to weave then back off a shade and lock it down.I can live with a slight weave way more than a tank slapper at 130 plus.

 

[jgotko]

Thanks Guys - Here is what I found.

Air Valve - Functioning properly, o-ring(s) look good/ok. Not sure why there was no air? When finished with the bearings I will refill to 5.7psi. May have to address this issue later.

Bearings - When moving bars left to right I feel no roughness or dents/chops. Bearings feel very-very smooth w/no grinding. I grabbed the forks and lifted up to see if there was any play up or down in bearings; there was none.

Bars Free Play - Basically bars are slamming on the hard stops left to right. If I move bars 1/2 way right or left, and let go, they fall fast & hard.

What do you think? I might as well do the FURBUR fix now that I'm going to have to tighten up the bearings. Anything I should make sure to do (or don't do) that may not be outlined in the manual?.....Thanks....J

 

[jgotko]

[Bump]

I have the steering assembly apart. Bearings are somewhat dry but look good & function well. I will repack with new grease.

:ummm: In my manual there are two (2) torques settings listed for the Steering head bearing adjuster nut. "Initial Setting" = 50 Nm / "Final Setting" = 3 Nm ---WTF HOMER!

Is the "Inital" 50 Nm the Bearing the Adjuster Nut itself and is Final refering to the locknut? Someone please expalin as I have missed the boat.

Does anyone think that a "Good" tool store would sell a C-Spanner with a 1/2 socket driver on it in lieu of purchasing Yamaha's special service tool to properly torque down the adjuster nut?

Thank You....J

 

[jgotko]

OK Then... Still talking to myself......Ummm....Yea....Well....

I figured out the crap I needed to figure out. Sometimes it is easier to ask if there is someone available. However, you learn much more by just diving in and getting it taken care of. Even learned to use a Torque wrench as I had never used one before. Tightened all steering to specified torques. Changed the fork(s) oil. Pressured forks according to manual.

Stability has improved and I can actually feel the front forks working now. I didn't even realize how much the bike was diving until I fixed it. What a diffrence just a couple of psi's can make. (wow) Forks are holding air. No low speed wobble.

ON TO THE NEXT PROJECT!!!! - LOL -

http://www.youtube.com/watch?v=EEle4A58gHw

Seriously, I need some new mirrors...

 

[clintard]

glad to hear u got it worked out

did u find out why the forks werent holding air? u said they are now so did u change the seals or was it something else

peace

 

[jgotko]

Nice to here from you Clintard,

When I drained the forks one ran clear and one ran dark. The guy I bought the bike from told me he had replaced one of the seals. This would make sense based on the color of the oil that came out. Not sure why someone would replace one (1) seal and not just do both while you were at it.(??) Anyway, all I can assume at this point was when the guy replaced the seal he never repressured the forks. I will give it a couple of days and check the pressure again to make sure I don't have a slow leak.

Take Care....Great weather this weekend for riding. :rocket bike:
Hope you (all) got to enjoy it....Jason

 

[Buster Hymen]

Nice to here from you Clintard,

When I drained the forks one ran clear and one ran dark. The guy I bought the bike from told me he had replaced one of the seals. This would make sense based on the color of the oil that came out. Not sure why someone would replace one (1) seal and not just do both while you were at it.(??) Anyway, all I can assume at this point was when the guy replaced the seal he never repressured the forks. I will give it a couple of days and check the pressure again to make sure I don't have a slow leak.

Take Care....Great weather this weekend for riding. :rocket bike:
Hope you (all) got to enjoy it....Jason

Hi Jason, sorry for the lack of replies to your questions. Any ways, it's better if you don't run air pressure in your forks as if done wrong can blow the seals. Using too much or putting the air in with an air compressor can end up damaging the seal. It would be better to run thicker fork oil with little or no air pressure or an aftermarket spring.

 

[jgotko]

Thanks Buster - I had read some threads on the forum about this and have looked into new springs but was unable to pull the $$ trigger last week. I think I will eventually go with the Race-Tech springs & emulators and run a 20wt oil without no air. (I beleive this was the suggestion)

As for now, the 5.7 psi that I put in the forks is making a "Good" diffrence. I did read the thread about being careful with the pressure. I ended up using a small hand pump. Thank You....J

 

[clintard]

Thanks Buster - I had read some threads on the forum about this and have looked into new springs but was unable to pull the $$ trigger last week. I think I will eventually go with the Race-Tech springs & emulators and run a 20wt oil without no air. (I beleive this was the suggestion)

As for now, the 5.7 psi that I put in the forks is making a "Good" diffrence. I did read the thread about being careful with the pressure. I ended up using a small hand pump. Thank You....J

what kind of hand pump do you use? ive been using an old bicycle pump laying in the garage and its a total pain in the ass. I plan on getting the racetech setup too but for now i cant afford to spend any money. Would make life easier while i wait if i had a better method for pressuring them LOL

 

[shawn kloker]

I set the regulator on my compressor for the psi that I wanted in the forks .Just checking fork pressure with a gauge drops the psi since they are such low volume.

 

[jgotko]

I bowered the pump from my buddy in lieu of going out and buying a bicycle pump. Honestly, this looked like something his gradfather's father made out of an old soup can. When he dropped it buy it looked so old and dirty I didn't think the piece of shit would even work. It must have been for blowing up Model-T tires or something? I've never seen anything quite like it. Probably never will again....

 

[Buster Hymen]

I set the regulator on my compressor for the psi that I wanted in the forks .Just checking fork pressure with a gauge drops the psi since they are such low volume.

I preferred a hand pump because I don't really trust most regulators to accurately regulate low air pressure. I think max was 15 pounds for the forks, and even that, I think, is hard on the seals.

 

[clintard]

I preferred a hand pump because I don't really trust most regulators to accurately regulate low air pressure. I think max was 15 pounds for the forks, and even that, I think, is hard on the seals.

thats why i havnt used the regulator myself. But this bicycle pump i have is worthless, i cant get anything half acurate with it. by the time u pump a little air into the forks and then check the pressure youve let all the air back out :bang head:

 

[frantheman39]

OK Then... Still talking to myself......Ummm....Yea....Well....

I figured out the crap I needed to figure out. Sometimes it is easier to ask if there is someone available. However, you learn much more by just diving in and getting it taken care of. Even learned to use a Torque wrench as I had never used one before. Tightened all steering to specified torques. Changed the fork(s) oil. Pressured forks according to manual.

Stability has improved and I can actually feel the front forks working now. I didn't even realize how much the bike was diving until I fixed it. What a diffrence just a couple of psi's can make. (wow) Forks are holding air. No low speed wobble.

ON TO THE NEXT PROJECT!!!! - LOL -

http://www.youtube.com/watch?v=EEle4A58gHw

Seriously, I need some new mirrors...

Just signed up today on this forum.
Yeah, my bike does the damn wobble thing whenever it hits a bump at whatever speed. Drives me nuts. I'll take it in and have it checked. I don't like working on my own bike, seeing how all it ever needs is the occasional tune-up!! 25k mile 1988 VMAX.

 

[ruvaulter]

Did it ever get fixed?

 

[[email protected]]

Dead thread bud.
If you have this issue, you most likely need to tighten up the steering stem bearings. Check out the videos on youtube by morleys muscle. Sean made a vidoe that walks u thru the process.