Topic: What might be causing my front end wobble

[Anti-Johnny]

So last night was an interesting one. I got some work done on my bike (Thanks Patrick!) but on the way home I had some serious head shake going on around 70mph. I am not sure if it is caused by my tire or perhaps because my fork seals and oil need to be changed. I dont have the space to do that for two more weeks though.

There doesn't seem to be very much return on my forks when the bike is just sitting there. The tire is in pretty good condition, has plenty of tread and no dry rot. My fork seals are pretty shot though, they have been leaking for a couple weeks. Could I just top the oil off for now?

I have been reading for several hours today to try to get an idea of what is causing it. Even read about a fork brace for right above the tire but they dont seem to be produced for a 750k5.


Any suggestions? Will changing the fork seals fix this? New Tire?

[KingCustomCycles.com]

Fluid for now, fork seals soon.  I would not ride it far, or fast, with a dry front end.

[Spanner 1]

6 beers will do that  

[MoMo]

Fork fluid can cause that, as can wheels out of true, unbalanced tires, loose steering  head bearings, even bad swing arm bearings, and wheel alignment.   Larry

[Nikkisixx]

6 beers will do that  

Not to an Irishman!  

I'd drain and refill the tubes, not just top off.  Then go for a short ride and see if the problem is fixed.  In the meantime order some seals.

[MCRider]

Did it shake before the work was done? If so, look there. The seals may leak, but I wouldn't think they are the "cause" of the shake. Mucky oil could be.

If its always been shaky, then all the usual suspects are, suspect. Steering head bearings are usually first in my book. Swingarm bearings next. Along with properly seated tires, balanced wheels, wheel bearings, etc.

While waiting on the answer, I'll say: the tires age is more important than its visual condition. 6 years is the end of reasonable life expectancy and none should be used over 10 years. This is because the tires like most rubber and vinyl products, outgas the chemicals that keep them soft. This is not obvoius to the naked eye, spontaneous failure can occur.

A fork brace is used to improve an already properly working fork. It should not be used to attempt to fix a problem that exists elsewhere. Make it work properly first, then add the brace. Same for a steering damper.

[Anti-Johnny]

Nothing was done to the wheels. Just an exhaust and stator cover swap. This was the first time that I had driven it any real distance, about 100 miles round trip.

I dont really understand how the steering bearings make a difference, but if they could help then I will pick them up for when I change my fork seals and boots.

It didnt seem to get bad until around 75-80. It was dark, and perhaps the road may have had something to do with it. It wasnt very windy either, only about 10mph, but I felt like I was having to correct like it was much windier.

For the oil, I know I drain the oil out of the bottom and add at the top of the forks. About how much force is under that top bolt? I wont keep my head right over it or anything, but am I going to have to expect to catch this thing? haha. had a bad experience with changing out some car shocks once.

And thanks again guys.

[Nikkisixx]

Yup, it is under some decent spring pressure so be ready.

You'll need to get the front end well supported to do pull the caps so while you are at it (with the front end a little off the ground) move the bars back and forth from full lock left and right.  Look for the bars to kind of fall into a notch or drag at the middle.  This indicates worn steering bearings, which will cause a vibration.

[Goofaroo]

I dont really understand how the steering bearings make a difference, but if they could help then I will pick them up for when I change my fork seals and boots.

Think of your bike as two halves. The only thing connecting the front half to the back half is the steering head.

[MCRider]

Yup, it is under some decent spring pressure so be ready.

You'll need to get the front end well supported to do pull the caps so while you are at it (with the front end a little off the ground) move the bars back and forth from full lock left and right.  Look for the bars to kind of fall into a notch or drag at the middle.  This indicates worn steering bearings, which will cause a vibration.

If you do as proposed, and you feel the "detent" in the steering as you pass thru dead ahead, and I'll wager if youre bike has more than 10,000 miles on it you will, your bearings are shot. Obviously you can still ride it. But on a crowned road for example, the steering will want to fall into that detent, and you will steer out of it to keep going straight. All this happens on a very imperceptible level, but its happening. This back and forth can initiate a wobble and other weird feelings in the handling of the bike.

The stock balls and races steering bearing are not up to the beating. Most of us upgrade to tapered roler bearings at the first opportunity.

As to your fork cap question, if the bike's front end is unloaded, the cap nut will push up a slight amount once it is unthreaded, 1/2 inch or less. Just keep your hand on it and it will be fine. If you don't unload the front end that nut will shoot thru the ceiling. Or your face if that is encountered first.

So, move the bike into the yard, remove the drain bolts (one side at a time) and pump the forks. Have everyone stand back as the oil will squirt several feet to either side. If you've got help, you can do it indoors. Someone must be tasked with keeping a container at the drain plug while the other pumps the fork. Remember the oil will come out under pressure upon each pump. Roll back indoors, leave the drains out and something underneath to catch the drippings overnight.

Loosen the cap nuts a full turn, you'll want to do that while the bike is stable, then jack up the front end, remove them the rest of the way, and proceed with refilling.

[bikerbart]

this was happening to me lately,it was a loose rear axle.Tightened it and the problem went away.

[KingCustomCycles.com]

I stick a small plastic elbow in the hole where the drain bolt goes and this deflects the oil downward into my pan.  Pump as mentioned above but slowly up and down will do it.  If you are doing the seals, just take the whole bottom off and clean the inside of the assembly with lacquer thinner and soft rags.  relube for assembly and fill per the manual with automatic transmission fluid (ATF)

[Duke McDukiedook]

Did this shake happen on grooved concrete or asphalt?

[jdubb1977]

fwiw, i used to have some front end wobble, too.  when i pulled everything apart, i found that my left fork spring had broken in half.  yikes!  i replaced both w/ new progressive springs, and it handles great now.  good luck!

[Anti-Johnny]

Ive thought about the progressive springs, but I am tapped out financially at the moment. I am going to go ahead and order that tapered bearing. I'll have the front of the bike off anyway, so it makes sense. The road condition varied, but I was on two different highways and it was about the same. We have decent roads in Texas, so I cant say how much that played a part.

I am going to try and drain and fill the forks this week to see if that makes much of a difference. I am also looking at new tires. They seem solid on my bike, but it seems like a good idea to swap them out for new ones just for piece of mind. People seem to like the BT 45 and the Dunlop 404.

I am trying to pay more attention to what my rear tire is doing. But I cant be sure if I am looking for something that isnt there and feel something that isnt happening. I will look up how to tighten my rear axle.

Thanks again guys. You all put me at ease when I go into noobie panic mode.

[Duke McDukiedook]

Your swingarm could be loose from play in the bushings being worn. My back end tightened up when I turned it over to Hondaman to work his magic on it.

I ask about the pavement because i noticed no matter car or motorcycle when I hit a certain portion of pavement on interstate near my house I get the wobbles because the construction crew diamond grinded the piss out of the concrete to get their smoothness bonus. I'm sure it tested great for overall smoothness but it rides like #$%*.
 

[flybox1]

My back end tightened up when I turned it over to Hondaman to work his magic on it.

best laugh i've had in weeks!!!!

[CrankyOldGuy]

I had a bad experience one time with a high speed wobble.  The spokes were loose, but not that noticeable.  Worked fine at low speed but wobbled like .... hmmm ..can't say that here ... at high speed.

Harry O.