Headshake?

[BigDukeSix]

When I first got my RX3 (2018 model), I noted that at speeds at and above 35 MPH, the front seemed to do this quick bouncing thing – maybe 5 times per second or so. It felt like it might have smoothed out a little bit by 45MPH and I couldn’t take it much faster than that because I am RPM limited in my break-in period. I pulled the front wheel, put it on a static balancer and noted it was out of balance. I balanced it, reinstalled and then went for a ride this morning. Interestingly, it seems to be a bit better, but I was still noting an issue – a bouncy feeling. Then at 45MPH, I tried taking my hands off of the handlebars and they started oscillating back and forth very quickly. When I grabbed the bars again, the oscillation stopped, but I was feeling that bouncy feeling through them – maybe what I thought was bouncing was really this oscillation all along? I don’t know.

This was my first time balancing a wheel, but I’m pretty sure I got it right – maybe I solved part of the problem, or maybe I solved a different one with that. I haven’t checked the rear wheel balance – could that be the culprit at this point? Can I just have a bad front tire maybe? Anything else I should check?

Any input on this would be greatly appreciated.

[ben2go]

Check air pressures.
Check your head bearing nuts are tight. There should be some slight resistance when the bars are turned from side to side with the wheel off the ground.
Check the torque on all the front and rear suspension bolts.

Also, check and set suspension sag. If the rear is too soft, it will cause head shake so bad that it can lead to a full on tank slapper.
Your rims could be warped or not centers around the hub. That would be felt as a bounce. Vids on youtube showing how to check and true a spoked wheel.
It's not uncommon to find a tire that is out of round or has a bad section. That would require a tire change but not to expensive on the RX3.
Check that the rear wheel is aligned. I measure between the axle bolt centers and the swing arm bolt centers. I also use a motion pro tool on some of my bikes. It's cheap quick and accurate. Links below.




https://www.amazon.com/Motion-Pro-08...language=en_US


Videos of alignment tool.
https://www.youtube.com/results?sear...alignment+tool

[BigDukeSix]

Originally Posted by ben2go

Check air pressures.
Check your head bearing nuts are tight. There should be some slight resistance when the bars are turned from side to side with the wheel off the ground.
Check the torque on all the front and rear suspension bolts.

Also, check and set suspension sag. If the rear is too soft, it will cause head shake so bad that it can lead to a full on tank slapper.
Your rims could be warped or not centers around the hub. That would be felt as a bounce. Vids on youtube showing how to check and true a spoked wheel.
It's not uncommon to find a tire that is out of round or has a bad section. That would require a tire change but not to expensive on the RX3.
Check that the rear wheel is aligned. I measure between the axle bolt centers and the swing arm bolt centers. I also use a motion pro tool on some of my bikes. It's cheap quick and accurate. Links below.

Thanks for the input. My air pressure is good. I'm working today but if I get a chance, I will check the rear wheel balance and then go from there with the other items on your list as needed. Hopefully I can get this problem solved soon.

[sqwert]

First thing to check is steering stem tight. Several problems reported from RX3 owners from 3-4 continents, so it's a manufacturing consistency problem.

[fjmartin]

I had the exact issue of headshake on mine when I took my hands off the bars....it progressed to a terrible tank slapper that I fortunately rode out of at 70 on the highway. It turned out to be the headset bearing adjustment. To test, put the bike on the centerstand if you have one or somehow get the front wheel off the ground and the bike stable so if won't fall. Grab the bottom of the forks and give a pull towards you. If they move, they are too loose. To adjust, loosen the top triple clamp bold that holds the forks on the bike. then there is the big silver nut on the triple clamp. Loosen it a bit. Then you'll see a big nut with notches. That's the adjuster nut. Tighten it till the play is out of the fork but the forks still move nicely from side to side. Tighten the silver nut, tighten the bolts holding the forks. Done. If you don't have a tool to grab the adjustment nuts detents, no problem...get a punch or screwdriver in there and tap it around with a hammer.


Joe

[sqwert]

Good explanation, fj. It is a simple fix, and I've had to tighten my stem twice in 11,000 miles. It isn't a problem unique to RX3s. Some bikes need regular care. some don't. Make and model don't seem to matter, it is an individual bike thing. That is way virtually all my bikes I ride regularly have been upgraded with tapered roller bearings. Properly installed and keep them dry, they are super stable and last forever. I prefer All Balls for their consistently superior engineering and quality products, but they don't have anything listed for the RX3.

[BigDukeSix]

Originally Posted by fjmartin

I had the exact issue of headshake on mine when I took my hands off the bars....it progressed to a terrible tank slapper that I fortunately rode out of at 70 on the highway.

Wow, glad you were able to ride that one out

Originally Posted by fjmartin

To test, put the bike on the centerstand if you have one or somehow get the front wheel off the ground and the bike stable so if won't fall. Grab the bottom of the forks and give a pull towards you. If they move, they are too loose.

Thanks for the description of the test. I tried this and didn't note any front-to-back play when pulling on the forks. I guess my issue is something else

[sqwert]

Originally Posted by BigDukeSix

Thanks for the description of the test. I tried this and didn't note any front-to-back play when pulling on the forks. I guess my issue is something else

Never have felt play in my front end, but tightening the triples stopped the tank slapper crap. Twice. This is a free, simple, 10 minute fix/check. Do it. Worse that can happen is it makes no difference. This should be a part of routine maintenance.

A center stand raises the front wheel perfectly for the procedure. No center stand, use any jack with a vertical top movement. Floor, bottle, screw, scissors, whatever. Doesn't matter. Set a board atop whatever jack to avoid damaging the skid plate. Jack up the skid plate as far forward as possible, just enough to level the bike and clear the ground with the front wheel. I've even seen people use a tiedown strap from crash bars on one side to crash bars on the other, over a swing set, engine hoist, shop rafter, etc. Anything works that will hold the bike up, level, and allow free movement at the head/stem. I've even used a wrecker truck wheel lift to throw a strap over. Anything solid enough works.

Loosen the lower triple clamp bolts, not the top. The upper bolts will hold everything in alignment and allow the upper triple to snug down to take up slack. Then loosen the chrome nut, tighten the slotted nut until resistance to movement is barely felt in the handlebars, then tap the upper triple down against the slotted nut with a block of wood. Very gently. No damage with wood. The forks will slide easily through the loose lower triples to match the change in distance between the triples from tightening the head/steam bearings. Now, tighten the chrome nut. Finally, tighten the lower triple bolts. All done.



If the forks don't slide through at least one triple the upper triple will not be parallel to the lower and all manner of evil may then commence.

Even if you don't feel play in the forks, this can still make a difference. If you feel fork play, you are way, way over due for tightening the head/stem bearings.

[Jay In Milpitas]

Originally Posted by BigDukeSix

Thanks for the input. My air pressure is good. I'm working today but if I get a chance, I will check the rear wheel balance and then go from there with the other items on your list as needed. Hopefully I can get this problem solved soon.

What I haven't seen mentioned is bead seating of the tires, both front & rear.

Easily checked with each wheel in turn up off the ground and spun while watching the sides of the tread to see if the tire is running concentric, the beads properly seated in the rims.

A wheel/tire assembly can be in balance with the tire not properly seated, which moves a bit from side to side, inducing a wobble in the forks.

If one or both don't run true, just deflate, lube (soapy water) and inflate to seat, then reinspect.

Good luck.

[sqwert]

Good point, Jay. Many tires have a line around the rim indicating proper seating. Not home to check the RX3, but that has saved me a few bad mounts over the years.

[BigDukeSix]

Originally Posted by Jay In Milpitas

What I haven't seen mentioned is bead seating of the tires, both front & rear.

Easily checked with each wheel in turn up off the ground and spun while watching the sides of the tread to see if the tire is running concentric, the beads properly seated in the rims.

A wheel/tire assembly can be in balance with the tire not properly seated, which moves a bit from side to side, inducing a wobble in the forks.

If one or both don't run true, just deflate, lube (soapy water) and inflate to seat, then reinspect.

Good luck.

Jay,
You might be onto something with this. I put the bike up on the center stand and sat in front of the bike. I closed one eye and spun the front tire while focusing on a spot on the ground at the edge of the tire. As the tire spun, the space between the spot and the tire increased, then decreased to the point where the spot was covered, then it showed up again and the gap increased back to where it started, and this repeated as the wheel completed more revolutions. It wasn’t a huge change, but I was able to note something.

Sometime between tonight and tomorrow, I should get a chance to try to reseat this thing. Hopefully this will solve my issue.

BTW, is your signature a reference to that James Garner movie Support Your Local Sheriff?

[Dualsport Chic]

I noticed this same thing on my 2016 RX3 - it is enhanced at night as the headlight beam shakes as you go down the road - really annoying. Let me know what you find as it has been this way since it was brand new and I'd really like to figure out the reason for it.

[NzBrakelathes]

The tyre/tire pattern can cause a slight left to right at very low speeds without hands on bars, you shouldn't take both off really!

The pattern has no center line or equal on both sides so tyre/tire steps left to right at very low speed without hands on bars

[BigDukeSix]

Originally Posted by Jay In Milpitas

If one or both don't run true, just deflate, lube (soapy water) and inflate to seat, then reinspect.

I tried this - I removed my front wheel, deflated the tire, broke the bead, wiped the whole thing down with soapy water (doing my best to lube up the tire all the way to the edge that would be in the wheel). Aired it back up and that didn't seem to help. However, when spinning the wheel, I used the pointed truing rod that came with the stand and it appears that the wheel is not true (I am now assuming this is what was causing my tire to move laterally while it was spinning).

Any idea if this could be my issue? It's not off by a lot but it is off. I need to get my hands on a spoke wrench I guess?

[ben2go]

Originally Posted by BigDukeSix

I tried this - I removed my front wheel, deflated the tire, broke the bead, wiped the whole thing down with soapy water (doing my best to lube up the tire all the way to the edge that would be in the wheel). Aired it back up and that didn't seem to help. However, when spinning the wheel, I used the pointed truing rod that came with the stand and it appears that the wheel is not true (I am now assuming this is what was causing my tire to move laterally while it was spinning).

Any idea if this could be my issue? It's not off by a lot but it is off. I need to get my hands on a spoke wrench I guess?

Very possible. Is your bike still under warranty? Talk with the guys at CSC. If you're comfortable truing a wheel have a go at it.