High speed wobble

[mcgovern61]

On the trip to the Midwest Meet, I noticed something that I have not normally had an issue with. At some of the highway speeds up in the 70-80 MPH range, as I would lean into the long highway curves (especially leaning left) if I hit a bump or expansion crack in the road, the bike would start to do a weird somewhat left to right and up and down front end wobble. Dropping the throttle suddenly and then punching and leaning harder helped stop the wobble most of the time. I checked my air in the forks and it had dropped to 12 lbs (I have stock springs in the forks). Luckily, Brian had a portable compressor and we pumped it back up to 20 lbs which would then help reduce the wobble.

Again, I know I had the bike loaded pretty heavy and not balanced as well as it should have been:

but the wobble was a little unnerving. I have ridden at high speed many times before, but the highway turns in West Virginia had a tighter radius than some of the highways elsewhere. When I got home, I checked the bike out and nothing seems out of the ordinary except I can feel a minor bit of cupping in my front tire on the left side..and I mean barely. Now, I do not know if that is a result of the ride and loading the bike heavy or was the cupping developing long before this causing the wobble?

Could it just be the front springs are shot?

The front tire has 20,146 miles on it now so maybe it is just time to replace the tire (even if there is still room left in the wear bars?)

Opinions.....comments?

 

[dan filipi]

I would go with tired front springs. They could theoretically tire out unevenly.
Coupled with your load throwing off geometry I think your on the right track.

 

[toytender01]

Try duplicating those turns with an unloaded bike and see if you have the wobble.

 

[mcgovern61]

toytender01 » Fri Aug 09, 2013 10:03 pm[/url]":4d0bkok7]
Try duplicating those turns with an unloaded bike and see if you have the wobble.

That is my next plan as soon as I can! Problem is, most of the roads around here in NJ are straight and flat. I would have to go almost 100 miles back through PA to find similar highway curves.

 

[zman]

I would suspect the springs as well, Stock are OK but add that load and it can labor old springs at those speeds, you need a fast reaction to the road and It seems they arent giving it.
Just my humble opinion.

 

[backlander]

I see Progressives on the horizon at Gerry's house. :mrgreen: :smilie_happy:

 

[slabghost]

20,146 miles on the tire! What tire is that exactly? It's either tired springs or a very old tire.

 

[mcgovern61]

slabghost » Fri Aug 09, 2013 10:47 pm[/url]":3blmi373]
20,146 miles on the tire! What tire is that exactly? It's either tired springs or a very old tire.

Bridgestone S11's. Manufactured March 2007.....installed November 2007.

 

[zman]

mcgovern61 » Fri Aug 09, 2013 9:56 pm[/url]":13wcqzno]

slabghost » Fri Aug 09, 2013 10:47 pm[/url]":13wcqzno]
20,146 miles on the tire! What tire is that exactly? It's either tired springs or a very old tire.

Bridgestone S11's. Manufactured March 2007.....installed November 2007.

Now you have me thinking..Brigstone S11`s or Shinko230`s..Double the miles sounds good but if the wobble is tire related?
If it is no trouble would you change out your springs this weekend and take it out for a spin and let me know opcorn: :mrgreen:

 

[pidjones]

I'd put new rubber on, and check the head bearing preload. Try to get the load more balanced front-rear next time. Then ride at a speed safe for your loading. 70 in sweepers may be fine unloaded, but with all that gear aboard is risky.

Sent from my LePanII using Tapatalk 2

 

[ekvh]

Can also be swing arm bushings/ bearing loose or worn. I had one I chased for a while on the front end. It ended up being the back end. Mine was a more like the tail wagging a bit but in the same situation as you describe, above 70 mph and when turning or when hitting a bump when turning.

 

[Piper]

Gerry, Glad you and Brian made it home safely.
I had exactly the same symtoms you describe on an 81. It would go into a slight wobble only in turns or highway grooves and it turned out to be just very slightly loose steering head bearings. After I tightened them up it completely went away.
A friend of mine restored a classic 60's BMW and right after he got it back on the road he got into a high speed wobble at 60 MPH and went down and was in the hospital for weeks and totaled the bike. Definitely something that needs to be fixed asap.

 

[brianinpa]

Gerry I have been thinking about this for a while now and was going to ask you about the steering head like Piper mentioned.

 

[mcgovern61]

When I restored the bike, I kept the steering head bearings from the original '82 since they only had a little less than 24,000 miles on them and they seemed to be like new.

However, I went through 3 sets of forks! The original '82 forks were pitted, the '81 was a front end wreck when I got it so those forks were bad and the set I finally got from Ebay were good, but I have no idea about the age or mileage on the springs.

I can pull the tree and recheck the head bearings. And I suppose I could pull the springs and check their length (Except for the fact my fork seals are not leaking, hate to waste good seals.) I am pulling the fairing after the fall riding season to go standard anyway so that might be a good time to do the rest. I was also considering polishing the fork tubes then so I could really pull everything then.

While the bike is down, I will also check the swing arm.

 

[mcgovern61]

zman » Sat Aug 10, 2013 12:36 am[/url]":2nrufezz]

mcgovern61 » Fri Aug 09, 2013 9:56 pm[/url]":2nrufezz]

slabghost » Fri Aug 09, 2013 10:47 pm[/url]":2nrufezz]
20,146 miles on the tire! What tire is that exactly? It's either tired springs or a very old tire.

Bridgestone S11's. Manufactured March 2007.....installed November 2007.

Now you have me thinking..Brigstone S11`s or Shinko230`s..Double the miles sounds good but if the wobble is tire related?
If it is no trouble would you change out your springs this weekend and take it out for a spin and let me know opcorn: :mrgreen:

Yep, I will jump right on it! :smilie_happy:

 

[pidjones]

You don't really need to pull anything to check the pre-load. Just lift the front and measure the force to turn the bars. Feel for ANY notchyness. Ball bearings can go bad very quick. Always replace with roller bearings.

Sent from my LePanII using Tapatalk 2

 

[Denver]

Disassemble the forks, were they leaking? new seals, check bushings, 2 per side. These parts with new springs often solve front end issues. Hope this is helpful

 

[mcgovern61]

pidjones » Sat Aug 10, 2013 8:40 pm[/url]":3vzkyirf]
You don't really need to pull anything to check the pre-load. Just lift the front and measure the force to turn the bars. Feel for ANY notchyness. Ball bearings can go bad very quick. Always replace with roller bearings.

The pre-load is OK! It is smooth turning with no notches! One down! :yes:

 

[mcgovern61]

Swing arm is tight - 2 down!

 

[mcgovern61]

Took a trip on the highway again, this time unloaded, 20 lbs air in the front and 58 lbs in the back. Leaning into a turn going left at 80 MPH I could feel an initial wobble but it cleared pretty quick kinda pointing to the springs again. I rechecked the cupping on the front tire and it is so marginal that I do not think it is related (just and old tire at this point).

I am under the opinion that the bike was overloaded and the load was unbalanced causing the front end to want to lift and bob at high speed. Like pidjones mentioned, it may just have been exacerbated by an unbalanced load.

Looks like progressives are on my winter wish list (plus the camper trailer :hihihi: ).

(Maybe a weight loss program too! :whip: )