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Odd "Weave" -Update.. SOLVED (and MRM feels like an ID Ten T!) :)

M

mcgyver74

Member
Member
Was riding home from Maine yesterday and started to notice an odd "Weave" to the bike,  when I hit a rut in the pavement  it almost felt like the front and rear tire weren't In line for a split second.  Never felt like I was in danger of going down but it's a new sensation (Different from the normal oddities of rough pavement)  Almost feels like the bike is just the tiniest bit wobbly when leaned over (Kinda hard to describe, it's very subtle but I know how my bike handles and this is odd )

I know I am due for a head bearing adjust and will be doing that tomorrow, I figure I'll also take a gander at the wheelbearings while I'm at it....but the bike only has 23k on it so they should still be fine...

Anything else I should look at?
 
Gut feel I'm thinking tires.... What's the tire status? type? condition? miles?
Explain what you mean by "rut."  A pothole or groove in the road surface?  Is it perpendicular or parallel to the direction of travel? 
 
Didn't you just make substantial changes to your suspension? My guess is you have some dialing in to do.
 
The tires are PR3's with a hair under 7k on them, but they look fine, I guess it's possible it's just the tire wearing..


@Fred, yes I did replace the fork springs and rear shock,  but that was about 1500 miles ago and this just started in the last 50 miles, I haven't touched any settings in about 600 miles...
 
What are your front and rear sag numbers in millimeters? I'm thinking you may have altered the bikes attitude which has changed the front geometry enough that it's impacting handling. You may need to raise the front end some.
 
I don't have the exact sag numbers since I still cannot find anyone to help me measure (and I don't have the tools to make your nifty tool) :(   


What is odd is that it was fine for over 1k miles, if I had the geometry out of whack I would expect this to show up right away  but it just started yesterday........    the front cannot be raised at all as i have the forks in the trees per factory specs (fork tube Flush with upper triple)


It may be the tires wearing oddly,  I do burn a LOT of slab so they could just be cupping and catching the ruts worse then normal, but I hate unexplained things  :(
 
Are you sure that all the bolts are tight from when the forks were removed for new springs and oil?
 
If your new rear shock has a stiffer spring in it, chances are your rear sag has decreased, which has effectively raised the rear end. This is why I think you may need some more preload on the front forks, to lift the front a corresponding amount, but to do it right, you really need to measure both the front and rear sag so you know where you stand. Anytime you make alterations to the suspension from stock, you need to reset the sag. Find a helper and "get er dun".

I'd probably shoot for about 32-33mm rear sag and 34-35 mm front sag and see how that feels.

Sounds like you're also about due for a new set of tires too. That could be the culprit as well.
 
Yeah, I need to find a helper and do this.  Maybe before I head out for VA tomorrow (For work..but I'm taking the bike :) ) I'll see if a neighbor can help me :)


It's possible it's tires... the tires do have a raised ridge in the center from all the slab I burn, 
 
Just be sure to record the initial sag readings before you make any changes, and then post them on here. Also make note of your preload adjuster positions before you change them in case you need to return them to the original settings you have.

You can do the front sag all by yourself by using a zip tie around the silver part of the fork. Pull the zip tie so it is tight on the slider, but can still easily slide. Now push the zip tie up so that it just contacts the rubber dust cap lip on the fork leg. Now sit on the bike an balance it as best you can on your toes, with all your weight on the bike, but don't bounce it. Carefully and slowly get off the bike so that you don't compress the suspension further when doing so, and centerstand it. Now lift the front wheel so it is off the ground, and measure the distance between the edge of the zip tie and the dust cap. This is your front sag.
 
Well I went out after work and took a quick gander, I don't think it's the wheel bearings, they don't have any lateral play and they rotate nice and smooth (I didn't pull the wheels, but the wheels spin freely with no "Notchiness" or growling)

I noticed the rear has a pronounced ridge in the center, I tried to photo it but it didn't show on the pics well...but it's there.  I'm going to tweak the head bearing in the morning before I head to Virginia, and I'll check the front sag using Fred's method, but at this point I'm leaning towards the tires just being badly ridged/cupped.  sucks cause the tires only have about 7k on them and they have PLENTY of tread left...

 
Fred_Harmon_TX said:
You can do the front sag all by yourself by using a zip tie around the silver part of the fork. Pull the zip tie so it is tight on the slider, .... This is your front sag.
Click to expand...

SO cool. Thanks :)
 
So I now know what the issue was and I feel like a M0r0n!!

Before I headed to VA on business (took the bike :) ) I retorqued the head bearing but that didn't seem to help.  On the way down I hit some grooved pavement and scared the bejeebus out of me so while I was down here I (very reluctantly) called a local dealer to take a look as I don't have time to look further myself :(

Well... I drop the bike, off and 25 minutes later he calls me and says it's all fixed...  The resolution?

THE FRONT TIRE WAS OVERINFLATED  :-[ :-[    It kept reading 44 on the TPMS which is 2lbs higher then I like but I've been there before with no ill effects... but according to the tech it was over 50!!  He dropped it to 42 and the "weave" is now gone

One thing he did tell me, was that he has seen with the TPMS that over 45PSI the accuracy of the monitors decreases significantly hence why I saw 44 and it was in reality over 50. 

He checked over the rest of the suspension just to be sure, but said everything else looks fine..

At least it's fixed, didn't cost much (They hit me for 1/2 hour which I thought was fair given that they were booked solid and still squeezed me in with no appt)  but now I feel like such a dope!! :)
 
Glad you found the problem. That is all that matters. I've done things just as bad, or worse.
 
From what I understand per the forum, is the sensors are temp adjusted, so what the dash says may not reflect reality on hot/cold days.

Wondering if this contributed to your situation.
 
I never trust the accuracy of the TPMS.  I always carry a pressure gauge in my tank box for that reason.  I use the TPMS as a warning system if I start to loose pressure but I've noticed that what my dash reads doesn't always match my handy guage.
 
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