Front tire shimmy - Harley Forum

Rocky · #1 01-13-2009, 03:41 AM

In the last couple of days I have picked up a front tire shimmy at @32-40 m.p.h. above 40 smooth as glass. Tonight I took the time to put it on the jack to check the free play in the head bearing, it appears to be tight. I inspected the tire it isn't worn out, still has @ 3/32 tread depth. I checked it for out-of-round (don't have a dial indicator that big, had to eyeball it) it does have a little bit of a hick up to it in a couple of places. I bought the tire warranty so I figure I'll take it back to the dealer to get their take on it. Does anyone on this wise panel have any other advice for me? Oh yeah I have 20,780 miles on it. It done this right off the show room floor and the tech tightened the head bearing and fixed it but, that's been almost 2 years ago.

Buzz Kanter · #2 01-13-2009, 08:47 AM

Quote:

Originally Posted by Rocky

In the last couple of days I have picked up a front tire shimmy at @32-40 m.p.h. above 40 smooth as glass. Tonight I took the time to put it on the jack to check the free play in the head bearing, it appears to be tight. I inspected the tire it isn't worn out, still has @ 3/32 tread depth. I checked it for out-of-round (don't have a dial indicator that big, had to eyeball it) it does have a little bit of a hick up to it in a couple of places. I bought the tire warranty so I figure I'll take it back to the dealer to get their take on it. Does anyone on this wise panel have any other advice for me? Oh yeah I have 20,780 miles on it. It done this right off the show room floor and the tech tightened the head bearing and fixed it but, that's been almost 2 years ago.

What kind of wheel (wire or mag)?

unfknblvbl · #3 01-13-2009, 10:18 AM

Just a thought, but when was the last time it was balanced? Or if wire (I don't know for sure if this could have any effect) when was it last trued and balanced?

Rocky · #4 01-13-2009, 01:09 PM

I forgot to mention that, it is a mag wheel, and the last time it was balance was when Barry tightened the head bearing for the steering.

frisco-rigid · #5 01-13-2009, 02:10 PM

Hi Rock

I often get a wee more front end shimmy as the tire gets old/worn..
Sometimes that's all it is.. My wild guess is that's what it is..
Sometimes a combo of improper air in a worn tire, something to think about..

The neck bearings do not normally get loose and it's Not like they need adjustment periodically.. They do need inspection and grease packing every couple years but they DO NOT "go outa adjustment" on their own unless they were done wrong in the first place..
If yours are too tight or loose a shimmy/wobble/shake can result but it usually happens immediately after an improper adjustment..
TOO tight is waaay worse than too loose..

You might check the Wheel bearings.. If you have an Indicator you can check while installed by mounting it solid, perhaps on the axel nut..
That's how I've done it..
Or by hand.. You know,, front end in the air,, grab the top and bottom and look for a wee/tiny/miniscule amount of wobble..

I guess a Mag wheel can go "outa round".. Never heard of it except from a Bad crash, but hey, I won't say it Can't happen..
You can check for outa round by mounting the indicator solid on the lower-leg.. OR,, by simply placing a bottle, can, sleeping dog, Welfare Queen--- anything stationary right dead next to (1/32") the wheel rim and/or tire and spinning the wheel,,,,, you'll easily see any run-out,, lateral or radial..

Like UN sugg'd, a weight coulda dis-lodged and fallen off..
When I get a tire/wheel balanced I draw a small diagram of both sides of the tire and what weights are where.. Then if a prob such as this arises I can see immediately if a weight is missing, and if not, I can eliminate that possibility..

Go ahead-on Big daddy

frisco-rigid · #6 01-13-2009, 06:48 PM

Hey Rock

I forgot to add that even if the wheel is almost in perfect true the tire itself can look a wee outa round,, it's a kinda common sight..
And this..
Did you check the "free-play" in the neck bearings by the "fall-away" test.?

If you have one of those front-ends that have to bounce right and left 3 or 4 times you're on your own..
BUT---
If you have a normal set-up then lift the front end barely off the ground and dis-connect at least the clutch cable control----anything that un-balances or gives resistance to the front end---- then aim the tire forward and gently push it to one side and observe how far until it Falls by itself..
Then repeat in the other direction..
I like mine to fall with-in an inch cuz I like my bearings like my women..

If it hasn't fallen by 2" it's too tight..
And very often one side will fall a wee sooner than the other..
The less you raise the tire OFF the ground --- the more accurate the test..
This is all in the manual also..

PeterV · #7 01-13-2009, 08:23 PM

I'll throw my own issue I had with this issue.
Had a front tire changed on the bagger two years ago.
Upon going for a ride, I became aware of a shimmy. It was of short duration (between 30 and 40 kph) and of low intensity. More like an annoyance, but it was there.
So I got on it.
First up, checked bearings with a dial. Zip, zero.
Next, rim trueness (spoked wheels). Dial was used agin. Wheel dead straight and centered.
Checked front disks for warping. Dead flat.
Checked calipers. Working fine.
Checked neck bearings. All was well.
Checked front/rear alignment. All good
That's when I said to myself..."Self, that back tire is, well, worn past my liking..."
So, off came the back wheel.
(At this point I'll mention that I roll on Dunlop D402s)
Back at the garage, the back wheel with a fresh tire was installed presto pronto.
Out for a ride and ....shimmy gone!
So now I know. A 3/4 worn Dunlop on the back with a fresh front Dunlop will get the front end wiggle ever so slight, but there nonetheless.

A long winded post..I know.

Hiya frisco!

Pete

unclepsycho · #8 01-13-2009, 11:03 PM

Hi there... Here's my 4 cents...(inflation)

I was told a while back that if you can drive "thru" a tire vibration, then it is out of balance. If the vibration continues at all speeds, then it would be out of round.

I dont have any research on this to back it up, but it seemed to make sense at the time.

good luck,
hope ya get 'er fixed.... a true front tire is surely a safer tire.

milindh · #9 01-13-2009, 11:14 PM

Like PeterV I'd be looking at the rear tire too.

What Unclepsycho says is true but you don't usually see that harmonic out of balance condition that you can drive through show up at speeds in the 35-40 mph range. Usually at a lot higher speeds.

I'm thinking it's a case of Funky Tire. Either front or rear.

frisco-rigid · #10 01-14-2009, 02:47 AM

Hey Pete
Good to see ya man..

Good sugg.. These kinds of probs often need many sugg's..

I've personally mixed new & old and diff brands for years and never had a prob so it didn't occur to me to mention it..

Heard of that happening,, just never happened to me and you know that I only talk about what I have experience with..

I put nothing past these devil machines..