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Front End Follies

Started by motohorseman, August 06, 2012, 02:06:21 PM

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motohorseman

Quote from: andyb on August 06, 2012, 09:34:42 PM
I've had a tire do that.  One fork leg was dry, one was filled with sludge.  Happened to a metzler, I think.



I've got a feeling you're right, normally that wear pattern is suspension related, or so it seems.

Time is limited, I'd rather do it right, but I may just try draining and replacing the fork oil. If it comes out looking really bad, well, guess I'll be pulling them off for a freshening up.

Thanks everyone!
Steve

soundmindryan

Quote from: racerman_27410 on August 06, 2012, 07:13:27 PM
Contact Avon and see  if they will do anything for you..... there is nothing that a motorcycle/rider can do to make a tire look like that.

Ditto. Avon has a factory road hazard warranty so they're used to replacing tires. I've used it. Contact your supplier. They may be able to help.
Ryan McCollum
Tulsa, OK
'89 FJ1200 White & Silver
'90 Yamaha Venture Royale

"I visited a scientist who had a helmet with magnetic fields controlled by computer sequences that could profoundly affect your mood and your perceptions."
-Douglas Trumbull

aviationfred

I will add my 2 cents. I have no experience with Avon tires. Giving the tire the benefit of doubt. I would look at suspension. check the fork oil levels and make sure they are at the correct levels. Another possibility is that one fork tube has risen slightly in the triple tree causing the tire contact patch to be at an angle.
I'm not the fastest FJ rider, I am 'half-fast', the fastest slow guy....

Current
2008 VFR800 RC46 Vtec
1996 VFR750 RC36/2
1990 FJ1300 (1297cc) Casper
1990 VFR750 RC36/1 Minnie
1989 FJ1200 Lazarus, the Streetfighter Project
1985 VF500F RC31 Interceptor

racerman_27410

Quote from: aviationfred on August 08, 2012, 12:02:16 PM
I will add my 2 cents. I have no experience with Avon tires. Giving the tire the benefit of doubt. I would look at suspension. check the fork oil levels and make sure they are at the correct levels. Another possibility is that one fork tube has risen slightly in the triple tree causing the tire contact patch to be at an angle.


that cannot happen.... the axle holds the wheel and forks square.  the forks and wheel all go up and down together regardless of fork oil level

most all of the new bikes have only rebound damping in one fork leg and compression damping in the other fork leg.... if your scenario worked as you say then all the new bikes would be suffering the same weird tire wear.

the problem is the tire.

Kookaloo!

axiom-r

Concur with Frank on this one.. That tire is a dud and Avon will replace it.  I went through several sets of Avons and discovered that they never really wore the same.  I used to think that I was riding more or less aggressively and that was changing the wear rate and pattern.  Then I realized that my riding has stayed pretty much the same across 4-5 sets of Avons. 

This was part of my motivation to get better wheels on my FJ - no more Avons...


tim
1992 FJ1200 w 2007 R1 Front & Rear

motohorseman

My prefered local shop did not have anything in stock in the 120/70-17 size  :dash2:

I'd ask what's the best tire, but, well.....  (popcorn)
Steve

andyb

Quote from: racerman_27410 on August 08, 2012, 01:40:52 PM
that cannot happen.... the axle holds the wheel and forks square.  the forks and wheel all go up and down together regardless of fork oil level

most all of the new bikes have only rebound damping in one fork leg and compression damping in the other fork leg.... if your scenario worked as you say then all the new bikes would be suffering the same weird tire wear.

the problem is the tire.

I disagree but you're absolutely right in principle.  The problem is that the forks are a mite flexible, and with unknown mileage on the parts, a little wear could go a significant distance.  Throw in the wrong tire pressure and a tendancy to cup?  Heck, throw in a brake caliper that isn't working well on one side, while we're at it, and significant sideways force can show up.  A wobbly, loose bearing should be pretty obviously wrong when ridden, but could allow the same play.  It's like when you ride an older bike with a very worn front end and a single disc brake that wants to turn when you're braking hard.

In theory a fork shouldn't flex at all and should only allow movement within the plane it's designed for.  I've owned a couple of forks that needed a fair bit of work to get nearer that point though!


racerman_27410

Quote from: andyb on August 10, 2012, 05:25:47 PM

I disagree but you're absolutely right in principle.  The problem is that the forks are a mite flexible, and with unknown mileage on the parts, a little wear could go a significant distance.  Throw in the wrong tire pressure and a tendancy to cup?  Heck, throw in a brake caliper that isn't working well on one side, while we're at it, and significant sideways force can show up.  A wobbly, loose bearing should be pretty obviously wrong when ridden, but could allow the same play.  It's like when you ride an older bike with a very worn front end and a single disc brake that wants to turn when you're braking hard.

In theory a fork shouldn't flex at all and should only allow movement within the plane it's designed for.  I've owned a couple of forks that needed a fair bit of work to get nearer that point though!

I dont care if you disagree or not andy.... you would argue with a sign post..... as long as the axle is thru the wheel and the fork tubes are secure in the triples both fork legs and the wheel  are going to move together. it aint principle.... its fact that the only way the wheel can move independantly of the forks is if the wheel bearings are completely disintegrated .... and i'm pretty sure the rider would know about that condition way before the tire wore out. 

dragging brake caliper adding side load?  LMAO  what a load of Bullcrap..... if that was the case how come bikes with only one front brake rotor dont do this to their tires or put their rider on their ass everytime the front brake is applied?

heck you can put two different rate springs in the forks and they will still go up and down together.
rebound damping in one fork leg and compression damping in the other fork leg?.... they still go up and down together
sloppy bushings in the forks? ....they flop around together

pull some more shit out of your ass.... its always good for a laugh.

Kookaloo!

andyb

Quote from: racerman_27410 on August 10, 2012, 07:40:38 PM
I dont care if you disagree or not andy.... you would argue with a sign post..... as long as the axle is thru the wheel and the fork tubes are secure in the triples both fork legs and the wheel  are going to move together. it aint principle.... its fact that the only way the wheel can move independantly of the forks is if the wheel bearings are completely disintegrated .... and i'm pretty sure the rider would know about that condition way before the tire wore out. 

dragging brake caliper adding side load?  LMAO  what a load of Bullcrap..... if that was the case how come bikes with only one front brake rotor dont do this to their tires or put their rider on their ass everytime the front brake is applied?

heck you can put two different rate springs in the forks and they will still go up and down together.
rebound damping in one fork leg and compression damping in the other fork leg?.... they still go up and down together
sloppy bushings in the forks? ....they flop around together

pull some more shit out of your ass.... its always good for a laugh.

I frequently argue with signposts when they've got speed limit signs affixed to the top of them.   :lol:

I've ridden (hell, it's in the garage) a bike that has a single front caliper and flexible, worn-out forks.  Grab a quick fistful of brakes...what little braking power it has, anyhow... and you'll get a quick chirp from the front tire.  Took forever to figure out what was happening, but if I stand up and watch the front tire there is a very noticable sideways twist of the wheel as the flimsy fork assembly twists and flexes.  Should this happen?  Obviously not, but the front assembly is the same age I am and the years haven't been kind to it.  I don't know if it was like this when it was new, as I was busy learning to walk at the time, but it's certainly done it since I've owned it.

Things wear out and stop working in exactly the way they were designed to do.  Occasionally a crap design gets through and they don't work the way they're supposed to even from new, but that's not hugely common thankfully.  Who hasn't ridden a bike where the front wheel isn't exactly in line with the steering head, or is it just me?  Or a bike that's been dropped and slightly tweaked the fork tubes?  Tires aren't supposed to wear on one side, but we've got a good example of one that did posted above.  While we're at it, they're not supposed to cup, either, but that certainly happens, right?

What I'm saying is that the tire is toast.  Replacing it will put another round one on the front and solve the problem.  In the next couple thousand miles it may or may not end up looking like this one if it wasn't the source of the problem, so taking the time to check and/or replace the fork seals, ensure that there's fresh fork oil of appropriate weight, and that the front end is working as well as it's designed will help prevent this from happening again.  It's also routine maintenance that's probably due.

When my FJ had a tire like this, it was when I purchased it from the prior owner.  Maybe he rode around in tight circles all day with no air in the tire, I don't know.  What worked for me was to replace the tire, replace the fork seals, cleaned the dust seals (which were okay, just dirty), drain what little ex-oil was in the forks, and refill with new.  Haven't seen the problem since.  All of this was necessary, as the tire was done, the seals were shot, and the oil was disgusting.  While I was doing it I cleaned and lubed the speedo drive, cleaned the calipers, checked the pads, checked the steering bearings, checked the forks for straightness, raised the forks 10mm, and changed to a heavier fork oil.  It's possible that any one of these things could have helped with the tire wear; it's also possible that the tire was inherently bad and none of it was necessary, but judging by the state that everything else was in and the improvement in handling afterwards that all of these were good things.  Had I just swapped tires and had the same thing happen in 1500 miles, I'd have been really annoyed with myself for halfassing things.


racerman_27410

Quote from: andyb on August 11, 2012, 06:32:46 AM
I'd have been really annoyed with myself for halfassing things.


you should be really annoyed with yourself right now..... we are not talking about your old bike we are talking about a fella who has an issue with a tire on his FJ and you are posting up crap. I had a heavy as hell 1970 honda 750 with one disc brake and spindly forks and it never wore a tire like this.

maintenance is fine and i highly recommend it but it doesnt have crap to do with what we are talking about in this thread.  He got a bum tire..... period.

Why dont you just move along to some other thread where you "might" be able to contribute something useful?
Its obvious you dont know what you are talking about when it comes to motorcycle suspension and how it works.


Kookaloo!

Frank

yamaha fj rider

+1 on tyre out of round. Hope this helps?

Kurt
93 FJ1200
FJ 09
YZ250X I still love 2 strokes
Tenere 700
FJR1300ES

bigbore2

Alright fellas, let's keep things here sophisticated.  We are all brothers.

motohorseman

No issues whatsoever so far with the new tire.

It may of been a bad tire from day one, it always did act strange.

Once again, when something goes bad slowly I can't tell how really bad it is until it's fixed - the new front tire has been amazing, like it always should of been.

This winter I think I'll do the forks and possibly the steering head bearings.

Thank you
Steve

winddancer

I had the same problem with my last set of tires but it was right after I changed my front fork valves I found one of forks was longer than the other I got them back to the same and the tire started to wear better