(http://bestdesignever.com/ducati/sprocket.jpg)
I need help!
:'(
My rear tire will slide towards the engine a tiny bit on the left side while riding ... OR ... something somewhere is bending. It's gotten so bad that my chain ate my sprocket (see video below).
Now, this is the scenario:
- Wheel is on tight, adjuster bolts tight, correct amount of sag/play on chain, tire seems straight.
Then
- After a while the chain is noticeably loose, but the nuts and bolts are all still nice and tight.
- I'll loosen the nut, tighten the adjuster bolt with maybe a 1/8 - 1/4 turn, tighten the nut, and be on my way for another ride.
- A few rides later ... chain is loose again.
Question:
- Why would my tire move like that?
That's the main question. Or is it even the tire moving -- maybe something else is bending. ???
Some details:
- I've had to re-adjust the tension several times (maybe a dozen at the most) over the last 6 months.
- I've just noticed that almost all of the teeth on my sprocket have been chipped off.
- Nothing is missing along the axle.
- The chain itself doesn't look damaged at all, not even scratched.
- I lube my chain regularly with Chain Wax
- I try to get my wheel as straight as possible. I use a metal ruler pressed against the sprocket to see how it lines up with the chain whenever I adjust it or reset it after removing the tire.
Any ideas?
Oh, and I made you a video.
Ducati sprocket chain (http://www.youtube.com/watch?v=mbt8AkmU5P4#normal)
Some of my theories:
- I'm too heavy for my bike
- I engine break too much
- The sprocket is warped (seems okay after I removed it)
- The swing arm is bending
- The adjuster bolt is stretching (or spinning)
- Something is missing along the axle (it doesn't seem so)
- The bearings are bad (they seemed okay after visual inspection)
:-\
How many miles on the chain? Worn out chains require frequent adjustment.
Are you adjusting the chain correctly? A bike with stock ride height needs 25mm of chain slack at the tightest point (spin the wheel to find the tight spot).
That sprocket is worn out anyway. Time for a new one, and while you're at it replace the front sprocket and the chain.
Your issues will disappear.
, but what about the sprocket being worn on one side, mostly - swing arm bearings?
Quote from: stopintime on December 29, 2010, 04:55:24 PM
, but what about the sprocket being worn on one side, mostly - swing arm bearings?
I doubt it.
I'm thinking alignment.
The parts are sacked so it's really hard to tell. If it was a brand new sprocket and was worn on one side I'd go looking for a cause, but this is just old age IMO.
I agree with dp. With every part worn out, it is hard to tell the chicken from the egg. I am guess the multiple tension adjustments were due to an old chain on its way out, and sprocket that was wearing quickly as well.
If the adjusters are tight, and the axle is tight, then the wheel cannot move.
mitt
Quote from: humorless dp on December 29, 2010, 04:45:31 PM
How many miles on the chain? Worn out chains require frequent adjustment.
Are you adjusting the chain correctly? A bike with stock ride height needs 25mm of chain slack at the tightest point (spin the wheel to find the tight spot).
That sprocket is worn out anyway. Time for a new one, and while you're at it replace the front sprocket and the chain.
Your issues will disappear.
You're probably right on the money, as usually.
My ride height is higher than stock -- just a little bit, less than an inch. So, what then -- how much slack should the chain have in the center if I've lifted the ride height? I never thought to spin the wheel to find the tight spot. I didn't realize it changed.
Both the chain and sprocket have a lot of miles on them. I wouldn't be surprised if it was over 10,000. I haven't replaced them yet and I've had the bike for 2 years now.
I will follow your advice. Hopefully I'll have the new parts on it by this weekend.
In the mean time I'll check all the bearings. It probably wouldn't hurt to just replace them regardless.
Are you definite that the wheel itself is moving? IE, have you looked at the adjusters and the marks and verified that it's moving? If they aren't moving, I'd bet the chain, being worn out keeps grinding into the roller pins. even fractions of a millimeter add up over 98 something links. That combined with all the other parts wearing down contributed.
Did you check the front sprocket as well?
Quote from: Michael on December 29, 2010, 05:10:27 PM
You're probably right on the money, as usually.
My ride height is higher than stock -- just a little bit, less than an inch. So, what then -- how much slack should the chain have in the center if I've lifted the ride height? I never thought to spin the wheel to find the tight spot. I didn't realize it changed.
Both the chain and sprocket have a lot of miles on them. I wouldn't be surprised if it was over 10,000. I haven't replaced them yet and I've had the bike for 2 years now.
I will follow your advice. Hopefully I'll have the new parts on it by this weekend.
In the mean time I'll check all the bearings. It probably wouldn't hurt to just replace them regardless.
You should increase your slack to at least 30mm.
There is a process to figure out the required slack exactly, but it really isn't necessary. My ride height is maxed out and I use 30mm.
Quote from: Michael on December 29, 2010, 05:10:27 PM
You're probably right on the money, as usually.
My ride height is higher than stock -- just a little bit, less than an inch. So, what then -- how much slack should the chain have in the center if I've lifted the ride height? I never thought to spin the wheel to find the tight spot. I didn't realize it changed.
Both the chain and sprocket have a lot of miles on them. I wouldn't be surprised if it was over 10,000. I haven't replaced them yet and I've had the bike for 2 years now.
I will follow your advice. Hopefully I'll have the new parts on it by this weekend.
In the mean time I'll check all the bearings. It probably wouldn't hurt to just replace them regardless.
Also, when you adjust your tension, you're snugging the adjuster bolt again after the axle is tightened, right?
Very hard for the axle to move if the adjusters are tight. Replace the chain/sprockets, snug up the axle bolt, tighten adjusters, then torque everything to spec, and Bob's your uncle. [drink]
Michael - Let me know if you need a hand installing the new chain, setting chain tension, etc. I have the chain rivet/breaker tools, etc. My observation would be that your chain/sprocket are simply worn out, and also note that you have an aftermarket rear sprocket on there which some heavy handed riders seem to wear out fast. I run aluminum and have not had problems, but have seen many examples of prematurely worn/broken aluminum sprockets.
Quote from: 671M900 on December 29, 2010, 05:12:51 PM
Are you definite that the wheel itself is moving? IE, have you looked at the adjusters and the marks and verified that it's moving? If they aren't moving, I'd bet the chain, being worn out keeps grinding into the roller pins. even fractions of a millimeter add up over 98 something links. That combined with all the other parts wearing down contributed.
Did you check the front sprocket as well?
I'm not sure that the wheel is moving, it just seems that way. The chain has gotten loose on so many occasions that I would be really surprised if the chain was simply stretching. The thing that has the adjuster marks isn't what I'd call reliably accurate, so it's hard to tell by that. You'd have to see it to know what I mean.
The hard thing, as was mentioned before, is that there are so many things going on at once it's hard to pin point a single issue other than old age.
Anyway, I did check the front sprocket, and no noticeable wear on that.
Quote from: erkishhorde on December 29, 2010, 06:24:05 PM
Also, when you adjust your tension, you're snugging the adjuster bolt again after the axle is tightened, right?
I am. :)
Quote from: Dietrich on December 29, 2010, 06:59:54 PM
Michael - Let me know if you need a hand installing the new chain, setting chain tension, etc. I have the chain rivet/breaker tools, etc. My observation would be that your chain/sprocket are simply worn out, and also note that you have an aftermarket rear sprocket on there which some heavy handed riders seem to wear out fast. I run aluminum and have not had problems, but have seen many examples of prematurely worn/broken aluminum sprockets.
D, that would be so awesome. I really want to go on the Tortilla Flat ride on Saturday. Do you have time between now and then?
I'm getting my parts through AZSBK, and I'm hoping they'll be in tomorrow. I'll let you know.
As others have said, replace the chain and sprockets, your existing parts are sacked.
Quote from: Michael on December 29, 2010, 08:07:25 PM
I'm not sure that the wheel is moving, it just seems that way. The chain has gotten loose on so many occasions that I would be really surprised if the chain was simply stretching. The thing that has the adjuster marks isn't what I'd call reliably accurate, so it's hard to tell by that. You'd have to see it to know what I mean.
The hard thing, as was mentioned before, is that there are so many things going on at once it's hard to pin point a single issue other than old age.
Anyway, I did check the front sprocket, and no noticeable wear on that.
Front sprockets are cheap and your chain will last longer if you replace everything as a set.
one day we'll have teleportation so when the thread gets posted we can all teleport over and stand around, nod knowingly and say things like "dude, it's rooted."
get a laser aligner too to make sure the chain is aligned properly.
You need the sprockets and chain anyway, and, unless the bearings are really bad, that wheel ain't moving. If that sprocket is aluminum, once the anodizing wears sprocket wear is rapid. On any sprocket, loose one tooth and the rest will follow shortly. After reassembly check sprocket alignment and wheel alignment just to be sure.
Quote from: brad black on December 29, 2010, 09:16:50 PM
one day we'll have teleportation so when the thread gets posted we can all teleport over and stand around, nod knowingly and say things like "dude, it's rooted."
get a laser aligner too to make sure the chain is aligned properly.
Struth!
Brad, you gotta be Australian. Am I right? [thumbsup]
Well, I like your teleportation idea (but hopefully it's not rooted).
And I love the thought of owning a laser alignment tool (http://www.amazon.com/LUSTERLACE-LASER-ALIGNMENT-TOOL-30007/dp/B000GVBV74), but I'll probably have to just make due with my ruler.
(http://www.motorcycle-superstore.com/productimages/OG/0000-Profi-Products-Laser-Chain-Belt-Alignment-Tool.jpg)
I suspect that IF your wheel wasn't straight the bolts that hold the sprocket in place would be digging into the swingarm either behind or in front of the axle.
As you mentioned the chain has been on a while, so that's the most likely cause for the frequent adjustments it requires, and the teeth rear sprocket might be breaking because of the skipping chain hitting them.
Good luck and keep us posted!
yes, australian.
the laser tools are only $90 or so on ebay.
I have the exact same bike as you, 96 m900. If you really think the back wheel might be moving a little, check both sides of the axle to make sure they are torqued to spec. I had one nut on there that was so tight I couldn't budge it. But it didn't necessarily spin the axle when tightening, so I could "tighten" that side to spec and the nut on the other side would still be loose. Last time I took the wheel off I made sure to take both nuts off, took some serious force to get the stuck one.
Just a possibility, but just because one side is tight doesn't mean the other is, good luck.
the centre bearing part of the axle is larger than the od of the threaded end parts where the nuts screw on, which is why the nuts can jam as xarlo says. it's a good point and something to be aware of.
Quote from: xarlo on January 01, 2011, 04:55:24 AM
I have the exact same bike as you, 96 m900. If you really think the back wheel might be moving a little, check both sides of the axle to make sure they are torqued to spec. I had one nut on there that was so tight I couldn't budge it. But it didn't necessarily spin the axle when tightening, so I could "tighten" that side to spec and the nut on the other side would still be loose. Last time I took the wheel off I made sure to take both nuts off, took some serious force to get the stuck one.
Just a possibility, but just because one side is tight doesn't mean the other is, good luck.
(http://ineedpopcorn.com/images/MythBustersS71.jpg)
That is a really good hypothesis.
If (hypothetically) I only tightened the left nut and failed to torque the right nut properly, then the right side might shift back a little twisting the wheel/sprocket enough to run into the chain.
I have adjusted the chain before while the bike was leaning on the kickstand (I was out of town, in a parking lot, with about an hour of riding ahead of me) and it could be plausible that I loosened the right nut and then forgot about it and only tightened the left. Maybe.
(http://www.bikebits4you.com/images/Chain%20Sprocket.jpg)
And I still think more than one thing is going on here --
1) There's the maybe-loose-right-nut theory to explain the chipped sprocket
2) Then there's also the age of the chain and the age of the sprocket
3) Also, I didn't realize the sag in the chain changed as the wheel rotated, so I might have adjusted the chain once, gone back to discover a looser chain and thought the wheel moved when it didn't.
So, it might be that I was assuming that two different symptoms were pointing to one problems, when in fact there were two separate problems.
*** UPDATE ***I put on a new sprocket yesterday and went on a good, long (fairly rigorous) ride this morning. The chain has the exact same sag as when I set it and the wheel is in the exact same place.
I spent a lot of time getting the alignment, torque, and sag perfect yesterday.
However, I still have the old chain -- which I intend to replace ASAP -- but it makes me think that a warn-out sprocket and my own bad wheel tightening practices are to blame.
SOLUTION:- New sprocket
- New chain
- Correct wheel/chain tightening technique
(http://image.motorcyclistonline.com/f/8863761+w750+st0/122_0310_Best_02z+Ducati_M900_Monster+Left_Side_Wheelie_View.jpg)
(This isn't me -- I don't wheelie)
(http://i329.photobucket.com/albums/l394/stopintime/poirot.jpg)