Chain wears the frame


17 replies to this topic
  • nostromo

Posted October 13, 2008 - 07:58 AM

#1

Hi Guys, I am a nubie, the site is a great help.
I have a 2008 450F with 300 miles only done the frame has lost a quarter of a inch due to the chain wear. Also when re jetting (taking the bike apart) i realised that the rear chassis was wearing thru also. The chain is tensioned right, the sproket is the correct way round, no play in bearings..
Has anyone else suffered or is mine the only one in the world as my dealer tells me? Thanks.:D

  • tribalbc

Posted October 13, 2008 - 08:17 AM

#2

Has anyone else suffered or is mine the only one in the world as my dealer tells me? Thanks.:D


No standard issue.

You have to make sure the chain is the right tension as per manual but the big one is to do your alighnment by measurement. The axle block's lines do not line up :worthy:
The easiest fix is to get some aftermarket axle blocks for easy chain adjustment. I got these from rocky mountain atv for $20. Well worth the money.




Posted Image

  • BajaFool

Posted October 13, 2008 - 10:29 AM

#3

Tribalbc,
Why do you believe that the aftermarket axle alignment blocks are any better than the factory blocks? Has you experienced an end to the chain rubbing problem since you changed to the aftermarket blocks?

I couldn't solve the chain rubbing problem on my 2006 WR and it is there on my 2008 WR after only 63 miles. Interestingly, I did not have the problem on my 2003 WR or any of the ten motorcycles that I had bought and maintained prior to owning the 2003 WR.

I believe that the cause of the problem is whipping from a chain that is too long to maintain its side-to-side rigidity. Yes, I know that the chains for the 2003-2008 are all 113 links + master link. However, I could go from a 50 teeth to a 52 teeth rear sprocket on my 2003 WR without adding a chain link and had to add a link to do the same thing on my 2006 WR. Something grew somewhere.

One thing that you have to do is use the alignment marks counting from the rear of the blocks, not the front. The right-hand block has 11 marks and the left-hand block has 9 marks in total. However, the marks are equally spaced on both sides, if you measure from the rear of the blocks. Additionally, if you look at the upper and lower alignment marks on the swing arm and compare their relative positions with the marks on the alignment blocks, you will see that they are not in the same location when compared to the nearest mark on the alignment block. You can't align the marks using the upper swing arm mark on one side and the lower mark on the other side, the chain will not be straight.

If $20 for new axle alignment blocks will solve the problem, I'm up for spending the money. But, I would like some reassurance that new blocks actually solved the problem and not just closer attention to alignment, when you installed the new blocks.

  • dazzabb

Posted October 13, 2008 - 10:55 AM

#4

http://www.thumperta...eating subframe

You're not alone!

  • msgbean

Posted October 13, 2008 - 10:56 AM

#5

Well said Bajafool. I don't know how many times I have read in this forum that the axle blocks don't line up. I have replied many times that the blocks are read from back to front but people insist on reading them from the front. I have an 07 and my subframe only has a couple of scratchs on it. Starting in 07 the amount of chain tention changed (10mm more) so it is not safe to just use the "three finger" method. I think if you maintain the proper tention and don't run a sloppy worn out chain the damage to the subframe will be minimized.

  • tribalbc

Posted October 13, 2008 - 04:23 PM

#6

Tribalbc,
Why do you believe that the aftermarket axle alignment blocks are any better than the factory blocks? Has you experienced an end to the chain rubbing problem since you changed to the aftermarket blocks?

I couldn't solve the chain rubbing problem on my 2006 WR and it is there on my 2008 WR after only 63 miles. Interestingly, I did not have the problem on my 2003 WR or any of the ten motorcycles that I had bought and maintained prior to owning the 2003 WR.

I believe that the cause of the problem is whipping from a chain that is too long to maintain its side-to-side rigidity. Yes, I know that the chains for the 2003-2008 are all 113 links + master link. However, I could go from a 50 teeth to a 52 teeth rear sprocket on my 2003 WR without adding a chain link and had to add a link to do the same thing on my 2006 WR. Something grew somewhere.

One thing that you have to do is use the alignment marks counting from the rear of the blocks, not the front. The right-hand block has 11 marks and the left-hand block has 9 marks in total. However, the marks are equally spaced on both sides, if you measure from the rear of the blocks. Additionally, if you look at the upper and lower alignment marks on the swing arm and compare their relative positions with the marks on the alignment blocks, you will see that they are not in the same location when compared to the nearest mark on the alignment block. You can't align the marks using the upper swing arm mark on one side and the lower mark on the other side, the chain will not be straight.

If $20 for new axle alignment blocks will solve the problem, I'm up for spending the money. But, I would like some reassurance that new blocks actually solved the problem and not just closer attention to alignment, when you installed the new blocks.



Since I've changed I've had zero wear on my frame/ subframe. I had it working with stock as well these just make it a no-brainer. And yes before I figured it out, I did get wear on the frame and subframe.

  • WR450FGreg

Posted October 13, 2008 - 10:05 PM

#7

.
The method we use with our roadracers is to ignore any axle block / swingarm marks and measure (with a tape measure) from the centre of the axle to the swingarm pivot on both sides.
Can't go wrong that way ..... generally.

(Ok, I've put my fire-proof suit on guys ... fire away, I'm ready!)


Greg

  • grayracer513

Posted October 14, 2008 - 07:16 AM

#8

This is mostly a chain alignment issue, although an internally loose, "whippy" chain can contribute to it. Under conditions of coast (decel), or light loads, the chain tends, because of its own inertia, to run off the sprocket it the direction the sprocket is pointed. If it points inward as it exits the sprocket, it runs that direction for about half the run to the front, then crosses over the center and curves outward in a wave sort of pattern.

The 'Fool is correct about the stock axle blocks. They're fine, but what a lot of people fail to notice about them is the they are different left to right. The drive side block has a ledge on the front to hold the axle from rotating as the nut is tightened, and so has one less mark on it, counting from the front. If you align the wheel by counting from front to back, it will point to the right. Count from the back.

You should take the time to precisely align the wheel once to verify the accuracy of the marks on any bike. Set either side block exactly on one mark, then align the wheel using only the other side and compare how well they match. If there is a difference, you can simply note it for the future.

The absolute most accurate means of aligning the rear wheel is by using either a straight edge or a rod clamped to the rear sprocket (chain off) or a similar jig that allows this with the chain in place. An error of 1/10 turn on the adjuster screw will be easily visible:

http://www.thumperta...ad.php?t=548940

Measuring from the swing arm pivot as suggested earlier is also reasonably accurate if done carefully.

Neither of my '06 YZ450's have a major problem with this, and I checked the alignment of both of them early in their life.

  • MountainMax

Posted October 14, 2008 - 07:37 AM

#9

you can buy cheap teflon blocks to save your frame, that's what i used anyhow

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • BajaFool

Posted October 14, 2008 - 02:11 PM

#10

WR450FGreg,
Yes, this is a good technique. Usually, there is too much stuff in the way or the necessary bolts aren't hollow to use the swing arm pivot bolt and the axle bolt. I just looked at the 2008 WR however, and it looks like you could stick a metal rod through the swing arm bolt and the axle bolt and make a measurement. The hole in the swing arm pivot bolt will just take a 25/64" drill, I didn't measure the hole in the rear axle nut.

My rear axle alignment is off 1/2 millimeter left to right, using a dial caliper and measuring from the last scribe mark on the alignment block and the forward face of the axle adjustment slot next to the lock nut on the adjustment bolt. I don't think any closer would make a difference in my chain alignment.

Just to check another way however, I went to Home Depot and bought 30" of 1/4" zinc coated steel rod. Then, after ensuring that it was straight (I rolled it on the stone kitchen counter top), I rolled the 2008 WR a few feet and laid the steel rod on top of the chain and to one side. Then I looked for any crooked places--- straight as an arrow.

After checking to my satisfaction that the chain was adjusted and was as straight as possible, I put the bike on a stand. Then I took the lower end of the rear shock loose and moved the rear wheel through its complete range of travel. At 48 mm, there is no bind whatsoever on the chain. Everyone should make their own test of this, but I think everyone who does this will find the same thing and will conclude that you can go a little under the 48 mm minimum on the chain tension without running the risk of pulling the countershaft out of the motor.

Finally, I wonder how many folks are NOT measuring the chain tension correctly? The specification reads, " 1. Elevate the rear wheel by placing the suitable stand under the engine. 2. Check: drive chain slack "a" above the seal guard installation bolt, out of specification--- Adjust. 3. Adjust: drive chain slack." Note in the illustration that measurement "a" is taken from the top of the seal guard installation bolt and to the bottom of the chain. In the old days, when men were men and women were glad of it, it was common to measure chain slack by first using the bottom of the chain as "0" and then pulling up on the chain and recording the distance that the chain travelled. This number was then compared to a factory tolerance. If you perform the chain slack measurement in this fashion on your Yamaha WR, because that's the way you did it in the old days, you have a chain that is much too loose.

Grayracer513, I like your idea for using the rod with the chain off the sprockets, I might try that for a final final test. However,I think my chain is running about a straight as possible, with the adjustments available.

  • grayracer513

Posted October 14, 2008 - 03:34 PM

#11

In the old days, ... it was common to measure chain slack by first using the bottom of the chain as "0" and then pulling up on the chain and recording the distance that the chain travelled. This number was then compared to a factory tolerance. If you perform the chain slack measurement in this fashion on your Yamaha WR, because that's the way you did it in the old days, you have a chain that is much too loose.

The chain's actual slack can't be measured on the aluminum framed WR/YZF models as it was back in the day, simply because when the is set at the upper end of the spec'd limit, it lays on the swing arm when pushed down, and is not true slack. Thus, the method of measuring up to the lifted chain from the swing arm. The method in the manual is simple and repeatably accurate, and the specs given are taken from the method you outlined, swinging the arm through its travel and measuring actual slack at the tightest point. But Yamaha is not looking for a "non-binding" condition like the one you mentioned. Their criteria is the standard 1/4" of true slack per foot of free chain at the tightest point of the suspension travel, or about 1/2" in this case. If you set that up, you'll find it comes out very close to 1.9" (48mm) when measured by the book.

I made a simple gauge block for my tool box out of a piece of hardwood on a table saw. It's 2" one way, 2.5" the other, and I use it as a simple go/no go gauge. (I run the chain a little looser than called for).

  • BajaFool

Posted October 14, 2008 - 07:53 PM

#12

Grayracer513,
I like the go/no go gauge idea. I assume that you made an "L" shaped tool, that is 2" on one leg and 2 1/2" on the other leg? If you wanted to make a go/no go gauge to the tolerance, it would be 1 7/8" (1.890" or 48 mm) one way and 2 1/4" (2.283" or 58 mm) the other way.

  • grayracer513

Posted October 15, 2008 - 05:12 AM

#13

It's just a block of wood about 4" long. Instead of being a 2x4, it's cut so that it measures 2" x 2.5". I know the book specs are 1.9" x 2.3", but those are my specs.

  • BajaFool

Posted October 15, 2008 - 10:26 AM

#14

Grayracer513,
Thanks for the information on the measuring block. Looks like I have another project for the day, along with putting heavy duty tubes in the tires on the new bike.

  • Charles De Mar

Posted October 15, 2008 - 01:46 PM

#15

I have a couple little nicks on my '06 subframe but nothing leaving me the idea the sub frame will fail anytime soon. I'm not a big heavy guy that would cause much deflection in the frame, swingarm or sub frame. I have had my wheel off a thousand times. I have even done trail side flat repairs and no munching. Just a few nicks:excuseme: any of you guys with the munching problem taken some hard falls that could have defected the subrame slightly out of factory spec?

  • grayracer513

Posted October 15, 2008 - 05:28 PM

#16

The '06 WR is the steel frame, and is a somewhat different thing. The sub frame hard points on the steel models are lower, so on the one hand, the sub frame on the steel models suffers more chain contact. However, the inside of the frame's swing arm pivot gusseting is a wide, flat, steel surface with rounded edges facing the chain, and it makes contact at about the same time or sooner than the sub frame does. Plus, I believe there's a little more space there.

By contrast, the chain contact on the aluminum bikes takes place on the back side of the sub frame mounting lug, below the sub frame itself, and on the edge of the swing arm mounting casting, which is essentially a "C" channel section piece, and wears fairly quickly. (see the second picture in the link I posted).

  • Charles De Mar

Posted October 16, 2008 - 06:32 AM

#17

The '06 WR is the steel frame, and is a somewhat different thing. The sub frame hard points on the steel models are lower, so on the one hand, the sub frame on the steel models suffers more chain contact. However, the inside of the frame's swing arm pivot gusseting is a wide, flat, steel surface with rounded edges facing the chain, and it makes contact at about the same time or sooner than the sub frame does. Plus, I believe there's a little more space there.

By contrast, the chain contact on the aluminum bikes takes place on the back side of the sub frame mounting lug, below the sub frame itself, and on the edge of the swing arm mounting casting, which is essentially a "C" channel section piece, and wears fairly quickly. (see the second picture in the link I posted).


I disagree
http://www.thumperta...nching subframe

  • grayracer513

Posted October 16, 2008 - 06:39 AM

#18

With what?




 
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