Swingarm eaten by chain

Here are my pictures :


and my chain roler is still there :


My boyfriends WRR as started to do the same thing :


I saw that you're talking about backing-in... can it be a cause to this ?

Because in supermoto we are backing-in a lot....

Heoz wrote:

What size sprockets are you using? I keep the chain 8mm from the swingarm and I'm using stock sprocket sizes. It was dug in fairly deep considering the bike only had around 100 miles on the clock when I noticed it. Seems the wear basically stopped after I did the first chain adjustment/lube. But, I also started coating the slider at the same time. I've worn out trail wings and replaced them in the mean time and the slider still looks good.

Stock gearing.

motokid wrote:

14mm means your on the tight side.

I'd rather be loose.
I bet I'm not more than 1/2 an inch from swingarm.

My slider lasted 10,000 miles and I engine brake a shit-ton. Starting to push the limits of breaking that rear loose and begin to feel some "backing in"

It's used for road racing and around town. I'd run more slack if it saw off road use. I can probably get 20k out of the swing arm slider at this rate.

Marylucky wrote:

I saw that you're talking about backing-in... can it be a cause to this ?

Because in supermoto we are backing-in a lot....

Think about this for a second.

Under acceleration the chain is pulling hard on the top to rotate the wheel.
More slack underneath.


Under deceleration the slack would be on the top side of chain and the taught part of the chain would be on the bottom of the swingarm.

I can't see any way the chain could eat that part of your case under engine braking or "backing it in".

I'm shocked your chain could hit that part of your case at all.

motokid wrote:

I'm shocked your chain could hit that part of your case at all.

She also rides offroad, my guess would be that this damage is more likely from a loose chain at full suspension droop (like a jump/whoop).

Arkmage wrote:

motokid wrote:

I'm shocked your chain could hit that part of your case at all.

She also rides offroad, my guess would be that this damage is more likely from a loose chain at full suspension droop (like a jump/whoop).

Then why don't more R riders see this kind of damage to their cases and/or the bolts that hold their Sandman covers on????

There's a lot of R riders here.

Anybody seen this kind of chain rub in THAT spot?

Based on the feedback above, it may be fair to say normal wear on top of the slider is from engine braking. For abnormal wear, I'm thinking chain adjustment/lube or a kink in the chain.

I use engine braking extensively with the exception being when a cage is too close behind. And just to be clear, I wasn't suggesting that engine braking is a bad thing, just that it seems logical that the chain is very loose on the top during engine braking so it will naturally end up rubbing the top of the slider. Thanks for the info on how your sliders wore on top!

Marylucky
I popped off the sprocket cover on mine and took a peek at that bolt receptor dealie and I don't see any marks. Same with the cover - no chain marks. While I don't back-in on the street, I use engine braking for all that it's worth.

My first thought would be a really loose chain. But, I'm having a hard time with that being the sole cause. Seems the chain would be slapping or something else noticeable before the point it would touch. Conceptually, something like going from full closed throttle engine braking with possibly the back brake thrown in to WOT might be able to create enough slack there for a short period of time during the transition. But even that seems like a reach. I hope someone has a definitive answer. I'm getting the popcorn out.

One thing I noticed in your pictures was a lack of case savers. Is that so you can swap in larger counter sprockets?

I don't really ride mine hard on the street. I do ride it hard in the dirt and that includes some decent air time.

motokid wrote:

[...]

I can't see any way the chain could eat that part of your case under engine braking or "backing it in".

I'm shocked your chain could hit that part of your case at all.

Yeah, I can't imagine backing it in on a track would cause that. But then again, I have no idea what could cause that. Seems to me that the chain would have to be very loose to get down that far, given where the front sprocket is and the lower chain roller/tensioner behind it. But I'm no expert, by any means. Mine certainly isn't like that, but I don't ride it on a track; for me it's either paved road getting to off-road, or off-road, or gravel road. Hell, I never even see chain marks in the accumulated chain-lube and crud on top of that stud, let alone on the stud itself.

Add me to the list.

10,000 miles on original chain and sprockets. Got lazy checking. Knew the chain and sprockets were shot but went for several long street rides at high speeds (4-5 hours at 70+ mph). Dumb ass!!

Did High Five's swing arm maintenance and discovered this:


Most important Q I have is this: I filled the damage with JB Weld, then smoothed and contoured with dremel. Do you think this is safe or do I need a new swing arm?

I think as long as you haven't worn through the bearing wall surface you'll be fine.

I would go with the "fix" you've described.

But your own personal feeling of "safe" is something that's hard to put a price on.

Kinda like putting a plug in a punctured tire. Some people would replace tire, some people would ride on plug for thousands of miles without a second thought.

Mine was at least that bad and I patched it with JB weld 2 years ago.

After numerous curbs, potholes, and jumps (including a few loading dock drops of 4+ feet) there is no evidence of cracking or other stress that would give me cause for concern.

You'll be fine.

motokid wrote:

But your own personal feeling of "safe" is something that's hard to put a price on.

Very true. In most cases I would just pop for the $50-100 for the peace of mind but in this case it's about $600. I'm in the process of gearing up for overnight camping off the bike so I'll be out enough $$$ for that.

The grooves were approx. 10-20% of thickness of bearing wall.

I added a few brief comments to the swing arm maintenance thread here if anyone is interested.

Gents, thanks for the replies. I was confident in my repair but I'm new to this and your assurances helped.

You could take it to a welder and have them weld the grooves up, it'll be as strong as new if your worried about it.
I'd just run it as is, theres lots of meat left for strenght, IMO it wont break.

Biglake wrote:

You could take it to a welder and have them weld the grooves up, it'll be as strong as new if your worried about it.
I'd just run it as is, theres lots of meat left for strenght, IMO it wont break.

I wouldn't do that. Without being welded and normalized in a jig there is no way to know if it will warp the swing arm until the damage is done. You'd also have to re-machine the bearing area afterwards.

Not sure if Yamaha did any post weld heat treat that you'd be throwing out the window.

I took mine off today for linkage maintenance, this is what it looked like.

wristpin wrote:

I took mine off today for linkage maintenance, this is what it looked like.

Miles on bike? Sprocket sizes? Chain maintenance? What does the guard look like? Repair plan?

I posted back on page 3 of this thread.

Bought a 08 with 10k miles yesterday. All stock. Checked the swingarm a few minutes ago. How bad is it?... im gonna cry




These pics came out messed up, but ill clean it and take more tomorrow. Hopefully you can still see my swing arm has some nice cuts in the metal. What the hell do i do... i have no extra money after buying the bike yesterday.

click me

The above thread shows pictures of a new slider off bike.

You NEED a new slider. About $40 from the right web site.

As far as filling in grooves....doe what the others here have done.

motokid wrote:

click me

The above thread shows pictures of a new slider off bike.

You NEED a new slider. About $40 from the right web site.

As far as filling in grooves....doe what the others here have done.

Think i can survive with just a new slider and frequently checking if its good/if my chain is in place?

Also, this slider works correct?
http://www.partzilla.com/index.php?p=product&id=755244&parent=1&is_print_version=true

You've got to get that slider off to get a good look at the swing arm.

Where in Florida do you live? I'd be happy to help if this is new to you. I just repaired mine.

gatorfan wrote:

You've got to get that slider off to get a good look at the swing arm.

Where in Florida do you live? I'd be happy to help if this is new to you. I just repaired mine.

Thanks man, I live in South FL, but I'm moving to Orlando in around 5 months. I have a truck as a daily driver, i won't ride the WRR too much. I also will be up in Orlando a few times in the next few months to check out places to live. I could go by Gainesville no problem. Think i could be alright with a new slider until we could meet up and you could help me with a weld (if you don't mind)? I'm a kid from Ft. Lauderdale, i've never even met anyone with any welding skill.

JB Weld is an epoxy.... it's not really actually welding the swingarm.

Just filling in the grooves with epoxy that's gets hard as hell.

motokid wrote:

JB Weld is an epoxy.... it's not really actually welding the swingarm.

Just filling in the grooves with epoxy that's gets hard as hell.

Oh, i have used epoxy on a few wakeboards and skimboards before. Its great to fill cracks in fiberglass. Never heard of JB weld. Could i do the same for the swing arm? I would have thought it would peel with the chain rubbing against it, but the above results don't look bad.

DestinationOffroad wrote:

motokid wrote:

JB Weld is an epoxy.... it's not really actually welding the swingarm.

Just filling in the grooves with epoxy that's gets hard as hell.

Oh, i have used epoxy on a few wakeboards and skimboards before. Its great to fill cracks in fiberglass. Never heard of JB weld. Could i do the same for the swing arm? I would have thought it would peel with the chain rubbing against it, but the above results don't look bad.

With a proper chain slider, the chain should never rub against any part of the swingarm.

http://www.jbweld.com/ <-- clicky

Just know that the chain slider is a wear item. It's got to be checked with some regularity and replaced occasionally.
Chain adjustment is crucial to longevity of the slider. Poor chain maintenance will result in slider needing to be replaced more often.

Check out this entire thread and you can see pictures of repaired swingarm damage.
Look into the JB Weld, and for sure buy a new slider. Also, check your chain tension/adjustment.