Non-periodic, loud grinding/clunking noise from chassis/transmission

[grommit]

I have an '03 with 25,000 miles on clock. Last week I had a 3K miles ride under heavy load (two up, side cases, top case) cruising peacefully at about 100mph.

At the 2,5K mile of my trip I start noticing an infrequent (every 5-10 secs), non-periodic, loud metallic grinding or clunking somewhere in her bottom part. It can be heard clearly at low speeds (up to 20-30 mph). Its frequency correlate with neither bike speed nor engine revs. It's best heard when engine is off and bike is slowing down. It seems to occur less frequently when bike is actively ac/decelerating. It is heard clearer when bike is heavily loaded.

I've checked a free play on both wheels, front fork & steering column - everything is as solid as a Kremlin wall.

I could not reproduce this noise by rotating wheels by hand, putting bike on its center stand.

However, whilst on center stand and revving rear wheel by engine, I can hear quite similar clunking coming from some point between the center of the engine up to pumpkin. The higher is the gear, the clearer is this clunking.

As I rode towards home, this noise becomes more frequent and loud. Luckily, I managed to reach home and I'm now ready to unbolt my beauty and [hopefully] cure her.

After reading the forum and thinking it over I'm suspecting a u-joint or wheel bearing failure.

What I need is an advice on how to pinpoint the cause of this noise?

Thanks,

Grommit

 

[wfooshee]

U-joint in the drive shaft? That's my first thought. It's also the cheapest, so good luck!

 

[C&C]

Universal was what came to mind, for me, also. Vibration/thumping are generally "U" joint symptoms.

 

[RadioHowie]

Vibration/thumping are generally "U" joint symptoms.

So are tires with separating carcasses. :dribble:

 

[grommit]

So are tires with separating carcasses. :dribble:

Well, I did not change tires. That noise just came from nowhere, no obvious causes.

 

[grommit]

Universal was what came to mind, for me, also. Vibration/thumping are generally "U" joint symptoms.

Did anyone experience a u-joint wear/failure? I have not found any cases documented here so far.

Anyway, will disassemble the drive shaft system (with excellent fjrtech instructions) and let you guys know what happens.

 

[Ignacio]

id anyone experience a u-joint wear/failure? I have not found any cases documented here so far.

I remember one or two failures with bikes >50K.....prior to the first U-joint at the output shaft. Maybe one of those U-Joint failure, but it was a high-mileage '03.

 

[grommit]

I remember one or two failures with bikes >50K.....prior to the first U-joint at the output shaft. Maybe one of those U-Joint failure, but it was a high-mileage '03.

Well, odometer reading on my FJR may well me screwed down. So she may potentially be an over 50K miles old beauty. You never know.

BTW, I replaced the CCT because of infamous chain noise - the old CCT felt much softer than the new one. That may be another evidence for her higher miles...

 

[Fred W]

Based on your description of the symptoms it really could be anything in the drive line. The fact that the noise lessens when either accelerating or decelerating is the clue there. I think the good news is that any lash in the final drive itself would be relatively well muffled by the pumpkins case and lubricant. That makes the very most likely candidate the u joint at the front end of the drive shaft as previously mentioned. It's pretty easy to get at, might as well take it out and give it a feel, etc and see if you can get a warm fuzzy feeling that replacing it will be money well spent.

The good news/bad news part of all of this is that not too many folks have ever had drive line problems on an FJR. So you are delving into fairly unexplored territory. I mean, this ain't no Bayrishe Motor Werken bike you know...

 

[Constant Mesh]

If the U-joint bearings were in such poor condition that they made grinding noises the joint would be so loose and clunky that it would be obvious when moving the rear wheel back and forth on the centerstand.

I've often wondered just how long the middle drive spring-loaded cam system will go before it develops a looseness which is unacceptable. The middle drive cam will offer a clunking noise too.

I can't imagine riding with a passenger at 100 mph.

 

[grommit]

If the U-joint bearings were in such poor condition that they made grinding noises the joint would be so loose and clunky that it would be obvious when moving the rear wheel back and forth on the centerstand.

I can feel/hear certain lash somewhere in transmission system when moving rear wheel back and forth. I'm not sure how much lash is too much. I can't produce such a scare, loud clunking when turning rear wheel by hand.

Anyway, I'm going to get the u-joint out and examine it. Will post a photo if the u-joint appears in an interesting condition.

I can't imagine riding with a passenger at 100 mph.

In Germany, they built an absolutely perfect highways all across the country. These are designed for high speeds. Urban legend says that there is no official speed limit there so you won't get a ticket for speeding (unless getting involved in an accident) but locally sold cars must have ECU programmed not to exceed 150 mph.

Also the drivers are mostly disciplined and friendly. Motorcycle riding habit there does not seem to have a heroic/carelessness perception in society, which is quite contrary to how it is in my country.

Sorry for offtopic.

 

[bikesniffer]

If the U-joint bearings were in such poor condition that they made grinding noises the joint would be so loose and clunky that it would be obvious when moving the rear wheel back and forth on the centerstand.

I can feel/hear certain lash somewhere in transmission system when moving rear wheel back and forth. I'm not sure how much lash is too much. I can't produce such a scare, loud clunking when turning rear wheel by hand.

Anyway, I'm going to get the u-joint out and examine it. Will post a photo if the u-joint appears in an interesting condition.

I can't imagine riding with a passenger at 100 mph.

In Germany, they built an absolutely perfect highways all across the country. These are designed for high speeds. Urban legend says that there is no official speed limit there so you won't get a ticket for speeding (unless getting involved in an accident) but locally sold cars must have ECU programmed not to exceed 150 mph.

Also the drivers are mostly disciplined and friendly. Motorcycle riding habit there does not seem to have a heroic/carelessness perception in society, which is quite contrary to how it is in my country.

Sorry for offtopic.

Some stretches of highway in Germany have indeed no speed limit, hence not an urban legend.

Drivers are not as friendly as you say, however if drivers in Germany see a motorcycle in their rear view mirror they almost always scoot to the right to signal that you can pass them (especially on 2 lane surface roads).

The highways in the US are just as perfect as the ones in Germany. In Germany most highways have 2 lanes and you can't pass a car in the right hand lane (illegal). By only having 2 lanes as opposed to 4 in the US where cars weave in and out of lanes from left and right, it's easier to scan what's happening on a German freeway because slower traffic needs to stay in the right lane.

 

[RadioHowie]

In Germany, they built genetically perfect highways all across the country. These are designed for high speed access to Poland and the Russian frontier.

 

[bikesniffer]

In Germany, they built genetically perfect highways all across the country. These are designed for high speed access to Poland and the Russian frontier.

hahahaha yes almost 72 years ago...and got their *** kicked on the return trip 66 years ago (their own very special Route 66)

Alfredo

 

[grommit]

If the U-joint bearings were in such poor condition that they made grinding noises the joint would be so loose and clunky that it would be obvious when moving the rear wheel back and forth on the centerstand.

I've removed left peg to see how u-joint is doing. As far as I can tell, it appears quite normal to me - no lash could be felt, no broken bearings visible. Here's a picture of my u-joint:

So these grinding noises might be coming from the rear part of the engine. However, I am not absolutely convinced that the noises I hear whilst running bike on central stand are bad ones. That's because I re-examined the front wheel bearings and the right one seems to be a bit loose when wheel is in certain position.

I'm going to remove the front wheel tonight to see the bearings.

 

[RadioHowie]

NICE close-up photo.....what camera?

 

[wfooshee]

You can't see bad u-joint bearings. Those roller bearings could be ground to dust for all you know looking at it. It may not be the problem, but it's not too hard to get at it. Remove the rear wheel, then remove the rear drive (4 acorn nuts, and the whole thing slides back, pulling the shaft out with it, then the u-joint slides out of the case. In your hand any problem will be obvious as sticky motion in the spider.

And RH's earlier comment about tire carcass may be valid, but I'd expect a definite periodic thump from something like that, and obviously related to road speed. He didin't say you changed your tires, he brought up the possibility of the tires you have maybe coming apart, delaminating. Not common, but not unheard of.

 

[grommit]

NICE close-up photo.....what camera?

That's Pentax WS80. I'd not recommend it as its CCD is extremely noisy in low-light conditions.

 

[grommit]

You can't see bad u-joint bearings. Those roller bearings could be ground to dust for all you know looking at it. It may not be the problem, but it's not too hard to get at it. Remove the rear wheel, then remove the rear drive (4 acorn nuts, and the whole thing slides back, pulling the shaft out with it, then the u-joint slides out of the case. In your hand any problem will be obvious as sticky motion in the spider.

My testing method was to lock the front part (engine-ward) of the u-joint with a screwdriver, then turning rear wheel by hand and trying to feel any free play in u-joint.

But I agree that the approach you suggested is much more precise than mine. I'll follow it once I replace the loose front wheel bearing and if that clunking won't go away.

And RH's earlier comment about tire carcass may be valid, but I'd expect a definite periodic thump from something like that, and obviously related to road speed. He didin't say you changed your tires, he brought up the possibility of the tires you have maybe coming apart, delaminating. Not common, but not unheard of.

That's right. I just misread RH's comment.