Full stop, all engines reverse - clanging sound ?

[normzone]

I was struggling to describe my morning's braking system validation exercise...it wasn't a panic stop, although I'm sure some onlookers thought so. I wasn't panicked - I had full confidence in my ability to stop.

And it wasn't an emergency stop - I was stopping, and there was no emergency. Just a driver beginning a really aggressive roll out of the turn lane right before I got there. I'm certain he meant to pass behind me as I went by, but I saw no reason to believe my eyes - he was moving pretty good. So I nailed the brakes and we looked at each other.

He did the usual " go ahead, go ahead " wave. I shook my head no and he went. I doubt he learned anything. Perhaps I could have followed him into the carwash and explained my decision, but I just went on my way.

But while we were in full brake mode, the bike made ... a clanging sound, or sounds. I'll have to see if I can recreate it on the way home. There's nothing in the saddlebags that would do that, and my vibrating exhaust baffle (that's my theory for the annoying buzz that happens in a certain point in the rpms) wouldn't sound like that.

 

[Triple Jim]

Was your clutch disengaged during the braking?  I once hit the brakes in my '74 Vega really hard while going about 30 on wet pavement, and didn't get my foot on the clutch pedal in time.  The rear wheels locked suddenly, so the spinning engine, transmission, and differential suddenly faced locked rear axles.  The result was missing teeth on both the pinion and ring gears in the differential.  Luckily I found a replacement complete rear end for $100 in a junk yard.

I'm not suggesting that you actually broke something, but a clank may have been the result of some driveline snatch if your clutch was still engaged.

[normzone]

Well, the clutch handle was fully engaged. Whether or not the clutch mechanism was fully engaged is unknown. I would think that the lag time would be minimal. But I shudder to think that the sound(s) I heard might have come from drive line.

  I guess there's a practice stop in the cards on my way home.

[Triple Jim]

Well, the clutch handle was fully engaged. Whether or not the clutch mechanism was fully engaged is unknown. I would think that the lag time would be minimal. But I shudder to think that the sound(s) I heard might have come from drive line.

  I guess there's a practice stop in the cards on my way home.

I'm not sure I'm understanding you.  By "clutch engaged" I mean the plates are squeezed together and the engine is connected to the transmission. 

[normzone]

Yeah, my terminology might not be helping.

The clutch handle was pulled to the handlebar as far as it would go, and the foot and hand brake were asked to show their stuff. I'll have to check for skid. Sounds like a great excuse to leave work early today, thank you.

 

[Triple Jim]

Ha, if I helped with that excuse, I'm glad.  As long as you pulled the clutch lever to the bar as you applied the rear brake, you avoided the problem I created when I braked without pushing the clutch pedal.

[oldbike54]

 Just about 5 minutes ago a car pulled out in front of me . All of the skills developed over 48 years of riding kept if from being a crash . Was watching the car for movement , so when it happened I was already on the brakes . A few choice expletives were said as she cut across my bow , but we missed by 5 feet or so .

 Dusty 

[Huzo]

What were you on ? Does it have ABS ?

[oldbike54]

What were you on ? Does it have ABS ?

 Which one of us , Norm was on a Bassa , I was on a Jackal , so no ABS .

 Dusty

[Huzo]

Which one of us , Norm was on a Bassa , I was on a Jackal , so no ABS .

 Dusty

Sorry Dusty I was thinking of Norm, just wondered if the abs was locking/unlocking and sending the shocks through the drivetrain but no go. Couldn't possibly have been the head stem races could it ? You'd think not...

[normzone]

Glad you're okay, Dusty, and able to post about it.

That's one of the reasons I don't feel too bad about the occasional full stop I practice when somebody rolls out as I'm approaching.

Someday when I'm assuming they're intending to go behind me I could be wrong. I'd rather have the suspicious reflex enabled, than the trusting one.

I love the way they wave you to go on, when you're stopped in the road eyeballing them. Why would I trust them enough to put myself in their sights again ?

I sure hope not, [Huzo]. That would be pretty loose, I would think, and the bike only has 60K miles on it.

[Doppelgaenger]

I've heard those sounds you describe the few times I've locked up the rear wheel. I thought something had broke the first time I heard it but all was fine. You can also get it to make similar sounds if you put the bike into gear up on the center stand, which I did once out of curiosity.

Disclaimer: Neither of these things should be done on purpose!

[Triple Jim]

Couldn't possibly have been the head stem races could it ? You'd think not...

That sounds possible.  I've heard clunks from them on at least one motorcycle I rode.  It's probably worth checking to find out.

[oldbike54]

 Norm , any chance it was more of a Cunka Cunka sound ?

 Dusty

[Bulldog9]

If it only happened when you were hard on the brakes it is a normal sound  when you lock up rear tire without pulling in clutch. Been riding shafties exclusively since the 80's (Yamaha XS1100, 850, 750, ZG1000 Concours, FJR 1300, Norge, Griso) all have done this.  Just driveline lash from locking up tire. If the sound is there while riding and accel/decel, then you probably have a problem.

[OlDogface]

If it only happened when you were hard on the brakes it is a normal sound  when you lock up rear tire. Been riding shafties exclusively since the 80's (Yamaha XS1100, 850, 750, ZG1000 Concours, FJR 1300, Norge, Griso) all have done this.  Just driveline lash from locking up tire. If the sound is there while riding and accel/decel, then you probably have a problem.

 :1:

[normzone]

Thanks [OlDogface] and [Bulldog9] - and I've some more clues to add to the investigation.

I went by the location (excuse to leave work early !) to look for tire marks but the area had been resurfaced recently and all was dark.

So I did a few recreations on the way home - and something was making noise up front.

There's unmistakeable marks where the Swanee fairing is riding down past the front fork seals - at this writing on both the seals and the fairing. When I got the bike I noted some marks on the fairing in that interface zone, but chalked it up to vibration evidence or some such thing.

Perhaps I'll try adding a click to the compression.

Dusty - will you please tell me more about the " Cunka Cunka " ?

[oldbike54]

 "Cunka cunka" happens if the engine gets down below a certain RPM when the bike is in gear and the clutch engaged .

 Cunka cunka cunka cunka , usually followed by CUNK , then nothing .

 Dusty

[Tom H]

Dusty,

Never had that sound on my oldies, but the Cali will do it if I'm going too slow for the gear. Like I'm idling up to a stop light and should have hit neutral or at least pulled in the clutch. This usually happens when I messing with my helmet strap or the like with my left hand.

Now I have had the "didn't get the clutch pulled in fast enough" moment on the oldies when I had an "O Crud" moment and hit the brake before the clutch while trying not to nail some @#!%^ in font of me.

Tom

[oldbike54]

 Tom , the worst case of "cunka cunka" I ever heard was a few years back . A friend was riding just about 8 bike lengths ahead , and began to act really weird . He was simultaneously both gyrating , hopping up and down on the seat , slapping himself , and some other very strange motions . Couldn't figure out what he was doing , simply slowed down at his rate of decel . At a very slow speed we were almost side by side as I attempted to figure out what was going on . His Guzzi was still in high gear , and we were probably doing 5 MPH , the bike making the "cunks cunka" noise in dramatic fashion . He came to a very sudden "cunk" stop , almost fell over , but managed to get a foot down     I really thought he was having a serious medical issue , but it turns out a wasp had flown into his jacket , causing all of the chaos . Instead of pulling in the clutch , his left hand was busy swatting at the wasp . All pretty funny later 

 Dusty

[Murray]

If not ABS I suggest the front forks slamming into their end stops.

[Wayne Orwig]

My thought is the rear tire was skipping, and you didn't notice. The backing plate that the brake caliper mounts to is pinned in place. There is slop in that pin and the plate was just clanging back and forth on the pin as the tire grabbed and let go.

[Tom H]

Dusty: LMAO!!! Sure it was not that funny for him!! Once rode through a flight of bees. Glad I had a shield and ducked under it, it sounded like a mess of BB's hitting the shield.

Tom