Loud clunk

[6 banger]

Anyone ever had a loud clunk sound come from the rear of the bike after the bike has sat for a few minutes after a long or short ride? It sounds like the driveshaft is bound up and it's releasing. The bike has 14000 miles on it and I bought it off my dad with 9000 on it. I know he put a new tire on it at 7000 which included the usual maintenance being done at the same time. Just wondering if anyone has experienced the same thing or might know what to check.

[R J]

Sounds like the exhaust pipe is snapping at ya as it is cooling down.

[fordmano]

Yep temp change would be my guess,, it might be running hotter than designed too. Might want to have the carbs synched and verify that your not running lean or overly rich. Are you forgetting to turn the choke off as soon as posible? I forgot to turn the choke off a LOT (ie: very often) before I had the carbs synched and figured out I was leaving it on now my stock pipes look like garbage. I used to hear the banging noises as the cannisters contracted back to normal shape and size...

You can see the yellowing of the cannister cover on this side it is a lovely golden color.

And here you can see the damage caused on one of the pipes from running lean with the choke off and also running overly rich because I left the choke on for WAY too long so many times. Both those conditions will cause excesive amounts of heat to buildup in the pipes.

[Ricky-D]

He was talking more about a clunk I think rather than the exhaust Fordmanco,,, but this is not criticism in any stretch I assure you. Sometimes my exhaust does the same. More like a ting!

I think that the possible noise from completely unwinding the drive train, then simultaneously loading it up when taking off, to me, can produce a pretty loud and surprisingly unnerving jolt.

There have been occasions when this exact thing has happened to me, mostly when navigating a turn or sharp curve.  Like: What the hell was that!

Trying to replicate it is seemingly impossible.

I wonder if anyone has lifted their Valkyrie off the floor to see what the total amount of free play they have in the total drive train.  I haven't, but the next time I lift the bike I am going to do that exact test to see how many degrees of rear wheel turn (free play) there is in my bike when in 5th gear.

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[6 banger]

Its definately not a "TING" sound but more of a heavy metal sound.  Still gonna get the carbs synced because its a good idea and have my mechanic investigate further on the drivetrain.  Will let you know what I find out.  Thanks guys.

[nugz]

had that same clunk about to weeks ago. thought it was the u joint, found out it was the drive shaft were it enters the rear cup. ended up replacing the drive shaft and top cup of the final drive. dealer said it happens when the seal around that cuo goes out. hope this helps and hope you dont have to go threw this.
nugz
sturgis sd

[Cholla]

May not be the same sound source, but I had a metal snap/muffled clunk sound from the rear when I switched from OEM to aftermarket dampners.  The pegs of the final drive flange were binding in bushings of the dampners (evident by rub marks too) because they weren't perfectly centered and had zero give.  I had to use a rubber mallet to pound the final drive flange into the aftermarket dampners, that should have raised a red flag right away .  Switched back to OEM dampners and all's quiet again. 

[Walküre]

Anyone ever had a loud clunk sound come from the rear of the bike after the bike has sat for a few minutes after a long or short ride?

YES!!! - that's the whump sound of my a$$ catching up with me!! 

Gotta love these bikes!

(sorry, couldn't resist! I've never gotten that noise out of mine)

[fordmano]

I am just curious why the drive train would "unwined" after it has set for a few minutes and not within a few seconds (or less) after stopping.

[fudgie]

Could it be the shocks 'springing' back up? 

[YoungPUP]

brake caliper binding up, and then un-binding as it cools down?

[6 banger]

I talked to my mechanic and he said there is a spring in the rear end that keeps tension on the driveshaft and that could be stuck and "springing" loose after it cools or just unsticks. I am definitely tell my mechanic what nugz said and see what he says. Got the carbs synced so the front wheel comes up slot easier now. Thanks fellas.

[Ricky-D]

I talked to my mechanic and he said there is a spring in the rear end that keeps tension on the driveshaft and that could be stuck and "springing" loose after it cools or just unsticks. I am definitely tell my mechanic what nugz said and see what he says. Got the carbs synced so the front wheel comes up slot easier now. Thanks fellas.

Your mechanic is nuts! (spring in the rear end that keeps tension on the drive shaft)

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[Grumpy]

I talked to my mechanic and he said there is a spring in the rear end that keeps tension on the driveshaft and that could be stuck and "springing" loose after it cools or just unsticks. I am definitely tell my mechanic what nugz said and see what he says. Got the carbs synced so the front wheel comes up slot easier now. Thanks fellas.

Your mechanic is nuts! (spring in the rear end that keeps tension on the drive shaft)

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Their is a spring that keeps the shaft in tension against the splines, could be the splines on the drive shaft are dry and sticking in place, worth looking at.

[John U.]

May not be the same sound source, but I had a metal snap/muffled clunk sound from the rear when I switched from OEM to aftermarket dampners.  The pegs of the final drive flange were binding in bushings of the dampners (evident by rub marks too) because they weren't perfectly centered and had zero give.  I had to use a rubber mallet to pound the final drive flange into the aftermarket dampners, that should have raised a red flag right away .  Switched back to OEM dampners and all's quiet again. 

Cholla, I had the same problem with urethane dampeners not fitting the drive flange (or vice-versa). I found that if I moved the dampeners into different positions I could find an arangement that allowed the flange to fit, without a mallet.
One advantage to a tight fit is that the flange will stay put while removing the wheel. If the flange doesn't stay with the wheel it can be a real PIA.

[Ken Tarver]

there is a spring on the "front" end of the drive shaft.

clunk? worn out shock bushings?

[Ricky-D]

Well, actually the spring on the front end of the drive shaft is there to keep the universal joint in the correct position with relationship to the output shaft of the transmission.

Without the spring, the universal joint would work off the output shaft of the transmission and eventually start to hit the inside of the swingarm.

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