Knocking noise?

[Rusty McNeil]

I'm posting this for a friend of mine that's not on the forum.

Engine is a 1500 tourmaster with probably 15-20,000 miles on it.

He's got a knocking noise in the driveline he says. Only when in gear, any gear, and the rear wheels turning.
Also say when in nuetral, engine off, on the center stand he can turn the rear wheel and it knocks/clunks.
He's already pulled the swingarm and rear wheel and says the driveshaft and u joint look ok. I didn't ask him about checking the rear gear assembly and don't know if he did.
He's already making preparations to pull the engine.
Is there anything thing obvious to be looking for here?
What about the big spring/damper thingie on the secondary transmission shaft?

I haven't observed anything myself yet, I told him I could come by tomorrow and take a look.

 

[one2dmax]

Check for broken rear diff. It's common for them to break the front pinion and overlook that it's broken. I'd put another one on (a loaner) and see what it does.

 

[Rusty McNeil]

Do they break but the bike still goes? Anything to look for or do you need disassembly to see it.

I'm going to take mine over there tomorrow to compare

 

[mattmullins]

Mine did

 

[tothemax93]

My 93 Vmax had a noise in the drive train while moving 35 to 45 mph. Local shop thought something in the middle gear. Turned out to be a problem in the differential. i just switched it out and problem solved. Put it up on the centerstand and run it. then do the screwdriver test. listen for where the sound is the loudest. thats how I figured mine out.

 

[Rusty McNeil]

We found it.

Pulled the u joint yoke and middle gear driven gear out and found two busted teeth on the middle gear drive gear. Nothing in the oil other than normal wear "shiney's" he said.

He said it's been whining/humming since day one with this motor. I wonder if this was due to incorrect middle gear lash???

Tranny is already undercut. Hopefully just the gear can be replaced and all will be well.

Does middle gear drive and driven need to be replaced as a set?

 

[one2dmax]

It is normally replaced as a pair but I would swap out just the one gear and give it a try. We've done that with good success. Hopefully there isn't any cracked teeth on the drive gear as that requires splitting the case for access.

Sean

 

[Rusty McNeil]

It is normally replaced as a pair but I would swap out just the one gear and give it a try. We've done that with good success. Hopefully there isn't any cracked teeth on the drive gear as that requires splitting the case for access.

Sean

It is the drive gear. Gonna have to split the cases for sure.
He's just happy that hopefully its wasn't even worse.

This is the bike that sheared the middle gear bearing retainer plate bolts off ( those four torx bolts) and pooched out the bearing when it was new. He fixed that right after it happened. Maybe that was the start of the problem but it's had prolly 10,000 miles since then.

 

[one2dmax]

I have quite a few of those used around here i'd set you up with for cheap.

Sean

 

[wildweasel_pt]

At least you were able to see the broken teeth. they could have been facing forward and you would miss it and still scratching your head now... LOL

 

[Rusty McNeil]

At least you were able to see the broken teeth. they could have been facing forward and you would miss it and still scratching your head now... LOL

He had already removed the clutch basket trying to get a look at the tranny (theres a hole behind the basket that offers a view of the tranny) so at that point it was easy enough to rotate the shafts

 

[Rusty McNeil]

Here's the damage

 

[wildweasel_pt]

Splitting cases there you go. They say you have to replace both conical cogs to match. I have already just replaced the output aft one with no problems and with lash measured by "hand" but that one i do not know...

 

[Rusty McNeil]

Splitting cases there you go. They say you have to replace both conical cogs to match. I have already just replaced the output aft one with no problems and with lash measured by "hand" but that one i do not know...

I came up with a setup for doing lash today when setting mine. Works pretty good.

I think there's some shims inside the case that have to be setup too if the Drive gear gets changed, I was looking in the manual and it looks like they do it the "math" way same way as the shell bearing. Using a number on the new gear and those marks are engraved above the middle gear.