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Drive Train knock

Posted: Mon Apr 06, 2020 7:52 pm
by Msstucky
2011 Patrol
Had an issue with a guard rail bout 2months ago, Hit side car fender hard. Now i notice (hear and feel) a rhythmic knock that increases with speed, but get quieter when i throttle back. I had a dealer check out the bike ...long story $1000 later and the knock is still there...won't go into name calling right now. Need help what would cause that knock. I feel it on the right foot peg, almost feels like the drive shaft is hitting the frame. any thoughts?

Charles Town Wv

Re: Drive Train knock

Posted: Mon Apr 06, 2020 8:09 pm
by Lokiboy
A few things

1. Please put you location incase there is someone nearby

2. Can you video?

3. Raise the pusher, have some one move the throttle and see if you can narrow down/confirm where you think the problem is

4. Does the sound sound similar to loose valves? If so, you may need to remove the cylinders and test the piston rods (there are threads on how to do this)

Re: Drive Train knock

Posted: Mon Apr 06, 2020 8:19 pm
by Wildhorse Cafe
Concider putting it up on centerstand or stands and jacking up the sidecar wheel on a stand. You can run the engine in gear with the 2wd engaged. You should be able to figure it out in short order.

Re: Drive Train knock

Posted: Mon Apr 06, 2020 8:27 pm
by jeffsaline
Does it do it when the engine is off and the clutch lever pulled in?

How about engine off and transmission in neutral?

Does the sound change at all when you are turning left or right?

Does the sound change if you lightly apply the front or rear brake(s)?

Best,

Jeff

Re: Drive Train knock

Posted: Mon Apr 06, 2020 8:36 pm
by Snakeoil
If it changes with rig speed, it is not an engine issue. Jack up pusher and hack wheels and turn by hand. Listen and feel. Put hand on final drive and feel while turning. Put hand on hack driveshaft and feel.
Turn hack wheel and feel and listen.
Wiggle hack driveshaft to see if loose.
Make sure hack wheel runs true.

If you find nothing, then securely block up the rear and hack wheels
NO JACKS!! USE BLOCKS. Put a strap on the rig to keep it from taking off. Chock front and rear of front wheel.

Start it, put in first or second and spin wheel(s) with engine. THIS CAN BE VERY DANGEROUS!! IF UNSURE, DON'T DO IT!!.

Listen for noise. A small tube held to you ear and moved around will help pinpoint where the noise is coming from.
Any indication that hack wheel hit, too? Look closely for scars/scuffs.

EDIT: See others responded while I was typing. Yes, center stand for raising rear wheel. Brain fart on my part.

Re: Drive Train knock

Posted: Mon Apr 06, 2020 8:49 pm
by Msstucky
Lokiboy wrote:
Mon Apr 06, 2020 8:09 pm
A few things

1. Please put you location incase there is someone nearby

2. Can you video?

3. Raise the pusher, have some one move the throttle and see if you can narrow down/confirm where you think the problem is

4. Does the sound sound similar to loose valves? If so, you may need to remove the cylinders and test the piston rods (there are threads on how to do this)
1. CharlesTown WV
2. Will do that in the am
3. same
4. Definitely not a loose valve sound- a clunking sound that i also feel though foot pegs.

Re: Drive Train knock

Posted: Mon Apr 06, 2020 8:56 pm
by Msstucky
Thanks all, will do and report it back.

Re: Drive Train knock

Posted: Mon Apr 06, 2020 10:52 pm
by S 854
...a knock that increases with speed and subsides when you throttle off... Might be unrelated to the overly friendly guard rail... have you checked your donut? ...and the output fork on the transmission?

Re: Drive Train knock

Posted: Thu Apr 09, 2020 7:17 pm
by LRP
Check to see that the sidecar driveshaft is in phase--both end yokes should be in the same plane. If it is out of phase, the universals will
accelerate and slow down with each rotation instead of remaining relativly smooth in rotation. That will cause the sidecar stub axle splines
to hammer in the wheel's splined hub. It can cause rapid wear in the hub and stub axle splines.

LRP
Dick

Re: Drive Train knock

Posted: Thu Apr 09, 2020 7:54 pm
by n3303j
Seen some final drives with ring gears that had soft spots. A few teeth would wear and the drive would rhythmically thump as the pinion went from the proper teeth to the worn ones.

Do 30 mph in first, then second, then third. If thump is constant in all gears at 30 mph then it is beyond transmission. If it changes with different gears it is ahead of (or in) transmission.

Best luck.

Re: Drive Train knock

Posted: Sat Apr 11, 2020 2:41 pm
by Msstucky
Put the bike up on stands and the sound is coming from rear drive housing. Look like i lost a tooth or two. Way beyond my experience...off to the shop it goes.