Drivetrain clunk when accelerating out of first

I've noticed a clunk from the drive train-coming from the back of the bike, I think either the drive shaft or rear end. It happens when starting out in first, it seems like just when the clutch has finished engaging. The clunk only happens in first. Is this a drive train maintenance issue? I took apart the rear end, lubed, O-ringed, and replaced the cush drive rubbers last year. I don't understand how it could be the drive shaft because it is not happening when the load on the shaft shifts. The clunk happens under load.

One other piece that might be relevant is that the clutch just started slipping when i get on the throttle. The bike has 72,000 miles and I assume it is the original clutch.

Got any ideas about the clunk?

Is this the right mileage to need a clutch or maybe I only need new springs?

Thanks,
Thomas

How many miles on the "new" cush dampers? Any "abuse"?
Would need to see some good photos of rear wheel bearing-boss and drive splines...
Next would be prop-shaft/U-joint...

Yeah, and the clutch issue of course...
Any recent changes of engine oil brand/type?
72K-miles sounds pretty much as the lifetime of the linings being reached...

How many miles on the "new" cush dampers? Any "abuse"?

>>About 6000 miles. I don't abuse the bike, but I do like to go quickly..

Would need to see some good photos of rear wheel bearing-boss and drive splines...

>>Drive splines looked good when I cleaned and greased them(w/the correct Honda Moly)
Next would be prop-shaft/U-joint...

Yeah, and the clutch issue of course...
Any recent changes of engine oil brand/type?

>>First oil change after I got the bike, at about 67,000 miles, was with Rotella, after a 1,900 mile trip, the clutch slipped when I got on it. Changed the oil again and never noticed slipping until the last trip, right after an oil change using Valvoline 10W30 MC dino oil. In between those oil changes I used Castrol 20W50 MC dino oil and don't remember the clutch slipping.

72K-miles sounds pretty much as the lifetime of the linings being reached...
>>Seems like I read a lot of people with slipping clutches had plates still within spec, just needed new springs. But most replace the plates anyway.
Thanks

When's the last time you changed your oil, and what did you change to? Oil that doesn't work well in your bike is the most common cause of the symptoms you describe.

thumperphile said:

........... and replaced the cush drive rubbers last year..............

Click to expand...

There are 2 pieces to the damper assembly, the rubber part and then the metal insert. Just curious, did you replace both as a set or just the rubber?

RUBBER, RR. WHEEL DAMPER 41241-MT3-003
PIECE, DAMPER WHEEL 41242-MR5-000

Have you ever found the source of this clunk? My ST1100 is starting to do this.

Bruno,

I have noticed the clunk... it was either oil or the rubber pieces and Al inserts.
What oil do you use?
How long have the alum and rubber inserts been installed (miles not time).

Hi Thomas, have you ever found the cause of this clunk accelerating out of first? My 1990 ST1100 has been doing this a while. I changed the rear cush drive rubbers and bushings. I also had the entire shaft drive out to inspect and grease it. Thanks, Bruno

Hi Mark, as I said to Thomas, I just replaced the cush drive rubbers and aluminum insert bushings 500km ago. There was no oil just grease and rubber residue around the old ones. I also had the entire shaft drive apart to inspect and grease. No obvious problems. All looked good there. Oil used for the last 2 years was 10W40 motorcycle oil as per Hondas recommendation. I am now trying Shell T6 full synthetic. Thanks, Bruno

Every Honda I ever owned had te clunk louder than the others when it goes into 1st gear. Unless it is something new I wouldn't worry about it.

Not the clunk going into first gear (hell, I had an airhead BMW for years, I know clunk). Once it is in gear, waiting for the light, letting out the clutch and then comes the clunk as you pull away. I rode my friends 1997 and there was no clunk. I have new drive rubbers and aluminum bushings 500 km ago. Rear drive line inspected and greased. 10W40 motorcycle oil every 5000 km.

Bruno said:

Once it is in gear, waiting for the light, letting out the clutch and then comes the clunk as you pull away.

Click to expand...

Neither the '94 nor the '00 emit a "clunk" as described upon take-off...
The '92 however once suffered an issue: special washer inside the final drive broke into pieces, allowing the ring gear to "float" away from the pinion under load, causing a significant "bang" (like a hammer hitting the swing-arm) when engaging the clutch in 1st...
w/shop rebuild the f/drive under warranty... quite a stunt to adjust the gears correctly though...

Other possible cause could be the U-joint and/or the safety coupling (later emits like a "ding!" under sudden stress)

Has anyone found a clear fix for this issue. My bike has done this since i purchased it. Feels like a hammer hitting the swing arm when pulling out. Slipping the clutch seems to prevent the hammer.

No help here. Sorry. I've never experienced this with either 1100.

Egad, its contagious. What my 2010 ST1300 has is spreading backwards. Read my threads: Clutch Noise Thread

In addition to replacing the primary shaft, primary drive gear, water pump chain, clutch basket bushing, and various and sundry O-rings and gaskets up front, I pulled the rear wheel, replaced the rubber inserts, removed the final drive and lubed the splines on the drive shaft (front and rear), and cleaned and re-pasted the rear wheel splines to final drive. No cure. I am now convinced that the noise is coming from the final drive, and my next foray into this will be to pull that apart to check clearances and wear on the gears. Seems like there is a lot of play between the pinion gear and the driven gear. I noticed this when I had the final drive off the swing arm.

Oh, and my bike clunks just as you said (when engaging the clutch) in most of the gears, though not every time. It almost seems that if I approach a curve on a trailing throttle, downshift and accelerate through the curve, I get the clunk. The braking force when decelerating seems to allow the acceleration to take up slack in the drive train with said 'clunk'.

SMSW said:

...there is a lot of play between the pinion gear and the driven gear.

Click to expand...

There should be nearly zero play to be felt when attempting to turn by hand... I guess the special spring/thrust washer has failed...

Thank you!

To add to the mix, today I noticed the clunk if I slow for a curve by closing the throttle (trailing throttle), then accelerate through the turn, i.e. I did not touch the clutch at all! And yes, when my pumpkin was off and I turned the splined socket on the driveshaft side of the pumpkin by hand, there was a LOT of play before the driven spline (that mates w/ the wheel) began to turn. Well, it seemed like a lot of play to me - what do I know? - but I assumed there would be very little gear lash. I'll be looking into this as soon as I can.

My situation exactly. I noticed it only happens when the bike is heated up. It is not the rear drive, that was all inspected, greased, and final cush rubbers and bushings replaced. I am thinking the clutch. But the clutch works great. Any suggestions??

I have this problem as well!! Cannot figure it out. New rubbers in. Had the drive shaft out last year. I hear its the u joint? even though it looks good, it can be bad? Hopefully someone can find the fix. If i really slip the clutch, no clunk.

Hello everybody.
I have just come across this topic. This is very revelant to me. I think the thread has drifted away from the initial question. The problem was that, when the thread starter already had his bike in first gear and as he left the clutch out and began to accelerate away there was a clunk. This clunk could be avoided by leaving the clutch out gently and accelerate gently. It is not the sound the gearbox makes as the bike is being put into gear. I have the exact same problem and after checking the final drive , and finding no problems, I am thinking that it may be the clutch. I have had this problem with some time. .???