Linhai 300 noise from transmission?
 

Hey guys, first time poster. I have a 2008 Linhai Mainstreet that's been giving me some problems. I was getting a lot of noise from the CVT case, so I replaced the belt. Well, seems that wasn't my problem, as I still have a bunch of racket back there. Sometimes when I have it on the CS I can spin the rear wheel and I hear a clack clack clack, same noise I get while accelerating from low speeds or decelerating. I need to know if this could be a transmission problem, or if it's simpler than that. Any input will be greatly appreciated.

Did you look at the rollers in the variator? One might be hanging up and causing the noise.

I did look at them when I took the belt off. They do need replacing, since they have flat spots, but the variator is opening and closing completely, so I don't think there's one hanging up. If this helps, I also have jerky acceleration and I have isolated the noise to the rear of the CVT case, near the clutch and tranny. I've been riding it like this, but I'm afraid there's something loose in the tranny and causing unwanted wear.

I would open up the variator cover, take off the belt and spin the wheel to try and isolate the noise. It could be a bearing in the transmission case or clutch, a broken spring in the clutch arms or a chipped transmission shaft gear. I'm trying to envision what else might be in difficulty. Yamahas have a history of sticking clutch arms and your Linhai is a close relative.

Or a swingarm bearing behind the muffler.

I was thinking it might be a bearing or the clutch. I'll take it apart tomorrow and look at the clutch.

Did you check your final drive gear oil? I have to take my covers off to check that myself.
If you remove the bolt and oil dribbles out your ok.
If nothing comes out a small squirt can and some hypoid oil need pumped in there.
I'd also blow out the clutch springs while it's open.

It might be worth changing the trans oil. If there is a problem in the trans the oil will likely tell through metal fragments or discoloration. It's only a few ounces of oil and a needed service. I've never seen trans failure under normal conditions, they are usually the last thing on a scooter to fail.
The clutch drum has some bearings and sliding / spiraled, rotating surfaces that might cause a chatter. Check to ensure your belt is an EXACT match to the OE part.

I changed my gear oil this morning, and it was silver/grey. Might be moisture, but there was definitely metal flakes in the oil. Haven't been able to get at the clutch since it's been raining on and off today. I listened to it today, and it only starts to make noise once the clutch has engaged. I also noticed that the clanking is in direct relation to rear wheel RPM. Rolling the scooter with the engine off I still get this noise. I'm kinda stumped right now.

This would be a good start for checking. But a clutch will not make much noise if the engine is off and the bike is up on the center stand. If one spins the wheel, the only things turning will be the clutch bell and the final drive gears, bearings and axle.

The engine needs to be spinning to drive the belt which turns the part of the clutch that engages the clutch bell....which turns the gears and rear wheel axle.
So if there is a substantial noise when turning the rear wheel, in both cases of engine off or on, that would lead me to think there is something going on with the gears or bearings in the transmission or rear wheel axle.
If there is some wobble of the rear wheel then this may point to axle bearing failing, but even so, rear axle bearing beginning to fail will not always cause rear wheel wobble. Still, it could be pointing more to the gears themselves or the bearings they ride on.
Another possibility for rear wheel noise is brake dragging, but this might not make a lot of noise.

Chatter on acceleration could be a problem with the variator or the clutch. (chatter would usually be less likely on deceleration)
Is it still noisy while moving along steadily at speed?
Yes? Might be transmission gears or bearings problem.
A problem with the engine would seem to be ruled out by determining that the transmission & clutch area as the general source location of the noise.
Any evidence of excessive oil leaking around the transmission cover, transmission oil fill or drain bolt? any leaks where the shaft comes out for the clutch or where the rear axle comes out of the case?

As Maddog advised, check the transmission oil and note how much comes out upon draining along with color and if any particulate. (there should not be any metallic grit) It should be reasonably close to the recommended amount advised for refill; maybe dark brown but not black.
Black? really old, used for too long unchanged oil or from being overheated too much. (or a combination of)

Ahh.. Your last message came out while I had still been pecking away off and on at my response.
Low miles on this bike? There may be >some< metal flakes with the first oil change in a new transmission, but not much. Oil is silver grey? that is worrisome unless something other than standard hypoid gear oil was used. (I have no idea what could be used that would give that color.) I have had no experience with a transmission that has failed, so I'm not sure how things might actually look. Moisture would have more of a tendency to make it look like coffee with just a little cream.

Did you notice if the drained amount was much less than the amount used to refill? or was it about the same?

Noise only when clutch engages? AND still makes the noise when rolling the the rear wheel while engine off? It's not the clutch then. From your description It would definitely indicate a problem in the gears and/or bearings. Metal flakes in the used transmission oil makes the transmission highly suspect. Especially if the oil had been too low.

Not sure of this Linhai model transmission history, but on Honda Reflex for example, the final driveshaft bearings can cause noise from being worn or loose and be more probable than the gears or their bearings as long as transmission oil has been adequate.

Noise in the transmission would come from worn, seized or chipped gears or from worn or damaged transmission bearings.

Do these and test before you tear into the transmission:
1) make sure rear axle nut is torqued properly.
2) make sure right side swing arm bolts to engine are torqued properly.
3) make sure the shocks are fastened securely.
4) make sure rear brake is not dragging.
5) X - OK, presumably you've done this already -> proper level of transmission oil.

One can hope that simple things will be the fix. (they do happen from time to time)

Thank you kz1000st, cheapeto, Maddog, and bandito2 for the help so far.

When I changed the gear oil, it was full almost to the filler hole (.25 liters). I did have problems with the rear axle nut coming off after 20 or so miles, and I did torque the hell out of it to get it to stay. I don't have access to a torque wrench or the torque specs, so I have most of them tight but not gorilla tight.

After I replaced the gear oil (I used Valvoline CVT Fluid, anyone have experience with it?) the sound was greatly diminished at first, but returned to original volume after a mile. I can't tell if it is still noisy at steady speeds over 30, since engine and wind noise overpower the sound.
No leaks around trans area at all.
Belt is exact size recommended in Linhai's manual.
Shocks are on properly and both rears are at the same load setting.
Rear brake does not drag (I think).

Sometimes it almost sounds like a slipping sound along with the metal-on-metal clank/grind sound. I'm going to make a video and link it here. Hopefully that will give you an idea of what I'm talking about.

Oh, and bandito2, my scoot has 8708 miles.

Clank and grind also sounds like clutch. BUT! fresh oil in the trans is not going to quiet the clutch in any way but will quiet the gears and bearings...... for a little while. And your bike is well past break in so metal flakes in the drained transmission oil that have no good reason to be there now are beginning to confirm bad bearing/s and/or gear/s.

A couple last questions:
Did the noise appear kind of suddenly or was it something that showed up gradually even if quickly over some miles? Has it been at it's current level of noise for a while or is it getting progressively louder/worse?

I recommend you dump the CVT oil from your transmission and use something of a higher weight before going any further. CVT oil is for automotive CVTs. According to the product information sheet it has a viscosity even less than 5W-20 motor oil. Usually a gear oil of 80W-90 is used unless 30W or higher motor oil is specified. A service manual for your bike should tell what gear oil should be used. I couldn't find the info online so I don't know really what the manufacturer recommends you should be using. But I feel I can safely say you absolutely should not be using automobile CVT oil. :s

Here's the video:
http://youtu.be/XAu3lG5w9B0