Independent Renault Forums banner

1 - 20 of 36 Posts

·
Administrator
Joined
·
13,087 Posts
Discussion Starter #1
Maybe some one could shed a bit of light for me. I have a nasty vibration/knocking at 4000rpm or at around 50-60mph. The chain and sprockets are due a change as they are on their last tightening, so at first I thought it was this... now I'm not so sure.

I can't work out if it only occurs while accelerating or if it is there just at speed. I thought it might be a wheel imbalance or a bearing but sometimes I find the it's worse when accelerating. It is at its worst at 3000-4000rpm and between 50-60 mph. Any higher/lower revs or higher/lower speed and its not as obviously/ doesn't occur. I'm worried its the valves or something nastier.

Any ideas?
 

·
Technical Supremo, Platinum Member
Joined
·
7,872 Posts
Has it just started? those engines are pretty bullet proof,
If it is speed related at those kind of speeds it could well
be wheel balance, has it lost a balance weight? check the
sprockets it could have lost a tooth if the chain is very worn.
 

·
Technical Supremo, Platinum Member
Joined
·
2,877 Posts
As Ralph says but I'd also be checking the rear cush drive rubbers too if fitted.
Be careful riding it until you're sorted Heather.
 

·
Administrator
Joined
·
13,087 Posts
Discussion Starter #4
Has it just started? those engines are pretty bullet proof,
If it is speed related at those kind of speeds it could well
be wheel balance, has it lost a balance weight? check the
sprockets it could have lost a tooth if the chain is very worn.
Yeah it started not long after getting the chain tightened and a new front tyre. It was serviced and MOT'ed at the end of May it seemed to start just after that. I'll check sprocket and for the wheel balance weight. It has got 16000 miles now on it so it is due a big service.

Not pushing the bike too hard Dave and as soon as I can I'll get it into the garage, or maybe chat up the next door neighbour (ex road racer and mechanic) and see if he'll help me change the chain and sprockets. I don't like messing with the bike myself too much in case I mess something up. The car I don't worry so much about. :wink2:
 

·
Technical Supremo, Platinum Member
Joined
·
9,486 Posts
Maybe some one could shed a bit of light for me. I have a nasty vibration/knocking at 4000rpm or at around 50-60mph. The chain and sprockets are due a change as they are on their last tightening, so at first I thought it was this... now I'm not so sure.

I can't work out if it only occurs while accelerating or if it is there just at speed. I thought it might be a wheel imbalance or a bearing but sometimes I find the it's worse when accelerating. It is at its worst at 3000-4000rpm and between 50-60 mph. Any higher/lower revs or higher/lower speed and its not as obviously/ doesn't occur. I'm worried its the valves or something nastier.

Any ideas?
Vibration is less of a concern but knocking noises are more of a worry. Depends if its from the engine or the chassis components. Do these signs appear if you rev the engine whilst stationary on its main stand? Could help if you can find a nice piece of quiet smooth road where you can run the bike up and down a few times to see if you can narrow down the area the noises are coming from.
Is the bike smooth .... then vibrates/knocks .... then fades away at higher speed? or is the effect present all the time.
Are the gearchanges snatchy? Does the bike run a nice straight line if you ride with just one hand on the bars?
 

·
Administrator
Joined
·
13,087 Posts
Discussion Starter #6
Vibration is less of a concern but knocking noises are more of a worry. Depends if its from the engine or the chassis components. Do these signs appear if you rev the engine whilst stationary on its main stand? Could help if you can find a nice piece of quiet smooth road where you can run the bike up and down a few times to see if you can narrow down the area the noises are coming from.
It is more of a vibration than knocking, I used knocking because of the way it feels on the bike. Haven't been able to work out whether engine or chassis, although it doesn't seem to come form the back end is the closest I've been able to narrow it to.
Is the bike smooth .... then vibrates/knocks .... then fades away at higher speed? or is the effect present all the time.
Are the gearchanges snatchy?
Yeah bike seems to be fine till 40mph then from there til 60 seems to be rough then after that seems ok again. Although worst when revs are between 3000/4000rpm and accelerating... I think :|
Does the bike run a nice straight line if you ride with just one hand on the bars?
Yep seems too.
:smile2:
 

·
Technical Supremo, Platinum Member
Joined
·
2,877 Posts
Make sure chain hasn't been over tensioned (as it's old it could have tight and slack spots) if it's been over tensioned it could put the gearbox output shaft bearing under excess strain. Don't want to be alarmist, but this would definitely give the symptoms you describe and on many bike engines it's a crankcase split job to change one.
 

·
Premium Member
Captur 2017 1.5DCi EDC
Joined
·
4,036 Posts
Like you said, wheel balance and bearings would be my first shot. What state is the rear tyre in. And wheel? No damage, uneven wear, bulges or similar. Sure there isn't a slight misfire at these engine speeds. If it is worse during acceleration I would expect it to something to do with the high loads on engine/gbox assy (is it mounted ok), output drives chain and sprockets, finally the wheel. No serious vibration in the handlebars I assume.
I'm with Dave above, if the chain is overstretched all sorts of problems like these can be encountered.

EDIT - also worth checking the rear alignment (wheel/sprocket with chain). Look for wear on sides of sprocket teeth.
 

·
Technical Supremo, Platinum Member
Joined
·
9,486 Posts
I'm inclined to agree with the others on the chain as that part has more play that anything else, and the weight of the chain in motion will be felt if its not in ideal condition or alignment. On your age of bike I wouldn't normally expect any problems with bearings etc ........ just normal service parts to replace.
The only real problem I can remember with any make of bike was the annoying cam chain rattle which seemed to appear at will regardless of engine mileage :frown2:.
 

·
Premium Member
Grand Scenic 1.6 2007
Joined
·
4,527 Posts
Yeah it started not long after getting the chain tightened and a new front tyre. :wink2:
Don't believe in co-incidences.
Is it possible that not all of the things loosened for the jobs above were tightened properly ?
Can you put the back wheel off the ground (no main stand I presume) and see exactly what tension there is in the chain at a few different spots.
Is the back wheel straight or are the adjuster things in the same place each side ?
 

·
Technical Supremo, Platinum Member
Joined
·
7,872 Posts
As above check the chain for tight spots also individual links that are stiff
don't want to straighten out with the others, anything like that change the chain
and sprockets if the bikes a keeper put DID X ring on it.
 

·
Super Moderator Technical Supremo Platinum Member
Joined
·
24,218 Posts
He did say his bees were awol >:)
Seem to bee. :grin2:

Got another lot in the compost heap.... was digging it over but wooops, I'm just going to leave you lot to it ! :surprise:

Sorry Heather, know nowt about bikes but wish you well in finding it.
Speed dependent vibration is often wheel balance on cars but only an observation, dunno how relevant on bikes.
 

·
Super Moderator
Joined
·
13,661 Posts
I'd say chain too. Mind you SWMBO Likes the vibes from the Guzzi. Nudge. Nudge :wink2::wink2:
 

·
Premium Member
Joined
·
8,608 Posts
I'd say chain too. Mind you SWMBO Likes the vibes from the Guzzi. Nudge. Nudge :wink2::wink2:
lacking good vibes at home? ;)

If I knew anything about bikes I'd say warped brake disk - as all other usual suspects were mentioned above (incl. tyre bulging).
 

·
Administrator
Joined
·
13,087 Posts
Discussion Starter #17
Thanks guys for all the responses!! :smile2:

Make sure chain hasn't been over tensioned (as it's old it could have tight and slack spots) if it's been over tensioned it could put the gearbox output shaft bearing under excess strain. Don't want to be alarmist, but this would definitely give the symptoms you describe and on many bike engines it's a crankcase split job to change one.
So the chain has about 3-4cm of play at the bottom.

Like you said, wheel balance and bearings would be my first shot. What state is the rear tyre in. And wheel? No damage, uneven wear, bulges or similar.
Rear tyre was changed about 2 months ago and looks in good condition. I had worried about a puncture at one point but the tyres both look sound.

Sure there isn't a slight misfire at these engine speeds. If it is worse during acceleration I would expect it to something to do with the high loads on engine/gbox assy (is it mounted ok), output drives chain and sprockets, finally the wheel. No serious vibration in the handlebars I assume.
I'm with Dave above, if the chain is overstretched all sorts of problems like these can be encountered.

EDIT - also worth checking the rear alignment (wheel/sprocket with chain). Look for wear on sides of sprocket teeth.
I don't think there is a misfire and the engine mounts all seem solid but haven't check this thoroughly. It was serviced so I would hope the mechanic would have caught something like that. There is no vibrations on the handlebars.

Don't believe in co-incidences.
Is it possible that not all of the things loosened for the jobs above were tightened properly ?
Can you put the back wheel off the ground (no main stand I presume) and see exactly what tension there is in the chain at a few different spots.
Is the back wheel straight or are the adjuster things in the same place each side ?
Cant the the wheel off the ground as this version has no centre stand (PITA) so will be getting myself a stand and probably a few other things :grin2: Y

I'm pretty sure now that the vibrations stem from the chain and sprockets. Knocked it out of gear on the way home yesterday, gave the engine a revved and the vibrations were not there. If at 50 and I hold in the clutch they still seem to be there though not as bad. It is due a new chain etc as I doubt it has ever been changed. I'll chat to the mechanic and keep you all informed

0:)
 

·
Premium Member
Grand Scenic 1.6 2007
Joined
·
4,527 Posts
If the problem was not immediately apparent after the last service then I fear something is loose. Probably the back axle. Get a tool on it after you check the symmetry of the tensioners. They should have marks on the swingarm or the tensioners or both which will put you in the approximately even zone. IIRC some of the CB900 were even colour coded with a red zone for excessive chain wear.
Check that the chain guard hasn't been removed and put back wrong.
How many miles are on this chain and what does the front sprocket look like?
Being smaller it wears out first and I usually would replace it at half the chain life.

PS Another way to check back wheel straightness is to measure the gap between the tyre and the swingarm. I reckon that for a twin shock swing arm it should be the same each side.
 

·
Administrator
Joined
·
13,087 Posts
Discussion Starter #19
Ok so little bit of an update... since boss is away I decided to play hooky for an hour and take the bike over to my mechanic! He had a good tinker and it pretty sure its the chain and sprockets causing the issue. He reckons the chain is a bit loose and it is ready to be changed. He had a good listen to the engine and reckons it is sound. He said he'd double check everything for me when its in anyway. So new kit being ordered and hopefully it will be sorted early next week!

:grin2:
 
1 - 20 of 36 Posts
Top