Nasty engine noise, that goes when clutch pulled in ?!?!

[Tom Russell]

As the subject line states, built up a T5 engine for a friend, where the gearbox had broke, so replaced the cluster and loose gears for a 2nd hand set (which looked in very good condition), but it's got this weird clunking noise on tickover in neutral, which goes away when I pull the clutch in?!?!

Whilst apart I also replaced the cush drive springs, the cruciform/selector and all engine bearings, seals etc.

I did suggest we replace the clutch, as a complete unit, whilst we had it apart, but the owner assured me it was ok.

Anyway, I've no idea if it made this noise before the gearbox broke and the scoot rides fine now and selects all gears perfectly, but it just sounds awful on tickover (until clutch pulled in)?!?

Any ideas guys???

[Badwolfli225]

I had one where the clutch but was loose that did the same thing . Pulled the cover and tightened it and it went away.

Other symptoms I was having was a near instant clutch lurch when popped into gear.

[LI150]

A mates scoot was doing a similar thing turned out clutch nut was loose. End result cause he ignored it was wrecked clutch and crank

[Tom Russell]

Ok, thanks guys

I'll have a look at the clutch nut first, which at least means that for now, I don't have to split the engine again!

[tony]

That is normally a drive bearing thats gone. As you load the clutch it presses on the bearing losing the rattle.

[Tom Russell]

That is normally a drive bearing thats gone. As you load the clutch it presses on the bearing losing the rattle.

Hi Tony,

Hope all is good with you!

Do you mean some sort of bearing within the whole clutch unit; I can see it has a bronze bush, is this what you mean needs replacing?? I'm half tempted to buy a complete new clutch unit, as the keyway on his wasn't great!

In any event, I've replaced both the flywheel side and drive side main bearings, and there is absolutely no movement in the flywheel (like there was before!!), I actually had hoped that in doing this, it would eliminate this horrible rattle!

Let me know your thoughts mate.

Cheers,

Tom

[tony]

mmm.... really? With motor off tom, and cowl off put your hand on the flywheel.. now with the other press the clutch. Can you feel any movement?

If no... warm it up and try test again.

I am certain this is the issue. Just because a bearing is new does not mean its inside tolerance. The C ratings are a guide to tolerance. And maybe you have one on the outside of this tolerance.
A motor like the Px/T5 really needs solid bearings both sides.

[Tom Russell]

mmm.... really? With motor off tom, and cowl off put your hand on the flywheel.. now with the other press the clutch. Can you feel any movement?

If no... warm it up and try test again.

I am certain this is the issue. Just because a bearing is new does not mean its inside tolerance. The C ratings are a guide to tolerance. And maybe you have one on the outside of this tolerance.
A motor like the Px/T5 really needs solid bearings both sides.

Ok, I will do as you suggest Tony, and totally understand what you are saying.

I changed both main bearings to try and get rid of this horrible noise, as I could (before changing them) visibly see the flywheel moving out about .5 mil when I pulled the clutch in?!?! Now, when running the flywheel DOES NOT move - it's solid - but I still have this horrible noise (until I pull the clutch lever in), but as said above, I will do what you have suggested.

I feel it might be time to take the motor out again - for the 3rd time!

Anyway, thanks again mate

[tony]

mmmm... ok... there is slack somewhere that is taken up by pressure on the clutch.. so... look at cush drive and bearing.
Just a curiousity Tom.. what happens if you hold the revs at say +1000rpm from idle and pull clutch in?

[Scooterso]

As the subject line states, built up a T5 engine for a friend, where the gearbox had broke, so replaced the cluster and loose gears for a 2nd hand set (which looked in very good condition), but it's got this weird clunking noise on tickover in neutral, which goes away when I pull the clutch in?!?!

Whilst apart I also replaced the cush drive springs, the cruciform/selector and all engine bearings, seals etc.

I did suggest we replace the clutch, as a complete unit, whilst we had it apart, but the owner assured me it was ok.

Anyway, I've no idea if it made this noise before the gearbox broke and the scoot rides fine now and selects all gears perfectly, but it just sounds awful on tickover (until clutch pulled in)?!?

Any ideas guys???

why did his gearbox break in the first place? when you pull the clutch you are separating the gears from the crank so you can change gears. if the noise goes away when you pull the clutch in, id suspect gear box issues, especially since the last one broke. although without hearing it its hard to diagnose. is it a thunk-thunk-thunk which stays same speed as idle of scoot? or a whining sound?