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

[Tom Russell]

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?

Hi Tony,

I've ordered a complete new clutch unit, as his had seen better days to be honest (and they're only about £40), but I will try the test you have suggested above and let you know what I find, but I did replace the whole cush drive unit (springs etc.) and the bearings in the top and bottom of the cluster

Thanks for your help with this, it's really appreciated, I'm fine on Lambretta engines, but as I've never owned a Vespa, I just struggle a bit

[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???

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?

Hi mate,

Thanks for your reply!

I've no idea why the gearbox broke in the first place, though when I stripped it down initially, there wasn't a great deal of gearbox oil, so I put it down to this?!

I'm going to check as Tony (above) has suggested, and in any event completely replace the whole clutch unit as that looked as though it had seen better days, however, my first thoughts were gearbox problems (again) for the reasons you suggested.

To confirm, it's definitely more of a thunk-thunk or even clunk clunk, rather than a whining sound, which totally disappears when the clutch lever is pulled in?!?! It's difficult to tell exactly where this is coming from in the engine, as even on tickover, his exhaust is so bl**dy loud!

[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?

Hi mate,

Thanks for your reply!

I've no idea why the gearbox broke in the first place, though when I stripped it down initially, there wasn't a great deal of gearbox oil, so I put it down to this?!

I'm going to check as Tony (above) has suggested, and in any event completely replace the whole clutch unit as that looked as though it had seen better days, however, my first thoughts were gearbox problems (again) for the reasons you suggested.

To confirm, it's definitely more of a thunk-thunk or even clunk clunk, rather than a whining sound, which totally disappears when the clutch lever is pulled in?!?! It's difficult to tell exactly where this is coming from in the engine, as even on tickover, his exhaust is so bl**dy loud!

lack of oil shouldnt break gears, it would seize up the bearings before that. only gearbox ive seen totally broken was a gs160 with the wrong selecter box bearing fitted. (vbb type vs gs160 type) which was allowing the axle to move up and down.

correct cruciform/selecter shaft was used? selects gears so it would appear to be, but early Pe and PX/T5 are different.
Was axle in good shape? no chunks missing? seat for spring/cush gear in flyside half was in good shape?

can you spin motor over and hear anything without it running?

[Tom Russell]

lack of oil shouldnt break gears, it would seize up the bearings before that. only gearbox ive seen totally broken was a gs160 with the wrong selecter box bearing fitted. (vbb type vs gs160 type) which was allowing the axle to move up and down.

correct cruciform/selecter shaft was used? selects gears so it would appear to be, but early Pe and PX/T5 are different.
Was axle in good shape? no chunks missing? seat for spring/cush gear in flyside half was in good shape?

can you spin motor over and hear anything without it running?

Thanks again for your continued help/input

When I orginally split the engine, like I said there was hardly any gearbox oil, most of the teeth on the four gear on the cluster had broken off, and the corresponding loose 4th gear was in a bit of a mess, and 3rd wasn't too good either. Also, the bearing in the flywheel side of the casing that the rear axle goes through into the selector box fell apart, so I've obviously now replaced this!?!!

So this evening, I've split the engine again -but this time, still in scoot - and everything seems ok, to the untrained eye?!

There is quite a bit of up and down movement in the rear axle when still left in the rear hub bearing/clutch side (with rear hub off) and likewise quite a bit more movement in the rear axle when it's placed in the bearing (new) in the removed flywheel side casing (in fact so much that it rubs on the kick start shaft, but there are no marks), but no noticeable movement when it was previously all assembled together?! Maybe the axle is worn out, but I've nothing to compare it with

Also, before taking it apart, I tried spinning the motor over without it running and couldn't hear anything noticeable.

I'm really tempted to buy a new rear axle, and bearings, but the axle alone is £70!

I'm waiting for the clutch pack to arrive, but I'm not sure what to do next?!

[lambro]

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

Out of curiosity, same symptoms but on a smallie??
Made it to IOW and back no probs, but rattle is horrible

[Tom Russell]

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

Out of curiosity, same symptoms but on a smallie??
Made it to IOW and back no probs, but rattle is horrible

You did better than my mate (different scoot), as I had to pick him up from Southampton in my van (Indian coil packed up on Lammy - I did warn him of using such crap)!

Anyway, hopefully between the two of us we can get to the bottom of these annoying rattles!!!

[Tom Russell]

Just some further observations to bring to your attention, whilst I have the engine split.

Even though I stated the rear axle moved up and down a great deal when placed in either side of the casing, when the two casing halfs are put together there is NO up and down movement in it, which is good in some ways, but also annoying as I was rather hoping this (rear axle and/or bearings) might've been the culprit!

I've also re-checked the endfloat on the output shaft - assembled with all four gears - and this is within tolerance.

Also noted that the gear cluster floats backwards and forwards on the input shaft by about .4mm; this is with either both casings put together, or just looking at it with the flywheel side taken off. Maybe this bit of floating is correct and required??!! Both the bearing and the needle rollers were all replaced. I can actually see (from the clutch side) the bearing moving away (by this .4mm) from the circlip which retains it??!! Is this correct

[Scooterso]

J

Also noted that the gear cluster floats backwards and forwards on the input shaft by about .4mm; this is with either both casings put together, or just looking at it with the flywheel side taken off. Maybe this bit of floating is correct and required??!! Both the bearing and the needle rollers were all replaced. I can actually see (from the clutch side) the bearing moving away (by this .4mm) from the circlip which retains it??!! Is this correct

once gear cluster (spring gear) is installed, there should be no play once the nut is tightened down. should be rock solid. maybe the center spindle is the culprit? did you replace the ball bearing and needle rollers in it?

[Scooterso]

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

Out of curiosity, same symptoms but on a smallie??
Made it to IOW and back no probs, but rattle is horrible

clutch on smallie has its own bearing as clutch is not directly on the crank. if rattingly goes away when you pull the clutch lever could be that bearing...its a thin ball bearing

[Tom Russell]

J

Also noted that the gear cluster floats backwards and forwards on the input shaft by about .4mm; this is with either both casings put together, or just looking at it with the flywheel side taken off. Maybe this bit of floating is correct and required??!! Both the bearing and the needle rollers were all replaced. I can actually see (from the clutch side) the bearing moving away (by this .4mm) from the circlip which retains it??!! Is this correct

once gear cluster (spring gear) is installed, there should be no play once the nut is tightened down. should be rock solid. maybe the center spindle is the culprit? did you replace the ball bearing and needle rollers in it?

Ok, thanks again for your help and for confirming this. Yes, I replaced both the ball bearing and the needle rollers, to be clear it doesn't wobble, it literally just moves in and out the 0.4mm, but if it's supposed to be rock solid, then I'll take this apart and investigate further!

I also had a good look at the gearbox and how it meshed with the cluster, and noticed that when in neutral, and I was able to spin the rear axle/layshaft (without the cogs moving as well), it would appear as though the cogs were collectively all oscillating on the axle, as if the axle was bent, or the shaft they sit on was oval and worn??!! The gears also did this same oscillating when I removed the gear selector and rod, so I can elminate them as a problem. Surely, it must be almost impossible to bend an axle, then again, maybe it happened when he broke the gearbox, but I suppose wear of the layshaft that the loose gears run on is more likely, as they did seem quite a loose fit, compared with a Lammy engine, that I'm more used to??

I then took all the gears off the axle and had a good look at it, and slotted it back in the rear bearing to see if I could see if it was bent, but it's very hard to tell - I just wish I had another layshaft/rear axle to hand to try!

Any more thoughts on my recent findings would be appreciated, thanks