Vibration, for serious discussion only

[HarryMann]

lots of references to drivehsafts without stating front or rear.. so always presuming rear

but why only 3rd & 4th on acceleration.

Nothing too strange about that, as its more likely a road speed thing (d/s and prop rpm) rather than engine revs

A CVJ that seems Ok but isn't as neil says ios highly likely, I'd not think it was that gearbox fix (yet)

=====

I've done what SB is suggesting before... Whaaat an eye opener! Esp. where prop clanking and bell-mode ringing is concerned, nearly deafened me standing underneath

NB. IIRC, these are non standard engine installations, not the 50 degree JX layout.

[jebiga41]

I've had vibrations off both my Syncro gearboxes, without the prop on ( rear-view mirror vibrating )both occurring around 55 mph a blip of the throttle and goes again, one that's been refurbed and the other original where as with the prop on nothing. Aidan said a certain speeds/rpms one can get a resonance which is no harm could it be that?

[PC52]

The plot thickens.
When the oil was removed the box was run up so the oil was hot.
Now after it has been stood for a week, we've strained through fine coffee filter and this is what is left.



I though we would see more aluminium or something. The 3/4 brown bits are seed pods from the many trees we have.

[Aidan]

that's all clean so must be clutch vibes

[ajsimmo]

Gearbox touching bash plate ?

Check this out, coz I had the exact same thing - horrible vibration at 1900 revs in 3rd and 4th (nowhere near as bad in 1st/2nd), particularly when accelerating through that band. Went away above 2000rpm, but still there a bit (if that makes sense).
Bash plate looked very slightly bowed upwards (only a tiny bit) so I took off bash plate and straightened out so was sure nothing was touching. When I refitted it went on easier, vibration completely gone, and running slightly cooler too (which I put down to better airflow between sump and bash plate).

Happy days

[silverbullet]

More suggestions. I know that my 2.6 has a real floor-drumming throb of a vibration that comes on at around 55 but disappears at 65 (just), before getting worse again.
It's either the n/s rear bearings or the o/s driveshaft and CV's (that I haven't renewed yet).
But...a couple of the alloys could be in better condition - one dent/flat to inner rim to each rear - and it's very sensitive to road surface conditions. Worse on a smooth road.
As for the gearbox, is it possible that 3/4 synchro hub is in the process of failing and so causing misalignment in the 'box? But you'd have more swarf, I'd have thought.

[PC52]

Update:
bashplate isn't touching - it is now eliminated (as its on the floor now)
cvj's are good, drivelines replaced
Play was found in the gearstick mechanism on the gearbox - don't think that could cause issues though.
So today box out and another box in.
Bit of a dash in the morning to finish off and then we'll see.

Suggestions taken on board and appreciated.

[syncropaddy]

Did you have a look at the clutch while you were in there? Do you have a dual mass flywheel?

[v-lux]

I have a low hum in 4th most noticeably.

Interestingly, I too have a slack output shaft from the front diff...

[PC52]

Did you have a look at the clutch while you were in there? Do you have a dual mass flywheel?

Clutch is fine apart from the few miles Sharon shaved off of it in Germany. Not dual mass - we put the biggy clutch in when we did the conversion.

[syncropaddy]

Clutch is fine apart from the few miles Sharon shaved off of it in Germany.

There you go .... thats the problem!

[JustSharon]

Clutch is fine apart from the few miles Sharon shaved off of it in Germany.

There you go .... thats the problem!

Etiam , tamen ego eram secundus

[syncropaddy]

Revera es

[JustSharon]

Revera es

gratias ago vos

[JustSharon]

Gearbox touching bash plate ?

Check this out, coz I had the exact same thing - horrible vibration at 1900 revs in 3rd and 4th (nowhere near as bad in 1st/2nd), particularly when accelerating through that band. Went away above 2000rpm, but still there a bit (if that makes sense).
Bash plate looked very slightly bowed upwards (only a tiny bit) so I took off bash plate and straightened out so was sure nothing was touching. When I refitted it went on easier, vibration completely gone, and running slightly cooler too (which I put down to better airflow between sump and bash plate).

Happy days

Bash plate is sorted. Still understand where you could get the vibes from.