Prop noise

[ninja.turtle007]

I get a donk sound on initial acceleration after changing gear. Sounds like it's coming from the front of the prop. I took a video earlier as there seems to be some play but not in the UJ's of the prop. I have no idea what is an acceptable level, but the noise is getting on my nerves.

http://www.youtube.com/watch?v=o5U59ZKNPhA" onclick="window.open(this.href);return false;

What do you think?

Thanks

[Aidan]

system backlash is normal, 0.15- 0.25mm at each diff plus splined joint on gearbox pinionshaft/front output shaft, plus splined joint front input shaft to vc plus splined joint vc to front pinion shaft plus any backlash in the two ujs = 5 ' rotational backlash as viewed at the flange as in the video

as ever an oil change will advise as to the overall state of the gearbox and front diff but even freshly rebuilt systems have similar rotational backlash, aka "they all do that", but some props are more sonerous than others and some clutches are more on/off as is some drivers clutch style ,than others

bigger the tyres, gripier the surface, more it may be noticed

1.9 with no donut may be noiser than donut damped prop, but not necessarily so as the internal shaft and bushes on the donut prop can bring a non rotational element of play into the equation

[KINGPRAWN]

i recently replaced my prop with a syncrospares one which has no rubber doughnut thing ,trying to get rid of a drone. this prop is pretty much perfect as far as getting rid of the drone goes and makes no clunking!!!.....but it seems as though my prop was on backwards for a petrol(doughnut was at the front NOT at the back).......

[ninja.turtle007]

Thanks for the replies. I should have mentioned it wasn't making the sound until recently.

The main thing I'm concerned about is causing damage by driving it. Going away in it in a couple of weeks time.

I'm sure I have seen somewhere a prop that had flash banding wrapped around it. Is this okay to do and would it help deaden the hollow donk sound?

Oil in diff and box was changed last year by previous owner. Do you think it's worth doing again?

[Aidan]

oil is cheap and if the plugs are clean then you know there's no heavy wear going on which = peace of mind in my book, and if no silcon in the front diff oil then you know the vc isn't leaking; fresh oil = better lubrication = less wear and the detergents in the new oil will remove carbon deposits (caused by heat cycled oil breaking down), so last years oil will bring a lot of crud with it when you drop it so you won't be circulating that through the box.

props can have play in UJs and not vibe and can vibe with no play apparant, there's no definative diagnosis, they usually go digital (that is notchy between two fixed positions very close to each other) because the angle of displacement is very small and virtually constant, whereas a live axle vehicle exercises the UJs through a far greater range of motion

[ninja.turtle007]

I'm also getting a drive chain kind of rattle sound at 2k revs. If I dip the clutch of increase revs it goes.

[ninja.turtle007]

Took the prop off and all problems have gone away. The UJ's are silky smooth with no noticable signs of wear. I will be changing oils on Friday to see what that shows up or doesn't.

[ninja.turtle007]

Just changed the oil in the diff. No metal on plug. Oil a little dirty but ok.

Not sure what to do. Do I replace the prop?