T5 differential weaknesses?
 

Does the C30 T5 have any common gearbox or differential weaknesses? I haven't found any common ones on line but my wife's 140k miles example now makes a "chahchahchahchahchahchahchah" noise like a worn gear. It is very faint (only I notice it) but it is there, and it wasn't previously.

The noise is directly road speed (not gear) dependent and remains during coasting in neutral with the clutch pedal depressed, so I am more inclined to think diff than gearbox. It doesn't however change with the loading or differential wheel speed associated with cornering - so if it is diff it is more likely the pinion and crown wheel (either one or both) than the sun or planet gears.

One thing that may be relevant is that over the first 50k miles and three years that the original keeper had the car, it regularly towed a caravan near the car's maximum tow weight. I know this from the Google Street View image I found of the caravan and car at their home, and the stack of Camping and Caravanning Club receipts stuffed in the service wallet. Many of the sites are in the Lakes and Highlands - so twisty and hilly locations.


Cheers.
2.4T

Never heard of a differential issue, more than possible that its a dual mass flywheel problem though.

If this sound is road speed related then it is worth checking that it is not a drive shaft problem....

Don.

The gearbox is very robust are you sure it is not a wheel bearing or even an unevenly worn tyre on the back ?

Thanks, Guys. You reassure me that what I thought (the gearbox and diff pretty much last forever) is accurate.

The nature of the sound makes me think it isn't driveshaft or wheel bearing, especially as cornering makes no difference, and with all four tyres being the same model as previously fitted and only 2k miles old, I don't think they are the cause . I can though stick the winter wheels and tyres on and see what happens. Let me try this over the days ahead.