Technical help! - illogical noise - already searched the forum...

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Technical help! - illogical noise - already searched the forum...

joe2

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Hi there

750cc Panda fire LHD

My Panda just went through its mot a couple of weeks ago. Gearbox a bit clunky but engine runs sweet. Took it for a good run recently and ever since I have this intermittent bearing noise I can't track down. Any ideas would be gratefully accepted.

It is a low howel - sounds exactly like a wheel bearing beginning to go - from the front right somewhere that comes on at anything over 20mph with turns to the left (and now also anything slightly left of centre). Seems that ordinary pootling around doesn't start it off - can have days without the noise. But a good run up to speed starts it off and it's then with the car for the rest of the day.

The fact it happens intermittently and only to the left seems to rule out constant things like a rubbing belt, gearbox, thrust-bearing etc.

Obviously thought it was a wheel bearing to begin with, however, the minute you press the clutch (during the noise) the noise stops instantly. Engine can idle or rev - no noise as long as clutch is in. No noise at low speeds clutch in or out, revs high or low.

So that seems to rule out wheel bearing, dragging brake, or any engine part also.

Pretty stuck for ideas now - what else could it be? What part is driven or engaged only when the clutch is out, that would suffer pain only in lh corners, slight or otherwise, over 20mph? Weird!

Thanks for any help
Joe
 
If the noise is on the right when going left it can really only be right drive shaft bearing, CV or wheel bearing. By disconnecting from the box via the clutch it somehow eases the strain on it.
 
Hi All

Thanks for the suggestions. Yep, drive shaft seems like a good place to start. Not convinced though. Working inwards, the wheel bearing would be whining away clutch in or out, same for the cv joint (though it's not in any way clunky right now). That just leaves the tripod joint. Never had one go before so I don't know what that sounds like but being as they're needle bearings I could imagine a low howling might be produced.

After that I guess it's a differential/gearbox thing since that's where the main group of driven bits live - hope not!

Can't get stuck in till the week-end so any more ideas in the meantime gratefully accepted - even potty ones!

Thanks a lot
Joe
 
It could be the tripod, but that has the same chance of it's noise disappearing with the clutch disengaged as a CV or wheel bearing. I would have said not much chance for all three, but we are clutching at straws.

Just realised that if you have a LHD, the right tripod joint is on your right hand side, whereas in a RHD, it would be on the left!
 
Hi Lewey

Fair point. Beginning to seem rather gearboxy then. Your idea about a thing being connected or driven and producing noise rather than when just rolling along might be the key - gears in motion, worn bearings, that sort of thing. Hmmm... well I'll have a good look round and see what I can eliminate.

Thanks for the ideas everyone.
 
Sixpotman - good point! I'll check that right now.

Urchin - my fault, should have been clearer. No noise when car not moving.

Definatly seems to be an in motion kind of thing. But since it doesn't come on straight away - 5 mins at 60mph will get it going then it comes on for the rest of the drive at anything over 20 with a bit of lh turn in it - it's a bit puzzeling.

Could just be the onset of old age for the poor dear, getting a bit creaky and that, but with luck it'll just be something daft and easily fixable like a dry speedo cable... I hope!

Cheers all.
 
Well, not so mysterious after all - but completely unexpected since she just sailed through the mot. Split inner boot, gearbox dumped its oil. Fingers crossed we caught it in time.

I haven't worked much on Pandas before so it's come as a surprise to find out that the inner boot is infact the gearbox seal. Was that really such a good idea?!

Anyway, thanks for your help everyone - got me looking in the right place without any mucking about. Much obliged.
 
All sorted, noise gone.

A few thoughts for anyone searching for split boot or gearbox noises...

I do find it an odd system to have the gearbox dump its oil as soon as the boot splits and I was wondering why there's no oil flung all over the place as a sign of things not being right - 2 litres of lost oil should be quite visible - but I see now that the boot doesn't rotate, there's a bearing at one end and the half-shaft rotates inside the boot. If the boot splits at the bottom the oil just drips out and can quite easily empty itself in one trip down the road and leave nothing when parked up to hint at trouble. I didn't even find much oil around the split.

Replacement of the boot is not difficult. Couple of bolts to remove before you can move the hub enough to get the shaft out, but nothing to worry about (13, 17 & 19 mm). The tripod joint then has to come off the shaft so you'll need circlip pliers. If the boot bearing is ok then it can stay on and the new boot can be worked over it. If it's damaged then knock it off using the vice but you'll need a piece of pipe just big enough to slip over the half-shaft so as to knock the new bearing into place without damaging it.

Dead easy really - biggest problem was getting oil into the gearbox without making a mess!

Cheers all
Joe
 
It is a terrible design and does often cause loss of gearbox oil. It slipped my mind because I run a different gearbox in mine. One assumes it was just incredibly cheap to produce. Only the Panda and some Unos got the design.
 
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