Clonk

[Scott560]

So my lude, ever since I've had it, always had a bit of slack in the drivetrain.

You could feel it in car parks or when changing gear at slow speeds, a distinct hollow knock from the gearbox when rolling on or off the power. This only ever used to be at slow speeds. My last lude did it to for 4years so it was just an annoyance.

Fast forward a couple of years and I finally get around to fitting my ATR brake set up on the front and new calipers and matching discs pads on the back.

Not so long afterwards, I've noticed that the clonk occasionally pops in when unloading the gearbox at normal road speeds (eg lift off Accel when doing 50 in 5th) not all the time but occasionally.

I suspect the gearbox (diff specifically) as with the car jacked up at the front, me on my back, rotate both front road wheels forward then backwards at the same time (no more than a few degrees of rotation) and I can replicate the knock. Visually and by feel there is no play in any of the CVs along the driveline, and the sound is coming from the diff area of the gearbox casing.

Anyone had similar before. I'm inclined to believe gearbox rather than mount because I replicate the noise whilst jacked up and things like engine mounts aren't loaded up at this point.

Potentially related, my car always used to drive straight but now has to be driven with a slight adjustment to the right.

Any suggestions or similar experiences? ATR gearboxes on eBay seem to be silly money (500quid plus) look tired - some well over 100kmiles.

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[Scott560]

So with a free weekend, and a quick browse of ebay, a U2Q7 box with crunchy fifth gear showed up for the bargain price of 70quid.

an 8 hour return trip to bradford (from oxford) later - and the plan will be to remove my box (M2P4) and inspect, im certain that the play/backlash is inside the diffs internal gears. Hopefully the diff from the ATR box can swap over without much bother, but will most likely enlist a gearbox place to do it so its correctly shimmed and new bearings as required.

anyone got a spare M2P4 (99-00 2.2VTi) box? Would make my life easier as car would be immobile whilst gearbox is off - then have to borrow the wifes car to transport the boxes around...

[stinkypaul]

I'm chasing a clonk, come to thinks it's one of the following (which I'm trying to make time to sort out):

Inner tie rods
Radius rod bushings
Engine mounts
upper wishbones: I noticed after refitting one recently that it clunked a few times before settling which made me realise its held in place by bolt tension and doesn't really seat; if it moves it clunks, loudly. I might consider some way of stopping this clunking but if I were you I'd check that these are fastened tightly enough.

[Scott560]

Weekend after next I plan to fit my new tein coilovers and as many of my strongflex bushes as I can muster (whole car kit coming, hydraulic press bought).

That should resolve rear shock knock and the radius arm clonk that the MOT tester picked up on (asked him to be very thorough due to track day in 2 weeks time)

Hopefully clonk will be found and sorted (with the exception of the diff clonk)

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[wurlycorner]

Hi Scott
Only just picked up this thread (not sure how I hadn't seen it before).
That's a massive bargain on that U2Q7!!!

There's no known issues with diff's and I can't say I've come across anyone having had one fail/get knocking noises before now.

Have you definitely checked the front engine mount? These are a known weak point for tearing. They normally cause drive-line shunt rather than a clonk/knock, but worth checking.

Have you also checked the driveshaft intermediate shaft bearing?

The other favourite is the for downpipe hanger bracket on the back of the engine to crack. This can cause the downpipe to clonk on the box/engine when drive is taken on/off. Have a look at that.