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Low Rev Clunk / Knock

roboxm3

Well-known member
Joined
25 May 2018
Messages
48
Morning All,

Is it a Boxster trait (986 S) to get a clunk/knock and sometimes "snatchy" engine/gearbox disengagement (i.e. when I depress the clutch) when at low revs?

It seems, if I'm not super-smooth and get the balance of depressing the clutch and lifting the throttle slightly wrong when changing from 1st to 2nd at low revs, it's not always the most refined affair, whereas if I let the revs build a bit, so the car's got a bit of momentum before I change, it's as smooth as you'd expect.

Cheers
 
Best guess .. duel mass flywheel is worn .. they tend to make a noise if the revs are too low .

If the clutch is starting to show its age then worth doing .. if not .. then its not cheap .
 
Thanks for the reply deMort.

The car's only done 38k from new but I suppose that's no real guarantee of anything either way

Is there any way of testing further, short of having the box off and having a look? Or are there any other telltale signs that the DMF is on the way out?

Other than the symptoms described the clutch isn't heavy and the biting point seems pretty 'normal" but then I suppose it would if the DMF was the issue and not the clutch itself.
 
Basically .. i can drive a car and tell if the flywheel has had it .. to explain though .. hmm .

very low rpm .. pull away .. a judder .. a noise is the best i can do .

I think more of a judder or a banging although not loud .. more felt than herd .

Im afraid milage doesnt mean much .. technically it should be fine .. but it depends on how it has been used in the past.

This is only a guess though .. a sound clip helps a lot .

To test .. well clutch out and move the flywheel side to side im afraid .
 
Hmmm based on what you've said, I'm not entirely convinced either way but as you say, it's likely one of those things that when you know, you just know...and I don't!! haha

Pulling away from a standstill, with no throttle, in 1st isn't an issue, just disengaging and re-engaging the clutch between 1st and 2nd below 2k rpm.

I'll see if I can record the start of a few journeys and get a recording if it happens, although I generally try to drive around it / avoid it where possible, there's just a couple of places where I prefer to short-shift on my regular route.

I appreciate you taking the time to help :thumb:
 
Mine's on its 4th clutch with 130k on the clock and original DMF. Sounds to me more like you've got too much backlash on you diff and pinion gear created by either worn diff bearings or incorrect shim setting.
 
Thanks Alex, very useful info. from you both.

I'm due a Saturday morning in the garage with my mechanic in a couple of weeks, he's letting me get my hands dirty helping (read: mostly watching) him replace all my hard brake pipes, so I'll mention the symptoms and your suggestions to him and see if we can have a look.

If I can get a recording in the meantime it might help one of you guys narrow it down for me.
 
Also check for excessive play in your gearbox and engine mounts.
 
Engine and gearbox mounts were on the check list, following my reading on here, fingers crossed for a simpler and cheaper solution than a new DMF required!
 

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