Big clunk under car on acceleration.

gmoney101

New Member
Messages
28
Hi folks, happy to be part of this forum. I have a Ghibli 2015 petrol, which has got 95k miles on it and is started to show a few blemishies.. The main one is a big 'clunk' that I hear towards the middle / rear of the car underneath. It almost always happens when I slow down in first or second gear to an almost standstill, and then put my foot down to pull away. Roudabouts are a classic example; I come up to the roundabout slowly, and if I pull away from about 5-10 mp/h 'clunk' it judders the car. It doesnt happen outside of that, unless I accelerate hard through the gears. It's like a 'bang' like a slippy driveshaf reengaging. Thanks guys, it doesnt feel too safe!! Dan
 

CatmanV2

Member
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51,409
Does it happen if you stay in the same gear, or is it happening on a shift?

Oh and welcome :)

C
 

gmoney101

New Member
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28
Thanks, glad to be here! It's in same gear. So it's just about the pulling away, not changing.
 

CatmanV2

Member
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51,409
Thanks, glad to be here! It's in same gear. So it's just about the pulling away, not changing.

So some *guesses* There are guidos (what we used to call donuts) on the drive shaft. On the old Alfas these used to break up, and that might do it.

It could be lash in the diff, or play in any of the splined shafts on the drive axles at the back.

Or it could be *really* simple and the stupid little 'shield' under the exhaust has been bent up and that, coupled with maybe some slightly soft engine mounts, is now banging on the exhaust.

Short answer is (unless someone comes along with a 'they do this when that happens' type answer, which is not impossible) get it on a lift and start wobbling bits. I imagine it would become pretty obvious quite quickly.

Whereabouts are you based?

C
 

gmoney101

New Member
Messages
28
Really apprecaite the tips there, anything to go off and investigate is good. What it 'feels' like is that if something that affects drive is spinning and starts to slow down, but doesnt complete stop as I decelerate.. but then when I hit the gas again the 'thing' has to reengate and cant quite grasp whatever it needs to and 'clunks' - that's super dim I know, but the best way I can think to describe it. I'm based in Hampshire.
 

conaero

Forum Owner
Messages
35,457
Well, I have replaced a couple of Ghibli diffs, they are not too expensive but I would get it up on a ramp and work from the gearbox back.

I would check the condition of the prop shaft centre mount first, grab it and push it up and down, there should be some movement but not banging.

Then I would look at the gearbox and diff connections, again, grab it and push it up and down.

The diff and the prop are about £1500 each but there are plenty of used options.

The rear suspension link arms (3 per side) are a known weak spot.

Other than that, you could simulate the noise on a ramp and listen for where its coming from.
 

gmoney101

New Member
Messages
28
Ok thanks, I'll reach out to a mechanic and ask him to do a few of these bits. I've also had the classic wastegate issues plus the aircon compressor has gone of late. So, they are stacking up quite nicely at present.
 

gmoney101

New Member
Messages
28
Like all other parts for this car the guidos are hard to track down by themselves. It seems like the entire unit needs to be bought by itself. I usually get everything from Scuderia unless anyone has any better alternatives?
 

CatmanV2

Member
Messages
51,409
I think it might be a search time. I mean, it's just a large lump of rubber essentially. Hopefully *if* that's the problem you can find a substitute

C
 

CJ Romeo

Member
Messages
168
Hope it’s something daft, mine developed a death rattle that turned out to be half of the X pipe clamp falling off and the top half rattling between the exhaust and the floor.

Fixed for £0 after I went back to the spot where earlier that day I thought I’d ran over some old debris…..and 10:yards away was the missing half.