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Before I get under the car thought I would ask for some suggestions as to what could be causing a single loud clunk from the front when hard cornering on the track. No such noise in regular road driving.

I am thinking sway bars. Thoughts?

Car has BC racing coilovers. A common problem is the locking nut comes loose. Checked it and bolts on the upper mounts and they are all tight.

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cornering in both directions?


maybe upper control arm contacting sway bar?

I found that, at least in my case that the adjustable sway bar and end links would contact the perch adjuster ring in certain situations when the bar was set on full soft.

Yep, both directions. Only started happening after an off track excursion. Sways are stock and never previously made noise. I think something has come loose.

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Worn/damaged control arm bush, probably one of the lower ones, or else a worn/damaged control arm ball joint, also probably a lower one.

Broken sway bar mount , the bracket that mounts it to the chassis

Have a look at the eccentric bolts that you use to adjust camber
sometimes they come a bit lose and can slop back and forth causing a loud click sound
you might have to adjust the eccentric washer 180 deg so it points up rather than down
you can usually tell if it's been moving, It'll have a shiny bit beside the washer

Also have a look at the rear mount for the front lower control arm sometimes you get a stone in it and it clicks

Olboy

got the same issue!!!

Well nothing looks broken. Tried to Wobble wheels and they don't budge. Sway endlinks and mounts all fine. No noise on slow speeds, reverse, full lock. Nothing.

Then tried some enthusiastic driving. Nothing.

Then after a hard right I quickly went left. A creaking sound. Worked out noise only occurs after hard corner then a dramatic shift in another direction including heavy braking. On track it clunks. On road it's more like a soft creak.

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I get the same thing, thinking it's the spring perch.

Jack a wheel up then drop it down again, makes the same noise right?

Yeah sounds like the perch at slower speeds but sounds bad on the track with a pretty solid clunk! There is roughly 4-5mm preload on the spring so it isn't exactly flopping about.
Hoping that's all it is.

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Pretty sure it's coil bind on spring perch. Just Jap recommend backing off preload a little.

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To check for an uncaptive spring, put the car up on stands and allow the wheels to reach full droop (disconnect the sway bars), simple test.

If it is when cornering on the limits could it be the bumpstops?

Endlinks are consumables so I'm betting one is worn.
Try swapping them to the other side to see if the clunk moves accordingly.

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