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I just got my car back from the dealer after the following work:

-new gearbox
-new clutch
-new flywheel
-new driveshafts
-back to standard sachs dampers (original ones at the front, brand new at the rear)

This little lot was the result of accidentally clocking 2nd rather than fourth from the limiter in third, while frantically chasing a Lotus Elise on my local track. It's not something I would recommend!

Anyway, 3200 quid later, the car is like new again, and I'm really into the sachs set up.

One problem though: when I bring the car up to anything above 4000rpm and then lift off suddenly (e.g. when approaching a corner), there is a strange noise like a sort of buzzing knocking sound. As if one part is vibrating and another part hits it.

The problem is particularly bad when going downhill, and seems to get worse the more lock I have on.

Any ideas what could be wrong?
 
Joined
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Maybe garage have over tightened subframe when fitting box etc.
Does engine move about, ie back & forth a lot?
Maybe engine mounts.
Could it be the manifold (when shutting off ie engine braking) vibrating under car again near/on subframe.

Unlucky on parts collection, done similar thing round Dono but got away with it, reactions :wink:
 
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I had a similar noise (at high revs and full throttle), it turned out to be the exhaust manifold hitting on the aluminium heat reflectors at the bottom of the firewall. They're easy to bend and reshape.
 
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