SR4 Drive Problem

[82c]

Just returned from a track day at Bedford Autodrome, great Radical circuit, an early finish due to a drive problem only when changing down the box, a strange clattering noise now and again whilst not being able to select the correct gear followed by a slowing down kangaroo effect, feels like gearbox has blown but then is perfect on up change, any ideas would be really appreciated, I am thinking the diff may be worn?

[SportsLibre]

Don't see how the diff could affect the gear change, as for clattering noise have you checked the chain for tight and loose spots?

[82c]

Hi,

Thankyou for reply, the chain appears fine approx 10mm play, the problem is not apparent on every down change, probably 1 in 10, especially after a high speed straight coming down to a tight hairpin.