Why would this happen?
 

Have an Stiv3 hill climb car. Changed the transmission to a short 4.11 diff RA spec to go faster(?).
Driving it now its all done, I notice that the waste gate of the turbo chatters on gear change. It never used to do this with the Sti trans. Gone is the blowoff valve whooosh on gearchanges also!
Any ideas for this? Car ticks over steady with the usual flat four music, revs its ti*ts off to 8000 and drinks gallons of Optimax. The engine is stock save the decat Magnex and Blitz turbo controler set at 2.31 Bar.Nothing unusual in all this except the change of noises...

Spooky or what?

911

Dumpvalve fitted wrong, vacumline to dumpvalve split or not connected..

JGM

JGM, thanks, especially as i forgot to say that changing the box I broke the vac line off the DV, and made a quick repair with a pipe and araldite to cure the poor tickover which it did. Then the noises came along.
Presume that the vac pipe is now blocked with glue so no compensation on the DV?
Friend is giving me a DV off his V3 RA which is perfect, hope that cures things. Could this condition create a loss of power as the car is not as ballistic as it was before the box change? ie, not achieving full boost??
911

Yes could effect it.. if the vac line is leaking slightly but not enough to disturb idle or it could be causing boost problems or you have broken a blade off the turbo..

the noise is not waste gate chatter (I used to think it was myself) but infact the turbo blades stalling as the air pressure hits them when you shut the throttle.

Depending on the turbo it will either be fine with it of fook it up.. I am not sure where TD05 or a VF on the Sti.. TD05 will be fine with no valve working VF I think is more sensitive..

Why not just replace vac line or shorten it.. better to do that then add another variable (the new valve).. fit it after once problem solved if you want to use it.

JGM :)

Thanks again JGM. Will strip the TMIC AGAIN and sort the things out, the clutch arm gaiter has also jumped out of the bell housing. Just read the thread on removing a scooby g/box and the demon 'jacking bolt' to help split the box off the engine, I spent a VERY frustrating time parting mine...wish I'd known that. I also forgot to fit the clutch arm to the box before I refitted the box, now that is a fun job to thread the arm in and clip into the release bearing...so that's why the bearing clips into the clutch diaphram spring! you live and learn. Prosche do it better on the 911!
Graham.

I used some metal cheese wedges to split mine.. what's this about a jacking point??

I found it easier to feed the release fork in after although before the gearbox was fully back on..

JGM :)

JGM, just fitted my friends spare DV off his v3 RA and everything is back to normal. DV whooshing, turbo silent and the pull in the gears as strong as ever!
Phew!
Graham.