Not at Gaydon, spending all the time I can find building, but not getting very far :-(
This is the cap I used, no leaks after fitting this bad boy.
My detailed build blog
Just to add to Marcus' description of the vibration issue ...
I've been for a ride in his car. Right from the moment you start the engine, even sitting still at idle, the whole frame sort of buzzes and zings in a way that is completely different to my K Series VVC. In my car you can hear the engine but you don't feel it when stationary; in Marcus' car you are very much aware of the mechanical goings on under the bonnet, you feel it through your bum, it your knees touch the sidewalls (I'm a tight fit in Tillets!) you sense the tingling and buzzing, your hands feel it. So it's not so much an issue of something contacting under load, it's a vibration that is there all the time and just builds as you accelerate.
The engine still feels very healthy though - and it goes like stink!
SV VVC 170 - 170.4 bhp @ 7100 rpm - 142.4 ft.lb. @ 4900 rpm
How's the Mazda box mounted? - It's definitely isolated from the chassis?
Yep it sits on a rubber cradle (big chunky C shape) bolted to the chassis.
I think you need to get that 7 up on a ramp and look underneath something is touching somewhere all the time and needs sorting and soon . I'd start at the gearbox mount
"I take her to the floor, looking for a moment when the world feels right"
Good point about the steering column.
Wiggle all the exhaust joints and brackets? Loosen them one at a time and see if it affects the vibration?
Ditto engine and gearbox mounts?
Take up thy stethoscope?
My brake and clutch M/Cs leaked on first track outing. Changed the cheap clutch cap for a Girling and cleaned and retightened brake cap. They don't seem to leak now but I cable tie some blue paper wipe around just in case!
As for the vibration, I can't see why the gearbox touching the chassis, or anything touching for that matter, would cause screws to vibrate loose, if the two events are connected. What is the source of the vibration would be my question.
I've never noticed any similar, significant vibration from my R400, nor any loose screws in 3500 miles.
just had another thought , I had an engine mount fail and the first clue was the vibration from the engine being supported on the alternator . Could it be a duff engine mount ?
Fit the master cylinder race cap with the rubber bellows, it solved the problem completely on my car. Don't forget to refit the original for future MOT's.