What ought I be looking for - I got a snatching tail rotor on my Rappy 30 when spooling up?

Could you translate that to Americanese please?

Good Luck,
d.tipton

Sure. I thought my clutch was breaking up cos the tail rotor kept stopping for a split second, like jerky until I wound up the speed. Checked the clutch - seemed fine. Checked the Sprague cleaned and lubed - seemed fine. Checked the tail belt for missing teeth, seemed fine so dunno what to look for next.
Ther, how's that?

Is the belt pulled tight enough or too tight. I had a not tight enough problem when i firt ran mine up. also, how much fuel have you ran through it. When I up-graded to a V2, I had to let the engine take 2 tanks of fuel before all of the kinks came out of the works.
Good luck,
Ron

Thanks for that suggestion. I think the belt tension is fine though and fuel - I've lost count. Actually, I think the OS32 is worn out but that's another issue.

Make sure you have no missing teeth on your belt. "Normally" that is a sign that the belt is to loose.

If you're sure its not belt tension then take apart the tail case and see if the pin is working its way out of the red pulley. It can get loose and rub against the inside of the tail case and cause the issue you describe.

Proper belt tension is about 3 to 4 mm of slack in the span between the drive gear and the back of the frames.

the raptors can suffer from week tail parts...
take your tail apart and check if the pin that goes through the pinion and belt cog...these are the 1st place id look when a raptor does this...

I'd forgotten about that!!!! Soon after I first built the Raptor back in 2002 that pin did come out and neatly cut a round hole in the gearbox housing and it was just about to fall apart . I was very lucky to get away with it and just had to replace the housing and pulley wheel. ! I have checked it and it's OK. Also, checked the belt and it has all it's teeth and it is nicely tensioned.
I can't decide if the OS is causing the snatching it's so hard to spot. The OS runs flawlessly.

Out today and still doing it but it I noticed it only happens before I get up to speed. Decided not to risk it and stripped the tail rotor gearbox but all was fine. Wondering if it could be clutch housing to drive pinion. I change the clutch quite a lot on this one (well it is a V1!!!) and never use any loctite when I put back the clutch bell?

Think I have possibly fixed it. The set screws in the tail rotor hub. I was able to tighten them about what I think is a turn each. They were well locked in place with loctite. Removed the tail grips and the locknuts and was able to screw the set screws in. There is still a touch of slop even now though. Also, I tightened the blades cos I think the snatching may have been a whiplash effect. Tried it today in this gorgeous weather and seems to have completely cured the problem.

It's back. Think tightening the blade grips and the blades merely masked the problem. It is definitely only on spool up. Dunno what to check next.