It's likely that however tight the nut is there will be relative movement of the coupling on the splines.
As has been mentioned previously, the coupling should be a VERY tight fit on the splines, requiring significant effort to join the two parts. If it just slips on then it's too loose. There must not be any scope for movement at all. How to fix the nut is another issue, but my feeling is that loctite and a plain washer is the way to go.
I agree - but hasn't it been found that several couplings are not a tight fit on the splines ?
Yes - for instance a customer Centa just upgraded - Original Centa slid off by hand - splines in perfect condition - PB Centa tapped on in its place. This on a 10000 mile stage 3 engine.
I'm going back to flat/star/original nut and MMC rollers for time being - as its worked fine for last 8 years on original Centa.
Not prepared to go to 660 Loctite, if you read the guidance from Loctite I think its safe to say you'll never get the Centa off ever again without destroying something else.....
