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Re: Propshaft

Our Austin 12 has a leather disc in front of the carden housing, it acts as a spinner, throwing detritus out of the way. I copied the idea some years ago on a Cup Model that continued to shed rubber and leather boots, worked a treat.

I agree with trimming the boot down, I also recommend that you attach it with jubilee clips rather than tie straps, these can be rotated to help reduce vibration, if needed.

It is also a good idea to compress the concertina of the rubber boots as much as you can when fitting.

Re: Propshaft

The fundamental problem is that the rubber boots supplied are, in fact, Mini or similar CV joint covers. They are designed to withstand the stress of rotating at drive shaft or wheel speed, around 1000 rpm or less.
An Austin Seven drive shaft rotates at engine speed when it top gear, say 3000 rpm plus. That's a 300%+ overload, hence they fail after a short time, especially if your car will get up to maximum speed.

Vauxhall/GM supplied a CV joint cover a few years ago, made from a harder material than rubber, these might be worth a try. Better quality neoprene boots last longer but still fail after a few thousand miles, due to the overload factor above.
I have tried a toilet flush coupling (the plastic cover between the flush pipe and pan), with a split wooden ring to adapt the propshaft diameter, but the real fix is to throw the carden shaft away and either make up a propshaft, using 1936 onwards components or to buy one of Mr Cochrane's excellent shafts. This fixes the problem and gets rid of all the horrible vibrations that threaten to shake the your fillings out!

Location: North Wiltshire

Re: Propshaft

Actually 900%!!
Centrifugal force increases in proportion to the square of the revs. Which is why balance problems show at speed. And why revs so stress engine components. Working a Seven up from its typical cruidng speed of 45 mph to valve bounce at 64 mph (or equiv in the gears) doubles many loadings.

Location: Auckland, NZ

Re: Propshaft

Bob Culver
Actually 900%!!
Centrifugal force increases in proportion to the square of the revs. Which is why balance problems show at speed. And why revs so stress engine components. Working a Seven up from its typical cruidng speed of 45 mph to valve bounce at 64 mph (or equiv in the gears) doubles many loadings.


Indeed it does, but with the Minis tiny wheels the half shafts will be spinning at over 3000RPM at 160kph! so we are all square again

Location: Fremantle Australia

Re: Propshaft

Mark Dymond
Bob Culver
Actually 900%!!
Centrifugal force increases in proportion to the square of the revs. Which is why balance problems show at speed. And why revs so stress engine components. Working a Seven up from its typical cruidng speed of 45 mph to valve bounce at 64 mph (or equiv in the gears) doubles many loadings.


Indeed it does, but with the Minis tiny wheels the half shafts will be spinning at over 3000RPM at 160kph! so we are all square again


I don't think so Mark. Minis are probably doing more around 85 kph at 1000 rpm to the wheels. That would do 160 mph at 3000 but "only" 1900 rpm at 160 kph.
We are now 250% centrifugal force. Too much but not so too much maybe?

Location: Brittany