Return to Website

Welcome to the Austin Seven Friends web site and forum

To get a quick overview of all the messages click on

" Switch to Threaded style "

Forum: Welcome Austin seven Friends
Start a New Topic 
   Board|Threaded
Author
Comment
Propshaft

Hello folks! I have a 1932 RN saloon and the rubber boot on the cardon housing is hitting the underside of the car when driving over a slight dip in the road. Changed the boot but it's still doing it, I'm a total novice and can't see anything wrong my self as everything looks right under there. There is loads of room around the boot when the car is standing still 😕 Any thoughts?

Location: York

Email  
Re: Propshaft

Are you absolutely sure that the noise is coming from that end? Usually the noise comes from the front when the fabric coupling gets worn and the spider flange (ie flanges on gearbox and front end) starts hitting the handbrake.

I'd remove the little hatch at the back, and the cover at the front and drive along with a mate. You should be able to see (or hear) what is happening.

Email  
Re: Propshaft

Yes, the rubber boot keeps getting rubbed flat and breaks

Location: York

Email  
Re: Propshaft

Perhaps the front torque tube anchor is the later longer one. This would bring the carden joint too close to the underside of the tunnel.
However I found the rubber gaiters were reluctant to stay on the carden housing and they then flailed about making a lot of noise. I've now fitted an A7 components hardy Spicer Shaft so problem gone.

Email  
Re: Propshaft

The tie wraps supplied with some of the rubber gaiters are as much use as a chocolate firegaurd, use a pair of jubilee clips not one which will cause vibration two screwed together to put the screws opposite each other.

Email  
Re: Propshaft

The rubber boots as supplied need trimming down. Their original size allows too much rubber to flex with centrifugal force with the lubricant acting as an additional force. Trim down a couple of concertina layers when fitting a new boot.

Location: Farnham

Email  
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.

Email  
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

Email  
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

Email  
Re: Propshaft

Quote: 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

Email  
Re: Propshaft

Quote: Mark Dymond
Quote: 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

Email