Disaster.

[Thowdfella]

Returning from a classic car show tonight, I started to move uphill from some traffic lights and there was a terrific bang and then the car would only move very slowly. I suspected a broken half shaft or a prop shaft coupling but managed to get a tow home? I jacked the back axle up and both wheels turn freely but when I turn them the prop shaft doesn't turn also if I turn the front prop shaft behind the gearbox the wheels don't turn. Too lat to carry on tonight but any ideas?








.....vbfhfgj

[Nick Turley]

Returning from a classic car show tonight, I started to move uphill from some traffic lights and there was a terrific bang and then the car would only move very slowly. I suspected a broken half shaft or a prop shaft coupling but managed to get a tow home? I jacked the back axle up and both wheels turn freely but when I turn them the prop shaft doesn't turn also if I turn the front prop shaft behind the gearbox the wheels don't turn. Too lat to carry on tonight but any ideas?








.....vbfhfgj

Oh dear.
With the car on stands take rear wheels off get someone to sit in the drivers seat and apply the brakes.
you also need someone as an observer.
Get under and turn the prop shaft, if the prop turns and neither axle shaft turns then let the brakes off and apply the brake at one side and then the other test by turning the hub  with the car in gear. Thus you will soon understand whether a half shaft has broken or a shaft is loose on one hub or the pinion is caput.

Good luck

[Andy Bennett]

Broken half shaft woodruff key?
Andy

[Bob Culver]

WE are all dead curious. 
A failed key might explain the slight drive. Could be the pinion flange key? I have seen axles with the keyway broken out on both sides. The key must have been hard. Perhaps soft keys are being used (With a good fit should not matter)
After all the recent discussion I imagined everyone would be operating without the split pin and attempting to tighten  their axle nut after every run!

[Thowdfella]

Broken half shaft woodruff key?
Andy

How wrong can I be!!! As I said yesterday, there was a loud bang and then the car would only go at about 3 mph and running very rough. This morning I did all As Nick suggested which proved that all seemed well at the back end so started the engine. Very rough and wouldn't rev. After a quick look - there's is only half a fan blade with the other half lying on the side. Amazing to me that this would reduce speed to crawling. Thanks to all.

[Ruairidh Dunford]

A broken fan can totally unbalance the whole engine - this has only happened to me once but it was, as you describe, horrific!

Easy sort though.

[Andy Bennett]

At least it didn't go through the radiator.

When I first bought my Austin seven I spent half an afternoon tinkering with the timing to stop the pinking, only to be told that the starting handle 'handle' quietly jingles to itself when rolling along.

Might prove a useful thread 'Unlikely causes of problems: you'd never believe it!'
Andy B

[Bob Culver]

I had a steel fan blade break in a Hillman. Made a large dent in a very heavy chassis meber. The vibration was incredible even at idle so had to remove the whole fan. it is surprising considering thr degree of (secondary) unbalance in fours anyway.
The possibolity is always worth bearing in mind when standing over an engine and revving it.