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Noise on over-run
#1
My 1929 Special (standard Chummy chassis) has recently started to develop a worrying noise on over-run at top speed (45-50). It occurs as the throttle is lifted, and on long downhill stretches of road.

Noises are notoriously difficult to describe, but this sounds like  two components rubbing together combined with a boy running a stick (qickly) along  a garden railliing!!!


I think I have isolated it to the gearbox/front transmission by taking the car out of gear at 50mph on a long downhill dual carriageway and turning the engine off - it's definitely not the engine.

All ideas and comments welcome.
Rick

In deepest Norfolk
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#2
Cardan joint ? Try some more grease in it ??
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#3
Fabric joint and nuts hitting the brake assembly ?
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#4
Try checking that the exhaust is not rubbing on the chassis somewhere.I have had it happen twice. It sounds like the back axle is shot.It only happened on the overrun on both cars.
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#5
Not sure if the description fits but a loose flywheel reportedly tends to reveal itself on the overrun.


Edit: ah, sorry - just read the bit where you eliminated the engine.
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#6
I'm following this with interest as my Ruby has a similar problem. It has defied all attempts at a solution.

Peter.
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#7
Rick,
 My first port of call would be the torque tube anchor.
J
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#8
Many thanks for the replies so far - keep them coming!

Chris - I am very familiar with wobbly flywheels and this is a very different sound, and is not abated by depressing the clutch, which I have found with loose f/w in the past

John - I have tightened the torque tube anchor. Handling has improved, but noise is just as bad and getting worse!

Will be carrying out an indepth inspection of the transmission shortly.

Watch this space.......
Rick

In deepest Norfolk
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#9
I've found one thing that could well be the cause of the problem:


.jpg   HardySpicer.jpg (Size: 71.77 KB / Downloads: 313)

The flexible coupling has certainly seen better days!
Rick

In deepest Norfolk
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#10
Hi Rick

In my view the symptoms that you describe is most likely to be the pinion moving away from the crown wheel when you lift off.
Depending on which axle you have got fitted decides the exact remedy.
If you disconnect the prop shaft you can feel if there is any play back and forth from the flange.
If there is I would suggest removing the torque tube and get it on the bench to eliminate the problem.
It may just need the thrust adjusting, then it should not require a reset on the axle.
On the other hand if the trust bearings are clapped (they should feel beautifully smooth to be OK) then a full strip down and reset with new bearings will be needed.

Hope that is helpful.
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