Propshaft shortening for SWB car

[JohnD]

Good Afternoon, 

Iam looking to shorten a later hardy Splicer propshaft for use on a short wheel base RK saloon with 3 speed gearbox. Does anyone know the magic number by how much a propshaft needs to be shortened ?

[AustinWood]

I'm not sure the later Hardy-Spicer will fit. The 3-speed gearbox output flange is three-bolt and I think Hardy-Spicers are 4.
A7 Components can suppy a shaft that fits.

[Charles P]

It won't fit directly but you can buy one of these adaptors from Tony Betts (and elsewhere probably) for £25. Then it'll fit when shortened.
http://www.7ca.co.uk/Q15.htm
As for the length it's not that critical since the splines allow for some variation. I put the prop in the lathe and machined out the weld holding the UJ forging, cut it down and welded it back together. It's been fine for 25 years and at road speeds up to 80.
You can, of course, buy a whole new shaft that avoids the adaptor but when I just looked they were out of stock.

Charles

[Howard Wright]

Hi John

If you have an early axle in the car you will need adapters at both ends I’ve got shortened prop-shafts on two cars 1929 and 1930.  Both are different fixings.

For one I took the shaft, gearbox output and pinion flange to Barr propshafts in Neath and they fitted two new ends, one drilled to suit the three bolt flange of the gearbox and they re drilled the pinion flange to suit a stock flange they had.

For the second Barr simply shortened the shaft and I turned new adapter discs to suit each end.

As for length as Charles says it is not critical. I measured between the gearbox output flange and pinion flange with the car on level ground and unladen.  I then asked Barr to cut and weld to suit. If you can weld it yourself, like Charles, I would suggest setting the shaft with the splines half open and then cutting to suit.

Cheers

Howard

[Chris Garner]

I would also suggest getting it balanced after the work.

[David Cochrane]

You can, of course, buy a whole new shaft that avoids the adaptor but when I just looked they were out of stock.

New ones are being made at the moment, and I hope to have them back in stock next month.

David

[john williams]

When I first got my RL in the early 60's, I fitted a ruby engine and gearbox. I fitted a shortened  Ruby prop shaft, and everything worked fine.
I rebuilt the car to original "spec" in 1977, and have run it that way until now. I have kept the shortened prop shaft, and a couple of weeks ago, tried to refit the shortened prop shaft, using the adapter for the 3 speed box, and a Ruby pinion flange.
 I could not get the front Hardy Spicer joint, when fitted to the adapter to clear the handbrake. So I have had to revert to the original "set up"! I have one of the later prop shafts, for fabric coupling front end, with the rear splines that will accept the sliding Hardy Spicer joint. A job for the future, to shorten this shaft, as the original sliding coupling is worn out.

[Charles P]

When I first got my RL in the early 60's, I fitted a ruby engine and gearbox. I fitted a shortened  Ruby prop shaft, and everything worked fine.
I rebuilt the car to original "spec" in 1977, and have run it that way until now. I have kept the shortened prop shaft, and a couple of weeks ago, tried to refit the shortened prop shaft, using the adapter for the 3 speed box, and a Ruby pinion flange.
 I could not get the front Hardy Spicer joint, when fitted to the adapter to clear the handbrake. So I have had to revert to the original "set up"! I have one of the later prop shafts, for fabric coupling front end, with the rear splines that will accept the sliding Hardy Spicer joint. A job for the future, to shorten this shaft, as the original sliding coupling is worn out.

The handbrake clearance can be a problem when using the adapter at the front. I managed to get enough clearance with some “finessing” but a major advantage of one of David’s new props is that they avoid this issue.

[Malcolm Parker]

The length of the propshaft must be such that it does not pinch up if the splined section 'bottoms' as the rear axle moves up and down.  If the back of the car is pushed down, the torque tube anchorage moves forward.  I would establish what the minimum distance is between the torque tube flange and the gearbox flange and work from there.

[JohnD]

Thank you everyone for the replys - they have been helpful.

I will speak with David Cochrane in due course as that will potentially save some hassle