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Propshaft fitting

Posted: Wed Oct 13, 2021 1:26 pm
by mikeo632
Come to swap my propshaft with a spare one from a donor car, but 1 is fitted with the sliding joint at the gearbox end, the other with it at the diff end?
Which is correct?

Thanks.
Mike.

Re: Propshaft fitting

Posted: Wed Oct 13, 2021 7:59 pm
by torque2me
mikeo632 wrote:
Wed Oct 13, 2021 1:26 pm
Come to swap my propshaft with a spare one from a donor car, but 1 is fitted with the sliding joint at the gearbox end, the other with it at the diff end?
Which is correct?

Thanks.
Mike.
If you do a search you'll find a fairly recent thread on this subject.

I always put mine back in the same orientation with the help of Tippex.

Kev

Re: Propshaft fitting

Posted: Thu Oct 14, 2021 8:06 am
by Charles H
Sliding joint at the rear.

Re: Propshaft fitting

Posted: Thu Oct 14, 2021 8:09 am
by mikeo632
Thanks.

Re: Propshaft fitting

Posted: Fri Oct 15, 2021 7:50 am
by Clifford Pope
There is frequent debate in the Series LandRover Club about this, and the concensus is that each joint should be at the gearbox end,
a) because they are higher off the ground so get less road dirt splash
b) because it's heavier than the plain tube so it reduces unsprung weight

I don't think either argument signifies in the case of the Triumph - the shaft is quite low at both ends, and the IRS means none of its weight is unsprung.
A conclusive argument I found was that the shaft is thinner at the sliding joint so easier to keep clear of the handbrake cable horseshoe if mounted at the axle end. (another argument for an exhaust without the middle silencers)

Re: Propshaft fitting

Posted: Fri Oct 15, 2021 9:29 am
by johnnydog
But then again, an auto has the sliding joint at the gearbox end.....

Re: Propshaft fitting

Posted: Fri Oct 15, 2021 2:05 pm
by harvey
FWIW. If you were to have the short yoke attached to the gearbox, and then drive it (without the prop fitted), it would fly outwards, and hit whatever with the force at the end of about 6". If you did the same with the propshaft, it would hit with the force at the end of about 4 foot (the length of the prop). That is trying to happen when the two halves of the prop are joined together, it's just the splined slider stopping it, and so that will wear the splines, and more so if the sliding joint is at the rear. Discuss.

Re: Propshaft fitting

Posted: Sat Oct 16, 2021 7:06 am
by Alec
Hello Harry,

sorry but I can't see your argument. The point is that the shaft as a whole is connected and restrained by the connection at both ends. Because of that there is no centrifugal force to throw the shaft outwards.
My Triumph parts book RTC9112 shows the sliding joint at the gearbox end.

Alec

Re: Propshaft fitting

Posted: Sat Oct 16, 2021 10:09 am
by Clifford Pope
The "pole vaulting" argument has featured on other car forums, and the conclusions seem to be pretty catastrophic at either end.
Four feet of propshaft flailing around is going to do a lot of damage anywhere, but perhaps would bring a speedy end sooner at the front (by stopping the engine) but might be much more serious at the rear.
However, seriously, how likely is it that the prop shaft will ever come apart like that?

I don't think wear on the sliding joint is caused by centrifugal force. I would guess it comes from simple sliding in and out as the suspension rises and falls, exacerbated by transmitting torque at the same time.

Re: Propshaft fitting

Posted: Sat Oct 16, 2021 1:50 pm
by Alec
Hello Clif,

you would have to endure a vibrating noisy car if the flange bolts were loosening. In reality it is very unlikely to happen.

Alec