Single Vs Two Piece tail shaft

Hi,

I've always changed my Escorts from two piece to single piece tail shafts for handling & weight reasons.

I'm now restoring a Mk1 and am wondering if that's such a good idea for general comfort and other reasons.....here's the question, anyone have any opinions on what those other reasons are ? Ford must have had a good reason to put in a heavier tail shaft with more moving parts, I'm just not sure what they were ?

Cheers,

Mark

Ahh, ok. Is the vibration difference noticeable ?

Easy;

Reason 1:
Safety.
Tailshafts are usually long tubes with very thin wall thickness and rotate and twist at many varying speeds, and at many angles as the rear suspension travels up and down. Motor vehicle manufacturers prefer to manufacture the tailshafts in two pieces rather than one piece to increase strength. ie two short shafts supported in three places in theory should be stronger than one very long shaft with only two supports. This reduces the strain on the thin tailshaft tube itself plus spreads the load across more universal joints.

Reason 2:
Harmonics.
Two shorter tailshafts will resonate less than one very long tailshaft. Thereby reducing in cabin noise and vibration.


If converting to a one piece tailshaft it is very important to add a saddle towards the front of the tailshaft and be fitted rigidly to the floor pan. This helps minimise the risk that should the tailsaft, or one of the uni's breaks, the tailshaft will be held captive so will not hit the ground with the potential of overturning the car if driving at speed.

The main reason most Escorts that were originally fitted with 2 piece shafts now have single shafts is the centre bearing support used to collapse and they are non replaceable.

Commodores have a similar set up and similar problem except the replacement part is readily available.

When the support collapses the bearing no longer sits centrally causing even more vibration.

G

IIRC Mythbusters tried this on a full size car - lot of mass to flip compared to an Escort...

I personally have seen a car rip its rear suspension mounts off the chassis and flip after dropping a one piece shaft - let me tell you nothing makes your cheeks clench like the sight of a rear axle cartwheeling down the road in front of you while a car does barrel rolls down the side of the road....

A random alignment of planets maybe, but I will always run a tailshaft loop on my cars......

I fabricate my own, but they are readily available on feebay (just search for "tailshaft loop") or your local spped shop

Cheers

James