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Short or Long Drive Shafts


Darren Groves

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The basic point is the end of 1972 when the Mk IV got its facelift and the dash went from black plastic to wood veneer/the fuel/temp gause needles went from pointing down to pointing up.

Car interiors could have been modified but if it's lower than an "L" it should be short/higher should be long.  If it is an "L" then you'll need to look closer.

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6 hours ago, Mjit said:

The basic point is the end of 1972 when the Mk IV got its facelift and the dash went from black plastic to wood veneer/the fuel/temp gause needles went from pointing down to pointing up.

Car interiors could have been modified but if it's lower than an "L" it should be short/higher should be long.  If it is an "L" then you'll need to look closer.

 

39 minutes ago, Pete Lewis said:

tape measure the shaft between flanges  long are 308mm  short are 283  

Pete

It is a 1972 (L reg) car with a plastic dash and I have measured the drive shafts and they are the short ones, but before the car was stripped it had a lot of positive camber at the back even when rolled to settle the suspension. I thought this might be down to seized rear trunions but all came apart easy when disassembled. Using short drive shafts instead of the long would give the same camber issues I guess, and as this is a car from the changeover year it is possible the wrong ones were fitted unknowingly by a PO.....I was just wondering if there was a definitive way of knowing which is correct for the car.

Darren

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I didn't think the spring changed.....

The radius arms and heelboard brackets did though. Another reason mismatched cars can be rather wayward handling.

Are you sure the spring bushes were not tightened with the wheels offthe ground, that can cause positive camber. Or a new spring.But the arly cars did sit a bit higher.

Simple answer, fit a lowering block....Or better, long shafts and associated bits.

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It's also worth noting that when the shafts changed (got longer), so did the "soft" brake hose, and the backing plate gained a bracket into which the "soft hose" went on one side and a hard pipe from there to the wheel cylinder into the other side. Of course, 45 years later, such visual "confirmation" doesn't necessary mean your assembly still has the correct shaft originally fitted.

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16 hours ago, Darren Groves said:

It is a 1972 (L reg) car with a plastic dash and I have measured the drive shafts and they are the short ones, but before the car was stripped it had a lot of positive camber at the back even when rolled to settle the suspension.

Hopefully I'm getting this the correct way around but could it just be an old spring that's past its best?

The spring will weaken over time meaning at rest the spring eyes sit higher relative to the drive shaft where it exists the diff., but nether the spring bottom leaf (top wishbone) or drive shaft (lower wishbone) change length so the wheel goes more 'top out'.  A new spring should fix that.

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dont forget that although the angle of the vertical link may change this is independant from the trunnion angle (because its free to rotate on its bushes) so the angle of the wheel depends purely on the angle of the half shaft. The flatter (softer) or higher (raising block) the spring the shallower the angle of the half shaft becomes and the more negative the wheel camber.

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Probably BUT a decent spring is VERY hard to find. I needed a new rear spring. Bought from one of the big suppliers and fitted. In one weekend it had sagged and the bushes were toast. I was refunded. That was a british made spring. So in reality you can order the correct part, but quality, let alone specification, is a nightmare. Remember most supplies will keep only one  type of swing-spring. (they also sell the mk3 spit spring as suitable for GT6 mk1, but pretty different rate)

I have heard good things about Owen Springs in Rotherham.

Don't forget all the other differences between setups, including the radius arms+brackets and easy to forget brake backplate...

As mentioned earlier, a lowering block may be the way to go.

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I doubt that these components are interchangeable and as I said previously cant see that the spring length alone will make much difference to wheel camber. It sounds to me that, assuming the spring is correctly mounted, you have one that has had an easy life and not flattened out much. However if youre worried about the positive camber (not so much of a problem with a swing spring car) then as Clive says a lowering block or more tools/spares in the boot will help correct it. 

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