Lotus Elan

removing failsafe driveshafts

PostPost by: kandmpc » Mon Jun 20, 2005 7:55 pm

Hello everyone, I am renewing all 4 rotoflex couplings and I notice that one side of the car if fitted with the 'failsafe' type driveshafts. Will I need to remove the strut to get the intermediate driveshaft and rotoflex couplings out.

Regards

Ken
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PostPost by: ppnelan » Mon Jun 20, 2005 9:32 pm

Hi Ken,

I had the same difficulties on one side of my +2.... The other side had a non-failsafe diff output shaft which gave just enough space to remove the donut...

As far as I remember, first I clamped the spring so the back didn't have to be jacked up a long way.
Then I undid the outer wishbone bolts - I think this was because the inner ones were stuck in the bushes; I was lucky that the outer ones weren't stuck in the aluminium strut ! You may find it easier to remove the inner ones instead.
Once the donuts are free, the strut & wishbone should swing outwards enough to remove them & the shafts.

I vowed to replace the shafts with non-failsafe ones next time around...

Good luck !
Meemo
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PostPost by: rgh0 » Tue Jun 21, 2005 11:42 am

Ken

Its been a long time since I did it but you can remove and refit the fail safe style shafts in the same way as you do the standard ones. There is enough freeplay to move the intermediate shaft to one side once the donuts are disconnected to clear the fail safe fittings at the other end.

It just adds another element of difficulty to an already difficult process. However with practice it gets a little easer after doing it 8 or 9 times over the years! Disconnecting the lower A frame from the strut so you can swing the strut out of the way to drop the intermediate shaft eases the problem.

However I converted my plus2s 130/5 with fail safe shafts to CV joints 15 years ago and have never regreted it.

Rohan
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PostPost by: chicagojeff » Wed Jun 22, 2005 7:05 pm

So here's a newbie question...how do you know what type --failsafe or not--are fitted?

Thanks, Jeff in Chicago "Still Underneath my Car" :wink:
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PostPost by: rgh0 » Thu Jun 23, 2005 10:47 am

Jeff

Look at the background drawing that comes up as you change views on this forum. Its a drawing of the failsafe driveshaft and donuts !!

Rohan
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PostPost by: prloz » Thu Jun 23, 2005 1:16 pm

Hi All,
Can anyone advise the dimensions of the pins and tubes fitted to the
failsafe shafts ?
Thanks in advance.
Peter.
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PostPost by: rgh0 » Fri Jun 24, 2005 12:57 pm

I have some intermediate shafts with the tubes in the garage somewhere I will dig them out and measure them on the weekend. I dont think I have any examples of the pins left as I ground them off when I converted to CV joints.

If you do install this system use bigger diameter or stronger pins and better welding than Lotus used. The only time I broke a donut with this system in my plus 2 the pin just broke off at the same time and the shaft flailed around damaging the chassis so "failsafe" was very much a nominal description !

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PostPost by: rgh0 » Sat Jun 25, 2005 1:33 am

Peter

I measured up the tubes on the intermediate shafts from my 1973 plus 2 S 130/5 as follows

length 45.0 mm
Outside diameter 28.7 mm
Inside diameter 20.0 mm

The ends of the tubes have a 45 degree internal chamfer on the tube end.
The tubes are mig or tig welded to the intermediate shafts with a 4 to 5 mm fillet weld. I will post a photo in the photos section.

I could not come up with any examples of the pins maybe some one else has an original one. From memory they were approximately 6mm diameter and maybe 30mm in length.

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PostPost by: prloz » Sun Jun 26, 2005 8:18 am

Hi Rohan,
Many thanks for your reply.
I have two complete sets of sprint donuts - seems a pity to waste them -
so I will probably modify the shafts to 'failsafe' and use them.
I can understand why the pin sheared off if it was only 6mm. dia. !
Regards,
Peter.
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PostPost by: M100 » Sun Jun 26, 2005 1:17 pm

The pins are 11mm dia and 42mm long on my (original Lotus) spares
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PostPost by: rgh0 » Mon Jun 27, 2005 11:03 am

I would have sworn that my pins were much less than 11mm when I cut them off. But then memory can play tricks with you after a few years. An 11 mm pin would be tight on clearance in the tube given the suspension travel especially in an Elan but if you got some to measure I would trust that more than my fading memories?

Curious

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PostPost by: M100 » Mon Jun 27, 2005 6:56 pm

The measurements came direct from the new Lotus ones supplied in the mid 80's which are in my parts stash - BUT they have never been on a car so who knows if they are right!

I've run standard driveshafts since day one and not the failsafes, I'm now contemplating changing to CV joints as i've only got one set of (good rubber spec) rotaflex's left.

Somewhere (maybe in the Robinshaw and Ross book?) there are the drawings for changing to failsafe. All my books are in storage at the moment otherwise I would have checked.

I've some used failsafe diff output shafts buried at the back of the garage that i'll get a look at in a few weeks. Let you know if they are different.
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PostPost by: prloz » Wed Jun 29, 2005 11:57 am

Thanks Rohan & M100,
Consulted my 'Robinshaw & Ross' but no failsafe diagrams or dimensions
in there.
Regards,
Peter.
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PostPost by: rgh0 » Wed Jun 29, 2005 12:14 pm

Peter

The only drawings I have seen are on this forum in the tech section under final drive with a lotus service bulletn on te change to the centred drive shafts. If the drawing is to scale the pin is around 45mm long like the tube and around 7 mm diameter like the ones I remember cutting off.

The implication from the service bulletin is that they were only ever fitted by the factory to plus 2's starting during Plus 2S 130 production during 1972 and never to Elans which had ceased production by then and whose suspension angles probably precluded it anyhow.

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