Lotus Elan

Foreign doughnuts

PostPost by: oldelanman » Fri Oct 01, 2010 5:52 pm

A word of warning.......

There are Rotoflex couplings advertised on ebay at the moment as being suitable for Lotus Elan. The items pictured look to me to be standard Hillman Imp items - without the antisurge plates between the mounting bolts - and whilst they would undoubtedly fit the Elan they are not the correct items and would therefore be likely to fail after a very short time.

Probably obvious but I thought worth a mention just in case anyone hadn't noticed the difference.

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PostPost by: billwill » Fri Oct 01, 2010 11:43 pm

My doughnuts ex-factory in 1967 did not have the in-between plates either, so those are possibly 'more' original. But naturally I would avoid them now. Those originals of min did last quite a long time.


But I would be more concerned about the quality of the rubber regardless of whether or not they had the in-betweeners.

Kangaroo hopping is much more likely with the weaker doughnuts.
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PostPost by: oldelanman » Sat Oct 02, 2010 6:13 am

billwill wrote:My doughnuts ex-factory in 1967 did not have the in-between plates either, so those are possibly 'more' original. But naturally I would avoid them now. Those originals of min did last quite a long time.


Once again Bill I bow to your superior knowledge. As my car has always had the anti-surge type I assumed they were standard Elan fitment but now I notice the workshop manual does say that they were originally a factory upgrade and only fitted as standard from chassis no. 8930. You learn something new every day ! Like you I would not consider fitting the "old" type now though.

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PostPost by: AussieJohn » Sat Oct 02, 2010 6:48 am

My S2 had the early ones when I bought it in 1969; cheap to replace then at ?3 each!
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PostPost by: billwill » Sat Oct 02, 2010 12:20 pm

Note: both of us are mentioning Two-seater Elans, probably the +2 never had the doughnuts without the in-between plates and such doughnuts may not be suitable at all for the slightly heavier +2.


One slight advantage of the earlier ones was that they stretched better (instead of splitting) when you jacked up the rear of the car wrongly. BTDTGTTS.
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PostPost by: saildrive2001 » Wed Oct 06, 2010 11:44 pm

My 69 S4 SE had the standard Hillman Imp type when new.
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PostPost by: worzel » Thu Oct 07, 2010 1:31 pm

Hi

What about Imp competition ones- roughly ?40 each inc vat. Any owner have expeerience of these?

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PostPost by: CBUEB1771 » Thu Oct 07, 2010 3:56 pm

billwill wrote:Note: both of us are mentioning Two-seater Elans, probably the +2 never had the doughnuts without the in-between plates and such doughnuts may not be suitable at all for the slightly heavier +2.


Well this got me curious. The +2 Service Parts list shows that the +2 was originally fitted with A026 D 0034 Rotoflex joints, S1/S2 Elan part numbers! The S1/S2 Elan parts list shows only one part number, also A026 D 0034. Oddly the later Elan parts list, which covers S1 through S4, indicates an earlier part number, 026 D 0034, then the A026 and finally a B026 D 0034 introduced with the S4 Sprint. There is a note that the A026 joints have to be fitted in pairs. The suggests that the A026 joints were the ones in which the stiffening plates were introduced. If so this would confirm that the +2 always had the stiffened units. The +2 then goes through a series of 050 D 0034, A050 and B050. This means the +2 eventually went to a Rotoflex joint never fitted to any Elan. That I never knew. Of course that means you have to believe the parts book.
Last edited by CBUEB1771 on Thu Oct 07, 2010 6:59 pm, edited 1 time in total.
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PostPost by: Gray » Thu Oct 07, 2010 5:02 pm

Hi

From memory the later reinforced doughnuts were introduced wth the Elan Sprint and Plus2 S130. I think early Plus2s still had the non reinforced doughnuts. But most were changed to the later ones at an early age as they reduced the surge/wind up.

Having helped sort out a Lous dealer stores in the mid seventies, some parts ordered according to the parts book could turn up being very different, often due to availability.

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PostPost by: pereirac » Thu Oct 07, 2010 5:18 pm

My Sprint had a mixture of doungnuts when I bought her....strengthened ones on one side and Imp ones on the other!! I thought the strengthened ones were Imp competition ones? I can't imagine Lotus having something specially made for them if they did not have to.

Where can you get Imp competition ones for ?40, sounds like a good buy to me?

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PostPost by: trw99 » Thu Oct 07, 2010 5:52 pm

I'm on my iPhone right now so can not cut and paste from my web site. If you go to the Sprint Differences page, scroll down to drive train, there is a good explanation of Tony Rudd's reasoning for keeping the Rotoflex.

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PostPost by: types26/36 » Thu Oct 07, 2010 6:00 pm

pereirac wrote:Where can you get Imp competition ones for ?40, sounds like a good buy to me Carl


They are listed here http://www.imps4ever.info/tech/suppliers/malcolm.html but I thought I saw something from Club Lotus to say they are not the same.
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PostPost by: Craig Elliott » Thu Oct 07, 2010 7:17 pm

Tim, as I understand it (can't remember where I got this from so it could be bull) the problem with handling and UJ based driveshafts mentioned by Tony Rudd in the quote on your website was down to the need to use sliding splines to adjust the length of the driveshaft as the suspension moves up and down. Unless these were properly maintained they could lock under power or engine braking and this could affect the movement of the suspension - hence the handling issues.

As far as I'm aware the modern CV joint wouldn't be affected by this and UJ based systems with splines usually have some sort of system to prevent binding (e.g. teflon coatings).

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PostPost by: andyelan » Thu Oct 07, 2010 8:33 pm

Hi Everyone

Back in the '60, British racing designers avoided the use of sliding spline driveshafts wherever possible. Rotoflex couplings offered a neat alternative when it was necessary to accomodate driveshaft plunge and were fitted to many '60 racing cars incluing those for Formular 1. Given their background it's hardly susprising that Lotus would adopt these when they designed the Elan. CV joints started to appear on racing cars late '60 early '70 (the JPS Lotus 72 had them) and continue to be used since. Solid universal joints were used cars such as the Elite and Europa (and E Type Jaguar) but it's notable that the suspension on these cars used fixed length driveshafts so again the use of sliding splines was avoided.

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PostPost by: types26/36 » Thu Oct 07, 2010 9:12 pm

Here are a couple of Club Lotus Info sheets that may be of interest.
Attachments
DOUGHNUTS CLUB LOTUS P1 [HDTV (720)].jpg and
DOUGHNUTS CLUB LOTUS P2 [HDTV (720)].jpg and
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