Lotus Elan

Going back to Rotoflex

PostPost by: rdssdi » Mon Apr 27, 2009 2:09 am

The discussion on originality is an interesting one.

When I began the restoration of my +2 I was not aware it needed a new chassis. Both Lotus galvanized and Spyder were available and luckily the exchange rate favored the dollar. At that time, I was not that interested in originality . I debated the pros and cons of the two chassis' with many people on this list. Spyder had a 25% discount and I purchased the Spyder chassis including their 1 cv and 1 rotoflex shafts and control arms front and rear. It performs well but as Kyle says it is not a Lotus chassis. I now lean toward originality with the only exception being safety.

I found that usually one modification begets several more. It becomes an exercise in design and frustration and is very time consuming. But many people consider it a challenge and rewarding.

I am presently restoring a 1968 TVR Vixen. I planned strict on originality with the exception of the fuel system. I have strayed a bit. The factory fuel tank is unprotected, too large and a safety issue. I have had a new alloy tank constructed with a "cage" constructed which protects the tank. It is also now several inches from the rear of the car instead of directly against the rear panel. I have also had a roll bar fabricated. The only other modifications I plan are an alternator replacing the generator and a more modern wiring loom with relays. The original did not even have a horn relay. Also modern retractable three point seat belts.

I had a difficult time deciding to use an alternator. The main reason being I am not a fan of the large current to the ammeter gauge.

I am maintaining the original color, wire wheels, interior and engine / drive-line. No Ford V-8 Tuscan fans.

I drove my Elan +2 to a BBQ last evening. Worked great. Finally having some fun.

Kyle, would you consider an Elan FHC? They seem fairly rare and I like their looks.
Bob
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PostPost by: msd1107 » Mon Apr 27, 2009 5:19 am

Bob,

There has been some discussion of alternators on the site. I seem to remember alternators as small as 30 amps. This would work perfectly with the -30-0-30 ampmeter.

David
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PostPost by: trw99 » Mon Apr 27, 2009 10:40 am

Shortly after Tony Rudd joined Lotus in 1970 he looked at the Rotoflex question and his investigation was reported in Motor Sport:

?When I visited Lotus some months ago I spent quite a while discussing the relative merits of Rotoflex couplings and sliding spline and universal joints in the rear drive shafts with Tony Rudd, the firm?s Director of Engineering. Rudd had been dubious of the Rotoflex or doughnut coupling before he joined Lotus and agreed that the diabolical surge they caused had to be cured. To this end various experiments were tried when he joined the firm, one of which was the use of the more conventional u/js. However, for some reason, concerned with the elasticity of the doughnuts, the handling undoubtedly deteriorated considerably using the metal joints. So Rudd did quite a lot of research on Rotoflex couplings and after a couple of improvements has now come up with one that almost entirely eliminates the wind up. These are naturally somewhat more rigid and perhaps, because of this, the ride seems to be a little harder than on the earlier and exceptionally smooth riding Elans.? [Copyright Motor Sport]

In addition, it is worth remembering that at the time the Elan was being dreamt up by Chapman, Rotoflexes were in serious use on the racetrack. The 1960 Lotus18 Grand Prix car had lower wishbone, twin trailing arms attached to the chassis with the wheel half-shafts forming the rear suspension. Later on, the rear suspension was modified to double wishbones, which relieved the drive half-shafts of any wheel locating function. The half-shaft couplings were changed to Rotoflex doughnuts as the half-shafts now effectively had to change length as the suspension flexed.

Whilst each to his own with regards to modifications, for me one of the benefits of driving an Elan in original form is experiencing ? again, in my case ? the joys and otherwise of motoring in the 1960s and 1970s.
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PostPost by: KyleK » Mon Apr 27, 2009 11:17 am

Bob,

Yes I would consider an Elan FHC. It would have to be original and in exceptional shape. I prefer a convertible though and have recently discovered the ss does not thave window frames either so S1, S2, SS would all be ok. I made the original post becuase I am seeing many Elans that are close to my requirments but except for the CV conversion, so I thought I could expand my criteria.

I am not limiting the expansion of my collection to Elans, however. Any Lotus - even the 70's ELite/Eclat would be included (though not likely I would find one in the condition I am looking for). The Elan and Cortina are tops on my list to expand, followed by Climax Elite, then Lotus Seven and Europa, then Esprit. I don't know why, but I am also interested in the Sunbeam Lotus. Probably because, like the Cortina, it is a bit of a sleeper and can fit four people. I'd probably be the only one in the US to have one if I went through the trouble of finding and importing one. I am currently looking at a Cortina and a Europa.

I'll entertain any Lotus you guys can throw my way, but in all cars I am looking for unmodified, original spec, excellent condition (restored is OK, possibly preferred) Lotuses.
Kyle Kaulback

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PostPost by: garyeanderson » Mon Apr 27, 2009 12:01 pm

KyleK wrote:Bob,

Yes I would consider an Elan FHC. It would have to be original and in exceptional shape. I prefer a convertible though and have recently discovered the ss does not thave window frames either so S1, S2, SS would all be ok.


Kyle
I think you will find that the SS being based on the S3 does indeed have the window frames, (aka DHC,FHC) and are not frameless as are the S1 and S2 roadster's.

Gary
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PostPost by: trw99 » Mon Apr 27, 2009 2:56 pm

Anyone have experience of 'Donut Savers'?

http://www.dogrings.com/donut_saver.htm

Seems they are produced in the US by someone on the vintage race scene who knows what he is doing.

Tim
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PostPost by: prezoom » Mon Apr 27, 2009 4:42 pm

The owner is Wayne Mitchell. I have known him for years. Has been involved with SCCA, HSR West, and VARA for many years. He makes quality products and used to own Hallibrand Engineering, the company famous for the wheels on Cobras. A couple of years ago he made the extended input shaft to match a dogbox tranny to my race car. Did a very nice job. Anything he makes, I would believe would be bullit proof. However........they were designed for use on a Formula Ford type vehicle, that has limited suspension travel. A good friend, who has raced Elans in the past, believes the Elan has too much suspension travel to have them work effectively. He uses them in the multiple FF's he preps for vintage racing, if it is a car he is unfamiliar with and does not know the history of the existing coupling. On new couplings he doesn't use them, but has seen near failure after one day's of competition on a brand new coupling. In the FF's, he has seen contact between the "saver" and the rubber of the coupling, especially when agronomist racing occurrs, thus his belief that they would be unsuitable for the Elan because of the short half-shaft.

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PostPost by: KyleK » Tue Apr 28, 2009 11:25 am

garyeanderson wrote:
KyleK wrote:Bob,

Yes I would consider an Elan FHC. It would have to be original and in exceptional shape. I prefer a convertible though and have recently discovered the ss does not thave window frames either so S1, S2, SS would all be ok.


Kyle
I think you will find that the SS being based on the S3 does indeed have the window frames, (aka DHC,FHC) and are not frameless as are the S1 and S2 roadster's.

Gary



My mistake, I was looking at photos of a partially restored car that did not yet have the window frames installed, on closer inspection there was a photo of the frames and electric window motors out of the car in the series.

Kyle
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PostPost by: CBUEB1771 » Tue Apr 28, 2009 11:57 am

trw99 wrote:Rudd had been dubious of the Rotoflex or doughnut coupling before he joined Lotus and agreed that the diabolical surge they caused had to be cured. To this end various experiments were tried when he joined the firm, one of which was the use of the more conventional u/js. However, for some reason, concerned with the elasticity of the doughnuts, the handling undoubtedly deteriorated considerably using the metal joints.


I am mystified by these stories of handling being degraded by use of "metal joints". Let's think about this. Suspension geometry is not affected by changing from Rotoflex joints to UJ/sliding spline, Hooke joint/sliding spline/Rotoflex, or CV conversions. The Rotoflex joint does add some spring stiffness and damping to the rear suspension but this is easily compensated with other adjustments. So would cause handling to deteriorate with "metal joints"? Perhaps it is binding in the sliding spline? That would upset handling but Lotus must have put sliding spline axles in the 26R for a good reason. The CV conversion I put into my +2 certainly did not degrade the handling or add noise/vibration/harshness. :?:
Russ Newton
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PostPost by: denicholls2 » Tue Apr 28, 2009 5:12 pm

Russ wrote:

I am mystified by these stories of handling being degraded by use of "metal joints".

Perhaps the brush was painted too broadly. I believe the intent was to speak of dual UJ's, as are used in the Europa.

The Europa uses the half shafts as the upper link, and I doubt many would dare to claim it handles badly. :wink: But a dual-UJ solution in conjunction with multiple links would require some form of length adjustment methinks, or interesting behavior would result. I do know that the Banks Twinlink for the Europa requires removal of the pins from the transaxle-side halfshaft mounts to permit the mounts to "float" on their splines, for example. There has been some heated discussion regarding whether this design is an improvement on Chapman's original, however.

A point of interest is that the racing version of the Europa, the Type 47, employed rotoflexes instead of the UJ's.
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PostPost by: cabc26b » Tue Apr 28, 2009 7:36 pm

A point of interest is that the racing version of the Europa, the Type 47, employed rotoflexes instead of the UJ's.


Valid observation however, the 47 suspension/drivetrain followed the current thinking on what was SOTA for mid engine formula cars and sports racers - reverse lower wish bone, Single top-link, parallel links running forward. rear anti-roll bar. all attached to a cast magnesium bearing carrier. The transmission, Hewland FT200, with a donut on the trans out-put shaft, UJ on the outer end only ( and this is either splined to the hub shaft or made/welded up as a single piece ) out board disk brakes and hub set up to take wheels with pegs . BTW the donut on the 47 is quit a bit larger than what you have on an elan - of course as with any lotus there exceptions - 47GT-54 ran with sliding splines and ujs on both ends .. all in all, not much in common with either the Europa or elan rear suspension ( solution not produced from the same criteria either)
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PostPost by: davea » Wed Apr 29, 2009 10:25 pm

I was told of, and seem to have experienced, a drop in rear roll stiffness after switching to
cv joints. (Mine are the style with the inner end of the CV plug into the diff
directly, not using the original 3bolt inner.) FWIW.
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PostPost by: richard sprint » Fri May 01, 2009 8:39 am

Was interested to hear that Miles Wilkins is not a fan of the CV joints prefering the ride of the rotoflexes - this is a man of years of experience....
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PostPost by: steveww » Fri May 01, 2009 9:11 am

The rotoflex joints should be considered a consumable item like brake pads. The current cost of a set of rotoflex joints is about the same as a UJ/CV conversion. The solid drive shafts will last a lot longer than the rotoflex leaving more money to spend on petrol, track days, rallies, B&B for weekend trips, race tickets i.e. driving the Elan :)

My S4 has the TTR conversion fitted and the only difference I noticed from the rotoflex is the lack of surge and judder.

There will always be the big debate over original vs modified. IMHO there are a number of sensible modifications to the Elan to improve reliability and safety. I think these choices boil down to whether you like to "park and polish" or Drive.

The Elan is the best handling car I have ever driven and that list includes some very impressive machinery. Even by modern standards it is a quick car and there is not much that will stay with one down a twisty lane or race track. I had a Porsche 911RS for 3.5 years and I can only remember one truly great drive for the Elan I can think of many, including yesterday taking the long route to the Post Office 8)

Each to their own, enjoy your Driving or polishing :wink:
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PostPost by: richard sprint » Fri May 01, 2009 9:50 am

Steve

Good post - what different systems are available in the CV form? I've yet to drive a lotus elan so very much looking forward to the experience - I'm more into driving than polishing but its also nice to have the car looking good and easy to maintain - a resto or not - was not really an option as the car had sat for 20 years and everything needs attention.

My motoring love for the past 15 years has been the E30 M3 and it was only because I occasionally needed 4 seats that did not go down the Porsche route back in the mid 90's.

I've enjoyed some good trackdays against the 90's Porsches, the later GT2's and 3's are just in a different world....
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