Lotus Elan

Going back to Rotoflex

PostPost by: Jolly Jumper » Mon Apr 20, 2009 8:05 am

elansprint71 wrote:Why do folks keep saying that rubber couplings give a "smoother ride"?


Because I have experienced it with two Elans. Changed to solid driveshafts and had more vibration as a result. Fact. Actually one of the purposes of the Rotoflex was to improve comfort and smoothness by taking vibrations out of the drivetrain.

elansprint71 wrote:What sort of modern car has rubber couplings? Are modern cars "not smooth"?


I am no engineer but I am quite sure many modern cars, like BMW or Mercedes, have rubber couplings. Not the same as the Elan obviously, and engineered to a much higher standard, but still the same thought is behind. Have a look: HERE. The Porsche 917 also had so these Guibo Coupling, but they were MASSIVE.
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PostPost by: paddy » Mon Apr 20, 2009 9:00 am

Don't dual-mass flywheels incorporate some of this driveline cushioning nowadays?

It seems to be fairly popular to replace these with conventional clutches when they fail - not worth the cost and adverse reliability.

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PostPost by: gerrym » Mon Apr 20, 2009 9:29 am

Re Modern cars and rubber couplings. These are pretty common in the drive-line of modern cars, especially rear-wheel drive. Usually there are mounted in the output from the gearbox where the torque is lower compared to the diff output. The big difference compared to the Elan application, is that the articulation requirements for a prop shaft are a fraction of what is required for the rear axle drive shafts (of the Elan).

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PostPost by: John Larkin » Mon Apr 20, 2009 9:39 am

I put Tony Thompson solid driveshafts into my S3 last year. I first drove my Lotus in 1974. I never found the rotoflexes to be a problem, and have never experienced a catastrophic failure of those couplings. Back in the 70s I think I remember replacing the rotoflexes only once as a precaution. I replaced them again about five years ago, and within months the rubber began to develop surface cracks. The old ones that I took off, and still have somewhere (I'm a squirrel when it comes to car parts), still looked almost new after about twenty years in use on the car. I have read so much about failures of modern rotoflexes that I began to feel uneasy about their reliability, and as they cost almost the same for a set as the conversion to solid driveshafts I decided to convert. I have kept the original driveshafts in case any future owner decides to revert. I am delighted with the solid driveshafts, and I have experienced no vibration or roughness. I have put on about three and a half thousand miles since they went in, including a fast continental run, and I have no regrets about changing. I no longer fear a flailing driveshaft coming up through the floor.

I feel quite strongly about unnecessary "upgrades" that alter the driving characteristics of an old car to make them feel more modern, but I think that reversible changes that make a car more reliable in modern driving conditions are acceptable, such as improved engine cooling or conversion to an alternator.

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PostPost by: Jolly Jumper » Mon Apr 20, 2009 12:03 pm

Just to put things into proportion, I must add the harshness introduced by the solid driveshafts is not *that* much. Certainly not enough to make you stop fitting them. I think they are good piece of kit. However, if your steel wheels are worn, you will feel them wobbling after fitting the solid driveshafts.
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PostPost by: cabc26b » Mon Apr 20, 2009 1:32 pm

Gents

I think it is un-fair for any one without a lot of seat time with the elans to come away thinking that the rotoflexs are anywhere near a life time piece or cannot / will not fail. They all deteriorate. The new ones faster than the old ( oem). The more horsepower you use the quicker they deteriorate and fail. If you are rough with them - deteriorate quicker. if you have an engine making more than 105-115 HP deteriorate even quicker. I recall them not recommended for any engine over 140hp.

Based on the elans I have purchased over the last 20 years more than 50% of the cars that I have owned had/have signs of catastrophic donut failure. BTW, I acquired all my cars with the original chassis.

As an aside I don't recall smoothness being top of mind when the donut was selected - the articulation of the strut suspension required something without bind and providing plunge - oh and since it's lotus it had to be cheap and out of somebody else's parts bin - they got em from the roots group as built for the imp .....

One more think before I get off my soapbox - The part i like about my street elans is that once you got through the trouble to head off the know issues and I am not implying a modernization plan , the cars are very reliable, you can leave them under cover for months and so long as the battery has juice and their fuel is not jelly the cars will fire up and drive off. you can't always do that with a 911S or a old itialian car.

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PostPost by: alexblack13 » Mon Apr 20, 2009 1:59 pm

Its failure that bothers me. I used to use a side lift truck with special mods to service our fleet of cars. Jags, fords etc etc..Done my +2 one day had a look at the roto's and thought, fine. Nice nick. They will last a few more miles.. They didn't.... 1 let go up at Knockhill.

Made a fair mess. Good job we had not been to Asda that day. Might have broken a few eggs :lol: :lol:

Horses for courses. I like original too. Who doesn't! But I feel a '''bit''' safer with the new driveshafts...

good luck either way. It will be fine.

Alex B.... 8)
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PostPost by: andyelan » Mon Apr 20, 2009 2:30 pm

Hi Everyone

Many of the comments raised here beg the question, why are we messing about with old cars anyway. To my mind, no matter how we talk them, up no Elan, however modified, will be as "good" as some of the moderns mentioned above, but that of course completely misses the point. A friend of mine has two old cars, a 1933 Riley Monaco and a 1988 Porsche 944. I asked him the question which is "best". It's completly irrelevant of course, both are fun in their own way. What is remarkable about the Elan it that we can even talk about a 40+ year old design in the same sentance as a modern.

Going back to the original thread, I've never found donuts a problem. What does annoy me, however, is that I've just had the suspension to pieces on a Plus 2 I've just bought and found a PO has assembled the donuts with standard bolts rather than the special long shank ones. Now it's clearly stated in the workshop manual about this but someones not look so the drive has been across threads not the plain portion of the bolt. Next thing one will fail and there'll be another story of Elan donut problems when actually it's all been down to incorrect assembly.

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PostPost by: memnon » Mon Apr 20, 2009 6:07 pm

Hi Andy,
Technically off topic now, but I'll answer.

How many modern cars can you name where you remember the journey?
How many modern cars can you name where you enjoyed the drive

How many "1600cc" Modern cars can you name that do 120(ish) mph and 0-60 in under 7 seconds and properly corner?

If you can find any that cost under ?20k let me know! 'cos I'd probably have one!
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PostPost by: Allison » Mon Apr 20, 2009 6:21 pm

Hi guys,

I think its an emotional choice because I don't see how it can be logical! Our cars cover miles of rough terrain and we've tried to keep everything original - well apart from the bits we can't - like a Spyder chassis, strengthened rear struts, adjustable rear spring platforms and electric fan (but only as a back-up).

We've always used Rotoflexes - in India, Africa, UK and Asia and in all that journeying we've only replaced one away from home on the road. people say they don't last long enough, I treat them as consumables - much like oil changes and brake pads. We've never been stuck anywhere as a result of a broken rotoflex.

And by the way we also use a dynamo - in Iceland we had a week with headlights on all the time and wipers most of the time - electrics perfectly happy.

Cheers,
Peter
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PostPost by: dusty » Mon Apr 20, 2009 7:24 pm

memnon wrote:
How many modern cars can you name where you enjoyed the drive



I had a new Scirroco 2.0TSi as a hire car when I came over to donington. I enjoyed driving that, went like stink! I drive a classic as my everyday car (BMW 3.0CSi) so its nice to have a go in a modern now and then.
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PostPost by: alexblack13 » Mon Apr 20, 2009 8:21 pm

Ehmmm ... I really enjoyed the drive down and back up.... In our Z4....Sorry!! :?


I wish I had taken the Elan though. :?

Did another 100 mls or so today. The weather was brilliant.

The car is still a bit 'fluffy' at low revs. Fitting electronic ign later this week with coil to suit. To make sure I am not chasing a lecy (Missfire) problem around the carbs. There is a def' fault with the acc'pump. Carbs off again this weekend to sort this out. Very rich on one carb.

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PostPost by: andyelan » Mon Apr 20, 2009 8:41 pm

Hi Memnon

Lotus Elise ??? :wink:

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PostPost by: 1964 S1 » Tue Apr 21, 2009 3:21 am

Thank you Peter as I am a rotoflex guy too. I bought my first used S2 Elan in 1972, I've owned 7 Elans, including a current +2 and have never experienced a failure.
For me, the smoothness issue is about fluid performance. I own an Elan because the car handles better than anything else I've ever driven, and, the STOCK drivetrain is rubber mounted. Even the differential if you think about it, from crankshaft output to rear hub drive...
Sliding U-joints have their benefits I suppose. Are CV joints available?
Greetings memnon, As far as modern cars where I've enjoyed the journey? EVERY time I take our Prius out... I LOVE IT. A turning radius smaller than the Elan ! A pig to look at but totally enjoyable to drive.
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PostPost by: type36lotus » Mon Apr 27, 2009 12:31 am

My 2005 Subaru WRX with Prodrive Stage III power pack certianly brings smiles to my face when I drive it. But I really do miss my Esprit and Elan :-(
Mike Geiger
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