ROTOFLEX QUESTION

[Jeff@Jae]

We've never had an issue with the CV axles we use (same as the RD Enterprises and Dave Bean Engineering axle sets) in over 20 years. There used to be life span issues with the inboard axles (diff output shafts) supplied when used on racing Elans but that was revisited years ago and that new design is what's been used on all the axles for at least 15 years. They work great and the Lobro CVs are lifetime on the lightweight Elan. You may need to change boots at some point way down the road but that's about it. We will not sell the current Rotoflexes but we would if we could actually get real Metalastic Rotoflexes. One benefit of the CV axles isn't mentioned very often but one I find really nice is how much better the gearbox synchronization works with out that surge of rotoflex energy fed back through the drivetrain when the clutch is used on a quick upshift.

[Spyder fan]

I never drove an Elan in the 60's and 70's (too young ) so I didn't get to experience the genuine Metalastic rotoflexes in good near new condition, but those that did tell me it made for a very smooth driveline if you timed it right between clutch and throttle foot. I do however remember driving Mini's with rubber Spider type joints on the inboard of the driveshafts in the late 1970's and early 1980's, this made for a very refined driveline. These were later changed to CV joints on the inboard which made for slightly harsher gear changes, to improve the NVH the front subframes were rubber mounted to the monocoque whereas before they had been solid mounted. The inboard CV joints were pretty much no maintenance, but it was a retrograde move for the handling because of the rubber mounts to the subframe, but hey Mini's were just meant to be transport.

[gearbox]

We've never had an issue with the CV axles we use (same as the RD Enterprises and Dave Bean Engineering axle sets) in over 20 years. There used to be life span issues with the inboard axles (diff output shafts) supplied when used on racing Elans but that was revisited years ago and that new design is what's been used on all the axles for at least 15 years. They work great and the Lobro CVs are lifetime on the lightweight Elan. You may need to change boots at some point way down the road but that's about it. We will not sell the current Rotoflexes but we would if we could actually get real Metalastic Rotoflexes. One benefit of the CV axles isn't mentioned very often but one I find really nice is how much better the gearbox synchronization works with out that surge of rotoflex energy fed back through the drivetrain when the clutch is used on a quick upshift.

Hi Jeff, Thank you for the information, I and everyone following this thread is appreciative for your input. But if you read some of the other posts in this forum and others, there has been a rash of premature failures from boots ripping and CV's breaking. Not sure why, but the common denominator from what I have read was the CV's binding at full droop. So to compare apples to apples, Does your system rotate freely at full droop? Or does it clunk or lock? Thanks again for your input in clearing up this mystery, or at least clearing up which product works, Allan

[trw99]

Apparently in the UK and Europe we will all be required to retrofit these old dinosaur parts if the EU get their way.

Dinosaur parts? I nearly choked on my wine! Look here Alan, they were good enough for Mr Chapman so they are good enough for me ... and you!

More seriously though, don't forget that the rubber coupling was an accepted engineering solution to a mechanical problem back in the early 1960s. Lotus and others used rubber couplings in their Formula One cars at the time. When the Elan was designed, it was envisaged to be a road car only and rubber couplings were deemed to be an appropriate way to transmit the power, maintain an excellent ride and absorb the multi-directional stresses imposed upon the driveline in normal road conditions. We all know that the Elan's reputation was built on its ride and handling, as well as its power to weight ratio. Yes the couplings 'wound up', but all contemporary owners rapidly got used to that and were able to drive smoothly and effectively.

Now, it was only when Lotus started to prepare the Elan as a race car that firming up the drive line was considered and again, we know that the 26R was fitted with roller spline shafts with UJs and crucially, a good deal of other beefed up components. Fast forward to now, and it would appear that many of us want to fit racing parts to our road cars. So let me remind you what Alan Rudd had to say on the matter back in 1970, as reported by Motor Sport:

"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.?

Now I accept that current rubber composition has been 'diluted' from the more effective stuff from back in the 1960/70s. An aside here, I had a school holiday job in 1970 working in a rubber factory in Leicester. I'm still high on the delicious aroma as those of you who have met me will know. We produced pipework for cars, brake pads for bicycles and rubber bands - they don't make 'em like that anymore, yer know! Anyway, that leaves us with apparently inferior rubber couplings now and I quite accept that technological advances mean we can contemplate solid alternatives.

I don't pretend to have the answer, but felt it helpful (or hopeful, I'm not sure which) to bring some perspective into this interesting thread. Being a purist I would advocate fitting the currently available rubber couplings and keeping an eye on them. But then I'm a dinosaur, which is where we came in ...

Tim

[Spyder fan]

Tim,
I got my copy of Club Lotus news today and the first pages I opened were the Elan section (of course) where you yourself write about Mr Rudd and the rotoflexes!

My other post recognises that they were no bad thing back in the day, but they are definitely not a "fit and forget" item, so regular checkups needed as you state. My own cars as you are aware have quite different drivetrains to standard Elan's and they were designed for CV style driveshafts which incidentally don't suffer failure rates anything like those reported on the Sue Miller items (zero failures afaik).

Anyway you old purist, what wine were you glugging? Blue Nun or Mateus Rose'? You do realise that most people back in the 60's and 70's wouldn't know Bordeaux from a Claret.......

[jimj]

I`m just, right now, having the CV joints replaced on my Miller shafts after 3 years and about 20,000 miles due to excessive play. I MUCH prefer the rotoflex softer drive but can`t do with replacing them every year. Unfortunately, the fit-and-forget reason for changing has proved to be not so. I assume that this is why Sue doesn`t sell them anymore.
Jim

[Spyder fan]

I`m just, right now, having the CV joints replaced on my Miller shafts after 3 years and about 20,000 miles due to excessive play. I MUCH prefer the rotoflex softer drive but can`t do with replacing them every year. Unfortunately, the fit-and-forget reason for changing has proved to be not so. I assume that this is why Sue doesn`t sell them anymore.
Jim

Jim,
You assume correctly, I have it direct from Don Hands who assists Sue that the CV joints supplied for their conversion has remained the same pattern part since they were first made, but that they only started experiencing failures in the last couple of years. The CV joint was originally european manufacture, but production has moved elsewhere (suspect China?) The supplier insists that they are within the design parameters and won't furnish free replacements for failed items stating they are fit for purpose intended which doesn't include non standard converted driveshafts for Elan's.

[gearbox]

I`m just, right now, having the CV joints replaced on my Miller shafts after 3 years and about 20,000 miles due to excessive play. I MUCH prefer the rotoflex softer drive but can`t do with replacing them every year. Unfortunately, the fit-and-forget reason for changing has proved to be not so. I assume that this is why Sue doesn`t sell them anymore.
Jim

Jim,
You assume correctly, I have it direct from Don Hands who assists Sue that the CV joints supplied for their conversion has remained the same pattern part since they were first made, but that they only started experiencing failures in the last couple of years. The CV joint was originally european manufacture, but production has moved elsewhere (suspect China?) The supplier insists that they are within the design parameters and won't furnish free replacements for failed items stating they are fit for purpose intended which doesn't include non standard converted driveshafts for Elan's.

Hi Alan;
This is were I get confused, I was under the impression that Sue was using the Lobro CV's which are the same CV's used in the Elantrikbits, JAE, RD, DB, etc. units. Now the post machining that Elantrikbits does, may be the differentiating factor, but Jeff from JAE claims the same reliability and I believe they use a stock Lobro CV. I also know that Sue went through all the possibilities including consulting with TTR to find a solution and was unable to find one. If Sue wasn't using the Lobro CV's, how easy was it for her to just switch. After all, these CV's are not a lot of money and compared with the cost of the finished shaft, it's a small percentage. So, I am not sure where the disconnect is, but I am hoping that someone would give us the answer so we can have a reliable option. BTW, what is not made in China these days lol.

[Spyder fan]

I`m just, right now, having the CV joints replaced on my Miller shafts after 3 years and about 20,000 miles due to excessive play. I MUCH prefer the rotoflex softer drive but can`t do with replacing them every year. Unfortunately, the fit-and-forget reason for changing has proved to be not so. I assume that this is why Sue doesn`t sell them anymore.
Jim

Jim,
You assume correctly, I have it direct from Don Hands who assists Sue that the CV joints supplied for their conversion has remained the same pattern part since they were first made, but that they only started experiencing failures in the last couple of years. The CV joint was originally european manufacture, but production has moved elsewhere (suspect China?) The supplier insists that they are within the design parameters and won't furnish free replacements for failed items stating they are fit for purpose intended which doesn't include non standard converted driveshafts for Elan's.

Hi Alan;
This is were I get confused, I was under the impression that Sue was using the Lobro CV's which are the same CV's used in the Elantrikbits, JAE, RD, DB, etc. units. Now the post machining that Elantrikbits does, may be the differentiating factor, but Jeff from JAE claims the same reliability and I believe they use a stock Lobro CV. I also know that Sue went through all the possibilities including consulting with TTR to find a solution and was unable to find one. If Sue wasn't using the Lobro CV's, how easy was it for her to just switch. After all, these CV's are not a lot of money and compared with the cost of the finished shaft, it's a small percentage. So, I am not sure where the disconnect is, but I am hoping that someone would give us the answer so we can have a reliable option. BTW, what is not made in China these days lol.

I suppose that this is where a little bit of knowledge becomes dangerous or just plain pub talk or " Chinese Whispers" . I must confess that I don't know whether Sue used the Lobro CV or not, but I do know that the failures have only been experienced in recent years. I can ask more direct questions if you can feed them to me, I'm sure Don will oblige and that Sue has nothing to hide.

[gearbox]

I suppose that this is where a little bit of knowledge becomes dangerous or just plain pub talk or " Chinese Whispers" . I must confess that I don't know whether Sue used the Lobro CV or not, but I do know that the failures have only been experienced in recent years. I can ask more direct questions if you can feed them to me, I'm sure Don will oblige and that Sue has nothing to hide.

Quoting Alexander Pope now are we? LOL. Yes, that is exactly what I have been seeing in various forums, that these failures have been occuring quite often over the past few years. My friend Adam Mills speaks with Sue often and a lot of my information comes from him. But if you can find out if she used the Lobros and what exactly was the problem if she did, and if not, what prevented her from trying them? After all, these shafts are not rocket science, and in one form or another, they are pretty much the same concept. But if there is a better version, we should find out. So let's drink deeply, or taste not the Pierian Spring. Sorry, but you started

[RogerFrench]

I'm pretty sure Sue told me back in April she hadn't been using Lobro CVs, and the manufacture of those she had been using had changed. She had a pair of some other supplier for evaluation, but they were much the same.