Rotoflex Couplings

[nebogipfel]

Sorry folks I know you will have discussed this previously but please be patient to a newish member of the forum.

At some point soonish I'm gonna have to make a driveshaft decision. I have looked at the Spyder conversion which to be honest I like the look of mainly because it retains one rotoflex to absorb some of the driveline shock loads, the standard elan final drive setup is not terribly strong after all ........but they are quite expensive at about ?530!

I think I reject "solid" ie two CV's or two UJ's because of

1. Increased loading on differential bearings, mountings and the rest of the rear end

2. Harsher ride quality

3. Lotus rejected UJ's in favour of more expensive rotoflex couplings and Chapman must have had a good reason!

After all this my question really is ........ how many of you out there are using Rotoflex couplings? are your experiences good or bad? have you suffered premature failure of the joints?

I have never had problems with Rotoflex's but most of my Lotus experience is from quite a few years ago

When my car is finished it will be a road car only and never be driven too hard as befits a 35 year old

[LaikaTheDog]

i used to get 'windup' when moving from stationary, feels like a surge through the car...I replaced my rotoflex with new ones, icluding he bolts and now I do not expereince this, as far as I can see going the cv combo is really for racers, nothing wrong with Chapmans judgement really

[nebogipfel]

Yes I know what you mean about windup. I'm old enough to have driven Elans with the old type couplings (They were very soft) the sprint types improved the situation quite a bit.

I have heard, from several sources that the couplings currently available are not of the same quality and are prone to premature and drastic failure.

I was quite happy with Rotoflex's in the past ........once I learned the driving technique

[1964 S1]

Hello, not sure if you have a plus two or not, but, I switched my +2 from u joints to used rotoflexes because I had some problems as you described, ,etc; Later I drag raced it at Brit Car Day and although not flogging, but driving way harder than normal, nothing happened. I had bought cheap used rotoflexes and half shafts just to make sure the problems I was trying to solve were caused by the u joints. (they were) I'm still running with those rotoflexes, not drag racing but driving fast with no problems. If you have a small Elan, I'd say stay with rotoflexes, for many reasons. I believe wind up problems are due to people who can't operate a clutch properly. As far as faulty new rotos, I haven't heard a thing about that...

[type36lotus]

I too have rotoflexes, but mine are only a few years old with about 1,000 miles on them. I don't really know if the wind up or not. The drive feel is not much different than my AWD Subaru RS. The Elan IS more fun to drive tho (not to say the Subie isn't either). The only bad thing about rotoflexes is if you don't have the fail-safe ones and one fails serious damage occurs as the shafts flail.

[elj221c]

Paul Matty is advertising Rotoflexes of supposedly original quality in the latest issue of the Club Lotus News. ie. Proper tubular bushes rather than the bent up metal strips used in naff quality ones, and reputedly stronger rubber. ?38 + vat. (usual disclaimers!)
I've no experience of solid shafts on the road. I always used the rubber and it served me well for many years including stop-start commuting in London. You should never have a breakage assuming regular inspection and the use of the proper bolts. You need to keep a check on their tightness as well.
Roy
'65S2

[trw99]

Rotoflex for me too. I agree that Chapman felt they were the way to go for his road cars. He did, of course, use UV solid shafts on the 26R, where he presumably felt the increased stress imposed by racing warranted them.

I understand that Mick Miller recently lost confidence in the constitution of the rubber used in replacement couplings and that Paul Matty is now selling a "Motorsport" coupling, claiming that it gives longer life, improved drive quality and a perfect fit.

[steveww]

My S4 is still on the old rubber rotoflex joints. It can be a bit bouncy until you get used to it. I drive my elan hard most of the time - Why not it is one of the best sports cars of all time. If you want to drive slowly buy a Nissan Micra

I think I am going to stay with the rotoflex things as the car does very little mileage each year (less than 3000) and I do not race it, well just the odd track day here and there

I keep a close eye on their condition, check for cracking, and make sure the bolts are tight. I think I will wire up the bolts when I can get round to it.

[rgh0]

For a road use elan the sprint style rotoflexes are fine provide the car is not used aggressively in competition and you checked them regularlyand replace them if they are developing significant cracks in the rubber. For a plus 2 the additional weight can cause surge problems even with many years of driver experience and proper quality donuts. In a road plus 2 I would change to Cv's as I have with mine due to this alone.

The absortion of shock loads the donuts provide does not seem to be significant in the elan drive train reliability.

The critical weak point due to torque shock loads was the diff output shafts in cars pre 1970 and these failed due to the splines twisting and breaking even with donuts. New billet replacements or post 1970 orginal shafts which appear to have better steel in them do not appear to have this problem.

The other weak point is the diff mounts, both the top mounts and torque rods mount to the chassis. These need to be kept tight as any looseness can cause damage. The additional shock loads from fitting CV's could aggravate these bolts coming loose if not asembled correctly but with correct assembly and routine checking cars with Cv's do not appear to have any more problems than cars with donuts in this area.

Lotus used donuts because they were cheaper than a U joint and sliding spline arrangement at the time and not subject to lock up, like the sliding spline was that affected the handling. Modern CV's did not exist in those days and are the best and cheapest solution and something Chapman would have used if they existed in 1963.

Rohan

[type26owner]

A little reality shot here might be timely. I was dismayed having recently installed cv axles to discover there was still an annoying bit of freeplay windup. I'd assumed it was being contributed solely by the donuts. That's actually wrong. Still got that feeling with the new cvs but it's only half the magnitude. Turns out it's the open diff gears' normal backlash and the driveline stiffness which was contributing half of that motion all along. Go figure! Don't make the same wrong assumptions. My car is an S2.
Keith

[steveww]

Anyone know what the bolt circle is for the elan donuts?
Demon Tweeks do drive donuts for Formula Fords which might fit and they appear to be heavier duty. May be a half way house between c.v. and original donuts????

[TonyC]

<!--QuoteBegin-elj221c+Apr 29 2004, 09:05 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (elj221c @ Apr 29 2004, 09:05 AM)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin--> Paul Matty is advertising Rotoflexes of supposedly original quality in the latest issue of the Club Lotus News. ie. Proper tubular bushes rather than the bent up metal strips used in naff quality ones, and reputedly stronger rubber. ?38 + vat. (usual disclaimers!)

Roy
'65S2 [/quote]
I just ordered a set of these as I need to replace all 4 on my +2, however the storesman called me back this afternoon to say they are holding off supplying at the moment as a customer has had two fail. The customers car was a single seater however, so I'm sure it is not quality issue per se. They are apparently running them on some of their road cars and hill climb cars with no failures either.

I was tempted to say supply me anway and I won't complain if they go wrong, but they want to get them checked out to ensure there is no design fault. I'd suggest less agresive road use would not result in a failure, but meanwhile I'll have to wait and the poor old +2 stays in the garage.

[nebogipfel]

Thanks for all the replies!

I would like to stick to Rotoflex's for both reasons of economy and originality

The Paul Matty couplings sounded good until TonyC just threw a spanner in the works

Sounds as if lots of you are using donuts without problems which is good to hear

[lotus026]

I just have to add that the $995 US that I spent several years ago to upgrade my '65 S2 from the early type Rotoflexes to the full CV joint halfshafts was the best money I'd ever spent on the car! Not only will I not have to replace them every few years in the normal course of aging rubber, but no more windup in the first 3 gears when being driven aggresively - and I'd been driving it for 10 years with the Rotoflexes, wished I'd switched earlier. But my car gets driven hard on the road and also does vintage races, track days and hillclimbs; so maybe they aren't for everyone. And the CV joints eliminate the possible problem of joint lockup with suspension travel if I'd gone to the U-joint version.....which I know is the proper one for a vintage race car, but I value driveability above all else!
Dave

[DrEntropy]

The ~only~ time I had to be flat-bedded home was when the +2 ruptured an inboard donut in an intersection... fair bit of pedal stabbing and attempted damage control just then. I hadn't replaced them when I should have. Both the S3 DHC and +2 have the sprint type, and after replacing the stub axles in the +2 with the "beefier" ones (Dave Bean) I've had no worries.