Never Re-Use your Rotoflexes !!!

[monoposto]

Hi All,

I can't believe it. Spent 3 hours this morning refitting my drive shafts only to turn the wheel and one of the rotoflexes split. They looked perfectly OK when I re-fitted them and they had only done @ 1000 miles. Mind you, they had been off the car for a while!
After struggling this morning with the rotoflexes, I'm thinking about changing to a rotoflex/CV conversion but would appreciate any input from those who have already fitted them. Does anybody have an opinion on solid or rotoflex/CV drive shaft conversions?

Lee

68 +2,
Chassis 244

[paddy]

How much time have you got?

It's been discussed a lot, quite recently here: elan-f14/going-back-rotoflex-t18224.html

Search and you'll find a lot more.

Comfort, handling, originality, reliability and safety are all factors that there are conflicting opinions on.

Personally, I switched to CV joints as one of the first things I did when I got the car, mainly on the grounds that I didn't want avoidable reliability problems and it is an easily reversible change. You should expect to uprate diff mounts and possibly also engine mounts if you do it because premature failure (already bad because of poor rubber in newer parts) seems to be especially bad with the cushioning of the driveline removed.

Paddy

[John Larkin]

I've done about 3000 miles on Tony Thompson UJ/sliding spline driveshafts, installed last year after much deliberating. I have not noticed any effect on ride or handling, but I did discover that I had tired differential mounting bushes (soon to be renewed). I suppose the removal of the cushioning effect of the rubber from the drivetrain put more stress on those bushes.

I probably would not have converted if I had been able to maintain confidence in the quality of the rubber in modern rotoflexes, but I am pleased with the TTR units.

John Larkin.

[stugilmour]

I just finished installing dual CV system supplied by RD Enterprises in the US. Can't provide any feedback in road use yet, as just working on the frame at this point. Not sure who manufactures these ones, but they use four VW supplied CV's with red intermediate shafts (shown on Ray's site).

One feature of these units is the system replaces the stock diff output shaft and yoke where the inboard rotoflex coupling connects. Have not done side by side comparo of different designs, but I would expect this to result in a slightly longer intermediate shaft between the two CV's, resulting in less deflection of the CV's? With both sides installed now, the CV's do not exhibit locking in full droop (wheels & tires not on yet), which I understand is an issue on some designs. Not sure if this issue is only on the Elan +0 or also occurs on Plus 2 with it's longer shafts.

In addition, with your early chassis number, you will probably be considering replacement of the output shafts with higher strength ones, which adds to the final cost of the total system if they are not included with the CV system.

Note that the rear brake rotor and inner hub holes have to be relieved slightly for this system to be fitted. Easily achieved, but make sure you discuss with Ray as this is required for fitment. I got some help on this detail from another list member who had done the install.

The CV package as supplied had the three outboard bolts installed in the boss holes incorrectly for Lotus fitment to the hub shaft triple yoke where the outboard rotoflex installs. These were easily changed using an 8 mm twelve point star "Allen" wrench to open the outboard CV. Torque on these fasteners was a modest 15 ft lb, so easy to do but had me baffled until I checked with Ray that this was OK to change.

As mentioned above, advise is to upgrade diff mount by retrofitting diff stiffening bracket on top diff mounts (stock feature in the +2S) and new diff mount bushes. I am just sourcing the bracket and plan to add while body is off (RD lists on his site, others probably easily supply). Understand may not be an easy job with body on and stock Lotus chassis.

One factor that might of contributed to early failure of your Rotoflexes. Not recommended to leave the suspension in full droop for extended period of time as distorts rotoflex in too extreme a manner. I had left my car in this position over the entire winter as I knew I was replacing with CV's. The Rotoflexes look to be in good condition, but I would be reluctant to re-use them.

Definitely a great upgrade in my view. Check out site search for lots of other info, opinions, and suppliers, and designs.

Edited to add a picture...

[chequeredflagracingjoe]

Hi stugilmour the CV kit you are refering to is made by a friend of mine. I have them listed on my web site for $ 1225.00
Thanks Joe

[stugilmour]

Thanks Joe. I wondered where they were sourced. Definitely an excellent piece. I added a pic of the install to date above.

[Frank Howard]

advise is to upgrade diff mount by retrofitting diff stiffening bracket on top diff mounts (stock feature in the +2S)

It is my understanding that this bracket also comes as standard equipment on the Sprint. Great write up and photo Stu.

[monoposto]

Wow - thanks everybody for the great advice. I'm not too sure which way to go but I think I may look at either the sliding shaft/UJ or the dual CV approach. I guess at the same time I should look into uprating the Diff mounts although I'm not altogether sure this can be done with the body on? It was good advice to look at changing the output shafts as well as the breakage of one of these was the reason the diff came out in the first place! To be honest, I was never impressed with the quality of the rotoflexes when I purchased them, the old ones having been on the car for years and still looked better than the replacements!

Oh well, perhaps I won't be re-installing the interior this week.

Lee

68 +2, No 244

[JJDraper]

Changing diff mounts is possible with the body on, but you need tor drain and remove the fuel tank. Easy enough, but a PITB.. I have used the Spyder compromise - half rotoflex/ half CV. It reduced surge, but you I needed to replace the two donuts after around 15k miles. A bonus is that the remaining donuts have an anti-flail gizmo that stops a failed donut causing major damage it it fails. In addition, after five years the gaitor failed... On balance I am happy with the arrangement, but sometime wonder what a twin CV arrangement would feel like.

Jeremy

[stuartgb100]

I have Sue Miller's cv conversion on my Sprint, together with TTR's uprated engine/gearbox/diff mounts and diff anti-tramp bushes.
Also have Sue Miller's uprated bushes everywhere else.

Unrelated, but also have TTR's GAS front and rear adjustable uprated spring/schock fast road conversion kits.

All been good for approx 4k miles.

Ride is fine.

Happy bunny !!!

Regards,
Stuart.

[peterako]

Hi Guys,

I have the Mick Miller CV conversion on my +2 for nearly 3 years and 25,000 miles.

They have been a major improvement over donuts in terms of handling and ride (imo). And added peace of mind (not worrying about donut failure). I looked at the price of new Donuts and the CV conversion certainly made financial sense too.

Highly recommended!

I have also recently put in TTR front shocks and springs (Fast Road)....soruced from Sue Miller ....

Can't praise them highly enough. I only have about 1000 miles on them, but they feel 'right'. Almost like they were designed and adjusted for the Elan +2

Best of luck,
Peter