Solid driveshafts - do they improve the driving experience?

[jimbo]

I've read a lot about the merits of replacing the rotoflex couplings with drives shafts such as those sold by Susan Miller or Tony Thompson. The main advantage seems to be reliability, but I've also heard that they improve the driving experience.

I'm just getting used to my Sprint and am curious as to how fitting a pair would change the driving characteristics?

Anyone care to comment?

Thanks!

James

[john.p.clegg]

Gets rid of that Kangarooing,especially in reverse....and you can give it a little more stick without worries...have not looked back..

John

[CBUEB1771]

Gets rid of that Kangarooing,especially in reverse

I agree with John completely. Trying to reverse up even a slight incline is very unpleasant with the Rotoflex joints. Changing gear up or down is much more crisp and rewarding with te CV or Hooke joint conversions.

[peterako]

Hi James,

I put Mick (Sue) Miller CV driveshafts on over a year ago and wouldn't change back.

They seemed to tighten up the handling on my +2. The rear end of the car seems to follow the front much more tightly and more predictably on twisty roads...

BUT....solid drive can also reveal other weaknesses in the car.

A fellow +2 owner discovered excessive lashback in his Diff that was previously hidden by the donuts....

Best of luck,
Peter

[msd1107]

Hmm, don't know what the carping is about. But then, I come from a motorcycle background where I had to start up a highly modified small displacement bike with a 1.9 1st gear.

It took a couple of tries to get used to the clutch engagement point and profile and the stomberg/weber tip in chacteristics. But otherwise whether 3.77/2.97 or 3.55/2.51 diff/1st gear there were no problems. And I am far from coordinated.

But then parking lot attendants never got the hang of the car, and it took my girl friend 3 tries to get started, but she never had any more trouble.

And then no rotoflex failures ever. I took the car in to the mechanic (a skilled Lotus/Jaguar guy) every 3,000 miles. The rotoflexes were replaced as necessary. Preventive maintenance is the key.

However, reading between the lines of the posts and elsewhere, it appears the current generation of rotoflexes are not up to the same standard as the originals (surprisingly, since all other rubber based components are much more reliable than they were 40 years ago)

So it is your call. The people who have made the switch are enthusiastic, and point out the instances where a rotoflex failure largely wipes out the rear of the car.

David
1968 36/7988

[miked]

James,

I went solid with uj & sliding spline. A Lot better. Whatever the rubber problem, the modern ones do go softer and become harder to drive. I have had older sets that are good though.

You do become acustomed to very careful throttle control.

Better gear changes and pull off's and a feeling of confidence. Also if you do back off in a bend, less fuss. I am told that the fear with solid was stiffening of the splines so they did not operate in bends. Was told that this gave them a bad name. I made a set up and fitted steering gator rubbers so they are always in their own moly' grease and work in and out nicely. Also I have the UJ's with the grease nipples.

I believe the only down side is droop and acute angle. Fixed by short stroke TTR Koni's or some strap arrangement. Keith (used to post) from USA, who is mentioned on one of the posts, has photos on here. Mind you who takes off in an Elan over hump back bridges?

Also nicer to split when doing stuff on the back end.

Win win in my mind.

Mike

[RotoFlexible]

There are two photos of Rohan's droop limit setup here:

http://www.lotuselan.net/forums/viewtopic.php?t=13630

I am having the same fabricated at this moment. I swapped over to CV-jointed shafts supplied by RD Enterprises, and at the same time fitted narrow springs and replacement Koni shocks (normal length). The upper mount for the strut locates the top of the shock shaft a little lower than if it were just going into the Lotocone - in effect increasing the droop and necessitating the limit straps. (It could be that the straps would be necessary even with the stock spring perch; I made all the changes at once so it's impossible to tell.)

Since I haven't driven the car yet, I can't comment on whether the CV shafts will provide an improvement in feel, although I suspect they will. I learned to drive the Elan young and got used to the Rotoflexes pretty quickly. I had one partially fail during an autocross but fortunately it didn't come completely adrift and bang up the car, and I was able to drive home (very gently).

[robertverhey]

Many years ago (in the '80s before the internet) I made up some solid shafts to suit my +2. They were based on VW Superbug shafts (which may or may not have needed shortening, can't recall). I did need adaptor plates made up to match the diff output shafts up to the VW shafts. And maybe the outers as well (which would mean 4 plates). I remember someone in Club Lotus Australia provided me with the schematics for these plates. Perhaps these plans are still floating around.....

Anyway it was a cheap option and transformed the car. In typical VW fashion these shafts were over-engineered so no probs handling the 130BHP

Robert

[Elanintheforest]

David...I think that it's the adhesive between the rubber and metal that's the problem with the current crop of rotoflex couplings, engine mountings etc.

I've never had a problem with the 2 seat Elan either, but the kangaroo effect is much more exagerated with the Plus 2...when lifting off and back on the power especially.

The rotoflex couplings are a pain to change...knuckle skinning and very hard work! They are now very expensive as well...with a set of bolts, over half the price of the shaft set up.

When it next comes time to change, I will be going for the shafts.

Mark

[redskatejbf]

The only downside I have found is there seems to be more noise transmitted into the car compared to the rotoflex driveshafts.

Regards John.

[JJDraper]

I agree with most of the comments about the improvements of solid shafts, but there is one fly in the ointment. My +2 has just failed its MOT due to cracks in both the drive shaft boots, after only four years and about 30k miles. They have not been covered in oil or any other contaminants, they have just cracked up. Could be due to the high level of flexing, I don't know what else it could be.

I haven't got the costs back for repairs, but it looks like it will be about the same as a set of doughnuts... (same labour costs). I will find out tomorrow if I can 'service exchange' the shafts.

You can't win!

Jeremy

[bcmc33]

I did the conversion simply for peace of mind based on experiences in a different life-time in my old S2.

[Frank Howard]

My +2 has just failed its MOT due to cracks in both the drive shaft boots, after only four years and about 30k miles.

Jeremy,

Part of my regular maintenance schedule for my front wheel drive cars is to spray silicone on the CV boots every time I change the oil. I believe it helps prevent the boots from cracking.

[john.p.clegg]

Jeremy
You can if you look around get replacement boots that you can fit without dismantling the shafts,they fit together with cable ties...
John

[hatman]

Is it possible that Lotus fitted doughnuts because they were cheap, light, cheap, worked (after a fashion) and didn't cost much?