Drive shafts

[Bahamayellow]

As you will have seen from my roll cage post I am slowly unpicking a number of the items stuck on the Elan Sprint I have. One thing I have debated for a while has been the driveshafts. At present the car currently has TTR solid driveshafts on and it drives nowhere nearly as smoothly as my Tatty S4 I had too many years ago with the Rotoflex couplings.

Has anyone converted back to Rotoflex or is the problem the same with a lot of rubber couplings these days in that the quality of the rubber is so poor that they're not worth fitting?

One item I did change which was a total revelation was the tyres Michelin XAS FF although expensive transformed the car in an instant.

Many thanks again,

Mike

[Mazzini]

Ha! I thought I was the only person to go from CV's back to Rotoflex couplings! I haven't driven the car yet, but I just wanted to put the car back to original specification.

[lotusfan]

One item I did change which was a total revelation was the tyres Michelin XAS FF although expensive transformed the car in an instant.

Just out of interest, what tyres did you have before and how old were they?

[Bahamayellow]

Mike I went through Uniroyals, Bridgstones and Goodyears all were new. The nearest I got were some cheap Chinese van tyres that Tony Thompson got me that he uses for his road Elan.

I took a deep intake of breath and vintage tyres knocked me 10% off at the Beaulieu auto jumble which made the whole thing more palatable.

[1owner69Elan]

You refer to solid TTR driveshafts. These are not CV’s but rather u-jointed sliding spline units. AFAIK. TTR doesn’t sell CV’s. Tony T felt that CV’s are sub-standard compared to his units.

I can imagine these TTR shafts don’t drive all that smoothly for a road car and in non-smooth road conditions.

You might consider CV’s before going back to rotoflexes.

[Bahamayellow]

Hi 1owner69

Thanks that explains the harshness I had assumed they were all the same I might try Sue Miller in that case.

Mike

[Grizzly]

I agree with 1owner69Elan, i have kelvedon/shaft tec drive shafts and frankly they are much smoother than the Rotoflex's.

I wouldn't say the CV shafts are fit and forget but they aren't far off, i am a bit of a purist so was a little loathed to put CV shafts on but i found the Rotoflex joints don't like to be parked up for any time and they seem to be of sub standard quality compared to the 70/80's items.

In my opinion i consider the Cv shafts a reversible safety upgrade (just make sure they have quality cv boots on)

[Davidb]

I dunno. I have U jointed/sliding spline drive shafts and I don't notice any problem with not being able to drive smoothly. Mind you, I have never driven an Elan with donuts though.
Surely any other car would be the same-apart from a GT40 maybe...

[Bahamayellow]

It’s not the smoothness of driving it’s the harshness of delivery but I did drive 2,000 miles across Spain and France and back home in the Sprint for our honeymoon 10 years ago. Guess I’m just getting old.

[Andy8421]

Many threads on this, but IMO, Rotoflex are just damn dangerous. The frame on my Sprint was mangled (I assume) by a PO and a flailing driveshaft. I am very glad I wasn't driving it when it did.

It always seems to be the diff end that goes - perhaps because it is hotter and oilier than the wheel end. The problem is that the driveshaft doesn't stop flailing until the car stops - or the driveshaft becomes wedged, locks the wheel and spins the car off the road.

CVs for me.

[HCA]

I am no expert engineer, but I did pick up from someone wayback who was involved in the design of the original Mini, that UJs 'lost' their effictiveness when deflected more than 5 degrees off their rotational axis, but within the 5 degrees they are better than CVs in delivering power.

If this is the case, I am surprised TT designed his with UJs. Even on a well set up Elan, surely there are many times in a race where deflection will be quite pronounced, no?

[Concrete-crusher]

Just a comment I installed the TT driveshafts, new shocks and springs and all new bushes including diff mounts and I'd say the drive is very smooth. I previously fitted new doughnuts and they only lasted a few years before splits appeared, that said they never actually failed.

Steve

[rgh0]

I am no expert engineer, but I did pick up from someone wayback who was involved in the design of the original Mini, that UJs 'lost' their effictiveness when deflected more than 5 degrees off their rotational axis, but within the 5 degrees they are better than CVs in delivering power.

If this is the case, I am surprised TT designed his with UJs. Even on a well set up Elan, surely there are many times in a race where deflection will be quite pronounced, no?

The TTR shafts use U/J as that is what the 26R used and what has to be used if into racing in Europe.

regards
Rohan

[Foxie]

Many threads on this, but IMO, Rotoflex are just damn dangerous. The frame on my Sprint was mangled (I assume) by a PO and a flailing driveshaft. I am very glad I wasn't driving it when it did.

It always seems to be the diff end that goes - perhaps because it is hotter and oilier than the wheel end. The problem is that the driveshaft doesn't stop flailing until the car stops - or the driveshaft becomes wedged, locks the wheel and spins the car off the road.

CVs for me.

I burst an outer rotoflex doing a racing start in the outside lane at traffic lights.

Swept the caliper clean of the strut.

Left me sitting there with a very red face !

Changed to CVs after that.

[miked]

Done thousands of miles in sliding spline UJ in both Elan's and Plus 2 and there is nothing wrong with them IMO. I value my backside as it is all rather close in an Elan.
As stated there is a lot written on here. Old rubber versus new etc. Even problems with poor grade CV shafts. Some not manifested themselves yet as owners not done enough miles.