Rotoflex rubber compound.

[ardee_selby]

Hi Guys,
It has been suggested to me (by UK specialist) that current
Rotoflexes use a poorer compound due to todays' manufacturing
restrictions on additives (presunmably on H&S grounds)and do not last
for any length of time.
This lead to a recommendation to buy a solid driveshaft conversion.

Was this a sales pitch or is there some substance it?

TIY Richard Selby - 36/7367

[kstrutt1]

Richard,
I certainly found the modern couplings don't last long in my +2S130,
mine broke up after 4 years and 5000 miles. I now have the spyder
conversion which keeps one rubber coupling but with a much more
substantual failsafe pin in the centre. (They were well made but quite
expensive)


Kevin +2S130


--- In lotuselan@y..., ***@***.***e:

[Blatchford Peter]

Kevin wrote :
"I certainly found the modern couplings don't last long in my +2S130,
mine broke up after 4 years and 5000 miles. I now have the spyder
conversion which keeps one rubber coupling but with a much more
substantual failsafe pin in the centre. (They were well made but quite
expensive)"

Hi Kevin,

How have you found the Spyder conversion? I have been thinking of
converting and would be interested in hearing any experiences and
recommendations. Does it effectively eliminate 'surging'?
Anyone else got any comments on the Spyder conversion, or any of the
others that replace both rubber couplings with CV joints? Spyder say you
need one rubber coupling to 'cushion' the diff, but others have said
this is not true.

Pete


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[davidcroft]

One thing I've been wondering about the Spyder system: Does the single
donut last any longer than the double donuts of the original set-up?

If you can expect similar longevity, then is the only advantage a
reduction in 'surge'?

Thanks

Dave

[kstrutt1]

Pete,
I have found them to be great, there is still a very small amount of
surge but it's nothing like it was and is now much easier to drive. As
an engineer and having worked in this field I would tend to agree with
spyder that the rubber joints should provide some degree of isolation
to shock loading, for a road car (especially the heavier +2) this a
reasonable cost effective compromise.
If money were no object then obviously the best solution would be to
uprate the stub shafts and diff then use CV joint both ends

Kevin +2S130


--- In lotuselan@y..., Blatchford Peter <PWBLATCHFORD@d...> wrote:

[kstrutt1]

Dave,
Spyder claim it does, I will know in about 3 years time!

They claim that the failsafe pin stops the rubber deforming so much,
they also supply genuine Metalistic parts which are supposed to be
better.

I also forgot to mention I did have a problem with the joints knocking
on the chassis when the car was loaded up and cornering, I added a
spacer under the top diff mounting to fix this.

Kevin +2S130

--- In lotuselan@y..., David Croft <dave@t...> wrote:

[Guest]

Hi All
I have used the competition version of Spyder's driveshafts in my Elan S4.
One flexible coupling is retained, I suspect to cushion impact on the
diff. output shafts rather than the CWP. It is excellent, making for a
taut drive and I think slightly improved handling - less tendency to
lift-off oversteer on fast uphill bends. Such a conversion is
(apparently) necessary for LSD use, something I am about to put to the
test with a Quaife TB diff. I would reccomend the conversion, the only
downside seems to be some increased noise from the rear end (but that
could be my diff!)

Nigel Furness

[Guest]

On Mon, 9 Jul 2001, David Croft wrote:


explosion' from the rear end with resultant damage to floor, fuel
tank, passenger and
diff. casing. How do I know? Its happened to me twice! And my two
donuts are not showing anything like the wear apparent when four are
employed over the same period of time.

Nigel Furness

[TimMullen]

The fail-safe pin would be quite nice. One question though, if you only keep
one doughnut, won't it have to flex twice as much? Would that cause them to
fail sooner?

Tim Mullen

Chantilly, VA
72 Elan Sprint - still has both rotoflexes...

[kstrutt1]

I would agree with Nigel, there is more road noise with the spyder
shafts.

Kevin +2S130

--- In lotuselan@y..., <nigel@a...> wrote:

[kstrutt1]

Tim,

As you say there is only one coupling per side and therefore half the
amount of deflection to absorb the initial shock therefore the loads
should be higher.
In practice the dougnuts are non linear and in both appplications they
effectively bottom out so the initial deflections are similar and the
drive line loadings are slightly increased.

Also with the standard couplings the driveline stiffness is very low,
consequently when you excite the driveline by opening or closing the
throttle the driveline and vehicle act like a spring with a mass on
the end and oscillate at a low frequency (2-3hz). This is the shuffle
motion you feel inside the vehicle, at these low frequencies the
amplitude is fairly large, damping low and parts of the inside of the
Human body are also excited making it all rather uncomfortable.
This means that the couplings are seeing several applications of load
in both directions giving very rapid wear.

When you stiffen the driveline, the natural frequency rises, the
damping in the system has more effect and the amplitudes are therfore
much lower, giving much lower levels of loading to the driveline and
driver.

Kevin +2S130.


--- In lotuselan@y..., Tim or Jo Mullen <elans4@e...> wrote:

[Arno Church]

I have fitted double CV joints to my S3 and I have found no problems. If the CV joints ( mine are based on VW Golf units ) can cope with a car weighing nearly double and have to cope with steering loads as well , I just do not see a problem with a lightweight car . My car is very responsive with no sign of surge , wind up, etc. Also the basic diff internals can cope with much more loads than the Elan can provide under normal and autotest use as these diffs (internals )were fitted to Lotus Cortina racers as well as the rally Escorts of the time
Arno


Pete,
I have found them to be great, there is still a very small amount of
surge but it's nothing like it was and is now much easier to drive. As
an engineer and having worked in this field I would tend to agree with
spyder that the rubber joints should provide some degree of isolation
to shock loading, for a road car (especially the heavier +2) this a
reasonable cost effective compromise.
If money were no object then obviously the best solution would be to
uprate the stub shafts and diff then use CV joint both ends

Kevin +2S130

[barrymckenzie73 at hotmai]

Hello All,

Mick Miller in the UK now supplies a double CV jointed driveshaft
conversion Using standard CV joints. I think it was designed and
possibly manufactured by GKN. The price I believe is ?350 for a pair.


Barry.

[kstrutt1]

Arno,
The guy at Spyder did point out to me that the cortina/ escort had
approx a 2 foot torsion bar between the wheel and diff wheras tubular
shafts are much stiffer, and also that the lotus stub shafts are
known to be weak. That said given that you have the smaller elan and
providing you are not planing snap starts(ie sidesteping off the
clutch) I see no problem with your solution.

Kevin +2S130





--- In lotuselan@y..., "Arno Church" <stuckect@i...> wrote:

cope with a car weighing nearly double and have to cope with steering
loads as well , I just do not see a problem with a lightweight car .
My car is very responsive with no sign of surge , wind up, etc. Also
the basic diff internals can cope with much more loads than the Elan
can provide under normal and autotest use as these diffs (internals
)were fitted to Lotus Cortina racers as well as the rally Escorts of
the time

[Arno Church]

Kevin ,
Thanks for the response which I agree with
One thing is certain, after all the elbow grease and with a thin wallet, I will leave all the action stuff for the racing Seven
Arno


Arno,
The guy at Spyder did point out to me that the cortina/ escort had
approx a 2 foot torsion bar between the wheel and diff wheras tubular
shafts are much stiffer, and also that the lotus stub shafts are
known to be weak. That said given that you have the smaller elan and
providing you are not planing snap starts(ie sidesteping off the
clutch) I see no problem with your solution.

Kevin +2S130