I drive an Elan +2s 130/5 with standard twin cam engine and the 5 speed Austin Maxi derived gearbox. Currently fitted with original style doughnuts, which I think are due for replacement. I have read all I can on this forum but still unsure on which way to go.
I don’t like the wind-up with the current doughnuts but feel that the cushioning must provide some protection to the drivetrain and particularly the reputedly fragile Maxi gearbox ( mine is OK so far but I drive very conservatively).
So my instincts lie with the Spyder CV + Doughnut set up, but it has the downside using the limited life doughnut. I see that Spyder claim longer doughnut life with their set up but can’t understand how that is achieved.
That leaves me with the Kelvedon CV+CV,system which seems to be widely used, and recommended as reliable. No cushioning in the system however, and i wonder if the reliability reputation comes from its use in the lighter Elan with the robust Ford 4speed box ?.
If anyone has got experience, good or bad, running either Spyder or Kelvedon system on a 5 speed +2 I will be very grateful to receive your comments.
Thanks,
Dick
PS: What’s the appeal of Elantrikbits kit versus Kelvedon ? Both claim to cope with droop OK
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Personally I don’t see the Doughnuts as protecting the gearbox that much although I am sure it must help to some degree.
The Doughnuts though I believe will give more protection to the Lotus differential assembly which in standard form is just quite literally hanging from a couple of smallish rubber mountings and the driveline torque being taken up by a couple of simple tie rods and rubber bushes!
It is a very fragile arrangement even in standard Doughnut form with the diff casing being made of aluminium. The diff case ears easily break off the upper part of casing and the tie rod holes easily get ovalised.
To me if you are going to go with CV’s, the Spyder arrangement of a CV outer and a Doughnut inner does seem a sensible compromise… My take on this is that there does need to be a rubber cushion in the driveline somewhere and the Spyder setup achieves this.
The Elantrikbits CV’s and the Kelvedon/Sue Miller Cv’s are very similar in execution. It is said that the Elantrikbits are of better quality but against that is the much higher initial cost of the product and the shipping from the other side of the world which does make them rather expensive here in the UK.
The above is just my take on it. You pays your money and takes your choice but personally I will be sticking with Doughnuts on my +2!
Hi Dick,
The TTR do suffer from droop and the Elantrikbits are better Engineered thanTTR.
I fitted Elantrikbits on my Sprint 100% nice kit super. Treated metal and Steel adapter plates not Alloy. Replaceable special fixing Studs top job.
Alan
My experiences are with original (2 doughnuts per side),
Performance Unlimited units, (an earlier version similar to the TTR UJ-type), and I found these hard on the diff and created noise.
I swapped them out for the Spider single inner doughnut + one CV, and loved them.
Next to no wind-up, quiet, and much kinder to the diff.
I wouldn’t hesitate in fitting them again to my next Elan.
There is no evidence of the cushioning effect of donuts being required or being signficant. The Lotus 5 speed box was used successfully in much heavier cars such as the Elite with a 2 litre engine and no donuts. I have used Cvs in my Plus 2S 130/5 and my 4 speed Elan for around 40 years without issues with gearboxes or diff . i dont drive gently in eaither car and the Elan does multiple racing drop the clutch starts at every race meeting without issue
The one donut and one CV version I could never understand as you still have the greatest problem present which is a donut failure wrecking the rear of the chassis and suspension.
If you want a reduction in noise and vibration and some protection to driveline components then you put the rubber donuts in the propeller shaft between gearbox and diff like many modern European cars do not on the diff output shafts where they struggle to handle the much greater torque and angular deflecton.
The biggest advantage of the ElanTrikBits Cv conversion is that the captive bolt design allow a small amount of movement to align with the diff output and hub axles holes which were not drilled very accurately by Lotus as the Donut would accomodate a large fitting tolerance
Rotoflex are effectively a constant velocity joint, the output and input speeds are the same. This is not true for Hooke style (UJ) joints. To avoid harmonic phase effects when the driveshaft is at an angle, a driveshaft needs a Hooke joint at each end. A mix of Rotoflex and UJ will introduce vibration into the driveline. Good explanation here:
Regarding ‘cushioning the diff’, I have never seen a race Elan using Rotoflex couplings. Given the much greater torque going through the diff (more BHP, stickier tyres), if there were cushioning problems, you would expect race diffs to continually fail - which they don’t. The only weak spot seems to be the early output shafts which can twist and fracture. Later shafts seem fine in this respect.
In conclusion, the Spyder UJ/Rotoflex shaft does not seem a well engineered solution.
Hi Andy,
Thanks you have explained it better than me.
If i was rebuilding an early Elan with the weak Shafts at the Diff i would fit the CV Shaft Kit from USA which include the new Shafts at the Diff.
Alan
I agree it is not a well thought through solution. The donut however will adsorb most of the angular speed variation induced by the single UJ in its output but there will be some added vibration due to this which is probably not noticeable in practice as i dont hear people with the Spyder drive shaft setup complain about this apsect
I fitted the TTR double UJ system to my first +2.
It was a bit of a pain. The ujs themselves needed bits grinding off to prevent binding at full droop and the splines always locked at a particular corner on my way to work. No idea why.
Tim
CV joints are the way to go especially on a Plus 2.
With longer suspension arms there is no problem that I know of putting them in maximum droop. I had the Kelvedon / Miller shafts on mine and they were perfect. Mine didn’t bind when a wheel jacked up off the ground was turned, and I had old Konis on the rear - standard length, no anti-droop. Could still rotate the wheel without the joints binding.
Driving the car was like night and day. No wind up and so I could drive as I would a modern car. I often drove enthusiasitically and never had issues, either with the drive shafts or transmission (which was a 5 speed like yours, except my engine was a Big Valve).
Fitting CV jointed shafts should be an easy choice to make. Much debate on the subject but I’ve read nothing about premature failure; whereas there are many stories of doughnuts “letting go” and the subsequent damage done to the rear of the car.
One comment I have read is that Chapman likely fitted doughnuts because of cost reasons, and CVs weren’t common at the time. Doughnuts could be seen on race cars of the period too, but bear in mind the suspensions of those cars didn’t have much travel, and the doughnuts were undoubtedly changed often. It is said that Chapman might have fitted the Elans with CV jointed shafts, had they been readily or cheaply available. Of course, we now see the cost of a new set of (questionable quality) doughnuts approaching the cost of a set of CV jointed shafts, so there’s not really much saving to be had by keeping the doughnuts.
Anyway, my recommendation is to fit them. You won’t regret it. As long as you are in the UK, I say get the Miller / Kelveden ones. They’re what I had on my Plus 2, and I have put a set on my S4 now (though with anti-droop dampers also, it has to be said; but then, I am restoring the car so damper replacement is mandatory anyway).
Hi Jonb,
Ok maybe TTR for some owners of +2 Elans personal choice.
As i see it rebuilding a Baby Elan I wouldn’t like bits of Cable/Braid dangling around. I don’t think good Engineering practice but in a long lost past i worked in Aerospace.
The total cost of rebuilding an Elan correctly is mega money. A few £100 extra will not change the total cost a lot.
Easy for me to say when it’s not my Piggy Bank being raided.
Jonb do you have much more to do on the rebuild.
Good luck
Alan
That’s correct, they’ve been like this for some time, so no problem with damaging bodywork nowadays…
Each to his own. I’ve tried all barring the double CV type now, and the Spyder solution is my choice, being quiet and vibration-free, unlike the U/J type.
No anti-droop straps are required on my car. The TTR shock absorbers have reduced travel so as not to cause CV joint lockup on full droop.
I’m at the “rolling chassis” stage now, with all suspension, hubs, brakes, diff, half shafts, steering rack and wheels fitted. Waiting on the engine machining work to finish, have rebuilt the gearbox. I’m looking at the looms now and wondering if they can be reused…
Long pondered as I am replacing old doughnuts
Rear springs (rates) and dampers(Armstrong) all NLA or to your own spec/whatever available today.(different chassis welding and spaceframe etc)
Overall spring rate at rear suspension doesnt change with CV joints?