Rotoflex "surge" - a definition?

[sutol45]

Your memory's good Alan. And the twin-doughnut arrangement was far worse with a 5-speed box due to the larger clutch employed!

I do think some commentators either have forgotten or weren't there at the time...

[AHM]

You really are missing the point! I mean, a Ford Cortina in the period did not have 'doughnuts' but you were still able to "release the clutch plate", hello?

Hello! ........That went over your head then!

Lotus was champions at adapting the high-volume components used by other local UK manufacturers into his own cars in order to reduce costs!

As was the necessity of every other low volume manufacturer ? Nothing Chapman or Lotus about it.

Chapman would have argued vehemently the attributes of a doughnut costing ?1 over that of a CV joint (had it existed in the 60s) costing ?2

Most CV joints were developed in the 1920?s/30?s although granted the VL joint was developed in 1962.
I think you do ?Chapman? a disservice. The argument was probably more about ride and handling which would have been compromised if the doughnut had not been used.

You really need to understand the logic and/or have been in that environment to appreciate the ideology applied...

A rather presumptive comment!

You really do need to do the research.

[AHM]

Edit: Was post to Jeff - Problem fixed

[AHM]

or weren't there at the time...

Gosh no... I wasn?t born!

I do think some commentators either have forgotten [/i][/color]

Well you can't be referring to me - I run the S3 on the original style Imp doughnuts, so my last experience was this morning.

It also requires a gentle and progressive right foot which is somewhat counterintuitive

[jimj]

Mr. Sutol, I too think you`re being unfair. I have CV joints but reluctantly, only because current Rotoflexes don`t last long these days. I much preferred the cushioning effect of a flexible joint and never had any issues with surge or kangarooing.
Jim

[Quart Meg Miles]

...and just a slight deviation of thread,if one has replaced the doughnuts with a more solid alternative U/J's,CV's would there be any need/benefit in fitting a single doughnut in the drivetrain (propshaft?)

John

The torque would be only a quarter or third of the normal and the resulting smaller surge would also be reduced by that amount at the wheel so wouldn't be noticeable, even with the original doughnuts. I haven't changed my UJs on the propshaft yet so lifetime of those isn't an issue either. So I don't think it is of any benefit.

[billwill]

From memory, a double doughnut system required a sensitive left foot to almost slip the clutch on take off before releasing fully once underway, launch control had to be learnt so as not to look stupid with all the hopping about that came with a heavy clutch release, different take off speeds required a sense of timing.

After a while you become so used to it that you find (well at least I do) that you cannot make it Kangaroo any more, even if you want to demonstrate it.

[vernon.taylor]

Salut

I tried a mate's S4 quite mightily and didn't feel any of the doughnut surge I feel in my +2. Both have the interleaved-type doughnut but impossible to say if they came from the same manufacturer.

When mine give out I'll probably go the Spyder hybrid route. I'm older than my car, but even at her age I needed a bit of cushioning against rough play - we understand each other.

Which leads back to my mate's S4. He claims it had been on the same doughnuts since 2000 when he bought it, 100K km ago. Thinking they were cracked, which they weren't, he replaced them with CVs. Six months later he now has disintegrated lotocones, rear suspension bushes, rear wheel bearings and a propshaft UJ. Apparently all these were original parts so a change was well due, but I do wonder if the CVs had anything to do with their final demise.

I would have thought that any interface cushioning would only protect the drivetrain from then on, so a propshaft doughnut (? la BMW) might protect the gearbox and engine, but the diff would have to dissipate all the energy received from the road using solid driveshafts.

@+

Vernon

[AHM]

In answer to the first bit - Something has to give!

I would have thought that any interface cushioning would only protect the drivetrain from then on, so a propshaft doughnut (? la BMW) might protect the gearbox and engine, but the diff would have to dissipate all the energy received from the road using solid driveshafts.

The 'weakest' part will dissipate or store the applied torque first.

In the case of a doughnut it will store it. So halve the number of doughnuts a la spyder, and you will approximately halve the surge.

so a propshaft doughnut (? la BMW)

The Hardy Disc - patented by Mr Hardy in 1914

[el-saturn]

yes i agree wholeheartedly with YOU suto45 - not an unimportant aspect was: he'd have all of the parts
on the old scales (as all of us do for racing bits!!) before he'd decide which and from whom - profit would
go into the various racing cars (not only F1) alpine greetings sandy

[vernon.taylor]

Salut AHM

Thanks for your reply.

In answer to the first bit - Something has to give!

The 'weakest' part will dissipate or store the applied torque first.

Which could explain the demise of my mate's S4 rubber bits (and bearings) I suppose.

In the case of a doughnut it will store it. So halve the number of doughnuts a la spyder, and you will approximately halve the surge.

So the other half of the torque energy has to be stored or dissipated elsewhere stressing the next weakest link (which is?)? Or will the two Spyder doughnuts have to store and then dissipate all the torque energy if there isn't anything weaker ?

@+

Vernon

[AHM]

Vernon,

I?m afraid it isn?t that simple. The effect of the doughnut is to temporarily store some of the energy so that the torque is applied more gently. Half as many doughnuts, store half as much energy, so will be half as gentle.

The parts give up because they are treated more roughly than they were intended to be. When we say stressing the next weakest link we need to know if that ?stress? is more or less than the design ?stress? of the component. If it is less, then the component will last a long time.

We need to look at the whole car. Stiffen-up the drivehafts, and the engine, gearbox, and diff mounts will take more of the shock. Stiffen them up and the suspension will take more etc etc... For every force there is an equal and opposite reaction... something has to take it.

Doughnuts, Spyder, or CV?s ? Depends on how you drive and what you like.

[AHM]

yes i agree wholeheartedly with YOU suto45 - not an unimportant aspect was: he'd have all of the parts
on the old scales (as all of us do for racing bits!!) before he'd decide which and from whom - profit would
go into the various racing cars (not only F1) alpine greetings sandy

Interesting then that the racing version sacrificed weight and cost!

[sutol45]

yes i agree wholeheartedly with YOU suto45 - not an unimportant aspect was: he'd have all of the parts
on the old scales (as all of us do for racing bits!!) before he'd decide which and from whom - profit would
go into the various racing cars (not only F1) alpine greetings sandy

Interesting then that the racing version sacrificed weight and cost!

This is getting silly! But I do think el-saturn (obviously 60+) and myself (defintely 60+) are on the same hymn sheet...

You need to engage your 1963 brain for both technology and costings and NOT the one from 2013! (50-years later)

Most of you guys think in terms of what you know now, and what's available now, and not what was known and available then!

Think LOW volume Lotus Elan against HIGH volume Jaguar E-type and you might begin to understand the dynamics of the Elan concept! In the day - Wow!!!

A road going Jaguar E-type, Ferrari, Aston Martin could NEVER follow (at pace) an Elan down a twisting, winding, ducking road, ever! And believe me I had mates with E-types and Marcos 3-litres and they couldn't...

And that was even more so when the Europa Twin cam came along...

And a lot of that is still true - and me the owner of an Audi RS3? (0 to 100mph in under 10seconds, wet or dry!)

Delivery of a brand-new Lotus Europa Twin Cam in June 1972 - Oh Happy days...

[AHM]

So you are still suggesting that having designed legendary rear suspension, with unique hub castings and hand made wishbones, that doughnuts were used because they were cheap...

Has it not occurred to you that the entire rear suspension, drivetrain, brakes etc. Except for the diff, shock tubes and the doughnuts are unique to the car. Lotus were uncompromising in their pursuit of ride and handling in the elan.

I suggest to you that the doughnuts were the only available solution that enabled the designers to produce such legendary handling on a road car at the time.
UJ and sliding spline
-Unnaceptable vibration
-Poor endurance
-Poor reliability

CV joints
-Unacceptably high installed angle ( yes they did exist ? No they wouldn?t have used them)

I give the designers credit for their purity of design, the success of which is borne out by most of what you have written, and their credentials by their subsequent careers.

Now what do we need to do with our 1963 brains?