Lotus Elan

Hickman and Chassis

PostPost by: vincereynard » Sun Apr 19, 2020 5:02 pm

A quick image of Hickman talking about how the steel backbone chassis came about .

Note they were costed at less than £10 a pop!

S4000002.JPG and


If anyone wants a bettter image I can scan it later.
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PostPost by: benymazz » Sun Apr 19, 2020 6:08 pm

vincereynard wrote:A quick image of Hickman talking about how the steel backbone chassis came about .

Note they were costed at less than £10 a pop!

S4000002.JPG


If anyone wants a bettter image I can scan it later.


Interesting stuff. I recall reading or being told by someone who had a conversation with Ron Hickman that this was the reason the S1 and S2 had the trunk (boot) lid that didn’t extend all the way to the back edge (as it did on the S3 and later); the rearmost body section was a “structural bulkhead” of sorts, and getting rid of the lip on top would have decreased its torsional rigidity.

I cannot imagine a monocoque Elan, who knows what fun and engaging maintenance problems that would have presented. I’m also imagining what a monocoque 26R would have been like from a reliability standpoint.

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PostPost by: trw99 » Mon Apr 20, 2020 9:22 am

Robin Read's take on this attached.

Tim
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PostPost by: JonB » Mon Apr 20, 2020 9:48 am

Now that is interesting. Vince's clip states that they chose doughnuts not because - as others have asserted - CV joints were not available at the time, but because of cost.
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PostPost by: Mazzini » Mon Apr 20, 2020 10:34 am

JonB wrote:Now that is interesting. Vince's clip states that they chose doughnuts not because - as others have asserted - CV joints were not available at the time, but because of cost.


Lotus being cost focused? Never! :lol: That said they are no different to many other manufacturers.
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PostPost by: vincereynard » Mon Apr 20, 2020 12:06 pm

JonB wrote:Now that is interesting. Vince's clip states that they chose doughnuts not because - as others have asserted - CV joints were not available at the time, but because of cost.


So who actually designed the chassis might be a matter of opinion. Didn't Chapman start out designing bridges? Basic stuff for him I would have thought. £10 each! How much did they charge for a replacement chassis back then?

Rotoflex are clever and a neat solution but probably not intended for Elan power and performance.
I don't think CVs were available in the early 60s? Nasty old Hookes were of course, which could have been used as a top link and eliminated the need for a full strut.
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PostPost by: rgh0 » Mon Apr 20, 2020 12:28 pm

vincereynard wrote:
JonB wrote:Now that is interesting. Vince's clip states that they chose doughnuts not because - as others have asserted - CV joints were not available at the time, but because of cost.


So who actually designed the chassis might be a matter of opinion. Didn't Chapman start out designing bridges? Basic stuff for him I would have thought. £10 each! How much did they charge for a replacement chassis back then?

Rotoflex are clever and a neat solution but probably not intended for Elan power and performance.
I don't think CVs were available in the early 60s? Nasty old Hookes were of course, which could have been used as a top link and eliminated the need for a full strut.


Minis had Cvs in 1959
Rotoflexs were and still are an industrial drive train component , they were never intended to have the degree of deflection required in an Elan suspension. Power and torque is fine they just dont like more than a few degrees of misalignment, 1000hp Porsche 917 used them !. They worked OK on race cars with little suspension movement and bigger donuts if needed for power and torque but on an Elan a fundamental design flaw with the suspension travel

Using Hookes joints in a drive shaft as the top link would have been a better solution as on my Esprit S1 but that needs proper inboard bearings on the diff output shaft to take the axial load which Lotus were clearly reluctant to do..... as per the Europa :lol: . It would have also made the back end of the chassis even cheaper :lol:

Lotus engineering while innovative, was crude and took a huge amount of risks and a bet it would get past the warranty period.

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PostPost by: Andy8421 » Mon Apr 20, 2020 12:31 pm

vincereynard wrote:I don't think CVs were available in the early 60s? Nasty old Hookes were of course, which could have been used as a top link and eliminated the need for a full strut.


Mr Rzeppa patented the CV in 1927, and Mr Issigonis used them in the front driveshaft of the MIni from 1959 onward.
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PostPost by: vincereynard » Mon Apr 20, 2020 5:48 pm

rgh0 wrote:Minis had Cvs in 1959
cheers
Rohan


Andy8421 wrote:Mr Rzeppa patented the CV in 1927, and Mr Issigonis used them in the front driveshaft of the MIni from 1959 onward.


'Course it did :oops: Hooke at the diff and CV at the hub early on. I've certainly fought with enough to remember that! :)

However if Chappers had used CV's would he have had the problem of having to limit wheel travel as happens now? No excuse with the +2 however!
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PostPost by: rgh0 » Tue Apr 21, 2020 12:39 am

The wheel travel problem is at full droop when there is essentially no load on the wheel so setting up the shocks originally so to restrict full droop a little on the Elan in order to use the Cv's available then if needed would not have affected the handling.

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PostPost by: alan.barker » Tue Apr 21, 2020 5:53 am

An Austin Cooper S 1964 1071cc i had wasn't CVs. It had drive shafts with a "X" with rubber moulded around. With curved bits of sheet metal bonded on outside.
"U" bolts held these to the drive shafts.
No CVs and was original.
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PostPost by: englishmaninwales » Tue Apr 21, 2020 6:09 am

alan.barker wrote:An Austin Cooper S 1964 1071cc i had wasn't CVs. It had drive shafts with a "X" with rubber moulded around. With curved bits of sheet metal bonded on outside.
"U" bolts held these to the drive shafts.
No CVs and was original.
Alan


Alan, I think you are describing the drive shaft inner joint. The outer joint was a CV.
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PostPost by: alan.barker » Tue Apr 21, 2020 7:11 am

Hi Malcolm,
sorry yes you are right. So many years ago and so much fun in the Mini :mrgreen:
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PostPost by: HCA » Tue Apr 21, 2020 8:22 am

There were quite a few catastrophic failures of the BMC CV with fatalities as a result around 1963/64. It was even a parliamentary issue at the time. I remember it well as my Dad locked Mum's Mini so no one could drive it until the planned fix was done! (I still remember the key number FS986! those were the days when no one questioned a snotty teenager ariving at a parts department asking for a key :D )

I wonder if the bad press and mechanical uncertainity might have been enough to put Mr Chapman off the idea of using them. If not, then certainly he would have looked at the fact that the highest production bhp the BMC joints were used for was [then] 80bhp in the 1275 Cooper S. I am not sure I would be too happy using them if my engines were producing in excess of 25% more :?
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PostPost by: rgh0 » Tue Apr 21, 2020 9:29 am

Well its good he chose to use donuts over Cvs due to problems on the Mini Cvs as the donuts never had any catastrophic failures did they :roll:

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