Lotus Elan

"Monocoque"

PostPost by: GrUmPyBoDgEr » Tue Nov 27, 2012 7:40 pm

elj221c wrote:dodo_z

From page 4 of this thread, my interpretation of the parts.

elj221c wrote:I have read and reread this thread and I can't find any reference to the Robinshaw and Ross book wherein, in my edition at least, there is a drawing showing clearly how the Elan might have been without the backbone frame.
It is on page 127 under the heading; The Two-Seater Elan. Some further notes. (Written by Ron H)
I assume that Gary has not seen this as his idea is based around a Spyder type frame. I suspect a few other contributors to this thread haven't seen it either. Interestingly the diagram has question marks pertaining to the suspension mounting reinforcing frame at the rear and what looks like some kind of outrigger to the battery box mouldings both sides and being attached to a tunnel reinforcing frame. Or maybe the thought was that the whole tunnel reinforcing fabrication might be superfluous? There are nine separate sections but the dashboard is bolted to the front bulkhead of the tunnel member.
1 & 2. The sill reinforcing latice.
3. Front turrets and cross member.
4. Rear turrets and diff cross member
5. Tunnel member formed of a bottom and three bulkheads.
6. Cross brace under the engine.
7. Cross brace to presumably hold the headlight actuators.
*. This number is not used although the S1 style dash is highlighted as one of the components so I assume it is number 8.
9?Rear suspension mounts. Not sure why the question mark as I would have thought that this bit would be required.
I would like to have scanned the drawing but it is copyright to Motor Racing Publications Ltd. Essentially all the components look similar the those that we recognise except the are now all joined by more sheet steel, the tunnel reinforcement being the exception as we know that the other three sides have been added. I'm not sure about 7 as I do not have pop up lights. Is there a cross brace at that point on 'proper' Elans?

GrUmPyBoDgEr wrote:Yes the dashboard has a very important function in fixing the sides of the body & the scuttle to the backbone of the body & chassis.
For that reason large fasteners & load spreading bushes pushed in to the plywood are used to take the loads that may be transferred through the dashboard.
Cheers
John


John, (back here! :) )

I replaced the dash on the S2 with a home made job but I don't remember any load spreading bushes on the original. Was that just on the S1?


John, (back here! :) Ha! that made I larf but be careful I could get very upset & disappear again :wink:

Back on topic; sorry I only have personal experience of my S4 which most definitely had the bushes in the original dash & I used those bushes in the replacement dash.
I find it hard to believe that they were not used on earlier Elans but maybe Lotus discovered that they were necessary/an improvement later in production.
Beware of the Illuminati


Editor: On Sunday morning, February 8th 2015, Derek "John" Pelly AKA GrumpyBodger passed away genuinely peacefully at Weston Hospicecare, Weston Super Mare. He will be missed.
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PostPost by: garyeanderson » Tue Nov 27, 2012 8:18 pm

The dash spacer/bobbins were probably introduced on the type 36 with the then new dash. The S2 did not have them, there were fiber washers, I do not know about the S1 but I highly doubt that the spacers were used and more likely that the orange fiber washers were used. (please correct me if my suppositions are incorrect :) ) The photos belong in a separate topic and I'll probably get trashed here anyway so I'll post them.

The spacers from the later dashes on the white ring, dash bolt and black fiber washer is from 26/4997, the other orange fiber washers are probably from 26/4020 but I can't be certain as I just don't remember.
26-4997 dash bolt and black fiber washer.JPG and


dash bolt from 25-4997 with original fiber washer and an earlier fiber washerr.JPG and


I have yet to see the photo in the later book, not likely to ever buy a second copy so I guess it remain one of life's mysteries that was never answered till I am tossed in a ditch by the side of the road.

Oh Yea - welcome back again DJ :D
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PostPost by: RotoFlexible » Tue Nov 27, 2012 9:49 pm

When I had my new S2 dash built, I asked the builder to include spacers (the original had none). He investigated, then said he couldn't because the bolt holes were too close to the edge of the dash; not enough meat to enlarge the holes to accept spacers.
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PostPost by: stugilmour » Wed Nov 28, 2012 12:01 am

Roy, I think John may be referring to metal bush fittings permanently mounted in each of the dash mounting holes. At any rate, that's what was on my stock Plus 2 dash and on my replacement one, although they would be easy to miss as not a separate part. They appear to be glued in to the holes prior to the clear finish being applied. I recall the dash supplier specifically mentioning them; my guess is some replacement dash suppliers may not include them?
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PostPost by: rodlittle » Wed Nov 28, 2012 1:46 pm

My S1 dash certainly didnt have them but I have put bushes in for the top dash fixings just to stop the wood fretting and the holes enlarging, just small annular bushes made of ally
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PostPost by: trw99 » Thu Sep 28, 2017 1:18 pm

This was one of the most interesting threads we enjoyed on here and, having spent an interesting half hour re-reading it, I felt it worthy of a bump for folks who have since joined the forum to share.

In addition, I wondered if any newer members can contribute further to the discussion concerning the rigidity of the body and chassis, as well as the idea that modern materials such as Kevlar could, if they haven't already, be used for a monocoque construction.

Tim
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PostPost by: el-saturn » Thu Sep 28, 2017 1:55 pm

gary - are you the gary anderson i met 25 (+/-) at your company where you were making F3 anson's?? i was there with my ol pal eric schwaller!?? sandy j (alps)
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PostPost by: RichC » Thu Sep 28, 2017 5:15 pm

gary's not around anymore.....
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PostPost by: billwill » Thu Sep 28, 2017 6:23 pm

trw99 wrote:This was one of the most interesting threads we enjoyed on here and, having spent an interesting half hour re-reading it, I felt it worthy of a bump for folks who have since joined the forum to share.

In addition, I wondered if any newer members can contribute further to the discussion concerning the rigidity of the body and chassis, as well as the idea that modern materials such as Kevlar could, if they haven't already, be used for a monocoque construction.

Tim


Vegantune of Spalding used Kevlar in the body structure of the Evante cars.
Plus Carbon Fibre in the 'bumper portion".
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PostPost by: Certified Lotus » Fri Sep 29, 2017 11:55 am

A great read! Thanks for reposting! Unfortunately I cannot add any value to the conversation as I'm not a structural engineer nor equipped to discuss the merits of modern composites.
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PostPost by: CBUEB1771 » Fri Sep 29, 2017 1:11 pm

el-saturn wrote:gary - are you the gary anderson i met 25 (+/-) at your company where you were making F3 anson's?? i was there with my ol pal eric schwaller!?? sandy j (alps)


The Gary Anderson who went on to become Jordan Grand Prix's chief designer and "our" Gary Anderson are not the same person. I posted a photo including "our" Gary Anderson a couple of weeks ago in the racing section with respect to the the vintage/historic race weekend at Lime Rock in the US. I hope to see "our" Gary Anderson again tomorrow at the VSCCA season closer event, again at Lime Rock.
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PostPost by: knockoffnut » Mon Oct 02, 2017 6:20 pm

I know that some Kevlar is already being used in some modern Elan body shells and stiffens them up considerably. I haven't seen any hard numbers but I believe that the torsional stiffness of the Elan's body shell is significantly higher than the torsional stiffness of the "chassis". I believe that the factory Elan chassis exists and functions primarily to spread out the suspension loads into the body shell, rather than as primary stiffness. Elites had issues with suspensions mounting points pulling out during racing and the Elan, with higher loading presented a bigger problem.
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PostPost by: Billmack » Mon Oct 09, 2017 11:36 pm

The elephant in the room so to speak is that the elite was never an open top car and already had structural issues. I'd have to say that an open top monocoque elan would have to be a non starter as an idea. I 've done considerable work with carbon tub formula cars and the hole that the driver sticks out of is very small with a lot of reinforcement around the edge.
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PostPost by: Mazzini » Tue Oct 10, 2017 7:42 am

knockoffnut wrote:I know that some Kevlar is already being used in some modern Elan body shells and stiffens them up considerably. I haven't seen any hard numbers but I believe that the torsional stiffness of the Elan's body shell is significantly higher than the torsional stiffness of the "chassis". I believe that the factory Elan chassis exists and functions primarily to spread out the suspension loads into the body shell, rather than as primary stiffness. Elites had issues with suspensions mounting points pulling out during racing and the Elan, with higher loading presented a bigger problem.


And to carry the weight of the drive components, but yes I think that's quite right.
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PostPost by: el-saturn » Tue Oct 10, 2017 7:56 am

how's about a wound cfrp tube to start with - peripherals as integral (one-pieced) as possible - just ta keep this interesting topic going: and yes we also had the 1st tubs made (in northhampton) using ally honeycomb panels! sandy
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