Lotus Elan

safety cage on street car

PostPost by: wolfchen » Mon May 24, 2021 7:49 pm

I was speaking with a local shop that services quite a few lotus and they told me that they installed a safety cage on a S3 elan, it consisted of a roll bar and seamless tubing the was concealed in the sills and then across the passenger compartment.

They claim it is installed without removing body from chassis and that other than roll bar it's invisible and that top fits as well. I didn't see the finished product but they told they had copied the idea from a spyder chassis option?

Has anyone ever heard of this, seen it done ? I wonder about adding any weight to a lotus , given the relatively flimsy nature of an elan how can this even work ?


Will post pictures when i see it in the flesh

Jeffrey Vogel
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PostPost by: Andy8421 » Mon May 24, 2021 8:27 pm

Spyder sell a roll cage for the Elan with a standard chassis that operates just as you describe. I fitted one to my Sprint.

The sill members are installed by cutting a hole in the wheel arch and sliding the bar inside the sill. There is a cross member at the very bottom of the footwell that joins the sill member to the chassis (frame). At the back the sill member joins the roll hoop.

After fitting the only visible part is the roll hoop itself, the sill members are hidden and the footwell cross member can be hidden under the carpet.

While I am sure it is better than nothing, I don't know how much strength the sill members have - generally tubes are good at axial compression and extension, but don't have much strength if the the force is applied laterally.

This thread has pictures of the Spyder cage and side intrusion bars fitted to a Spyder chassis, but the same arrangement works for a standard chassis.

https://lotuselan.net/forums/viewtopic.php?f=36&t=26060&start=
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PostPost by: jasper2347 » Mon May 24, 2021 9:28 pm

Does the Elan have sill members the same as the +2? Our +2 sprint car cage just bolts to a 90 degree folded floor plate angled to use the standard seatbelt bolt. The cage 'foot' then bolts through this plate and the floor with another plate on the underside. A short bar then links across the floor to the other seatbelt mounting (which is fastened to the chassis) via another plate. Easy to fit and remove if you don't like it. :)
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PostPost by: Andy8421 » Tue May 25, 2021 4:53 am

jasper2347 wrote:Does the Elan have sill members the same as the +2? Our +2 sprint car cage just bolts to a 90 degree folded floor plate angled to use the standard seatbelt bolt. The cage 'foot' then bolts through this plate and the floor with another plate on the underside. A short bar then links across the floor to the other seatbelt mounting (which is fastened to the chassis) via another plate. Easy to fit and remove if you don't like it. :)

No.
The Elan's sills are empty. There is a lattice framework that runs from over the rear wheel arch to under the dash that provides strength around the door frame that 'closes' the sill.

Picture here:

https://lotuselan.net/forums/viewtopic.php?f=36&t=29662&start=
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PostPost by: jasper2347 » Tue May 25, 2021 7:23 am

Interesting, thanks for the info. The +2 must have them in for strength. They do have a jacking point at each end as well which is very handy. :D
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PostPost by: wolfchen » Tue May 25, 2021 10:40 am

looking at the referenced posts and photos of cage on bare chassis , I don't see how it actually adds any safety in a side impact , it's so low and basic chassis is a piece of folded steel that in a rollover the bar might help but
in any other type of crash it would be marginal at best ,An elan is so low that the impact from a full size vehicle would be well above the sill line.

If you were racing the car it might add some torsional stiffness to handling , but I don't see it as adding safety to a street car
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PostPost by: Andy8421 » Tue May 25, 2021 1:30 pm

wolfchen wrote:looking at the referenced posts and photos of cage on bare chassis , I don't see how it actually adds any safety in a side impact , it's so low and basic chassis is a piece of folded steel that in a rollover the bar might help but
in any other type of crash it would be marginal at best ,An elan is so low that the impact from a full size vehicle would be well above the sill line.

If you were racing the car it might add some torsional stiffness to handling , but I don't see it as adding safety to a street car


Spyder advertise the bars that run along the sills as follows:

"Attach to the main roll over bar hoop, occupy the left and right hand sill cavities, run across each foot box (beneath the pedals) and connect to existing body to chassis pickups. Protects both driver and passenger against side and wheel intrusion"

As I mentioned above, I am sure its better than nothing, but how much better, I am not sure.
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PostPost by: jasper2347 » Tue May 25, 2021 2:55 pm

Agree with Andy regarding side impact assist. Most vehicles these days are huge compared to our old classics. Our roll cage is there to hopefully stop the crash helmet wearing out on the track should we ever capsize. :D
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