Lotus Elan

Side impact protection

PostPost by: davidallen » Tue Dec 21, 2004 10:49 am

Hi,

I removed the chrome window frames from my +2 last night for rechoming, and
I was wondering if it was worth adding some additional side impact bars into
the door frame, before replacing them?

Obviously any design would have to be light, not foul with the window, and
be installed through the gap left by the window frame. I was thinking along
the lines of a thin walled tube, about 1" dia, or a top hat section, running
along the length of the inside of the outer door skin, with captive nuts
either end so it could be bolted to the inner sides of the door. I would
then lay fibreglass over the tube to bond it to the inside of the door outer
face.

This would beef up the door frame, and hopefully any side impact would
transferred to the car body.

Do you think this would be practical safety improvement or little benefit on
a project already way behind schedule?

Do not the elites etc have something similar?

David (windowless +2)
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PostPost by: lotuselan2 » Tue Dec 21, 2004 11:27 am

David
Just buy a Hummer and put the +2 in the back!
Ken
'69 Lotus Elan +2 with Cosworth BDR
'84 Ferrari 400i
'94 Subaru SVX
'04 Audi allroad
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PostPost by: mikecauser » Tue Dec 21, 2004 11:51 am

On Tue, 21 Dec 2004 10:49:19 -0000 "ALLEN, David" <***@***.***> wrote:

I removed the chrome window frames from my +2 last night for rechoming, and
I was wondering if it was worth adding some additional side impact bars into
the door frame, before replacing them?

Obviously any design would have to be light, not foul with the window, and
be installed through the gap left by the window frame. I was thinking along
the lines of a thin walled tube, about 1" dia, or a top hat section, running
along the length of the inside of the outer door skin, with captive nuts
either end so it could be bolted to the inner sides of the door. I would
then lay fibreglass over the tube to bond it to the inside of the door outer
face.

This would beef up the door frame, and hopefully any side impact would
transferred to the car body.

Do you think this would be practical safety improvement or little benefit on
a project already way behind schedule?

Do not the elites etc have something similar?

In a way. Essentially the 3rd generation Lotuses have a steel door,
with a bit of glassfible bolted to it to make it look nicer :-) The
side impact beam carries the hinges at one and the the latch mechanism
at the other. If you are planning to bolt a beam to the glassfibre I
don't think it's going to do much good, you need to attach it to
something stronger. OTOH it's not going to do any harm, so why not?


Mike
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PostPost by: M100 » Tue Dec 21, 2004 1:00 pm

On Tue, 21 Dec 2004 10:49:19 -0000, "ALLEN, David"
<***@***.***> wrote:


This would beef up the door frame, and hopefully any side impact would
transferred to the car body.

Do you think this would be practical safety improvement or little benefit on
a project already way behind schedule?

Do not the elites etc have something similar?

The key word is hopefully - IMHO It would only work if the additional
structure properly transferred the load into the rest of the body via
something substantial - very beefy hinges and door latch plates,
neither of which the Elan has. The body structure is not that strong
either so any DIY solution might just end up presenting more of a
problem with intruding bits of metal in an accident.

The Elites have a door beam, and won a safety award for it if I recall
correctly but is probably antique compared to modern solutions. The
problem is modern vehicles are much stiffer with crumple zones
designed only to protect the passengers and not the vehicle that they
hit. Only last night on TV they showed the results of a 35mph head on
offset accident between a 10 year old Renault Espace and a modern one.
The 10 year old one was not survivable for the driver but those in the
new one probably escaped injury - even the airbags were not deemed to
be required as it was a minor impact with virtually zero intrusion
into the passenger compartment. The accident expert on hand said that
if it was two 10 year old vehicles colliding it would probably be
survivable for both - and this is progress?

Once you are in a collision situation the only benefit in the
engineering of the Elan I can see has to be in its low weight as it is
more likely to be deflected by something heavier. I've seen foam
filled doors on a fixed side window racing Elan a few years ago, not
practical for everyday use though! If you wish to cater for
collisions with modern machinery (even something like a supermini)
then the only way you are likely to cope is with a properly
triangulated rollcage structure between you and the door - I'd love to
be proved wrong though and would be first in the queue if someone came
up with something commercial.



Martin

72/45


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PostPost by: motocicletta at aol.com » Tue Dec 21, 2004 5:30 pm

Hi,
The one thought that I would offer are that side impact beams in any car door
transfers the load from the door into the body by pressing on the A pillar
and the B pillar. I had a chance to look inside the door of a late model Camaro
not to long ago and was surprised to see that the impact beam was just a
piece of round tube about !" in dia. and was only loosely secured at each end.
The door was a plastic molding and the result of a side impact would be to press
this tube against the A and B posts.

Unless you have something strong and sold to absorb the load a side impact
beam will be just one more thing coming at you in case your hit and one more
thing to rattle the rest of the time. Unless you have or add more structure in
the body than I think you have it seems to me to be a waste of effort.
Certainly it would be in an Elan.
Jeff Manuel
65 S2
motocicletta at aol.com
 

PostPost by: "e s" » Tue Dec 21, 2004 7:35 pm

1] it would give you a false sense of security. If youve ever had the headliner out, you know how foolish it is to think of it as a 'hardtop'
2] i don't think there is room, and if there is, you want to attch it at both ends hinge and latch or it would become a spear in a otherwise minor accident.

3] the hinge and latch are just in the glass so.......


----- Original Message -----
From: "Martin Evans" <***@***.***>
To: ***@***.***
Subject: Re: [LotusElan.net] Side impact protection
Date: Tue, 21 Dec 2004 13:00:11 +0000


On Tue, 21 Dec 2004 10:49:19 -0000, "ALLEN, David"
<***@***.***> wrote:


> This would beef up the door frame, and hopefully any side impact would
> transferred to the car body.
>
> Do you think this would be practical safety improvement or little benefit on
> a project already way behind schedule?
>
> Do not the elites etc have something similar?

The key word is hopefully - IMHO It would only work if the additional
structure properly transferred the load into the rest of the body via
something substantial - very beefy hinges and door latch plates,
neither of which the Elan has. The body structure is not that strong
either so any DIY solution might just end up presenting more of a
problem with intruding bits of metal in an accident.

The Elites have a door beam, and won a safety award for it if I recall
correctly but is probably antique compared to modern solutions. The
problem is modern vehicles are much stiffer with crumple zones
designed only to protect the passengers and not the vehicle that they
hit. Only last night on TV they showed the results of a 35mph head on
offset accident between a 10 year old Renault Espace and a modern one.
The 10 year old one was not survivable for the driver but those in the
new one probably escaped injury - even the airbags were not deemed to
be required as it was a minor impact with virtually zero intrusion
into the passenger compartment. The accident expert on hand said that
if it was two 10 year old vehicles colliding it would probably be
survivable for both - and this is progress?

Once you are in a collision situation the only benefit in the
engineering of the Elan I can see has to be in its low weight as it is
more likely to be deflected by something heavier. I've seen foam
filled doors on a fixed side window racing Elan a few years ago, not
practical for everyday use though! If you wish to cater for
collisions with modern machinery (even something like a supermini)
then the only way you are likely to cope is with a properly
triangulated rollcage structure between you and the door - I'd love to
be proved wrong though and would be first in the queue if someone came
up with something commercial.



Martin

72/45


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PostPost by: davidallen » Wed Dec 22, 2004 1:07 pm

It looks like the Camero design is virtually identical to my suggestion! I
totally agree with all the comments that the body tub has to be strong
enough to take the additional load, and I guess the elan is not.

However, without any additional side impact bars, a hit from another car
would go straight through the doors, no question, so if anyone has any
pearls of wisdom or suggestions while I still have the doors in pieces I
would be interested to hear them!

David

-----Original Message-----
From: ***@***.***lto:***@***.***
Sent: 21 December 2004 17:30
To: ***@***.***
Subject: Re: [LotusElan.net] Side impact protection



Hi,
The one thought that I would offer are that side impact beams in any car
door
transfers the load from the door into the body by pressing on the A pillar
and the B pillar. I had a chance to look inside the door of a late model
Camaro
not to long ago and was surprised to see that the impact beam was just a
piece of round tube about !" in dia. and was only loosely secured at each
end.
The door was a plastic molding and the result of a side impact would be to
press
this tube against the A and B posts.

Unless you have something strong and sold to absorb the load a side impact
beam will be just one more thing coming at you in case your hit and one more

thing to rattle the rest of the time. Unless you have or add more structure
in
the body than I think you have it seems to me to be a waste of effort.
Certainly it would be in an Elan.
Jeff Manuel
65 S2










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