Lightening bodyshell

[msd1107]

Well, for what ever reason, the body is off the frame and completely stripped. Car is lots lighter that way!

So I want the car to be as light weight as possible when it is put back together.

Tony Thompson sell lightweight replacement body shells. But ignoring the cost issues, all he has are roadster bodies and I have a FHC and don't want to change. It is one of the first S4s produced.

So, has anybody lightened their body shell?

What did you do? And how much weight can I reasonable expect to lose?

Or, in theory, what can I do and how do I go about it?

And what other techniques do you have for saving weight?

Thanks for any advice.

David
1968 36/7988

[nebogipfel]

Unless you are racing the Elan, why bother?

A standard Elan could hardly be described as heavy.

Elan shells are pretty thin and fragile, particularly later ones and for a road car what little you might gain will not be worth it.

Most lightweight shells are Elan shaped but usually not very pretty on close inspection, it isn't a priority and they don't need to be.

The easiest way to shed some weight would be to chop the roof (and consequently remove the rear screen) but in doing so you would probably get an aerodynamic disadvantage from the less slippery shape.

Any difference you make, is at best only going to be measurable in fractions of a second.

[types26/36]

what other techniques do you have for saving weight?

Atkins Diet............

[msd1107]

Hi Brian,

Good technique. Steak eaters rejoice!

I am 70kg at 183 cm, so there is not a lot to go in that direction.

David

[msd1107]

John,

Racers reduce weight in order to try to gain a competitive advantage.

But it is just as important for street driver to drive as low weight vehicle as possible.

Consider. Assume I reduce the weight of an Elan from 1600 to 1300 lbs. That is equivalent to raising the engine horsepower from 130 to 160. And the car is much more tractable with a mildly tuned engine.

Also, the energy consumption of the car is proportional to its weight (to a first approximation). Decreasing the weight translates to a 18% energy consumption reduction, or, alternatively, in increase in mileage of 18%.

Also, the coefficient of friction of the tires is inversely related to the load on the tires. So the cornering g's would increase, and the braking distance would decrease.

Also, the reliability would increase, since less stress is being placed on every component. So brake pad life goes up, tire life is extended, engine overhaul intervals are extended, etc, etc.

Chapman would have produced a 1000 lb Elan if he could have. Remember, that is his theory.

Unless you run a DHC without a top, there really is no weight savings. And, as you pointed out, a DHC has less efficient aerodynamics.

So, this is a complicated topic. But the theory indicates that if we can develop weight reduction strategies, then we all benefit, especially the owner who applies the most of them.

If the weight reduction genie magically passed over your garage tonight and removed 300 lbs, you would be most pleasantly surprises the next morning upon driving the car.

David

[nebogipfel]

John,

Racers reduce weight in order to try to gain a competitive advantage.

But it is just as important for street driver to drive as low weight vehicle as possible....................................

If the weight reduction genie magically passed over your garage tonight and removed 300 lbs, you would be most pleasantly surprises the next morning upon driving the car.

David

From the point of view of racing I agree completely. My point was can you significantly reduce the weight of a road going Elan without ruining it? I think not

If I had a visit from the genie tonight I would want to know where my trim, side windows, passenger seat, dashboard, spare wheel, carpets etc had gone and why my beautiful classic Elan was ruined for the sake of half a second on a stopwatch.

Unless you are trying to wring every last bit out of a car for racing purposes it's pointless.

Just an opinion of course

[elansprint71]

Leave the body alone, get some lightweight wheels and alloy brake calipers!

[cabc26b]

Removing weight from an elan is an expensive prop. You are either buying costly alloy bits or costly composit bits . in the end expect only to remove about 250Lbs ( 125 kilos) and you will pay dearly for it,

Save the money and invest it in a super nice paint job....

[garyeanderson]

All that horse hair sound deadener is heavy stuff, glass rear and side window can be replaced with plexiglass/lexan, 26r type of headlamps save a bit up front but you only have a single vacuum canister on a S4. The heater is 10 or more pounds with coolent and hoses, the seats need help too, just a lightweight shell for the driver (Beau, my yellow lab likes the passinger side without the seat anyway). The block, bell, gear case, tailshaft, differential nose housing all in ally or magnesium, electric motors in the doors are a couple pounds each. some one has mentioned the alloy calipers, front hubs and magnesium or alloy wheels and a set of bias ply tires Hoosier a70 13 are as light as you can get (and leave the spare tire home with the jack and knock off hammer). Boot and bonnet can be molded a bit lighter. I got my S2 down to about 1280 pounds before I put some weight back on. I thought I could get another 100 off if I tried ($) with a stock S2 body, not one of Tony Thompsons lightweight ones. I would think that it would be tough to get a Coupe much under 1300pounds, a roadster S1 or S2 could probably be gotten down under 1100 pounds and still be street legal (light, wipers, horn, e-brake etc). The lightest Race Elan I have read about was 1000 lbs, I have no other info on that Elan.

Gary

PS- I forgot, replace those heavy CV's with donuts and stock half shafts

[cliveyboy]

David
I think loosing weight on the actual body shell will be difficult.
Bonnet, boot lid, light pods and doors could be replaced with carbon fibre but "massively expensive".
Interior must be a good place. Strip out everything and replace with bear minimum. Small instrument dash etc and then diceide how much comfort to add and how much interior you want.
Another possibility not mentioned is an aluminium engine block.
Even a wiring loom using light weight cable can save a bit of weight.
The wood in the boot covering the spare wheel is out. 1kg saved at no cost.
Spare wheel out replaced with a can of foam. (can of foam out replaced with a break down card).
Seriously though I think with a little bit of sensible thought you could quite easily save a small amount of weight. It might not make much noticable difference to performance but theoretically less weight to carry means less fuel used.

Clive

[Rick]

Hi
I'm a non-Elan owning lurker (hope to get one one day!). Anyway, I've just saved 9kgs on my old Alfa with a Red Top 30 battery.

http://www.dmstech.co.uk/varleyredtop.htm

Admittedly the previous battery was chuffing huge, but even so there's some easy weight savings to be made here and it's got some serious cranking power. Just a thought.

Great site by the way. Loads of useful stuff!!

Cheers
Rick

[Emma-Knight]

saving weight by fuel calculation (1/2 full tanketc) is a nice idea. But - compared with all those cars around you - a standard Elan doesn't weight so much A good trimmed engine will give better fuel performance and braking shouldn't be an issue - otherwise you'll end up with some nice SUV in your boot! Driving an Elan is driving a very nice 40 year old car, with 60's 0r 70's style. Undoing all this will end up in a modern light weight car, at about the same costs as a new thing. I enjoy the history inside my car, even if rotten here and there.

The original parts were fitted with Colin wandering around the production line - and if he could have saved material in production process - he would have done!

My opinion...

Anna

[archigator]

I had my Sprint FHC body shell completely stripped and repainted a couple of years ago. My bodyshop guy, who specializes in Corvettes, was amazed as to how light-weight standard Lotus fiberglass parts were compared to Corvette fiberglass.

Gary
'71 Sprint FHC
Miami, FL

[patrics]

Hi David,
How much weight you can save off the body depends on how badly it?s been repaired in the past, how many coats of paint and how much under seal has been thrown on. I think it also depends on the age of the car ? an early S4 will probably be heavier than a Sprint but your better off with the quality of the earlier shell.
I?m doing my shell at the moment and certain parts like the bulkhead need strengthening not lightning - in fact I haven?t found anything other than the bonnet and boot lid everything else as far as a road car is concerned could be more robust.
For some reason the bonnet and boot are ridiculously heavy ? unless I?m missing something, why are they so heavy?
I weighed most of the trim on my S4 and the only parts which seamed unnecessarily heavy, was the parcel shelf, side trim and boot mat. If you remade these you would probably save 2 kg which on its own is not much but if you try and take the weight out of everything then it will add up.

Weight savings are easy to get when replacing alternators, starter motors, flywheels and radiators -TTR rads are incredibly light.
The heater also weighs too much at 5.6 kg ? should be able to half this weight.
Unbelievably the TTR drive, hub and output shafts complete are 1.2 kg lighter than the standard rotoflex setup.

Regards
Steve

[denicholls2]

If you're starting with a 40-year old shell, you're wasting your time lightening it unless you want to go racing and don't care what it looks like after you're done. In that case, get a cutsaw and go after anything the rules don't require.

Lightening a body you want to look nice is just plain a mistake. As others have said, it mostly needs to have material added, which is what those stress cracks are all about. You're sending out an invitation if you take more material off.

I'll opine that your only lightweight body option is to remold everything in carbon fiber, and pay careful attention to the resin mixes and strength requirements as you do that.

I'm sure we'd all love to see the result, but not many would want to pick up the tab.

Have fun regardless!