Max
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| posted on 5/7/02 at 08:43 AM |
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Weight loss
Hello all,
Are there any good tips for weight savings, i.e. which is better for side panels, aluminium sheet or fibreglass. Now I’m going down the BEC route,
I’ve decided in for a penny in for a pound. (But I draw the line at reducing the weight of my supple, Adonis-like frame….) Are the fibreglass seats
offered by many suppliers worthwhile? Any idea how much they weigh?
What would you guys recommend as a good tyre and wheel size? Jon, looking at the pictures of the Isonblade, am I right in thinking that you’re using
Focus rims with 195/60 15’s? Also is that a Caterham rear view mirror? I looked at those on their website recently and the price caused my heart to
stop momentarily... 
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Alan B
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| posted on 5/7/02 at 12:56 PM |
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Hi Max,
For some strange reason this thread caught my attention 
What I do is list in reasonable detail the cars components and allocate weights to them (actual if possible, or good estimates) then order them by
weight. (OK, fairly obvious I know). Then you'll find someting like 20% of the parts make up 80% of the weight (the old 80:20 rule, pareto I believe)
Those are the parts that need the most attention, You have obviously addressed the main one (the engine) but I think you'll find that uprights, hubs,
calipers, wheels etc. will all come higher on the list than seats and side panels.
It's easy to have 60 pounds in a front corner and saving 10 pounds isn't difficult , but when you have a seat and side panel that may only weigh 10
pounds combined then you can see the savings are more difficult.
These are just rough estimates, but you can se my point, go for the big, easy targets first.
All IMO of course.
Cheers,
Alan
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Alan B
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| posted on 5/7/02 at 01:04 PM |
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Another couple of points:
Don't forget stuff left out completely weighs nothing, do you need a heater, wipers, windscreen etc.?
Also, do a cost per weight saved check. You mention the fancy mirrors, but what's the cost per pound saved? I'd guess it's actually hundreds of
quid per pound 
They may look cool, but aren't good value from a weight point of view.
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Jon Ison
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| posted on 5/7/02 at 04:13 PM |
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Well, the seats you mention i find ok till your moving, then they hurt, how dare you say Ca***am ???  pheraps they copied mine, its an SPA carbon
fibre one, infact all 3 are. spot on with the rubber, went that way to get the gearing rite without messing with the diff, i plan 205's on back when
NOS is fitted.
With the bike route weight is a consideration so if it aint doing a job don't fit it, those who have looked close at the car will also have noted
that some of the bolts have been drilled down the center, it all counts have you felt the weight of cortina callipers ? thats why i fitted
willwood, plus they stop you quicker.......Alan is rite though it is worth thinking £ per Lbs, but i liked the mirrows, and you do need to see the
ever shrinking cars behind you.....
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cymtriks
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| posted on 5/7/02 at 08:49 PM |
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It is possible to reduce the frame weight by about 10 percent and gain about 100 percent in chassis stiffness by optimising the chassis design. The
total number of tubes in the chassis is also less with my modifications. I'm not certain if I made it clear that the sheet steel needs to be 18gauge
to get these results so take note now. My earlier postings on this site and on the Yahoo theory forum tell you how. This is, as the figures suggest, a
very significant improvement. I used the same computer analysis tools that the major car makers use just in case you are wondering. I hope you find
this interesting.
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Barker
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 posted on 8/7/02 at 12:19 PM |
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Dear Max
My main aim for building is to get a very light responsive car having driven heavy production cars.!!!
Obviously bike engine is way to. lightest for torque and power are the v twins like the susuki TL. Gearbox is light but you lose out not having a
combined diff like car combinations.
Ally body panels are much lighter than fibreglass.
The pucca padded seats are around 8 - 10 Kg and under £100 each see demon tweaks for example. I have also looked for the the weight of the fibreglass
seats but never found it.
Have just striped the front uprights off sierra donor and cant believe the weight. I intend to machine down the discs and cross drill them. Reducing
metal on the upright itself is more tricky since its cast.
Way over designed for car at hopefully 400Kg.
Few other thoughts-
No windscreen heater/wippers washer.
No reverse gear
Mid engined [avoids prop]
bike battery and fuel tank
Pete
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Max
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| posted on 8/7/02 at 01:13 PM |
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Pete,
Thanks for the info, I’ll certainly be leaving out the windscreen and the associated paraphernalia.
I’m not sure, but I’d guess that without the windscreen in the way the drag factor of the car would be lower hence higher top speed and/or faster
acceleration – any thoughts?
How are you intending to machine and drill the discs? It would be very easy to get them out of balance or seriously weaken them. Being Ford parts
there are some very cheap performance discs on the market that have already been drilled and lightened for you. I know it’s not in keeping with the
Locost ethos but an extra 40 quid on the budget still leaves you £210 to build the rest of the car
Cheers,
Max
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interestedparty
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| posted on 8/7/02 at 04:42 PM |
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quote:
I’m not sure, but I’d guess that without the windscreen in the way the drag factor of the car would be lower hence higher top speed and/or faster
acceleration – any thoughts?
Total air resistance is drag factor multiplied by frontal area. Reduce either of these and you reduce overall resistance. The angle and shape of a
locost windscreen are such that removing it will reduce frontal area and drag factor. Got to be a good move unless it rains.
The effect of air resistance increases as square of speed ( or something like that) so the effect of reducing it will have more effect at higher
speeds so will have much more effect on 0-100 than on 0-60.
John
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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