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MG Midget and Sprite Technical - Adding lightness

I'm interested in lightening my car. Its pretty standard atm, all steel bodywork etc, alloy wheels, bucket seats.

Just weighed some panels (on bathroom scales).

Bonnet - 13.2kg
Door - 5.9kg
Wing - 6.8kg
will weigh boot lid tomorrow, guessing 7kg ish.

I guess I’m after any itemised masses that people might have collected, racing boys especially.

Has anyone weighed an FIA roll cage or roll over bar? I think I need one.
R T Jakeman

Shouldn't the thread be entitled 'removing heaviness'?

;o)
Dave O'Neill 2

Wasn't Colin Chapman renowned for adding lightness?

It was said that his "Sevens" added lightness every trip as the 2BA nuts and bolts came undone and fell off

I don't have weights but my two Honeybourne Mouldings front wings came in a single package that I was able to pick up single handedly without spilling my coffee in t'other hand...

Figlass bonnet weighs the square root of bugger all too

Or do I mean the cube of even less?

I dunno

I didn't do skool the day they done adding up



(Yes I am eternally ashamed, too blarry late to moan now)
bill sdgpm

what year is your midget? There was about 105 lbs of reinforcement added between '74 and '75, and the 1500 weighs about 45lbs more than the 1275 (when you include transmission).



Norm
Norm Kerr

I have from earlier thread:

"boot lid is 5kg with lock and badge still on"

A
Anthony Cutler

just weighd the complete midget
it's a "66 mkII
with a spare normal tools and a full tank of petrol 749KG
It is all steel just took the bumpers off
Onno Könemann

Onno, that sounds spot on:

749kg = 1650 lb

the MkII was listed by BMC to be 1490 lbs, but that was "unladen" (no fluids, no accessories, basically just metal, and trim).

for the MkIII, BMC listed both the unladen and the kerb weight (kerb = all fluids and accessories), and the difference between them was 191lbs. The fluids alone weigh in at 30lbs +.

So, for a quick reference, 1490 + 191 = 1681lbs.

I bet the bumpers on a MKII are just about 25lbs.

ta da! Your car is spot on (give or take a few pounds, different era tires weigh different amounts, and stuff like that).

Norm
Norm Kerr

Bill, I thought the quote was:

"adding power makes you faster on the straights, adding lightness makes you faster everywhere"

My complete car weighed 711kg, no bumpers, alloys, roll over bar, standard seats, K series engine and ford box.

Found my old roll over bar this morning, 10kg.

Excluding running gear, I want to take about 25kg out of the car. Which would be possible with ally wings, bonnet and boot lid. I'm not keen on fiberglass panels (the ones you can buy anyway) bad shape, chop strand matting, way too much resin, variable thickness etc etc. Great for a racer, just not really good enough for a road car.

Can the aluminium bonnet and boot still be bought from somewhere?
R T Jakeman

ally doors are available....
David Smith

Yep, seen some of those on ebay.

2kg each. So 6.5 to 7 kg ish saving in total, for 400 quid. £60/kg. I've put them on my wanted list.
R T Jakeman

RT. What do you weigh? Might be cheaper to go on a diet, save money on food and put the savings into a more powerful engine. A win/win situation. LOL.
Bernie.
b higginson

Norm
Cool thanks for the info.

Bernie
That would be my best bet
It would be easyer to lose 10/15KG my self...


I vaguely remember frontline doing a alloy bonnet and boot lid.
But i can't find it anny more.

Need a bonnet with louvres..... might as well be alloy.
If it is remotely affordable.
Onno Könemann

I've never been keen on aluminum alloy doors on a Spridget unless it has door bars. In a side impact it would be painful and unpleasant. I told Tim this but he made them anyway. In racing if you had aluminium alloy doors you'd have to fit a cage with door bars which I guess would defeat the weight saving.
Daniel Thirteen-Twelve

Fibreglass is too heavy, at least in road-car thickness. Carbon fibre is the way to go.
My rule of thumb for weight savings is $100/kg, that being about what it would cost to chase more power for the equivalent performance gain.
For major weight loss, toss the seats and fit some shells that weigh only about 4kg each. Get rid of the underseal and sound deadening (free). Toss the window glass and winder, and the windscreen. If you have splined minilite wheels, convert to bolt-ons for major weight savings.
My car went over the scales a couple of weeks ago at 640kg.
Mike Allen

Even with steel doors, I always used door bars on the race car, so there would have been a weight saving by using aluminium.
Dave O'Neill 2

Where abouts in Lincs are you? You are welcome to come and have a look at my car (in Lincoln) to see what I've done to lighten it. It's in bits at the moment so you can weigh panels, parts etc to see what the differnce is. I've tried to incorporate 'adding lightness' to the rebuild and it can get to be a bit of an obsession!!
John Payne

nowt that cant be sorted with a hole cutter



PeterJMoore

I'm 75kg, but I’m 6ft tall, don’t really have much weight to spare.

I'm not sure about the side impact argument. I tend to think that there isn't much safety on offer in the midget. Although with a full cage it would be pretty robust, really don’t want this weight though, or look.

Onno - think frontline stopped selling the ally panels. Presumably they were done at Abingdon? unless someone else has a press.

John - not actually in lincs anymore, milton keynes now. Are you building a racing car? whats the target weight? I think Peter just confirmed your point about it becoming an obsession.

Peter – I admire your commitment, what was the saving on the boot lid?
R T Jakeman

Mines a hillclimb/sprint car and when I started the rebuild it was 665kgs with 2 gallons of fuel, A series with type 9. My 'target' is to lose 30kgs by the time it's back together. Some of that is by spending vast amounts of money and some by doing vast amounts of work!! It's still going to be road legal and has steel panels except for bonnet and boot lid. If I ever get it finished I'm interested to see what (if any!) difference it makes as the engine is going to be untouched (thats if it hasn't seized up by then!).
John Payne

Not sure yet, gonna weigh it against a stock one tomorrow

Having said that, it was a test run, there is a LOT more to come out of it. Also, going to make a single skin fibreglass one out of very very lightweight glass sheeting.

i mean see-through light ;) i will weigh those too though
PeterJMoore

Someone was making a short run of ally front hubs a while back... might be worth considering... plus IIRC BGH do an ally T9 gearbox case...

A
Anthony Cutler

This thread was discussed between 06/08/2010 and 09/08/2010

MG Midget and Sprite Technical index

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