Adding Lightness
(my homage to ACBC)
Once you start down the adding lighness road, it is a slippery slope to OCD land.
Many years ago a race car builder gave me some advice that I have taken to heart. He said "in the quest for more lightness, once you have removed all the easy weight, the only way to remove another lb (told you it was a long time ago) is to remove an ounce from 16 places".
Replacing fibreglass with carbon fibre
With a car that weighed around 700Kg as standard, there didn't seem a lot of scope for removing unnecessary weight. However, a fortuitous meeting with Nick at Carbon Weezel sent me down the carbon fibre route. He made a boot, bonnet, dash, hood tray, door cards and roof tray for me. The boot and bonnet alone saved over 10Kg!
I am not using the hood tray or dash (design change), so they are up for sale on this site, if anyone is interested :-)
Carbon fibre bonnet. 5kg ligher than original.
As is the carbon fibre boot.
Carbon fibre dash made, but a change of plan meant it wasn't used.
I am now making my own carbon fibre items, using both wet lay vacuum bagging and 'out of autoclave' vacuum bagging techniques. Replacing fibreglass with carbon fibre reduces item weight by 50 - 75%, depending on the thickness of the original glassfibre. I started off with door skins, which I made by simply laying two layers of carbon over the existing skin. I hadn't progressed to vacuum bagging at this stage so they are heavier than they could have been.
Skin stripped of paint and treated with PVA release agent.
Carbon fibre being applied to door/mould.
Carbon fibre skin attached to door
I don't do things gradually, so the next item was a whole roof! Again two layers non vacuumed. It came out pretty well but I have to add the glass lips, so I may redo this using the vacuum bagging method.
Preparing roof for release agent
Resin spread over roof in preparation for first layer of carbon fibre.
First layer of cloth in position
Second layer added
Roof done, apart from glass lips.
By the time I decided to make the floors I had graduated to vacuum bagging. I was also getting ambitious and decided to include dense foam as a filler, making the floors very stiff. Even with four layers of carbon they were less than half the weight of the originals.
Driver's floor just out of vacuum bag and edge trimmed.
Likewise, passenger floor, but not yet trimmed.
Driver's floor dry fitted. Recess allows seat to be lowered so helmet clears roof.
The boot area didn't escape treatment. Floor, lamp panel, wheel tubs and firewall replaced with carbon fibre.
Boot floor
Rear panel
Wheel tubs and firewall.
The cabin is devoid of fibreglass. Dash, door cards, centre console, seats and rear bulkhead are all carbon, or will be once finished and fitted :-) See elsewhere for details on how these parts were fabricated.
Dash dry fitted
Rear panels. Front sections of wheel tubs and middle section of rear shelf.
Centre console. Used three layers as no curvature to add strength.
Second attempt at making a seat. Only two layers and weighs 740gms! A little too flimsy so will be used as passenger seat and driver's version will be 4 layers plus 3mm foam core.
Removing unecessary metal.
A lot of parts are overdesigned so are ripe for lightening. An extensive trawl of the car resulted in many parts being lightened.
Rear wheel hub
Propshaft flange
A little anal, maybe, but once you start down this road.....:-)
Steering roack clamps
Dammper spring seats machined to within an inch of their lives.
Lightening the diff cover plate using my CNC mill. Drilling holes has never been so much fun :-)
Rear verticals drilled, hopefully not too much.
Drilling front wheel sensor trigger.
Rear wheel sensor drilled and fitted.
CV joint lightened. Note that three bolts replaced by short studs.
Aluminium bolts don't escape lightening.
Took a little practice, but I can now centre drill titanium bolts.
Door hinges relieved of excess metal.
The chassis didn't escape attention. Drilled holes in locations that weren't considered structurally critical.
Marking out prior to drilling
Front damper support. Damper relocated so not using this top plate.
Every little helps.
Front suspension turret. As damper has been relocated from this thick top plate I felt free to airate it a tad.
If you look closely, you will notice that the handbrake frame as well as the handle have been attacked by the hole maniac.
Pilot holes for bigger drill bit. Since this photo was taken I have cut the horizontal section off as it is no longer required to support the damper.
I also punched holes in the main box section and chamferred them thereby actually adding some ridigity to the flat steel. The large holes are there as standard. The flange with a lot of holes has been largly removed as the new carbon fibre floors will be bonded to it and it doesn't need to be so wide.
Removing unecessary fibreglass
Where I am, presently, unable to replace fibreglass with carbon fibre I am removing as much of the fibreglass as possible. Where I can't cut holes (outer panels such as the wings) I have sanded the inner surfaces and removed a couple of hundred grams.
Door wells haven't been forgotten.
Boot also treated.
Over 400 holes per door.
A 100gms here, a 100gms there......:-)
Alternative materials
With the standard 'structural quality' bolts on cars being grade 8.8 it is possible to replace them with stronger, lighter items. I am talking titanium here. Very expensive but around 44% lighter. Where fixings are not stressed aluminium fixings can be used as these are almost two thirds lighter than steel and nearly half that of titanium.
Some of the many titanium bolts.
I even bought a few titanium nuts
RS Cosworth rear bearing carriers replaced with aluminium Sierra versions.
Internal door handle. Top is original steel, bottom is aluminium
Aluminium engine mount spacer is lighter than original steel spacers.
Glass, being very heavy, just had to go. I am replacing all the glass, including windscreen, with 3mm abrasive resistant polycarbonate. 4mm glass is 10.5kg/m2 and 3mm polycarbonate is 3.7kg/m2. One new front screen and a pair of 50 year old door windows or sale :-)
Wiring
The original wiring has been ditched as it is nearly fifty years old and now bears little relation to the new equipment. The new wiring will be race spec lightweight stuff.
Removing unecessary equipment
In some ways, this is the easiest way to remove weight. Original equipment I have done away with includes; heater, radio, electric windows and carpets.
Additionally, I have replaced the original steel fuel tank with a smaller aluminium one.
Non racing lightening.
Empty boot of anything not required (leave spare tyre, jack, essential tools, spare bulbs, warning triangle, ec).
Clear rubbish from floor of car and glove compartments, door pockets etc.
Don't run with a full tank of fuel. However, this will require more trips to the fuel station which may negate any fuel savings :-)
Fit lightweight, but rigid and comfortable, front seats.
Race lightening.
Only limited by imagination, time, money and regulations. For the purpose of this exercise we will ignore the last two :-)
Remove everything that is not required to run the car:
Take out spare tyre and everything else in the boot, including carpet.
Remove radio, amp, speakers etc
Remove heater and associated pipework.
Remove rear seats if fitted.
Remove carpet and any underfelt, sound deadening etc.
Make sure only 1 1/2 threads extend past top of nut.
Maximum 2 x bolt diameter of bolt thread in blind holes. Minimum is 1 1/2 diameters.
Use half height nuts.
Don't use flat washers unless necessary. Replace locking washers with thread locker, lighter and more effective.
Cut out the burgers, fast foods and beer/wine.
Now it gets more difficult (and more expensive).
Replace front seats with lightweight racing seats. Leave out passenger seat when not required.
Remove all unnessesary wiring.
Replace side and rear windows with Lexan or equivalent. A lot of race regs prohibit changing the windscreen.
Replace alternator with a lightweight racing item.
Same with starter, if available.
Small, race battery.
Replace front engine pullies with aluminium ones.
Wheel companies, such as Image Wheels, will lighten their already lightweight wheels further, dependant on your car's weight and planned use.
Lightweight body panels - fibreglass or, preferably, carbon fibre.
Lightweight, usually aluminium, front hubs.
Lighten rear hubs.
Drill brake discs.
Skim backs of brake pads.
Replace as many steel nuts and bolts as possible with titanium or aluminium.
Replace steel with titanium, aluminium of even carbon fibre, taking care to allow for the stresses th part has to contend with.
Remove unnessary material from chassis. This need to be undertaken with great care as you don't want to compromise its rigidity or structural integrity.
Replace steel fuel tank with aluminium version.
Replace steel brackets with titanium or aluminium versions.
Lightweight flywheel, unless drag racing.
Lightweight propshaft, aluminium or carbon fibre. Carbon fibre has the added advantage of dampening drivetrain shock loads.
Lightweight CV joints and rifle bored driveshafts.
Aluminium diff casing if it isn't already and they are available.
Strip all paint from remaining body panels that haven't been replaced with GF/CF and replace with just enough to get desired effect. A few extra coats of paint can equate to a couple of pounds in weight.