SLC technical questions

Hi there,

I have been playing with the thought of buying an SLC superlight for a long time. Before I go into the project, I would like to get a few more technical details, if anyone here has some answers, i would greatly appreciate it.

1) Aluminium frame rear: what size are these? They appear to be 50x50x2 but not sure. I have seen few frames now and noticed that some of these kit cars have really low torsional stiffnesses. Wondering what the situation is here with the SLC. Does "superlight" mean "so light that torsional stiffness is also very low"?

2) Aluminium grade: what grade ist that aluminium tub? Is this 6060? Can it be welded?

3) Accuracy after welding: how accurate is that aluminium chassis? Are we talking few millimeters out on the pick/up points, more or less?

4) Corrosion resistance with salt water: an issue in some places where salt is used on the road for half of the year. I noticed some are painting the frame, some not. What is the consensus here?

5) Why the choice of aluminium / imagine using 316 stainless steel / no corrosion issues anywhere. Wall thicknesses would have to be 1/3rd for roughly the same mass and the same stiffness.

6) What is the weight of the chassis including the suspension? I want to use a turbocharged motorcycle engine with 280 horsepower - the weight including gearbox and drivetrain is below 100kg. I want to get below 600kg with the build. Happy to make compromises on wheels (narrow wheels), etc.

Any input here would be greatly appreciated!

Howard Jones

6) You can't build a 1350-pound SLC............drop the mike. 1350 pounds is an early small motor Radical. A radical is a MUCH smaller car. Look at it this way. My SLC is about 2450 ish. To take 1000 pounds out of the car you would have to REDUCE EVERY PART ON THE CAR by more than 40%. Not possible. Period.
Thanks for the reply. This will be quite challenging - and result in probably a completely custom made car that has nothing to do with the SLC. One question: do you have a mass overview of your car? Some baseline that I could attack and actually ask "what would you need to do to get half the mass of every part"? That would allow me to move ahead. Thanks
Agree with Howard

Berlow is my mass spread sheet for my space frame project. Its not yet quite complete, and already I am over 1850 pounds. Most Items are verified masses, others are estimated and their might still be some bits to add.

PartQtyMass kgTotalpounds
Spaceframe chassis1.00115.00115.00254
Roll bar1.0013.0013.0029
Spaceframe chassis panelling1.0038.0038.0084
Engine to gearbox adaptor1.004.004.009
Engine RV81.00125.00125.00276
Gearbox Audi1.0070.0070.00154
Exhaust Manifolds2.006.4012.8028
Exhaust Silencers2.003.306.6015
Gear Lever assembly1.001.781.784
Gear Linkage complete1.005.005.0011
Steering rack - cortina1.004.004.009
Steering rack clamps1.000.840.842
Steering rack lower bracket1.000.600.601
Steering shaft upper1.001.801.804
Steering shaft mid1.000.800.802
Steering shaft U Joints3.000.481.443
Shock support plate1.000.650.651
Rear wishbone upper2.000.721.443
Rear wishbone lower2.001.272.546
Rear wishbone toe link2.000.180.361
Ampep Silverline rod ends & spherical bearings.24.000.358.4019
Front wishbone upper2.000.541.082
Front wishbone lower2.001.282.566
Front push rod2.000.290.581
Front upright with disc2.0010.6021.2047
Rear upright with disc2.007.3014.6032
Wheels Front - 6 J Miniltite / 225/60 BFG2.0022.0044.0097
Wheels Rear - 7 J Miniltite / 245/60 BFG2.0023.8047.60105
Protech coilover dampers + spring4.002.369.4421
half shafts & CV joints2.008.0016.0035
Front Brake caliper2.004.338.6619
Rear Brake caliper2.003.607.2016
Steering wheel1.001.221.223
Pedal box,1.001.621.624
brake / clutch cylinder3.000.290.872
handbrake lever1.000.600.601
Body rear clip1.0030.0030.0066
Body nose1.0025.0025.0055
Body scuttle1.008.908.9020
Body LH door1.005.405.4012
Body RH door1.005.905.90
Rear subframe1.003.303.307
Rear clip support1.001.701.704
Door mounts2.000.230.461
Body panel catches, pit pins and fixings1.005.005.0011
Alloy fuel tank - foam filled3.0015.0045.0099
Fuel sender1.000.000.000
Alloy flush fit fuel filler, neck, hose and fittings1.000.000.000
Pro Fuel Filter1.000.000.000
Braided hose kit chassis runs for brakes & clutch1.000.000.000
Alloy radiator for US V8's1.0015.0015.0033
Cooling hose & Alloy chassis pipes1.0010.0010.0022
CF66 Twin Fan kit for high BHP1.0010.0010.0022
Coolant swirl pot & expansion tank1.005.005.0011
Body loom, relays & fusebox.1.0015.0015.0033
Front and rear light pack.1.0015.0015.0033
Head Rests1.000.000.000
Wheel nuts1.000.000.000

Chris Kouba

One question: do you have a mass overview of your car? Some baseline that I could attack and actually ask "what would you need to do to get half the mass of every part"? That would allow me to move ahead. Thanks

Why attack Howard's list? You'd be better served to make your own instead.
To cut the SL-C by ~40%/1,000lb mass simply isn't practical or reasonable. You'd be better off buying something else or scratchbuilding your own car. That amount of reduction is like trying to unscramble an omelette. It's not possible, and even if you could, you'd need an engineering degree and years of work to figure out what parts could be cut, how much, where, and then the time and money to actually execute the reduction.

Off the top of my head the obvious ways to reduce weight is to strip all interior parts and exterior extras like wheel well liners, go for the smallest all-aluminum engine you can for the HP you want and slap some turbos on it, then remake the entire body in carbon fiber. That should knock off close to 500 lb or so. Oh, and skip the air conditioning. This is a car that will not be practical for anything other than racing, and it will be really expensive to get it there.

Howard Jones

I would be happy to provide you with a complete list of parts necessary to build a car with a target horsepower and weight target. Other requirements will necessitate additional costs. This will require you to provide a proposed contract for me to review and counter. Should you do so I will require you to agree to compensate me for the cost of review of your contract proposal including but not limited to legal review and drafting my counteroffer. Please include a proposed method of payment and payment schedule with proposed milestones. Please provide which jurisdiction you currently reside in and be prepared to provide background information including banking records.

Be aware that I intend to propose an escrow process at your expense as a method of ensuring timely payment(s).

Should you be willing to go forward you can send me your contact information via PM.
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"Superlite" is a marketing moniker. Representing a general desire to use light weight materials to build a reasonably light car at a reasonable price point. How unreasonable you are from there is entirely up to you.
I don't know why more people build a Lotus seven / Caterham seven style car, How to build a cheap sports car and Build your own sports car for as little as 250 are both good books. You want light weight this could be it.