Lightweight car
Discussion
Hello I am designing a lightweight car. The car has to be weight below 550kg for tax purposes.
I am now looking for a uprights+wheel hub combo to satisfy my needs.
- I am going with unequal double A-arm suspension
- top speed will be about 100km/h
- The parts need to be _lightweight_
- The car will be rear wheel drive
- The parts need to be affordable and easily to purchase also for later if more cars are built.
Anyone with some good ideas?
I am now looking for a uprights+wheel hub combo to satisfy my needs.
- I am going with unequal double A-arm suspension
- top speed will be about 100km/h
- The parts need to be _lightweight_
- The car will be rear wheel drive
- The parts need to be affordable and easily to purchase also for later if more cars are built.
Anyone with some good ideas?
Try looking at the Triumph Herald/Spitfire upright/hub assembly. It's very light, very cheap, readily available and has excellent geometry (used on the Lotus Elan and the Lotus/Caterham 7, amongst others, of course).
If you're going RWD, then the Lotus Elan driveshaft assembly (with rubber rotoflex couplings instead of CV joints) is quite lightweight and you can buy matching front and rear Lotus hubs that give you access to very light, magnesium peg-drive knock-off wheels, if you wish (though the wheels are a bit pricey; there's always the standard steel Elan wheels that are pretty light and only £85 each, though).
550kg isn't really very light, especially if you only need enough power to hit 100kp/h.
I'd suggest you should be aiming at <500kg for a coupe or <430kg for an open 2-seater. I'm designing a single seater road car confident of achieving <350kg and with aspirations to get close to, or below, 300kg... but that's using a lot of fancy materials and custom components (including wheels that incorporate the bearings, so don't need a separate hub).
If you're going RWD, then the Lotus Elan driveshaft assembly (with rubber rotoflex couplings instead of CV joints) is quite lightweight and you can buy matching front and rear Lotus hubs that give you access to very light, magnesium peg-drive knock-off wheels, if you wish (though the wheels are a bit pricey; there's always the standard steel Elan wheels that are pretty light and only £85 each, though).
550kg isn't really very light, especially if you only need enough power to hit 100kp/h.
I'd suggest you should be aiming at <500kg for a coupe or <430kg for an open 2-seater. I'm designing a single seater road car confident of achieving <350kg and with aspirations to get close to, or below, 300kg... but that's using a lot of fancy materials and custom components (including wheels that incorporate the bearings, so don't need a separate hub).
goos said:
The car will be a electric car so batteries are 100-200kg. The car will also have roof+doors. The law also restricts the motor to be 15kw max.
I will look into the suggestions, anyone have weights on those parts?
Have a look a this then 370kg, roof and doors on the way and it's already available as an electric quadricycle which is what you are talking about.I will look into the suggestions, anyone have weights on those parts?
Edited by qdos on Wednesday 26th November 07:40
Furyblade_Lee said:
Bike engine Sam?....... ;-)
Yes, bike engine. As you know, I'm not a huge fan of them when appplied to something as heavy as a 'Seven', but below 350kg, they undeniably come into their own.
...and the unit I've selected was deliberately chosen to overcome the things that wind me up most about 'conventional' BEC's (stupid short gearing combined with manic revs) - it's an Aprilia Tuono R V-twin; 1-litre, 139bhp at a relatively lowly 9,500rpm, so at peak power revs it's only firing as rapidly as a 4-cylinder engine revving at 4,750rpm. Dry sumped as standard and all magnesium construction, so no oil surge problems and very light, even for a bike engine, too.
Yes, it'll be expensive, but at the rate design work is progressing at the moment, I'll have plenty of time to save up. 
It's intended as a road car, not a track day special, so getting heat into the tyres isn't a major consideration. I'm using tall, narrow profile tyres, anyway, with the intention that it'll slide around a bit, for light weight and compliance.
As you'll be aware from your Fury, one of the big problems with very light cars on less than perfect tarmac is that outright pace is often limited because they end up skipping around so much. One of the main objects of the exercise, therefore, is to see how the normally unfavourable sprung:unsprung weight ratio of a very light car can be managed, along with weight transfer, to allow unusually compliant springing, to the benefit of both ride and traction.
Suspension design is trick, but I'll say no more than that because I haven't applied for the patents yet.
I haven't selected the calipers yet, but brakes will be floating drilled plain (unvented) disks all round, with the rear being a single disc, mounted inboard on the differential (I'll temporarily fit a spool for the SVA).
It's intended as a road car, not a track day special, so getting heat into the tyres isn't a major consideration. I'm using tall, narrow profile tyres, anyway, with the intention that it'll slide around a bit, for light weight and compliance.
As you'll be aware from your Fury, one of the big problems with very light cars on less than perfect tarmac is that outright pace is often limited because they end up skipping around so much. One of the main objects of the exercise, therefore, is to see how the normally unfavourable sprung:unsprung weight ratio of a very light car can be managed, along with weight transfer, to allow unusually compliant springing, to the benefit of both ride and traction.
Suspension design is trick, but I'll say no more than that because I haven't applied for the patents yet.
I haven't selected the calipers yet, but brakes will be floating drilled plain (unvented) disks all round, with the rear being a single disc, mounted inboard on the differential (I'll temporarily fit a spool for the SVA).
Sam_68 said:
Yes, it'll be expensive, but at the rate design work is progressing at the moment, I'll have plenty of time to save up.
It's intended as a road car, not a track day special, so getting heat into the tyres isn't a major consideration. I'm using tall, narrow profile tyres, anyway, with the intention that it'll slide around a bit, for light weight and compliance.
As you'll be aware from your Fury, one of the big problems with very light cars on less than perfect tarmac is that outright pace is often limited because they end up skipping around so much. One of the main objects of the exercise, therefore, is to see how the normally unfavourable sprung:unsprung weight ratio of a very light car can be managed, along with weight transfer, to allow unusually compliant springing, to the benefit of both ride and traction.
Suspension design is trick, but I'll say no more than that because I haven't applied for the patents yet.
I haven't selected the calipers yet, but brakes will be floating drilled plain (unvented) disks all round, with the rear being a single disc, mounted inboard on the differential (I'll temporarily fit a spool for the SVA).
Hi Sam, you're designing a very ineresting sportscar, and I like the concept, it makes a lot of sense in the future. It's intended as a road car, not a track day special, so getting heat into the tyres isn't a major consideration. I'm using tall, narrow profile tyres, anyway, with the intention that it'll slide around a bit, for light weight and compliance.
As you'll be aware from your Fury, one of the big problems with very light cars on less than perfect tarmac is that outright pace is often limited because they end up skipping around so much. One of the main objects of the exercise, therefore, is to see how the normally unfavourable sprung:unsprung weight ratio of a very light car can be managed, along with weight transfer, to allow unusually compliant springing, to the benefit of both ride and traction.
Suspension design is trick, but I'll say no more than that because I haven't applied for the patents yet.
I haven't selected the calipers yet, but brakes will be floating drilled plain (unvented) disks all round, with the rear being a single disc, mounted inboard on the differential (I'll temporarily fit a spool for the SVA).
Looking forward to seeing some pictures of your litlle sportscar......
I'm sure you've seen this concept:
http://www.roadrazer.co.uk/default.asp?pid=7
Could be close to your sportscar in concept, even if it's a 2 seater.
Cheers mate
Italo
Edited by fuoriserie on Friday 28th November 08:40
Sam_68 said:
Try looking at the Triumph Herald/Spitfire upright/hub assembly. It's very light, very cheap, readily available and has excellent geometry (used on the Lotus Elan and the Lotus/Caterham 7, amongst others, of course).
If you're going RWD, then the Lotus Elan driveshaft assembly (with rubber rotoflex couplings instead of CV joints) is quite lightweight and you can buy matching front and rear Lotus hubs that give you access to very light, magnesium peg-drive knock-off wheels, if you wish (though the wheels are a bit pricey; there's always the standard steel Elan wheels that are pretty light and only £85 each, though).
550kg isn't really very light, especially if you only need enough power to hit 100kp/h.
I'd suggest you should be aiming at <500kg for a coupe or <430kg for an open 2-seater. I'm designing a single seater road car confident of achieving <350kg and with aspirations to get close to, or below, 300kg... but that's using a lot of fancy materials and custom components (including wheels that incorporate the bearings, so don't need a separate hub).
Ohh, sounds interesting. Have you got a link to a build site or anything?If you're going RWD, then the Lotus Elan driveshaft assembly (with rubber rotoflex couplings instead of CV joints) is quite lightweight and you can buy matching front and rear Lotus hubs that give you access to very light, magnesium peg-drive knock-off wheels, if you wish (though the wheels are a bit pricey; there's always the standard steel Elan wheels that are pretty light and only £85 each, though).
550kg isn't really very light, especially if you only need enough power to hit 100kp/h.
I'd suggest you should be aiming at <500kg for a coupe or <430kg for an open 2-seater. I'm designing a single seater road car confident of achieving <350kg and with aspirations to get close to, or below, 300kg... but that's using a lot of fancy materials and custom components (including wheels that incorporate the bearings, so don't need a separate hub).
I think these cost £2-4k
Quadzilla site or similar said:
Ever since Jonathon Ross took delivery of his new Bug Rider 250 it’s been impossible to keep up with customer demand for the Quadzilla® Bug Rider range. The new shipment features a host of improvements to ensure that the Bug Rider stays the UK’s number one choice of road legal buggy:
High specification road buggy sets new standards for handling, build and design. The Bugrider is Pocketbikez premium choice for serious on road performance. Totally equipped with a digital instrument set in an integrated dash. Fully adjustable Recaro style bucket seats and safety belts for an ergonomic driving position. Fantastic to drive with superb road performance. See full specification below. Full 12 months warranty & free 12 months breakdown recovery scheme in operation with Quadzilla road legal Quads / Buggies
Latest Developments:
More aggressive front chassis design with new front mounted radiator
Larger capacity 10 litre fuel tank
Temperature gauge and polished alloy wheels as standard
Improved mirror mounting points for better visibility
Improved paint quality to Japanese Standard
Improved waterproofing on wiring harness for those river crossings
New ball type CV joints for smoother action and improved performance
Reduced off road vibration with improved damping on fenders, engine mounts and radiators
SPECIFICATIONS:
Engine - 249.1cc 4 stroke
Gears - Automatic with reverse
Weight - 324 Kg
Start - Electric
Cooling - Liquid cooled
Brakes - Triple disc brakes
FEATURES:
Alloy wheels as standard
10 litre fuel capacity
Adjustable recaro seats
4 point race harness
Dual a-arm f' suspension
12V power point
Seats 2 adults
High specification road buggy sets new standards for handling, build and design. The Bugrider is Pocketbikez premium choice for serious on road performance. Totally equipped with a digital instrument set in an integrated dash. Fully adjustable Recaro style bucket seats and safety belts for an ergonomic driving position. Fantastic to drive with superb road performance. See full specification below. Full 12 months warranty & free 12 months breakdown recovery scheme in operation with Quadzilla road legal Quads / Buggies
Latest Developments:
More aggressive front chassis design with new front mounted radiator
Larger capacity 10 litre fuel tank
Temperature gauge and polished alloy wheels as standard
Improved mirror mounting points for better visibility
Improved paint quality to Japanese Standard
Improved waterproofing on wiring harness for those river crossings
New ball type CV joints for smoother action and improved performance
Reduced off road vibration with improved damping on fenders, engine mounts and radiators
SPECIFICATIONS:
Engine - 249.1cc 4 stroke
Gears - Automatic with reverse
Weight - 324 Kg
Start - Electric
Cooling - Liquid cooled
Brakes - Triple disc brakes
FEATURES:
Alloy wheels as standard
10 litre fuel capacity
Adjustable recaro seats
4 point race harness
Dual a-arm f' suspension
12V power point
Seats 2 adults
qdos said:
15kw power is about 20 horse power. The spec goos is trying to keep to is a heavy quadricycle spec which he is trying to achieve with an electric motor. It's quite quite different to a regular Kit car spec guys.
Agreed... though in our defence he did omit to mention the fact that he was trying to design an electric vehicle in his original post - it makes a bit of a difference! 550kg is easy to achieve with a petol engine. 300kg plus a couple of hundred kilos of batteries is a different matter, particularly if you want roof and windows (which in turn dictate heater/demister and winddscreen wash/wipe systems.I'd still stick with my original recommendation of Triumph uprights, but only because I cant think of anything else that would meet his other criteria of low cost and easy availability, for use with a double wishbone suspension.
Most current quadricycles, like the Quadzilla, are here today, gone tomorrow, so fail on the future availability test (even if you could persuade the manufacturers to supply you with the components on a production basis). There are Kart component packages that tick most of the boxes, but they're not suited to double wishbone suspension.
If you want off-the-shelf availability with guaranteed future supply, then Triumph remain the lightest, cheapest and most readily available components I can think of, but they are undeniably over-engineered for an electric commuter buggy.
The other obvious components would be Mini (as used on many early bike-engined single-seaters like the Jedi and Terrapin), but they're not especially light.
I'd be inclined to suggest that he follows the example set by later Jedis and most other bike engined single seaters and quadricycles and uses a fabricated upright, perhaps using Kart stub axles, brakes, bearings and hubs.
Goos is based in Finland so I expect Spitfire parts are pretty hard to come by, more so than here (I happen to have GT6 sourced ones on my Ginetta G27)
Quadricycles actually sell very well in Europe and are hardly "here today gone tomorrow". Aixam Mega for example have sold over 100,000 units and I'd go for those as donar parts myself. Try also Microcar, Ligier and SECMA I'm pretty sure though that they all use the same suppliers for the hubs and brake assemblies, usually Comex
As a matter of interest the weight of batteries is not included for electric vehicles in the classification criterion.
Quadricycles actually sell very well in Europe and are hardly "here today gone tomorrow". Aixam Mega for example have sold over 100,000 units and I'd go for those as donar parts myself. Try also Microcar, Ligier and SECMA I'm pretty sure though that they all use the same suppliers for the hubs and brake assemblies, usually Comex
As a matter of interest the weight of batteries is not included for electric vehicles in the classification criterion.
qdos said:
Goos is based in Finland so I expect Spitfire parts are pretty hard to come by, more so than here (I happen to have GT6 sourced ones on my Ginetta G27)
Quadricycles actually sell very well in Europe and are hardly "here today gone tomorrow". Aixam Mega for example have sold over 100,000 units and I'd go for those as donar parts myself. Try also Microcar, Ligier and SECMA I'm pretty sure though that they all use the same suppliers for the hubs and brake assemblies, usually Comex
As a matter of interest the weight of batteries is not included for electric vehicles in the classification criterion.
not many spitfires here... and i would prefer to buy new stuff from the shelf but seems that's just an utopia. I have been looking into a Polaris Outlaw 525, its hub+knuckle weights around 3kg total and the parts can be bought as new.Quadricycles actually sell very well in Europe and are hardly "here today gone tomorrow". Aixam Mega for example have sold over 100,000 units and I'd go for those as donar parts myself. Try also Microcar, Ligier and SECMA I'm pretty sure though that they all use the same suppliers for the hubs and brake assemblies, usually Comex
As a matter of interest the weight of batteries is not included for electric vehicles in the classification criterion.
Yep the batteries are not included so it gives you a nice freedom
goos said:
qdos said:
Goos is based in Finland so I expect Spitfire parts are pretty hard to come by, more so than here (I happen to have GT6 sourced ones on my Ginetta G27)
not many spitfires here... Sam_68 said:
goos said:
qdos said:
Goos is based in Finland so I expect Spitfire parts are pretty hard to come by, more so than here (I happen to have GT6 sourced ones on my Ginetta G27)
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