Today's random thoughts: motorcycle powered cars?

"BaconSandwich is tasty." (baconsandwich) 07/17/2015 at 13:59 • Filed to: None

2

31

A friend and I were having a discussion last night, which got me thinking: how difficult would it be to make a rear-engined motorcycle powered car? I’d think the hard bit would figuring out the transmission and differential. If a person was to use the existing bike transmission, that’d be fine, but how would it hook up to any sort of differential?

In general, we were both a fan of the idea: a small, light, rear engined car that uses a motorcycle engine. Why a bike enigne? It’d make it feel like you are going a million miles an hour, but in reality, you wouldn’t be going that fast. In other words, it’d be fun without getting you in trouble.

Any thoughts on the topic?

G_Body_Man: Sponsored by the number 3 > BaconSandwich is tasty. 07/17/2015 at 14:02

3

This has a motorcycle engine and transmission. Otherwise? FSAE teams have been doing it with four wheels for years.

boxrocket > BaconSandwich is tasty. 07/17/2015 at 14:02

1

Dropping a Hayabusa engine in a Smart ForTwo is a popular modification.

Sampsonite24-Earth's Least Likeliest Hero > BaconSandwich is tasty. 07/17/2015 at 14:03

0

There are plenty of liter bike swap kits for everything from classic minis to mr2s

SidewaysOnDirt still misses Bowie > BaconSandwich is tasty. 07/17/2015 at 14:03

0

Make the car light enough, and even a bike motor will get you into trouble. A ton of small racecars are built using bike engines. The cheapest and easiest way to get power to the ground is with a solid axle that’s chain driven. Quaife makes a limited slip diff with a chain drive input specifically for this kind of application, but it’s a bit expensive. IIRC, it’s like $1500 or something.

Jeff-God-of-Biscuits > BaconSandwich is tasty. 07/17/2015 at 14:06

1

http://jalopnik.com/5890529/the-fa…

RamblinRover Luxury-Yacht > BaconSandwich is tasty. 07/17/2015 at 14:07

1

/front-engined

/thread

GhostZ > BaconSandwich is tasty. 07/17/2015 at 14:07

0

This is how we ended up with the Honda Z, Morgan 3-Wheeler, Bond, and Peel.

RamblinRover Luxury-Yacht > SidewaysOnDirt still misses Bowie 07/17/2015 at 14:08

1

Alternately, one can use a motor/trans pack from a shaft-drive bike...

Twingo Tamer - About to descend into project car hell. > BaconSandwich is tasty. 07/17/2015 at 14:08

1

Based on MotoIQ’s hayabusa Miata, very.

GhostZ > SidewaysOnDirt still misses Bowie 07/17/2015 at 14:08

1

Make the car light enough, and even a bike motor will get you into trouble

Hayabusa Smart Car, anyone?

SidewaysOnDirt still misses Bowie > RamblinRover Luxury-Yacht 07/17/2015 at 14:09

0

Yeah, but that’s likely to give you more packaging problems and now you need a custom driveshaft that will connect to whatever diff you’re using..

Chuck 2(O=[][]=O)2 > BaconSandwich is tasty. 07/17/2015 at 14:10

2

http://www.roadandtrack.com/car-culture/en…

Snuze: Needs another Swede > BaconSandwich is tasty. 07/17/2015 at 14:10

0

Check out some of the FSAE cars. They are all RWD, rear engine, motorcycle powered.

SidewaysOnDirt still misses Bowie > GhostZ 07/17/2015 at 14:10

1

I was thinking Turbo Hayabusa GoKart, myself....

GhostZ > SidewaysOnDirt still misses Bowie 07/17/2015 at 14:11

2

BaconSandwich is tasty. > G_Body_Man: Sponsored by the number 3 07/17/2015 at 14:12

0

Ah, the T-Rex, right? I think if I was going to build something, I’d want four wheels. I was unaware that it used a bike engine, though. Interesting!

BaconSandwich is tasty. > boxrocket 07/17/2015 at 14:12

0

I’ve seen a few videos out there of it. I think there may have even been a ‘busa swapped Smart in town last weekend for the Street Machine Weekend.

BaconSandwich is tasty. > Sampsonite24-Earth's Least Likeliest Hero 07/17/2015 at 14:13

0

Interesting. I’d think that something (relatively) heavier like an MR2 wouldn’t do so well with a bike engine. A Mini, though... that’d be fun.

BaconSandwich is tasty. > SidewaysOnDirt still misses Bowie 07/17/2015 at 14:15

0

I’d think that a solid axle wouldn’t work so well - lots of slipping when going around corners and whatnot. Even if it wasn’t a limited-slip diff, I’d think a regular differential would be drastically better than a solid axle.

TheHondaBro > BaconSandwich is tasty. 07/17/2015 at 14:15

1

SidewaysOnDirt still misses Bowie > BaconSandwich is tasty. 07/17/2015 at 14:16

0

It’s not so bad. Karts and F500 cars run a solid axle and they’re plenty quick.

BaconSandwich is tasty. > Jeff-God-of-Biscuits 07/17/2015 at 14:16

0

That’s... insane. Other than the drive train, I wonder what else was modified. I’m guessing lots.

BaconSandwich is tasty. > RamblinRover Luxury-Yacht 07/17/2015 at 14:18

0

Hah, that’d be fun! They seem to be pretty pricey though. I’m thinking more BAC Mono with a 600 cc bike engine in the rear, for kicks.

BaconSandwich is tasty. > GhostZ 07/17/2015 at 14:19

0

Can’t say I’ve heard of the Bond.

BaconSandwich is tasty. > Chuck 2(O=[][]=O)2 07/17/2015 at 14:19

0

Yes! I’ll need to watch the video again to see how he did the rear end. Jay seemed to love the thing! If I’m not mistaken, it’s a fellow Opponaut who did that.

BaconSandwich is tasty. > Snuze: Needs another Swede 07/17/2015 at 14:21

0

Interesting. I just might have to do that. I wonder how hard it is to get parts, and how expensive those parts are, though. I recall someone else here on OppositeLock that was doing some sort of similar racing league, but they were using a Honda Fit engine. The transmission on it was crazy expensive, though.

BaconSandwich is tasty. > SidewaysOnDirt still misses Bowie 07/17/2015 at 14:21

0

Interesting. I’ve never actually heard of F500 until now!

BoxerFanatic, troublesome iconoclast. > BaconSandwich is tasty. 07/17/2015 at 14:31

0

They exist, albeit usually 3-wheels, because it is a motorcycle. 4 wheels makes it a car, and much more 0ver-regulated to try and sell.

They use the integral gearbox from the bike engine, unless it is the Morgan 3-wheeler, which bolts an S&S harley-style v-twin to a Miata gearbox under the car.

Unless you use a Honda flat-6 from a nearly-new Goldwing, they don’t have reverse gear most of the time, and that would have to be added after the fact, usually between the gearbox output and the final drive.

For a 4-wheel vehicle, or a traditional Trike (rear axle, front single wheel, which is the worst layout) the differential is usually chain-driven with a sprocket in place of the typical ring-gear. Otherwise, they use an automotive bevel-drive differential and axle with a driveshaft, on a shaft-drive motorcycle engine.

But frankly, a reverse-trike, like the T-Rex, Polaris Slingshot (GM EcoBoost automotive drivetrain), CanAm Spider lineup, Morgan 3-wheeler, and others... is just fine, and is a more efficient direct-drive of the single rear tire, and if the tire is wide enough, the motorcycle engine can take good advantage of it, as well as the reduced vehicle mass of not having the fourth wheel, and more involved rear axle.

Engineering surrounding fitting a top-suspended engine and gearbox into a car, engineering the reverse gear, and the final drive usually is daunting enough to engineer from scratch that automotive engine swaps are more common, as most automotive engines are bottom-cradle-mounted and engineered to drive basically the same way, transverse, or longitudinal, respectively.

RamblinRover Luxury-Yacht > BaconSandwich is tasty. 07/17/2015 at 14:53

1

Bond Bug.

Snuze: Needs another Swede > BaconSandwich is tasty. 07/17/2015 at 15:06

1

Well FSAE is a collegiate series, so you have to be in a college with a team to do it. We fabricate a lot of parts (chassis, uprights, suspension bits) as well as things like intake and exhaust. Also, for safety sake they limit the cars with 20mm inlet restrictors and 600cc engines, so they cap at around 80HP (theoretical max, realistically closer to 70HP).

However, the rules package for FSAE is very similar to SCCA A-mod which is essentially the “unlimited” class in AutoX. Except there you can run bigger engines, etc. But SAE is a great place to look if you want to do a formula style BEC (Bike engine car). Also checkout the “Non-Traditional Build Log” over at locostusa.com as there’s quite a few guys doing BECs there.

As far a driving a car with a bike engine there’s 3 realistic choices:

Turn the engine 90 degrees and replace the drive sprocket with an output shaft to drive a traditional car diff. It’s probably the simplest and most straightforward way to go. You won’t have a reverse though so you’ll have to get creative.

Regular old chain drive with a floating diff (this is how most FSAE cars do it). This is a lot lighter than the above, but a bit more expensive and complicated since you need a custom diff that’s desinged to be floated, big ass (and expensive) bearings and you’ll have to fabricate a mount and it needs to be pretty precise to keep everything in alignment. The big downside is there’s still no reverse so you need to create something, a lot of people go with electric motors.

F-N-R box. This is a box with some gears in it and a chain drive sprocket on the outside. It handles the final reduction internally, contains some sort of limited slip diff, and has forward, neutral, and reverse gearing. Its kinda heavy, and very expensive, but also makes life easy.

Snuze: Needs another Swede > BaconSandwich is tasty. 07/17/2015 at 15:07

1

Also, weight kills BECs. Motorcycle clutches are only made to handle the engines max HP plus a few hundred pounds plus aero loads (not insignificant, bikes are actually pretty awful from an aero standpoint). But a car adds so much more mass, it’s very easy to burn up clutches.

But if you keep the car light... hold on. They can get really fast if you’re using something like a 600 or 1000cc bike engine.