FWD to RWD conversion?

[Frank Lee]

^

[trikkonceptz]

Originally Posted by ddanz27

First of all, price is not an issue as I hope this to be a sponsored electric show car.

The three main goals

1- Extreme light weight-
2- as aerodynamic as possible-
3- a daily driver capable vehicle with a range of 60 miles, probably achieved with a small generator installed.

To date there is not a real "aftermarket following" of "street racers" and "car guys" that are on the band wagon. I am trying to prove to these knuckle heads that the future is now and continuing down the road of modifying your car to burn more fuel to make it go faster is almost history. I am setting out to prove that electric can be for lack of a better word... COOL. These guys dont want to see Geo Metros and mid 70s and 80s junkers that have been converted to electric. They want to see something that is proud to show off and something they can continue to "tinker" with and modify to their liking. I hope this answers the question, what am I setting out to do...

I can definately appreciate your intension here, but if price is no object and this is the crowd you wish to attract, point your guns towards the truck guys and build an electric truck. Many exist, you get a rwd configuration, a bed for infinate batteries, which will extend your range goals and still have all the aftermarket options your heart desires.

Hell get unique, build up something heavy that can move with electric and still cover the distance you want. Imagine a slammed dually on electric power that has a 120 mile range. Now there is a show car that will grab some attention.

[Clev]

Originally Posted by ddanz27

Does anybody dissagree that there is really no point in a transmission in an EV?

I absolutely disagree. Like an ICE, an electric motor has a powerband and limited torque/horsepower output. You will greatly extend your range, as well as the life of your motor and batteries, by being able to downshift to accelerate on hills or when heavily loaded (or when the battery voltage sags at the end of your charge.)

[Christ]

Use an AC motor, that will spin high... then there is no need for a transmission. You can use simple diff gear and tire size swaps to accomplish what you want.

Think Tesla.

[Clev]

Originally Posted by Christ

Use an AC motor, that will spin high... then there is no need for a transmission. You can use simple diff gear and tire size swaps to accomplish what you want.

Think Tesla.

That would be okay if you're using advanced batteries. A Tesla weighs 2,700 pounds; a base Neon is about 2,600 pounds as an ICE; a conversion with enough lead-acids to approach the voltage needed for an effective AC conversion will be closer to 4,000 pounds.

[Christ]

Show car... I doubt highly that it's going to remain stock at all, so in order to make it appeal to the widest range of people, certain things could be "altered" to accomodate for the weight... also, being sponsored, it will probably use Lithium variant batteries, which will help with weight also.

That said, if you don't want to think Tesla (which is designed to be uber-fast and poop on "real" sports cars) then think Mini-E.

It makes 150kW and 220nM, weighs 3230lbs, goes 0-62 in 8.5s, has an approximate top speed of 95 MPH, and ideally could get 156 miles of range (104 average combined).

Oh - it has a fixed ratio gearbox as well.

[Clev]

Originally Posted by Christ

Show car... I doubt highly that it's going to remain stock at all, so in order to make it appeal to the widest range of people, certain things could be "altered" to accomodate for the weight... also, being sponsored, it will probably use Lithium variant batteries, which will help with weight also.

That said, if you don't want to think Tesla (which is designed to be uber-fast and poop on "real" sports cars) then think Mini-E.

It makes 150kW and 220nM, weighs 3230lbs, goes 0-62 in 8.5s, has an approximate top speed of 95 MPH, and ideally could get 156 miles of range (104 average combined).

Oh - it has a fixed ratio gearbox as well.

Again, I'm talking in practical terms. An AC system of that power rating is about $10-12k... just for the motor/controller/charger. Plus, the battery pack is only 572 lbs (though 5,088 cells. Yipes!) With enough money, any EV of any capability can be built--even one with good acceleration without a transmission. For a realistic street EV based on a Neon (yes, even a "show" one), a transmission will be needed to get good acceleration and a decent top speed.

[hypermiler01]

BMW? 300ZX? G35? RX7? Lexus SC300?

And if you are going with DC, you certainly will want to be able to shift. Most DC motors are only good for 6000 rpm, and don't have all that much torque, unless you are sucking huge amps.

What Clev said.

[bikin' Ed]

Originally Posted by Frank Lee

OK, I'll work on this one a lil bit myself.



cuz when you pull the fwd eng and tranny out what are you left with? a couple shafts whose inner ends are floating in mid air. bolting motor onto live rear axle = simple in comparison



I can't identify any reason why this would be so. In fact, in the case of my Tempos, it may be worse just for the reason that it has 4 wheel independent suspension, which I'd imagine wouldn't maintain as good alignment control as a vehicle with a live axle.



then he still has the lack of anything to hook the cv shafts to; and now he also has to fix the steering straight ahead. and, find a home for struts if it doesn't already have them, or if they aren't compatible. this sounds like the most complicated way of all!



keep the fwd how specifically? using the tranny, using only the diff part of the tranny, making a homemade or adapted diff... what?

FWD is more efficient than RWD (all other things being equal) because of alignment. Front wheels will begin to pull immediately when put in gear. RWD will have to push the front end around to get it straight before it goes forward. I know that isn't a very technical reply, but I'm thinking that the info might have been on R.Q. Riley's site. If I can find it I try to post a link.

[MechEngVT]

Just FYI assuming you stick with the Neon:

Using available Neon aftermarket parts will attract certain demographics at an enthusiast gathering that will either react in a "LOLZ coolz wutz dat?" or a "yeah, but how quick is it through the cones?" Assuming you want to demonstrate electric drive's potential (pun only slightly intended) to supplant fuel burning in the here and now you should Autocross it (SCCA Solo II) as Neons do pretty well in that forum. When a Neon is driven hard through corners they will lift the inside rear tire completely off the ground to achieve the proper cornering response as three-wheel cornering dynamics differ greatly from four-wheel dynamics. I doubt that this characteristic would be complemented by RWD.

Keep the FWD and even the transmission. Figure out which gear/final drive combination suits Auto-X speeds (usually up to 35/40 mph) to maximize your motor's effectiveness without shifting. Keep your center of gravity low and weight bias slightly forward (about equal to stock) to keep the oversteer-inducing wheel lift (they really do apex a corner faster that way).