General Motors puts Rear-Wheel-Drive Models on Hold!

[Elie]

http://omidr.typepad.com/torque/2007/04/general_motors_.html

My beef is the following...

Rant mode on!

What's wrong with GM????? Why can't they produce economical vehicles, why do they have to make them 10litres or more to get 100 more horsepower out of engines?

Don't they have the technology? I guess not, why don't they take lessons from BMW, and Japanese manufacturers, heck even Hyundai instead of halting production or further development of rear wheel based cars?

Sheesh!
It's true what they said in Top gear...

"They can build the shuttle, they can build the SR-71 blackbird, stealth technology, but they can't make cars!"

Rant Mode Off

Sorry guys but this is insane!

Oh well.

At least the Camaro is saved...

[Dr Mordrid]

RWD vehicles are heavier than FWD and GM has to meet the new US C.A.F.E. standards. To do this they need lighter cars.

This and the plug in mini-cars & hybrids they showed at NYC make me think they're going whole hawg into Volt technology a lot faster than anyone thought. IMO the days of pistons driving wheels through gears & axles is nearing its end, and the GM guys I've talked to say it can't happen fast enough for them.

I've seen and touched that hardware and it looked/felt very far along. They are by no means starting from scratch.

BTW Elie: Volt tech cars can be every bit as fast as the Tesla, as in kick you in the ass from 0 RPM to ~14,000 RPM. It's a new paradigm ready for "optimizing"

[Gurm]

Piffle. You can make light, economical RWD cars. GM just DOESN'T WANT TO.

[Dr Mordrid]

Chassis for chassis FWD is lighter. Less weight in the rear due to no differential case/axle housings and rear frame can be lighter because there is less drive line to support & no need for anti-torque strengthening. Less weight amidships because of reduced/no hump & no drive shaft & mounts. This reduced weight lets you use a smaller engine/transaxle etc.

[Gurm]

Chassis for chassis FWD is lighter. Less weight in the rear due to no differential case/axle housings and rear frame can be lighter because there is less drive line to support & no need for anti-torque strengthening. Less weight amidships because of reduced/no hump & no drive shaft & mounts. This reduced weight lets you use a smaller engine/transaxle etc.

Sure sure. But you know what? I _like_ more weight in the rear. I _like_ having a car with a 55/45 weight distribution. I _don't_ like having a car that's so front-heavy, the rear end comes unglued in a heavy wind.

And who cares about engine size, when carmakers like BMW are perfectly capable of squeezing great economy out of a bigger engine? That's the best of BOTH worlds!

[The PIT]

Ach just put a sack of spuds in the back that'll solve the weight problem

[Dr Mordrid]

And who cares about engine size, when carmakers like BMW are perfectly capable of squeezing great economy out of a bigger engine? That's the best of BOTH worlds!

You're missing the point; internal combustion engines are on the way out save for recharging batteries, and then they'll be small fixed RPM gas or more likely diesels. Fixed RPM = more efficient.

Power, and loads of it, will be delivered by electric motors delivering 50-200 hp each with many cars having 1 in each driven wheel (yes; IN the wheel). No tranny. No transaxel. Electronically controlled direct drive.

Others will use a gearbox, but with only 2 forward gears. Want reverse? Reverse the polarity.

Cars driven in this manner will make that BMW (and most other cars) look like a snail because they have virtually no torque curve; max torque from ZERO RPM. If anything the engine controller will have a limiter to stop you from smoking a tire to the belts the first time you drive it.

These are in the production plan NOW. GM is talking 2010 officially, but with the new CAFE & pending CO2 standards wiping plans for their planned RWD models this may well speed up that timetable.

Paradigm shift.

[az]

As rarely as I agree with Mordrid, this time I do. I've seen cars with electric motors in the wheel hubs and little diesel engines driving generators as "the future" for a few years now, since I first heard of the concept of hybrid cars.

You can lose so much weight and mechanics (making cars cheaper, more reliable, more economic, more versatile): Starter, gearbox, clutch, differentials, axles... Of course the generator and batteries (which are only buffers anyway, so dn't need to be that big) would add weight as would the hub motors, but not as much, and we could finally see some better car designs with flat floors. Designers would be free to put the motor/generator where it would fit best into the space concept and weight balance. Almost full torque from 0 RPM throughout the whole range, truly individually controlled (and not only braked) wheels for better ESP, the potential to upgrade a car from two-wheel drive to four-wheel...

[Marshmallowman]

yeah,but performance wise the extra weight in the wheels and extra wear due that weight moving with suspension travel is probably not all its cracked up to be. but some day

Though I think near 99% of solar cars use integral engine/wheel assemblies...but they are all hand made and somewhat specialist items.

PS and a rear/mid mounted engines don't require drive shafts, and can even be made with transaxles as well.

I think it comes down to the fact GM is just not very good at making efficient cars.

[cjolley]

This change is about as likely to come from General Motors as Switzerland is to become the next conquerer of Europe.

Not that it's impossible, but would take a MAJOR cultural change at GM, which is not exactly known for it's dynamic culture.

[az]

Marshmallowman: Are there many mid-engned four-seat cars? With a small Boxer driving a generator, you could fit the engine in the middle under the floor.

[Dr Mordrid]

That major cultural change has taken place. I talk to these guys; some are neighbors and some much closer. GM's Volt show car was the tip of an iceberg.

The first vehicle from this is the 2007 Saturn Vue Green Line SUV, in showrooms now, but it's a "normal" hybrid with traditional drive still in the mix. Later models will use the Volt all-electric/plug-in system where the engine just drives a generator.

GM is not stupid. They see the hybrid sales numbers as well as the coming tough CO2 and CAFE standards. They can either adapt now or wait and get further behind. Their putting the RWD cars on hold is a sign they're preparing to adapt.

[Elie]

I really hope so Doc, let's see what they come up with in the coming future.

[Marshmallowman]

Well front wheel drives do allow for a simple bolt hybrid upgrade...fornt wheels conventional rear wheels electric.
Didn't audi come out with "hybrid" in the 80's, it was more as a boost/4wd feature than for efficiency(used for rally)

[Dr Mordrid]

Example of motor-wheel (there are MANY);

Link.... (Check out the Flash diagram)

Elie: Canadian company

IIRC these were used to drive the rear wheels of the Citroen C-Metisse shown at last years Paris auto show. I think they're also working with Volvo and Mitsubishi.

>
The motor wheel uses a brushless inverted rotor configuration that can be embedded inside a regular-size wheel. TM4 Transport's basic motor technology results in a light, compact and highly efficient unit. The power converters can be installed either inside or outside of the wheels. This system permits high-precision control and independent torque applied to each wheel while maximizing regenerative braking capacity.
>
>
Motor wheel specifications in brief

(other versions are available)
Peak Power 80 kW 107 hp (NOTE: EACH!)
Nominal Power @ 950 rpm 18.5 kW 25 hp
Peak torque 670 Nm 494 lb ft
Nominal torque @ 950 rpm 180 Nm 133 lb ft
Peak speed 1385 rpm
Max continuous speed 1235 rpm
Efficiency under continuous load @ 950 rpm 96.3 %
Maximum supply voltage 500 VDC