4x4 efficiency vs hybridizing?

[taco]

I have ifs and manual hubs.
2 lo range ftw

[TestDrive]

Originally Posted by Daveedo

I'd agree with all of that but politely question the last bit about gears. It could be a typo in the source your got it from cause 4x4s almost always tend to have lower gears (higher numerically) than 2x4s. Usually to account for more weight and larger tires the manufacturer will want the motor to rev a little higher at the same speed than the 2x4 which doesn't have to deal with the weight/tire issues. I would guess those two numbers are backwards. Or the numbers could be for an auto vs a manual transmission (alot of times the auto's have different gearing to account for a difference in efficiency).

The source was Cars.com. I was thinking lower gears for the 4x4 so hard, what with cut & paste, that's what I thought I was posting. Looking a little closer at Car.com's specs, those gears are supposed standard equipment on each version.

Powertrain
Axle ratio 3.73
Axle ratio : 3.42 Optional
Axle ratio : 3.08 Optional
Axle ratio : 4.10 Optional
Rear-wheel drive Standard
Source: 2000 Chevrolet S-10 4x2 Standard Equipment and Specs

Powertrain
Automatic locking hubs Standard
Axle ratio 3.42
Axle ratio : 3.73 Optional
Part-time four-wheel drive Standard
Four-wheel drive Standard
Electronic transfer case Standard
Source: 2000 Chevrolet S-10 4x4 Standard Equipment and Specs

Wouldn't be surprised if you couldn't put 3.08s into the 4x4, but that would just be another expense (and might not work so well depending final curb weight and desired hauling capacity.)

[Daveedo]

Friend of mine had an 85 3/4ton chevy 4x4. It came with 3.43s iirc. It could barely get out of its own way if you were towing and he towed a HUGE boat. Well he wanted to upgrade his weeny 10bolt/semifloating 14bolt axles to one ton stuff so I helped him find a dana 60 front and a full floating 14 bolt rear and swap them in. The new axles had 4.10 gears (most one ton stuff does). He could haul stuff much easier but his freeway mileage plummeted.

[wwest40]

Has anyone considered how much design effort it would take to avoid "driveline windup" and/or tire scubbing, synchronize, almost perfectly synchronize, two separate drive systems, one front and one rear...?? The RX400h does that by using two separate synchronous AC drive motor systems.

[Clev]

I would recommend direct-driving the front with the electric motor and driving the rear through the transmission with the gas motor. You can drive the front through the transfer case and transmission, but there's a fair amount more drag, and I'm not sure that the transfer case is designed for continuous use over thousands of miles at a stretch.

[Deezler]

Guys,

I believe the Toyota highlander hybrid is exactly as described. The rear wheels are powered by electric drive only, assisting the front gas drivetrain only during acceleration and slippery conditions. It gets around 30 mpg city, I think.

[ConnClark]

DIY four wheel drive and four wheel steering.

Red Green Show Video

[The Atomic Ass]

Originally Posted by TestDrive

Not to mention the shorter gears.
2000 S10 4x2 axle ratio: 3.73
2000 S10 4x4 axle ratio: 3.42

You either have that backwards or the 4x4 has taller gears.

And apparently someone already pointed it out to you.

[The Atomic Ass]

Originally Posted by Clev

I would recommend direct-driving the front with the electric motor and driving the rear through the transmission with the gas motor. You can drive the front through the transfer case and transmission, but there's a fair amount more drag, and I'm not sure that the transfer case is designed for continuous use over thousands of miles at a stretch.

That wouldn't make any sense. Converting to a front-only setup would be much more efficient, would allow the vehicle to be lowered to a more 2wd-like stance, and eliminate a lot of dead weight in the process. Also, you can't just remove the transfer case from a 4wd, you would need to get ahold of a 2wd driveshaft, as the 4wd shaft is shorter.

[The Atomic Ass]

Originally Posted by wwest40

Has anyone considered how much design effort it would take to avoid "driveline windup" and/or tire scubbing, synchronize, almost perfectly synchronize, two separate drive systems, one front and one rear...?? The RX400h does that by using two separate synchronous AC drive motor systems.

Wouldn't necessarily be required. The front end would be trying to accelerate, the rear end would simply help it. One or the other is going to be shut off at speed anyway.