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Nak

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3rd party chime-in time!

Universal constant:
Tires > Drive type

In low traction situations:
AWD>FWD>RWD (front-engined cars)

In calm, dry pavement situations:
RWD>FWD>AWD (for complexity, wear, and gas mileage)

For cost savings:
FWD>RWD>AWD (cheaper car, cheaper parts)

In drag racing:
AWD>RWD>FWD (except when cost, weight, and drivetrain strength make RWD>AWD)

When looking for predictable handling mechanics, like tendency to oversteer:
RWD>AWD>FWD (like drifting or racing)

When trying to stop in low traction:
FWD=RWD=AWD

...what's this thread about, again?
I like it! I'd make two slight changes:

First:
In low traction situations:
AWD with Tru Trac>AWD>AWD with open center differential>FWD>RWD (front-engined cars)
AWD>RWD>FWD (Engine either over drive wheels or mid - engine, also near 50%-50% weight distribution)

Second:
When trying to stop in low traction:
Stopping distance:
FWD=RWD=AWD
Stability:
AWD=RWD>FWD


Good point about tires. I can't count the number of 4x4s I've pulled out of a ditch when driving off-road. All with street tires. Or AWDs in the ditch, on-road in snowy conditions with either summer tires or under-whelming all-seasons. I love driving in severe snow storms in my Blazer with chains on all four tires. It's amazing what a Detroit Tru Trac in the rear end will do to a 4x4. Audi Quatros used to have the same type of differential in both front and rear. Those cars were and are the best snow cars ever made. The only thing that stopped them was when they ran out of ground clearance. Too bad they dropped the Torsen differential (different name for the same thing as a tru trac, a helical gear differential) in favor of electronic traction control. Interestingly, you can buy a tru trac type differential for the 3 and the Y. If it weren't for the cost I'd do that and keep my Y. $2500 per axle, plus installation. Drive train warranty also voided. :oops:
 

pt19713

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Why do you keep posting information that anyone with the IQ of a rock would have already figured out pertained to ICE vehicles and not EVs? Why don't you try the experiment I suggested? Why did you claim that you tried to buy a Kona in Canada when you clearly didn't? Why do you claim to be interested in the Mach-e, when you couldn't even be bothered to go look at one at the auto show in the city you claim to live in? Why do you claim to own a Model 3 when your posting history proves you have zero experience driving one? Why do you claim to live in a city when you're completely ignorant it's localisms? The obvious answers to all of those questions are not complimentary to you at all.
Probably pointless to continue arguing with LYTMCQ.
Maybe he/she doesn't understand there's no driveshaft & differentials in an AWD EV, so the extra weight, cost and complexity of ICE AWD doesn't apply to EVs.

The Tesla AWD systems have the rear motors doing the majority of the work ~ 90% of the time. The only times the front motors kick in are in low traction conditions and when you're heavy on the accelerator and the extra power is needed. At all other times, it's RWD.
 

sockmeister

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I like it! I'd make two slight changes:

First:
In low traction situations:
AWD with Tru Trac>AWD>AWD with open center differential>FWD>RWD (front-engined cars)
AWD>RWD>FWD (Engine either over drive wheels or mid - engine, also near 50%-50% weight distribution)

Second:
When trying to stop in low traction:
Stopping distance:
FWD=RWD=AWD
Stability:
AWD=RWD>FWD


Good point about tires. I can't count the number of 4x4s I've pulled out of a ditch when driving off-road. All with street tires. Or AWDs in the ditch, on-road in snowy conditions with either summer tires or under-whelming all-seasons. I love driving in severe snow storms in my Blazer with chains on all four tires. It's amazing what a Detroit Tru Trac in the rear end will do to a 4x4. Audi Quatros used to have the same type of differential in both front and rear. Those cars were and are the best snow cars ever made. The only thing that stopped them was when they ran out of ground clearance. Too bad they dropped the Torsen differential (different name for the same thing as a tru trac, a helical gear differential) in favor of electronic traction control. Interestingly, you can buy a tru trac type differential for the 3 and the Y. If it weren't for the cost I'd do that and keep my Y. $2500 per axle, plus installation. Drive train warranty also voided. :oops:

Agreed with all of the above. Definitely true about FWD and Front engined cars having more stability in stopping in low traction.
I think most manufacturers these days have their own marketing speech versions of "tru trac", "trac-lok", various levels of limited slip differentials and so on... And jeep goes down a confusing road with Quadra-Trac, Quadra-Trac II, Quada-Drive ...o_O
 

sockmeister

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I'd disagree that FWD beats RWD in complexity. With a FWD car, you've got TWO half-shafts and their linkages to change driveline direction twice, the differential, and transmission all crammed into the engine bay area. The engine is also usually transverse. In addition, the front wheels are required to do all the steering, 90% of the braking, and all the acceleration. This constantly puts them at the limit of traction.
FWD cars have horrible tendency to get into understeer; but the one advantage of understeer is that panic braking can sometimes actually help regain a loss of steering traction. It's otherwise really bad.

By comparison, a traditional RWD is quite simple. More expensive, yes, due to the longer driveshaft and less compact design, but they are simpler, stronger parts that will outlast those of a FWD car. Nearly all trucks are either RWD or 4WD.

I'd also disagree that a FWD beats RWD in turns, for the reason stated above -- the FWD nose-heavy tendency to understeer considerably. RWD is preferred for most traditional racing. Even more so when the car is mid-engined.

I'll agree that FWD (in front engined cars) is better getting traction in slippery conditions. The weight's over the drive wheels.

Also agree that EVs have a much different dynamic we have to think about. RWD and FWD are generally gonna be the same, BUT RWD is going to have a huge advantage when:
1) Accelerating, because the car will squat and transfer weight backwards to the rear wheels, thereby giving them more traction, and
2) Steering, because you generally want to split the jobs of the two axles. Asking the steering wheels to also be the drive wheels will tend to push them past the limit of traction, especially in curves.


TL:DR: Agreed on some points! And cars are hard.
 

sockmeister

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Probably pointless to continue arguing with LYTMCQ.
Maybe he/she doesn't understand there's no driveshaft & differentials in an AWD EV, so the extra weight, cost and complexity of ICE AWD doesn't apply to EVs.
Ehh maybe, but I am just joining in and catching up. This thread is dead anyway 😆.
These have been some interesting debates.
 

engnrng

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"Most of the time" and "Generally speaking" are NOT the same as your earlier claim of "In all cases AWD beats FWD beats RWD". Keep changing your story so you can eventually say something that is correct and meaningful by accident. Your inconsistencies, contradictions, and attempts to back up your claims with non-technical articles are making me dizzy after a 45 year career in Engineering. I will go back to reading the comments from some of the knowledgeable and thoughtful posters on this forum. Or, you could just acknowledge that your attempt to go down this rabbit hole was misguided, then apologize, and go back to making positive contributions!
 

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"Most of the time" and "Generally speaking" are NOT the same as your earlier claim of "In all cases AWD beats FWD beats RWD". Keep changing your story so you can eventually say something that is correct and meaningful by accident. Your inconsistencies, contradictions, and attempts to back up your claims with non-technical articles are making me dizzy after a 45 year career in Engineering. I will go back to reading the comments from some of the knowledgeable and thoughtful posters on this forum. Or, you could just acknowledge that your attempt to go down this rabbit hole was misguided, then apologize, and go back to making positive contributions!
+100

That's his/her MO in basically every thread I've seen. Post some BS, refuse to support it or, at best, try to support it with snippet of a quote from a link that has nothing to do with the point being discussed. Rinse. Repeat.
 
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Nak

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I think most manufacturers these days have their own marketing speech versions of "tru trac", "trac-lok", various levels of limited slip differentials and so on... And jeep goes down a confusing road with Quadra-Trac, Quadra-Trac II, Quada-Drive ...o_O
You are correct. Manufacturers try and hide the type of rear differential, because most are inferior. I probably added to this by using the term "Tru Trac". In the 4x4 world I frequent, that term is used because the Tru Trac is pretty much the only aftermarket helical gear differential. Most OEM use "limited slip" or " Posi" terminology to describe clutch activated differentials, which are decidedly inferior to helical gear differentials. (Except in certain motorsports applications.) As far as I am aware, and I could be wrong, Audi and possibly Suburu are the only OEMs I'm aware of that have used helical differentials. Most--if they offer anything other than an open differential-- use clutch or "plate" differentials because of lower cost than helical differentials.

I think manufacturers do this because the vast majority of consumers remain ignorant of how important differentials are. For instance, 2WD really means 1WD (or even zero wheel drive!) with most vehicles. There are some very few FWD or RWD cars that have something other than an open front differential, meaning 99% of FWD and RWD cars are one wheel drive cars, and most AWD cars are 2WD, some are actually 1WD! (Open center and front & rear differentials.) A RWD vehicle with a helical differential is actually 2WD and superior to almost any FWD 1WD vehicle.

I mentioned zero wheel drive. An AWD, FWD or RWD vehicle--without electronic traction control--with open differentials can easily become a zero wheel drive vehicle if some of the wheels have zero traction. (In the air or on ice.) Put one of the drive wheels of FWD or RWD on glare ice or slippery mud and you aren't going anywhere with an open differential. Put a helical differential in the RWD, and it now has superior traction to the open differential FWD. The RWD will now be able to drive even with no traction on one drive wheel. The open differential FWD remains stuck. With an open differential, the wheel with the least traction is your limiting factor.

Electronic traction and stability control complicates matters some, but is still inferior to vehicles outfitted with helical differentials. The best possible option for an ICE vehicle would be 3 helical differentials combined with electronic stability and traction control. With that set up you have true AWD with all wheels capable of receiving at least 25% of engine torque under any situation.

EV AWD has the potential to be far superior to ICE AWD because front and rear motors are decidedly better than using a center differential. Tri-motor would be superior to two motors, and quad motors better yet. Even a two motor EV equipped with helical differentials would be superior to any mass produced AWD to date.

We haven't even begun to discuss true locking differentials.
 

TheLight75

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My Kona easily spins its wheels even in Eco mode. Starting off the line in Sport mode is very difficult because of how quickly the wheels spin.
 

ChasingCoral

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My Kona easily spins its wheels even in Eco mode. Starting off the line in Sport mode is very difficult because of how quickly the wheels spin.
I've heard that complaint about the Kona from multiple reviewers, including Robert Llewellyn & Kyle Connor.
 

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I've heard that complaint about the Kona from multiple reviewers, including Robert Llewellyn & Kyle Connor.
I have driven a Kona twice and both had spinning wheels and torque steer, my e-Golf also has spinning wheels if you are too eager but no torque steer.

This is why i am fine with the rear wheel drive Mach-E:D
 



 









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