Why not front wheel drive?

Why not front wheel drive?

It is my understanding that the default set up is rear wheel drive and all wheel drive in spring 08. But why not front wheel drive? I live in New York city and I have seen many cars (specially taxy cabs) stuck or in small accidents because they slip a lot in the smallest hill with just light snow on the roads. So if I want this car with front wheel drive, I am forced to wait/buy for the all wheel drive one? Feels off to me that since Tesla is going for the safest cars, we don't have an option for front wheel drive.

Tropopause | 24. elokuu 2017

Front wheel drive was designed to simplify ICE vehicle manufacturing and increase cabin space (No driveshaft, transversely mounted engine/transmission.) FWD traction and performance is inferior to RWD but in an ICE FWD prevents fish-tailing on slippery surfaces. Tesla's traction control is precise and instantaneous (unlike ICE) therefore preventing slippery surface issues while maintaining the advantages of RWD. It's the best of both worlds.

JMobs | 24. elokuu 2017

This isn't a traditional car. Many people have the false sense that front wheel drive is better cart blanche. What really matters is where is the weight, and where are the drive wheels. Drive wheels+weight over them+good snow tires=safer car.

In a normal car, the engine is in the front. Therefore, having a front wheel drive would be great because the weight over those tires would provide better traction. In a Tesla, the drive unit is connected to the drive wheels. Couple that with a very low center of gravity of he battery, it wouldn't matter if the drive wheels are in the front or would result in the same outcome.

PaceyWhitter | 24. elokuu 2017

Tesla prioritizes safety but also sporty driving experience so they chose rear wheel drive. For safety you could wait for the AWD or just buy a good set of snow tires.

Rocky_H | 24. elokuu 2017

I see people only emphasizing about the weight being over the wheels as the only factor and therefore dismissing it in the Tesla case are missing something. Having the steering wheels being the driven ones is also a significant advantage factor in slick conditions. I do like my front wheel drive Civic better than my rear wheel drive Model S in slick conditions, but the Tesla is pretty good most of the time. Really, though, if you have to deal with snow quite a bit, you should probably go for snow tires, though. They will make worlds more difference than FWD or RWD. Or, yes, wait for AWD. But yes, for any other time outside of snowy traction issues, RWD is more important for driving performance.

RedShift | 24. elokuu 2017

Let me try to answer this.

FWD was invented as a way of making the ICE setup a bit more efficient, and bit less complex to save money in the manufacturing process as well. Interior space improved due to more compact packaging and a lack of a rear drive shaft. So far so good. However, heavier FWD setups (>3500 lbs, roughly) tend to suffer from bad driving characteristics such as understeer, and are not that great for sporty driving. Their steering tends to be less lively as well (though this is not a rule) due to the fact that wheels that turn are also shouldering the burden of being driven by the engine. Static weight distribution (curb weight of the vehicle divided among the axles when standing still) is not that great. Typicallly something close to 60% front, and 40% rear. This is felt during cornering in the form of understeer.

Now, RWD: wheels that turn are not being driven in this setup. There is less weight on the wheels that turn. Ergo : better steering feedback, better turn-in response. Static weight distribution improves to be nearly 50%-50% in carefully laid out setups like BMWs. Or the Alfa Romeo Giulia. Benefits of this setup are felt during not just sporty driving but even regular driving. Feels more natural and planted. So far so good. However, the drawback is that you paid for all of this in a regular ICE car with more cramped interiors due to the torque tube running along the length of the vehicle to drive the rear wheels. Rear wheels slipping over ice is also a common phenomenon in the older days without stability programs that are ubiquitous nowadays, almost eliminating that problem. There was one subtle issue that RWD suffered that was not so bad in FWD setups - when a driver started to lose control, say during a fast turn, it was easier to control a FWD car and correct the slip as rear wheels breaking traction was thought to be (ahem!) more difficult to control. This is true for most regulr drivers. With some experience, RWD can be as easy to control, but hey, we are talking about regular drivers.

Now to Tesla. With the Model S, there was a need to compete directly with the luxury peers, most of them RWD, and a few AWD. So, they chose RWD, for sportier setup that was expected in this price class. However, due to being electric, there was no need for the engine to be in the front (motor is more compact) so they placed it in between the rear wheels. No torque tube. So, packaging became very efficient. More room inside. Also, this became somewhat analogous to the FWD ICE setup, only in the rear location.

Going from that basic architecture, they decided to extend that to the Model 3 as well. I'd there a technical reason not to locate the motor in between the front wheels? No, probably not. However, Model 3 was benchmarked, reportedly against the likes of the BMW 3 series, the reigning champ of compact sports sedans. So, there was a need to make this RWD as well.

So, now you know more than you probably wanted to know about FWD and RWD cars. :-)

evchathaway | 24. elokuu 2017

Just the perfect amount of knowledge, I would say. I am delighted that the Model 3 is RWD. Having grown up with traditional RWD in New England, I believe it is fine except for the worst conditions. It also offers feel and control that FWD simply lacks. IMO that also applies to many current "AWD" vehicles, which are really FWD with occasional engagement of the rear wheels (looking at you CRV, RAV-4, Rogue, etc.) That may help when accelerating in slippery conditions but otherwise contributes more to marketability than to roadability.

carlk | 24. elokuu 2017

The biggest advantage of front wheel drive is the space and weight saving because it does not need a drive shaft. That advantage disappeared with the electric car. The biggest disadvantage of FWD car is its handling can not match that of RWD cars because power and steering need to be handled by the same set of front wheels at the same time. That's why you see FWD usually used in lower end compact cars while RWD usually are used in higher end larger or high performance cars.

As for slipping modern traction control has pretty much taken care of it. The infamous "BMW twitch" which has bothered many people is no longer there (btw even with that BMW has never considered going FWD). For Tesla the traction control is even better since power regulation and feedback for EV is much faster than what ICE cars could achieve. Like others said the RWD model S, which was the only model Tesla has made in the beginning, was proven to be a great performer on snowy roads.

ReD eXiLe ms us | 24. elokuu 2017

This question has been asked many times. Even the smallest, tiniest, wimpiest, most ineffective of ICE motors is several hundred pounds heavier than the electric motor used in a Tesla, once decked out with all its accessories. Because of this, you get improved traction by mounting the motor and transmission over the front axle of a FWD ICE powered vehicle. Because an electric motor is so much lighter than the ICE, there is no improvement whatsoever by using that configuration instead of rear wheel drive, plus it can be argued that if anything, handling and control are compromised as a result.

Try asking the question the other way around... Why should an electric vehicle be front wheel drive?

- To improve handling? Nope.
- To improve range? Nope.
- To create more space in the passenger cabin? Nope.
- To leverage an existing econobox front wheel drive platform for a low range, low volume, electric vehicle conversion to be offered/leased/sold as compliance cars? Sure.
- To perpetuate the notion that only those who are willing to relegate themselves to ugly commuter torture chamber city bound weird mobiles drive electric? Yup.
- To continue the notion of compromise as a theme by charging a $20,000 premium over and above the base price of the ICE version to get a vehicle with only 1/4 to 1/3 the overall range? Absolutely.

Since Tesla does not have an ICE business to protect, they have no motivation for building front wheel drive electric vehicles.

Shock | 24. elokuu 2017

It's rare the first response to a thread crushes it, but hats off to @Tropopause (plus other answers later on).

I've only ever owned FWD and AWD but the fish-tailing of yesteryear has been significantly decreased by legal mandate of stability control in all modern cars. I first tested this on a V8 charger a few years back in the snow. I was downright shocked at how well it worked driving that around in the snow. To be honest I'd still rather have FWD in the snow as I am thoroughly used to under steer and how to deal with it, but I think I could make do with modern RWD.

johnmann | 24. elokuu 2017

As others have stated here, RWD is superior to FWD in almost all circumstances. In addition to what has been mentioned you get better traction while accelerating since weight is automatically transferred to the rear wheels. More importantly is improved and more intuitive control when skidding in a turn or fishtailing. It is natural to let off the accelerator when fishtailing and to turn into the direction of the skid. Both of these reactions are correct for RWD, but the opposite of the correct maneuver for a FWD vehicle.

hairito24 | 24. elokuu 2017

Hey all, thanks for all the replies. I am no car expert at all. I am the type of person that just puts in the key and goes. that said, I done my share of driving and I grew up on a street which is somewhat incline. But as many of you have pointed out, this car is different. I didn't think of how the weight of the car is different for conventional ones. There is still the push vs pull theory in slippery conditions to consider, but good snow tires should fix that. Thanks.

Atlanta09 | 24. elokuu 2017


I'd encourage you to do some reading on the physics of FWD, RWD outside of this thread as it's a little misleadingly pro-tesla.

you should immediately be skeptical when you see stuff like this at the start:

"FWD traction and performance is inferior to RWD but in an ICE FWD prevents fish-tailing on slippery surfaces. Tesla's traction control is precise and instantaneous (unlike ICE) therefore preventing slippery surface issues while maintaining the advantages of RWD. It's the best of both worlds."

very few things are the "best of both worlds" and this is not one of them. Fact is that FWD is easier to correct in slips because it feels more natural to untrained drivers who aren't thinking about which axle the power is being distributed to, their weight distribution etc.

Also, "Even the smallest, tiniest, wimpiest, most ineffective of ICE motors is several hundred pounds heavier than the electric motor used in a Tesla, once decked out with all its accessories."

Arguably true depending on what you define as "accessories", but guess what a Lotus Elise doesn't have- a thousand pound battery pack.

All that being said, the 47/53 and 48/52 weight distribution in model 3 variations certainly makes the FWD, RWD decision matter alot less in Teslas vs. ICE but I'd argue FWD is still easier for most inexperienced drivers to control in panic / sliding situations.

Imagine you need to navigate a bowling ball around some obstacles and you can either push or pull the ball. You'll probably be more successful pulling it. The power is better applied to a point in space that is closer in direction to where you are moving.

carlk | 24. elokuu 2017

After attacking other people's theories moving a bowling ball is the best argument one could come out with. That is pretty hilarious.

Atlanta09 | 24. elokuu 2017

@Carlk not a bowling fan eh? pick any object you like. its easier to control an object when the force is applied nearer the direction in which the momentum is carrying the object. And its certainly easier to intuit the outcome of the force you are applying when the force is being applied closer to where you are sitting and your line of sight is focused.

Plenty of complicating factors if you wish to introduce them, but not a complicated concept in its most basic sense. | 24. elokuu 2017

Another issue with FWD is torque steer. While not an issue with low torque motors/engines, as the vehicle has more torque abilities (i.e. Tesla and high performance ICE engines) and you accelerate, the steering will want to turn to the left or right. This can be downright scary in an emergency situation. It's likely the major reason higher performance vehicles rarely use FWD. There are some mechanical tricks to reduce this issue, but I think only the Citron SM front wheel drive car has implemented it.

carlk | 24. elokuu 2017


I've owned arguably the best handling FWD car, Honda Prelude Type SH, and the best handling RWD car, Porsche Cayman S. I can tell you FWD is absolutely no match for RWD under pretty much any situation, even on somewhat wet surfaces with traction control turned off if you know how to drive it. Tell me what is the best handling FWD and RWD cars you have driven that prompted you to make such comments?

Using those two car companies that have made some of the sportiest cars in their respective market as examples. Porsche has NEVER made a FWD car. Honda has always been making FWD cars but when it comes to all out sports cars NSX and S2000 they want nothing but RWD for them. You just can't make FWD car to handle that way. If the Model 3 handles as good as Motor Trend said you got to be kidding to think that could be achieved with FWD.

ReD eXiLe ms us | 24. elokuu 2017

Atlanta09: You missed the point of my post. Front wheel drive for ICE vehicles was developed to solve specific problems that do not exist with rear wheel drive electric vehicles. Only if you intend to low power, non-performance, transportation appliance, commuter tin-can, consumer vehicles does front wheel drive 'work' as an apparent 'solution' for electric vehicles -- precisely what traditional automobile manufacturers have done almost universally.

[ ASIDE: I have, for several years, looked forward to Honda proving that rationale wrong for front wheel drive electric cars, but they have staunchly REFUSED for some reason. Maybe it will be Renault instead? They have at least attempted to build a more rally inspired version of the fully electric ZOE... YouTube -- 87zVVIgGXfw ]

The Lotus Elise in its mid-engine configuration carried the bulk of its weight over the rear axle, just as did the Tesla Roadster, and both were rear wheel drive. To my recollection, there was never a front wheel drive or all wheel drive version of that car.

Your argument may or may not work to satisfy 'trained' drivers. But I am a longtime 'car guy' and you know what I have noticed? Despite the regularity by which automobile journalists speak of the inherent joy and unmatched control-ability and predictable handling of vehicles that have the vaunted '50/50 weight distribution ratio'...? Time and again over the years the vehicles that fared best in objective track test results for road-holding via slalom and skidpad during head-to-head tests were those with a weight distribution ratio closer to either 60/40 or 40/60.

Ultimately, your post is about the differences between front wheel drive and rear wheel drive. In this context, it is like arguing the difference between a Big Wheel and a Green Machine around forty-five years ago -- which is better? Some kids claimed it was definitely the Green Machine because of all the unique tricks and power slides you could perform in it. Then they shut up when I pointed out, then demonstrated, that I could do all the exact same maneuvers on a Big Wheel.

So, please understand, when it comes to vehicles, I am largely drivetrain agnostic. I don't care about anything but results. And the actual, factual, truthful RESULT is that compliance cars from traditional automobile manufacturers with a bunch of crap under the hood that are set up for front wheel drive have been consistently inferior at DEMONSTRATING the inherent SUPERIORITY of electric drive over ICE, as compared to the rear wheel drive and dual motor all wheel drive fully electric vehicles from Tesla.

That is not fanboyism. That is not bias. That is FACT.


ReD eXiLe ms us | 24. elokuu 2017

Atlanta09 wrote, "its easier to control an object when the force is applied nearer the direction in which the momentum is carrying the object."

True enough, horses tend to be attached to carts and carriages at the front, so that they pull the vehicle behind them. But then, horses don't have opposable thumbs with open palms, or particularly wide backs either. It is a lot easier to PUSH a Buick that has run out of gas than it is to PULL it by manpower alone. Elephants are a lot bigger than horses, so it typically makes more sense to put the whole carriage/sedan/riding canopy on top, instead of using them to pull a cart. As a kid, I would carry some things to the barn, push some things to the barn, and drag some other things to the barn, from the house. Dependent upon the method of conveyance, one item might be easier to transport via one means than another. That did not invalidate the need for options, though.

sosmerc | 24. elokuu 2017

Gotta be some old SAAB rally drivers rolling over in their graves by some of the comments here ):........and I should mention ice racers too. I think there are a few instances where FWD in the hands of a skilled driver MAY be superior.
But again, if you are already going way too fast in a corner on a slippery surface there's not much to be done no matter what vehicle.
Personally, I like the way FWD and AWD works when driving in stiff winds...especially side winds. The vehicle tracks better for sure. (nothing like watch a RWD Ford Transit van going down the freeway in windy conditions ! Give em plenty of room folks!

ReD eXiLe ms us | 24. elokuu 2017

TeslaTap & carlk: +1! I find it interesting that so many claim to be unnerved by torque steer, but are perfectly fine with the rear end of a car stepping out on them -- I see it as the exact same adjustment, done for the same reason as a driver -- keeping the car straight on launch... I also find it encouraging that for companies that are similar in origins, and different in their general philosophy, that Honda and Porsche still agree that rear wheel drive is the way to go (now with hybrid systems too) when it comes to motorsports.

Rocky_H | 24. elokuu 2017

@Atlanta09 +1

Tropopause | 24. elokuu 2017


How about the Falcon 9, or any spacecraft? Push or pull?

andy.connor.e | 24. elokuu 2017

Snow tires are cheaper than AWD. Just saying....

Model_D | 24. elokuu 2017

I currently drive an EV with front wheel drive and rear weight bias. It is programmed to severely limit torque at slow speeds. In spite of this it is still spins the tires if you try to accelerate too quickly as you cross the painted lines on a crosswalk. And traction control kicks in if you try to accelerate in a turn at anything below 40 mph. It was a totally different experience driving a loaner RWD Model S. I have driven my FWD EV in rain, never in snow. I lived in the NE with a 2wd pickup that didn't have traction control three winters, two with snow tires. I would take my pickup on all season tires without traction control over my FWD EV in the snow.

johnse | 24. elokuu 2017

@Tropopause "How about the Falcon 9, or any spacecraft? Push or pull?"

Light sails!! They pull.

Really out there it doesn't matter. It's just hard to deal with the flame if the rocket is in front of you :)

johnse | 24. elokuu 2017

Atlanta09 wrote, "its easier to control an object when the force is applied nearer the direction in which the momentum is carrying the object."

Pulling the bowling ball, then pulling it at 90 degrees to the motion vector will quickly have the ball swing around, pulling towards the outside of the turn.

The extreme version of this is the Semi truck/trailer combination. You have power and steering at the front of a heavy trailer. Try to apply too much turning force in bad conditions and you get a jack-knifed truck.

JMobs | 25. elokuu 2017

To solve all of this hubbub-OP, buy the AWD version. I live in California but will frequent CO in the winter and I won't own anything other than an AWD.

dave.m.mcdonough | 25. elokuu 2017

The only reason econobox FWD cars do so well in the snow is because they are also horribly front-heavy. Weight transfer is still a thing in the snow, those taxi cabs are better off being RWD trying to go uphill. What you are seeing are people using worn out tires that are unsafe at any speed for the conditions. It's mostly just about the tires.
I have personal experience driving a little RWD BMW and a FWD Transit connect in the snow. The BMW would race circles around the Transit in a blizzard, and going uphill is no comparison. FWD is just worse all around.

A lot of excellent responses all around, I guess I really don't have much to add other than THANK GOD Tesla is not afraid to break the mold and make it RWD. GM and others making their electrics FWD is really just being lazy, there is literally no advantage it it, under ANY conditions.

carlk | 25. elokuu 2017

Absolutely. GM's reason is clearly that's the only thing they got in their parts bin.

Rocky_H | 25. elokuu 2017

@dave.m.mcdonough, Quote: "The only reason econobox FWD cars do so well in the snow is because they are also horribly front-heavy. [...] there is literally no advantage it it, under ANY conditions. "

No, no, no. That is false. That is not the only reason, and it does have an advantage in one condition. Having the wheels that are steering be the driven ones has a noticeable, practical, effective advantage in very slick icy conditions. Though your wording was incorrect, here is where it does line up with your thinking. That is a very rare situation, and the vast majority of the time, rear wheel drive is more advantageous.

RedShift | 25. elokuu 2017


Putting more weight on the rear wheels negates that advantage. I know a few cars that already have that weight placed over the rear wheels. Teslas. :-)

Plus, modern stability programs help a lot too, unlike the older rear drive cars without those stability programs.

Rocky_H | 25. elokuu 2017

@RedShift, No, I have a Tesla, and it doesn't negate that and doesn't accomplish that function. Needing to spin the front wheels some while they are turned can pull you in the right direction, while if they are unpowered, they don't get you anywhere and just slide straight forward or go nowhere while the back end of the car slides sideways.

Tropopause | 25. elokuu 2017

Let's just get tank treads and be done with this. ;)

Tropopause | 25. elokuu 2017

I may have come up with a new use for BEV's. The Tesla Tank.

RedShift | 25. elokuu 2017


Are you talking about when you are stuck? Coz regular icy roads or snowy ones do not require that front wheels be driven. People used to drive around old Caprices or Crown Vics with sand bags in their trunk in winter and they generally did okay.

Rocky_H | 28. elokuu 2017

@RedShift, No, not when stuck. Mainly when trying to start moving, and it is very slick under all of the wheels. Sure, people did "okay" with lots of things, but some things do behave a little bit better. People can do "okay" eating spaghetti with just a spoon, but other ways are better. My front wheel drive Civic certainly handles it better than my rear wheel drive Tesla. That's just the way it is and always has been. But again, that's a pretty small percent of the year's driving, so it's not the main factor.

Rocky_H | 28. elokuu 2017

@RedShift, Ah, forgot one more aspect. When I was describing when this happens, I talked about when trying to start moving. The other main factor is obviously when turning. In a lot of snow, the front wheels of the Tesla will sometimes plow straight ahead and not make the turning motion since they are not able to pull the front of the car into the direction to begin the turn. Again, rare situations, but I'm surprised I actually have to explain this to people.

Rocky_H | 28. elokuu 2017

I'm kind of getting this impression that too many people on this forum have only driven high end cars, which are generally rear wheel drive. They don't seem to have a good understanding of the advantages of front wheel drive, which is what I have driven all of my life until the Tesla.

sosmerc | 28. elokuu 2017

Different strokes for different folks I guess. But I agree Rocky, under most slippery conditions my preference would be AWD first, then FWD second. (same applies for windy conditions).

RedShift | 28. elokuu 2017

I've driven both. Got stuck in a blizzard in my first car, a 1988 Camry which was FWD. :-)

I'm not sure what your particular driving scenario was, but good winter tires help the grip too, in driving. RWD gets a bit getting used to if you are coming from a FWD car. In general you need to be more cautious in your Tesla. If only because the repairs are more expensive and take longer than a Civic. :-)

Model_D | 28. elokuu 2017

Ask anyone who drove the original VW beetle in the snow how it was. They will tell you it was awesome in the snow. That was a RWD vehicle with a rear weight bias.

Rutrow | 28. elokuu 2017

I'm not going to try to make a physics argument about whether FWD or RWD is better in one circumstance or another, but if we're mainly talking about low speed maneuvering to keep from getting stuck, with the close to 50/50 weight distribution of Teslas, in "D" you've got rear wheel drive, in "R" you have front wheel drive! Try them both until one or the other gets you out of the tricky situation.

Now... If someone wants to advocate for FWD at cruising speeds, I'd highly recommend LOTS of practice with driving via the back-up camera, but the Tesla is a vehicle well suited for you. It's my guess that their electric motors are just as efficient and fast whether in forward "gear" or reverse. 130 mph in reverse isn't out of the question. Here, fork lift drivers probably have a skill advantage, being familiar with rear wheel steering characteristics.

RedShift | 28. elokuu 2017


One more thing : if the loss of traction in your Tesla was because there was application of power during the turn, then it is explained by the dynamic weight transfer to the rear, causing front wheels to momentarily have less weight over them, thus losing some traction.
By lifting off the throttle you might be able to regain some grip.

Carl Thompson | 28. elokuu 2017

"Ask anyone who drove the original VW beetle in the snow how it was. They will tell you it was awesome in the snow. That was a RWD vehicle with a rear weight bias."

Hah, yeah, my first 2 cars were beat up old VWs back when I was poor. Back then I lived in Maryland which get's its share of snow and ice and I never got stuck or lost control in those cars while driving in winter conditions. Girls loved them too!


dave.m.mcdonough | 28. elokuu 2017

For the low-speed conditions you're referring to, there's only 2 parts to the equation:
1: The tires
2: Seriously you better not still be using summer performance tires.

Rocky_H | 29. elokuu 2017

Quote: "@rocky

One more thing : if the loss of traction in your Tesla was because there was application of power during the turn, then it is explained by the dynamic weight transfer to the rear, causing front wheels to momentarily have less weight over them, thus losing some traction.
By lifting off the throttle you might be able to regain some grip."

You have GOT to be kidding me. There is NO "dynamic weight transfer" of a 5,000 pound car going under 20 mph.

Heh, yeah, you're totally right on. :)
No, I would never use summer tires. They are all season, but I don't do the switch to winter tires. Being in the desert climate where we are, we don't get much snow. It's like a day or two, and then it gets cleared off, and then there no more for about another 2 or 3 weeks. So it's not really worth it to me for the very little usefulness it would have. Besides, we do sometimes just use the Civic for that day or two, which is both cheaper (in case someone slides into it) and front wheel drive.

RedShift | 29. elokuu 2017


"There is NO dynamic xfer in a 5000 lbs vehicle under 20 mph"

Here is a simple equation (there are many other factors, but these affect the dynamic weight transfer most)

Longitudinal load xfer = acceleration x weight x Center of gravity/wheel base

20 x 5000 x (18/116.5) = 15450.74 lbs.

This is for 0-20.

For 10-20mph acceleration it's still 7725 lbs of load xfer.

So, no - it's not nothing.

Rocky_H | 29. elokuu 2017

@RedShift, You should really take a look at how that load transfer equation works. First off, in business, engineering, etc. it's good to do a sanity check to see if your number is anywhere close to the ballpark to see if you have the problem set up correctly.

When you ran that equation for accelerating from 0 to 20 mph, and it showed a weight shift of over 15,000 pounds for a 5,000 pound car, that should have been a clue that it couldn't possibly be right.

Now there are multiple math errors here:
I did not say the speed change was from 0 mph to 20 mph. I said the speed was under 20 mph. The change in speed would be very little in these cases--maybe 2-3 mph.
The other math error is that you just put in 20 as the acceleration number. A change in speed from 0 to 20 mph still doesn't tell you the acceleration rate. Did it take one second to make that speed change, or one week? Those are very different rates of acceleration.

Anyway, I'm not going to correct all of the calculations for you, but suffice to say it's obvious to anyone who drives that when you change your speed a couple of miles an hour, there is not a noticeable weight transfer. That only becomes noticeable and has any practical measurable effect in stronger accelerations. And I assure you, I am not trying to launch while turning a corner when it is icy.

DTsea | 29. elokuu 2017

lets do the math correctly. 7725 lb of load transfer would be 5000/2 + 7725 on the back, and 5000/2 - 7725 on the back. Car would tip over. Obviously nonsensical result.

Accelerating 10 to 20 mph on ice in 5 seconds is 3 f/s^2 or 1 m/sec^2 acceleration. That is 0.1g. In the equation above Redshift used 20g (the acceleration parameter is supposed to be in g terms- the weight is in pounds- force units- not mass units). Oops!

So correct weight transfer factor is more on the order of .1*5000*(18/116.5)= 77 lb.

Which is negligible, relative to the 5000 lb weight of the car.

Thank you kindly.

RedShift | 29. elokuu 2017

Ok, I made a mistake in taking 0-20 mph directly. End result is that the weight transfer, while much less than 15000 lbs (yes, I knew that was wrong on the face of it, but I didn't take the time to correct it. Why? :-) had a lunch meeting to rush to, and a morbid desire to see how much flaming I will get for posting the above :-)

So, if we take acceleration in the 0.1 g is still equates to the weight of a child being transferred to the rear axle. There are other effects, that might reduce that number or increase depending on anti dive geometry and others, but this is still not zero. It might be negligible in relation to 2000 lbs (no 5000 lbs) or so that was riding on the front axle. But it isn't zero.

Dtsea, thanks for the correction.