4wd and MR question

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Ceolix

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Ceolix
guys i really tried to think on this straightly, but i got no conclusion.
There is something that bothers me when it comes to 4wd and MR.
How come 4WD accelerate faster than MR?

4WD:

- no grip on rear wheels, just WHP
- slowest weight distribution

MR:

- grip on rear wheels (because of the engine)
- faster weight distribution


Somehow 4wd still accelerate faster?
if 4wd has no grip at rear wheels how do they accelerate faster
and how they don't suffer from oversteer anyway?

if anyone could explain me this, i would be grateful.
thanks in advance
 
4WD cars have plenty of grip at the rear, just the same as FR. In GT5 the 4WD cars have no problem accelerating due to the game not accounting for the car having trouble working out where to send the power, like it would in real life. And 4WD don't oversteer because, well, do FR cars? A 4WD is essentially an FR or, in some rare cases an MR, with the added grip from the front wheels being driven; if anything, that causes understeer.
 
Your concerns about 4WD really are unfounded. I don't know why you think 4WD has no rear grip. A 4WD car isn't going to have no grip just because there isn't an engine sitting on the rear tires. If it did, then front engine/rear drive cars would suffer.

4WD accelerates faster because you have 4 tires with power from the engine helping to move the car. This means more grip overall and you can apply more power for acceleration. If you do this in a FR or MR car you will spin up the rear tires and go nowhere.

Most 4WD cars also have the ability to split the power between the front and rear wheels. So you could have 40% power front and 60% power at the rear which will help control wheelspin and help launch the car.

Oversteer is generally caused by the car being setup too loose and the rear end wants to step out and spin the car. 4WD suffers from this less by virtue of the power splitter keeping power more evenly distributed. The front wheels having power helps pull the car into a straight line and the rear wheels not having full power will help keep the rear end from stepping out.
 
Ceolix
if 4wd has no grip at rear wheels how do they accelerate faster
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As already said, it's not like there's no grip at all. If that would be the case than MR/RR cars wouldn't steer either, right?

Ceolix
and how they don't suffer from oversteer anyway?
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I hope you're not using racing tires on a road car, but you'll notice that depends from car to car,... and tuning. You can tune how much power goes to the front/rear tires on some 4WD cars.

I don't have too much experience with 4WD cars - apart from all the Subaru IMPREZAs and all Mitsubishi Lancer Evolutions - but indeed, most tend to understeer, rather than oversteer.
Try some of the Subaru's, mainly the (faster) V and VI versions. They're really good cars but besides that they tend to oversteer rather than to understeer if you use stock tires. If you use some Lancer Evolutions you can really feel the grip shift between rear and front at times, it's not really as pleasent or smooth. In general they tend to understeer more, from my experience at least. :)
 
So, let me see if i got it:
the most grip the car has on the front wheels
it will be easier for it to transfer this same grip to the rear wheels?
 
Ceolix
So, let me see if i got it:
the most grip the car has on the front wheels
it will be easier for it to transfer this same grip to the rear wheels?
Click to expand...

Reminder, the AUP stresses you should use proper grammar including sentences and capitals at all times.. https://www.gtplanet.net/aup/

4wd's in GT have a fixed split of torque front and rear. The max is 50F/50R, the min 10F/90R. In high powered FR's, MR's and FWD's, you often get a lot of wheelspin at the drive wheels when launching because there is more power than grip. 4WD splits that power between front and rear, allowing 4 tires worth of grip for launch, as opposed to 2 wheels for the other drivetrains. More grip = more energy converted to motion as opposed to heat in the tires through wheelspin = faster launch.

Many 4wd's also come with torquey motors, which also helps with launch and low rpm grunt.
 
Johnnypenso
Reminder, the AUP stresses you should use proper grammar including sentences and capitals at all times.. https://www.gtplanet.net/aup/

4wd's in GT have a fixed split of torque front and rear. The max is 50F/50R, the min 10F/90R. In high powered FR's, MR's and FWD's, you often get a lot of wheelspin at the drive wheels when launching because there is more power than grip. 4WD splits that power between front and rear, allowing 4 tires worth of grip for launch, as opposed to 2 wheels for the other drivetrains. More grip = more energy converted to motion as opposed to heat in the tires through wheelspin = faster launch.

Many 4wd's also come with torquey motors, which also helps with launch and low rpm grunt.
Click to expand...

I just can't understand how 4wd can have grip without
a reinforcement like the engine, if it only has WHP on rear
how does that mean it has traction?

i still dont get it:guilty:
 
The frame/chassis/body + all the running gear of the car + downforce + gravity = more than enough weight to keep all 4 tires touching the ground.

You don't need 500 lbs of engine sitting on the tires to give traction. How you think front engine/rear drive cars work? We can explain all day how grip works but it sounds like you are asking why it works that way and that is questioning why physics work the way they do.

Do you understand how 4WD works?
 
Venymous
The frame/chassis/body + all the running gear of the car + downforce + gravity = more than enough weight to keep all 4 tires touching the ground.

You don't need 500 lbs of engine sitting on the tires to give traction. How you think front engine/rear drive cars work? We can explain all day how grip works but it sounds like you are asking why it works that way and that is questioning why physics work the way they do.

Do you understand how 4WD works?
Click to expand...

so what about some cars heavier than 4wd?
they don't get rear grip because of their weight
they have rear traction only, that means only that rear tires have more WHP
than front tires, that's why they slide
so why wouldn't 4wd slide?
it has the same WHP has front tires, so how can it have grip
without something putting pressure on the rear tires?
they should slide and have slow acceleration because rear tires
would give first signals of tire wear and the rear couldn't stabilize so good

(sorry for my bad english by the way)
 
If a 4WD car has no grip or has less grip on the rear wheels, then maybe you just felt that because the torque distribution is set to 90-10, which means most torque is distributed to the front wheels rather than the rear wheels. Obviously, it will affect the handling of the car.
 
GTV0819
If a 4WD car has no grip or has less grip on the rear wheels, then maybe you just felt that because the torque distribution is set to 90-10, which means most torque is distributed to the front wheels rather than the rear wheels. Obviously, it will affect the handling of the car.
Click to expand...

There is no such thing as 90F/10R in GT, the max front is 50 as in 50F/50R. From there it goes to 10F/90R in increments of 5.
 
GTV0819
If a 4WD car has no grip or has less grip on the rear wheels, then maybe you just felt that because the torque distribution is set to 90-10, which means most torque is distributed to the front wheels rather than the rear wheels. Obviously, it will affect the handling of the car.
Click to expand...

The torque distributor goes from 50/50 to 10/90 [F/R] so you'll never be able to sent more torque to the front wheels than to the rear wheels.

And for the 4WD and grip issue, you also have weight transfer when you accelerate, so you'll get more grip on your rear wheels.

Also 4WD cars usually have a static weight distribution of 50/50 to 40/60, so still enough weight on the rear wheels to give traction.

In general 4WD cars accelerate faster because all the wheels can deliver torque to the road, where RWD cars only have the rear wheels for that. This means that when you put the same tires on the 4WD and the RWD car and both have more than enough power, the amount of torque the tires can transfer to the road will be exceeded when maximally accelerating. The RWD car will be limited by that, while the 4WD then also has its front tires which can transfer torque to the road. This, most likely, will be less than the rear tires but still its more than nothing what the RWD car has ;)
 
AudiLord
The torque distributor goes from 50/50 to 10/90 [F/R] so you'll never be able to sent more torque to the front wheels than to the rear wheels.

And for the 4WD and grip issue, you also have weight transfer when you accelerate, so you'll get more grip on your rear wheels.

Also 4WD cars usually have a static weight distribution of 50/50 to 40/60, so still enough weight on the rear wheels to give traction.

In general 4WD cars accelerate faster because all the wheels can deliver torque to the road, where RWD cars only have the rear wheels for that. This means that when you put the same tires on the 4WD and the RWD car and both have more than enough power, the amount of torque the tires can transfer to the road will be exceeded when maximally accelerating. The RWD car will be limited by that, while the 4WD then also has its front tires which can transfer torque to the road. This, most likely, will be less than the rear tires but still its more than nothing what the RWD car has ;)
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that doesn't make sense to me.
lets go by parts:

FR car has the most WHP and grip on rear, also grip on front wheels
In the acceleration, the front wheels weight transfer their weight to the
rear wheels and add more traction, and somehow they slip when you're
accelerating, how could they slip if they have grip?

now on 4wd:

they have WHP in all wheels. in acceleration
they do have initial grip due to the weight distribution.
but how come FR cars don't have weight distribution as wheel.
slightly seeing, FR also has grip on 4 wheels.
FR acceleration should be faster because it has and gets more
grip than 4WD's
 
Your over thinking this.... AWD, 4WD will have better acceleration overall because all the power is distributed to all 4. Weight is a factor as well. However.. RR Setup like RUF will have a better acceleration because the engine is sitting on the rear wheel giving it more grip when accelerating.

It also depends on the Transmission Setup. As weight factor will play in. However more power a 4WD Vehicle has it has a tad of a Advantage. For example a R35 GT-R with 950hp will be fast then a 970hp Ferrari Enzo. Because all the power of the Enzo will be sent to the rear wheels. This will cause lots of wheel spin compared to the R35 which won't have as much because all the power is being distributed around all 4-Wheels making a better launch then the Enzo.

However if you compare both stock. The R35 will be quicker to 0-60 but the Enzo is lighter and has a higher top speed.
 
Ceolix
that doesn't make sense to me.
lets go by parts:

FR car has the most WHP and grip on rear, also grip on front wheels
In the acceleration, the front wheels weight transfer their weight to the
rear wheels and add more traction, and somehow they slip when you're
accelerating, how could they slip if they have grip?

now on 4wd:

they have WHP in all wheels. in acceleration
they do have initial grip due to the weight distribution.
but how come FR cars don't have weight distribution as wheel.
slightly seeing, FR also has grip on 4 wheels.
FR acceleration should be faster because it has and gets more
grip than 4WD's
Click to expand...

Oke, maybe this helps:

If you have time, try reading this: Race Car Vehicle Dynamics, W.F. Milliken, D.L. Milliken, SAE International, 1995.
ISBN 1-56091-526-9.
Google it and you will get some pdfs ;)

If you have less time try this one:
https://www.google.nl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDEQFjAA&url=http%3A%2F%2Ftransporter-game.googlecode.com%2Ffiles%2FVehicleDynamicsForRacingGames.pdf&ei=YShMUoivG6a10wXO5oGYBQ&usg=AFQjCNFnGTeFMVjfSatWqNQykNrNcZ2rUA&sig2=RHTgmRoV--2wgVhW8PWliA

Maybe then you'll understand all your questions ;)

Vehicle dynamics is not really simple to explain on a forum like over here, and your questions are purely vehicle dynamics related ;)
 
Ceolix
grip ... weight ... traction
Click to expand...
There are some basics that need addressing here.

Weight is the downward force of the vehicle's mass due to gravity. ALL cars have weight on ALL wheels, unless they are lifted off the ground.

Grip is a function of friction (the resistance of two surfaces to slip) and weight. ALL cars have grip on ALL wheels, unless they are lifted off the ground or experiencing a surface or loss of control that reduces friction dramatically.

Traction is a function of motive power and grip. Cars only have traction on the driven wheels.


So, FR, FF, RR and MR cars only have two wheels experiencing traction and any loss of friction on one axle (due to power overcoming grip - wheelspin) eliminates it, while 4WD cars have four wheels experiencing traction and still have traction when one axle loses friction.

Which accelerates quickest if all five types of car are otherwise identical? The 2WD cars or the 4WD one?
 
TheKitten
Your over thinking this.... AWD, 4WD will have better acceleration overall because all the power is distributed to all 4. Weight is a factor as well. However.. RR Setup like RUF will have a better acceleration because the engine is sitting on the rear wheel giving it more grip when accelerating.

It also depends on the Transmission Setup. As weight factor will play in. However more power a 4WD Vehicle has it has a tad of a Advantage. For example a R35 GT-R with 950hp will be fast then a 970hp Ferrari Enzo. Because all the power of the Enzo will be sent to the rear wheels. This will cause lots of wheel spin compared to the R35 which won't have as much because all the power is being distributed around all 4-Wheels making a better launch then the Enzo.

However if you compare both stock. The R35 will be quicker to 0-60 but the Enzo is lighter and has a higher top speed.
Click to expand...

Then shouldn't FR cars accelerate more than MRs?
if i got it right, the enzo that is a MR send it's front grip power
to the rear. but FR has better front grip than MR, shouldn't
FR accelerate faster if it has more power to send to the rear?

PS: front wheels from RR cars should spin too, because
they don't have grip, and they don't spin.
 
Last edited:
Ceolix
the enzo that is a MR send it's front grip power
to the rear.
Click to expand...
The Enzo drives the rear wheels only. There is no power at the front.
Ceolix
but FR has better front grip than MR
Click to expand...
But the front wheels aren't powered, so it doesn't matter how much grip they have.
Ceolix
FR accelerate faster if it has more power to send to the rear?
Click to expand...
If an FR car and an MR car have about the same engine output, they will have about the same power at the rear wheels.
 
Famine
The Enzo drives the rear wheels only. There is no power at the front.But the front wheels aren't powered, so it doesn't matter how much grip they have.If an FR car and an MR car have about the same engine output, they will have about the same power at the rear wheels.
Click to expand...

So if rear traction cars only drive with rear wheels
why FR cars don't accelerate faster? is it because
MR has traction + engine that gives traction on it's rear?

and by the way what do you mean with "drive with the rear wheels only"?
All cars accelerate with front wheels first:idea:
 
Ceolix
So if rear traction cars only drive with rear wheels
why FR cars don't accelerate faster? is it because
MR has traction + engine that gives traction on it's rear?
Click to expand...

Yes, now you're getting it!

Ceolix
and by the way what do you mean with "drive with the rear wheels only"?
All cars accelerate with front wheels first:idea:
Click to expand...

FR = Front engine, Rear wheel drive.
MR= Mid engine, Rear wheel drive.
 
thanks everyone for helping me
i think i got a slight idea how this works.
thanks!

i kindly ask an admin to close this :)
 
Johnnypenso
There is no such thing as 90F/10R in GT, the max front is 50 as in 50F/50R. From there it goes to 10F/90R in increments of 5.
Click to expand...
AudiLord
The torque distributor goes from 50/50 to 10/90 [F/R] so you'll never be able to sent more torque to the front wheels than to the rear wheels.

And for the 4WD and grip issue, you also have weight transfer when you accelerate, so you'll get more grip on your rear wheels.

Also 4WD cars usually have a static weight distribution of 50/50 to 40/60, so still enough weight on the rear wheels to give traction.

In general 4WD cars accelerate faster because all the wheels can deliver torque to the road, where RWD cars only have the rear wheels for that. This means that when you put the same tires on the 4WD and the RWD car and both have more than enough power, the amount of torque the tires can transfer to the road will be exceeded when maximally accelerating. The RWD car will be limited by that, while the 4WD then also has its front tires which can transfer torque to the road. This, most likely, will be less than the rear tires but still its more than nothing what the RWD car has ;)
Click to expand...

I know. I just forgot to mention it. Thanks for that one.
 

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