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Old 3rd May 2012, 16:52   #1
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Default Do RWD vehicles have lesser traction on inclines?

The road in front of my house is a rather steep incline, and you have to stop, then turn while doing the half clutch dance to get the car into the house.

My indica, and the spark and zen which my neighbours have have no issues handling this. But on the other hand I'd always wondered why the eeco and the omni of another neighbour spun their rear wheels like crazy when doing this ritual. I used to think it was because of their less than perfect driving skills or lesser torque. But yesterday a friend of mine was trying to park his scorpio inside our house, and he simply couldn't. once the front had turned, and went a bit above the plane of the incline, the rear wheels lifted, and they were just spinning away with absolutely no traction. I was thinking at least one of the wheels should grip, but nothing happend. The same guy owns a bunch of other cars, and he's driven to my house before, so that rules him out.

I'm still trying to wrap my head around what happened. Shouldnt at least one wheel grip? isnt that what differentials are for?
Do RWD vehicles have lesser traction on inclines?-210186_216492935033033_100000169832602_1007721_5842359_o.jpg

this is what the road looks like, and thats the entry to my house on the left

Last edited by greenhorn : 3rd May 2012 at 17:02.
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Old 3rd May 2012, 17:03   #2
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Default re: Do RWD vehicles have lesser traction on inclines?

Quote:
Originally Posted by greenhorn View Post
The road in front of my house is a rather steep incline, and you have to stop, then turn while doing the half clutch dance to get the car into the house.

My indica, and the spark and zen which my neighbours have have no issues handling this. But on the other hand I'd always wondered why the eeco and the omni of another neighbour spun their rear wheels like crazy when doing this ritual. I used to think it was because of their less than perfect driving skills or lesser torque. But yesterday a friend of mine was trying to park his scorpio inside our house, and he simply couldn't. once the front had turned, and went a bit above the plane of the incline, the rear wheels lifted, and they were just spinning away with absolutely no traction. I was thinking at least one of the wheels should grip, but nothing happend. The same guy owns a bunch of other cars, and he's driven to my house before, so that rules him out.
Ideally RWD will have more traction on inclines. The weight is shifted towards the rear on inclines and being RWD, the vehicle should have more traction on the rear wheels. The scenario in front of your house must be unique. Can you please post a picture and a video of the Scorpio not being able to climb. Maybe experts can explain.

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I'm still trying to wrap my head around what happened. Shouldnt at least one wheel grip? isnt that what differentials are for?
In an open differential, power will be provided to the tire with lower resistance and it will spin away to glory. Thus the one with traction will not be able to get the car out. That is why people install MLDs and LSDs and lockers.
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Old 3rd May 2012, 17:05   #3
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Default re: Do RWD vehicles have lesser traction on inclines?

It's true that Front Engine Rear Wheel Drive cars have lesser Traction. The FWD cars on the other hand have the benefit of the heavy engine aiding the traction on the driven wheels in the front.

In the good old days, I have seen ambassadors driven in reverse up the steep inclines and on ghat roads.

Scorpio has open differential, if one wheel loses traction all the power is sent to the free wheel and the other wheel gets no drive at all.

Last edited by speedmiester : 3rd May 2012 at 17:07.
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Old 3rd May 2012, 17:21   #4
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Default re: Do RWD vehicles have lesser traction on inclines?

I wonder if this answers your question: As a child, when we were living in Ooty, I remember the incline in to the front yard of our house was very steep and dad's amby would struggle up spinning the tyres a couple of times to make it up that slope. And this was when it was dry.

When it rained and got a little slushy the car would refuse to go up the slope with its tyres hopelessly spinning.

But dad had a brilliant solution. In times like these, he would simply turn the car and reverse it up the slope (Make shift front wheel drive) And the car would go up with not so much as half a spin of the tyres
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Old 3rd May 2012, 17:35   #5
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Default re: Do RWD vehicles have lesser traction on inclines?

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Originally Posted by aadithsince1980 View Post
But dad had a brilliant solution. In times like these, he would simply turn the car and reverse it up the slope (Make shift front wheel drive) And the car would go up with not so much as half a spin of the tyres
It's the reverse gear ratio that's at work here and also the additional traction on the front wheels of the ambassador.
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Old 3rd May 2012, 17:47   #6
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Default re: Do RWD vehicles have lesser traction on inclines?

Greenie, good question. For a moment I did think that the RWD vehicle will do better because it is pushing the load of the vehicle- that there is no trailing load for the driven wheels.
Quote:
Originally Posted by speedmiester View Post
It's true that Front Engine Rear Wheel Drive cars have lesser Traction.
Wonder if @Speedmiester has provided the answer here.

The Zen, Indica etc have a front engine, FWD. The wheels with power are also loaded with the weight of the engine to give adequate traction.

But the Scorp being Front engine + RWD - does have the load on the front wheels, but the front wheels are not powered. May be the Scorp will do better if there was some load over the rear wheels, to aid available traction. You could try having a couple of people sit in the back.

Can you also try to reverse the Zen & Indica up the slope, to find if it is available traction or about FWD / RWD. I wont be surprised if these two will do better in reverse.

IIRC from the 4x4 sections here & FB, heavier vehicles do perform better because they are able to get better traction.
(NOte: above point is at a summary level, and I am not going into depth there. 4x4 experts can add details.)

Let's leave the Omni & Eeco out of the equation for now
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Old 3rd May 2012, 18:19   #7
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Default re: Do RWD vehicles have lesser traction on inclines?

Is it just about the weight of engine and traction on the fwd. What about rear engine (mid engine) with rear wheel drives. Even there I would guess, the traction would not be as good as fwd in snow or loose surfaces?
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Old 3rd May 2012, 19:00   #8
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Default re: Do RWD vehicles have lesser traction on inclines?

Its the load on the front wheels(engine) which does the trick.
When we went to gangotri, the empty eeco did not climb a snowy incline. But when the boot was filled with 4 people, she went up with some struggle.

Thats why you will see 2WD SUVs struggling to climb slippery slopes where cars like Alto and M800 do it easily.
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Old 3rd May 2012, 20:47   #9
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Default Re: Do RWD vehicles have lesser traction on inclines?

Quote:
Originally Posted by greenhorn View Post
But on the other hand I'd always wondered why the eeco and the omni of another neighbour spun their rear wheels like crazy when doing this ritual...
The OMNI and Eco are notorious for this exact defect!. They are feather light at the back, and offer absolutely no traction in challenging situations. In fact, we have an Omni in our farm, and during monsoons, while using it to ferry the coffee sacks through slush, we keep one sack full in the back always (even after emptying and in return trip), just to put some weight and some traction into the rear wheels. Or else, the OMNI doesn't move an inch and sprays slush all over.

-----------------------------------

Buuuttttttt... I think there more to it in this situation. On the incline its the weight as discussed above, but while taking the turn, its not weight but lack of articulation.

Meaning: All the vehicles you mentioned comes with rigid chassis to make it road friendly (and are not off roaders). Now, as the chassis doesnt flex, while taking the turn to your home, the rear wheels lift up (just like a dog pees ) and does not stay put. Once you lose traction to any one of your wheels, the open differential makes it impossible to move.

Quote:
My indica, and the spark and zen which my neighbours have have no issues handling this.
These cars are FWD's and hence articulation doesn't come into the picture, as both the front wheels stay put on the ground. And yes, the added weight of the engine helps.

To get an exact picture, try this: Try to turn up to your house in reverse in your Indica. The same thing that happened to the Scorpio will happen.

Quote:
Shouldnt at least one wheel grip? isnt that what differentials are for?
Here's how a differential works.

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Old 3rd May 2012, 20:48   #10
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Default Re: Do RWD vehicles have lesser traction on inclines?

I agree with the weight on the front wheels theory.

But perhaps feedback from the steering wheel & steering inputs made by the driver also helps the FWD car gain traction? If the front wheels are slipping, any driver would automatically "feel" the wheels slip through the twitching steering and would either take his foot off the accelerator a bit or turn the wheels slightly or do both.

There is no such feedback/input in a RWD vehicle.
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Old 3rd May 2012, 20:53   #11
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Default Re: Do RWD vehicles have lesser traction on inclines?

I think it has a lot to do with the weight of the engine up front pushing the front wheels down, giving it more traction up a slope. In a front-wheel drive car of course.

I remember asking my father if a Mercedes could climb stairs and he had reassuringly said NO. After explaining to me that it's RWD. To which he had also added that our Zen could do it without much problem.

Last edited by suhaas307 : 3rd May 2012 at 20:55.
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Old 3rd May 2012, 22:27   #12
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Default Re: Do RWD vehicles have lesser traction on inclines?

Quote:
Originally Posted by dhanushs View Post
Buuuttttttt... I think there more to it in this situation. On the incline its the weight as discussed above, but while taking the turn, its not weight but lack of articulation.

Meaning: All the vehicles you mentioned comes with rigid chassis to make it road friendly (and are not off roaders). Now, as the chassis doesnt flex, while taking the turn to your home, the rear wheels lift up (just like a dog pees ) and does not stay put. Once you lose traction to any one of your wheels, the open differential makes it impossible to move.
This was pretty much the answer i was looking for. A little wheelspin going up was okay, but losing traction totally during the turn was what surprised me. I guess when I'm upgrading, a RWD is out of the question for me, as it totally will not drive into my house .

Would a 4WD scorpio have the same problem, or will enough power be sent to the front wheels ?

Last edited by greenhorn : 3rd May 2012 at 22:30.
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Old 3rd May 2012, 22:46   #13
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Default Re: Do RWD vehicles have lesser traction on inclines?

A tyre's traction on any given surface is (besides other factors) also a function of how loaded it is, ie. the weight it is carrying. The graph of tyre traction vs load is quite linear (straight line) before tapering off.

Using the above reason, FWD vehicles have more traction on most surfaces, even inclined ones. The reason being that even on an incline, the front wheels still have more load than the rear. RWD vehicles theoretically ought to have more traction since the weight is transferred rearward on an incline, but, it is still not enough to offset the weight of the engine forward.

This, combined with an open differential is responsible for RWD wheels spinning without traction.
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Old 3rd May 2012, 22:50   #14
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Default Re: Do RWD vehicles have lesser traction on inclines?

Quote:
Originally Posted by greenhorn View Post
Would a 4WD scorpio have the same problem, or will enough power be sent to the front wheels ?
A 4WD Scorpio will drive up to your home eeaaassssiiillllyyyy...

Also, there is one jugaad trick to make 2WD RWD's which lift off one wheel and get stuck en route to your house, move.

Get a long and strong stick and put it through the wheel that is spinning freely (while its stopped of course!). Turn the wheel slowly till the stick locks the turning of the wheel. With the wheel and stick in that position, try to move the vehicle slowly again.. remove the stick as soon as the wheel touches ground or is fit for traction.. and voila!

You will have your guest in your home!

P.S:- This method is called Jugaad Differential Locks!
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Old 4th May 2012, 03:25   #15
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Default Re: Do RWD vehicles have lesser traction on inclines?

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Originally Posted by speedmiester View Post
It's true that Front Engine Rear Wheel Drive cars have lesser Traction. The FWD cars on the other hand have the benefit of the heavy engine aiding the traction on the driven wheels in the front.

.
Seen an old neighbour using sand bag at the boot (or ask us kids to get in the rear seat) to avoid the issue of wheel spin in his Sipani D1. the rear wheel used to scream and spin while getting into an uneven parking space
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