Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 12th April 2011, 02:02   #1
Senior - BHPian
 
n.devdath's Avatar
 
Join Date: Jun 2009
Location: Bangalore
Posts: 3,960
Thanked: 1,714 Times
Arrow Slushy/Sandy/Muddy Trails: FWD or RWD?

Yesterday, while thinking about an incident that happened to a friend's 2wd Scorpio during his recent visit to Coorg had me thinking this:

Given an option of having either a Front Wheel drive

OR

a Rear Wheel drive vehicle for all roads/slush/sand etc, which one would better pull itself out if and when stuck and why?


I know that if the rear wheels of a FWD are stuck, it has a better chance and so does a RWD, if its front wheels are stuck and it goes without saying that we are comparing vehicles with similar weight, power and torque figures here.



I thought of posting this in the 4x4 section but that is not frequented by most 2wd vehicle owners.

@Mods: Please merge the thread if found repetitive.
n.devdath is online now   Reply With Quote
Old 12th April 2011, 06:46   #2
Senior - BHPian
 
shankar.balan's Avatar
 
Join Date: Apr 2008
Location: BLR
Posts: 8,027
Thanked: 5,325 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

going by experience I would bet on RWD because FWD vehicles also have the added burden of steering the vehicle and supporting the engine weight.

recently on a trip to Ooty there was an SX4 who had steered himself into a slushy muddy part of the verge while trying to make space for a bus which was coming in the opposite direction.

he simply couldnt get out - his car was fully loaded up with his family etc and the front wheels were simply spinning in the slush and it appeared he had a terrible job trying to steer as well. finally 3 of his passengers got out and with a bit of push and a huge amount of effort, he got himself out.

of course, ideally it would be lovely to have all wheel drive or 4WD but thats not always practicable or available.

having said all of this, yes, it is definitely possible even for RWD vehicles to end up in a similar mess as that SX4, but I personally would prefer taking my chance with an RWD rather than an FWD in such situations.
shankar.balan is offline   Reply With Quote
Old 12th April 2011, 08:17   #3
Senior - BHPian
 
Lukeskywalker's Avatar
 
Join Date: Feb 2006
Location: Bangalore
Posts: 1,396
Thanked: 1,149 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

Like Shankar.balan has said, even RWD vehicles could get stuck in slush, but I still would prefer RWD over FWD as if one is moving forward, one can see the wheels getting stuck or losing traction and back out, which will not be the case if vehicle is FWD, I remember getting stuck on a beach with a FWD automatic sedan, the weight of the engine and inability to steer was a major factor which had me wishing for a RWD.
Lukeskywalker is offline   Reply With Quote
Old 12th April 2011, 09:26   #4
Distinguished - BHPian
 
sudev's Avatar
 
Join Date: Jan 2008
Location: Gurgaon
Posts: 3,510
Thanked: 2,385 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

IMHO on the contrary the FWD has better chance to come out of slush etc. than the RWD.

For one the direction of travel is the direction in which power is being applied.
Two the engine weight acts to improve the wheel grip.

Simply because of one isolated example do not conclude that RWD is better. I have seen so many time 4x4 vehicle stuck where a 2wd guy went past easily. More than anything it is matter of skill first. Ground clearance is the other aspect.

Once your wheel is spinning applying more power become useless and that is where most in-experienced drivers make a mistake. The spinning wheels are more likely to dig you in further.

A steady approach is best and so is keeping momentum. Once stuck you need to use your brains to think a way out rather than accelerate or slip the clutch.

Have been to places in M800 where Jeep's were finding it tough and slippery. Driving control and appropriate power control were the key.

@MODS: I think similar thread existed some where though I do not remember the title.
sudev is online now   Reply With Quote
Old 12th April 2011, 09:36   #5
Awaiting Email Confirmation
 
Join Date: Jun 2005
Location: ERNAKULAM
Posts: 947
Thanked: 317 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

I totally agree with Sudev. The wheels that have the most weight on them should be the wheels onto which power is applied. This means in a front engined car FWD is best and in a rear engined car the rear wheels should be the driven wheels. Mid engined vehicles would not be used in the slush anyway.

Please do read up on friction and the criteria that caused friction. BE ready to be surprised at the formula for friction.
drpullockaran is offline   Reply With Quote
Old 12th April 2011, 10:38   #6
Senior - BHPian
 
Join Date: Dec 2009
Location: Ghaziabad
Posts: 1,007
Thanked: 760 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

I'm a bit confused with the previous 2 responses.
From what we all perhaps know from experience, pushing is easier than pulling.
However, the rationale presented in the previous 2 responses also seem correct.

Would it be wise to segregate our responses in the following manner?

Slush / Mud
Front Wheel Stuck - RWD Advantage. Clearly the vehicle would be able to push out.
Rear Wheel Stuck -FWD Advantage due to Grip available in the driven wheels.

Sand
Front Wheel Stuck - RWD Advantage. Easier to push it out / reverse out.
Rear Wheel Stuck - RWD Advantage. Pulling vehicle through Sand is phenomenally difficult. Probably better to try and give rear wheels some traction, by introducing stones / plank / etc...

So, overall I would love to get stuck with a RWD, although it would not be nice to get stuck at all, unless you have a 4WD.

I could be way off the mark here, but this is just from what I have experienced personally. Experts please correct the mistakes.
roy_libran is offline   Reply With Quote
Old 12th April 2011, 10:44   #7
Senior - BHPian
 
shankar.balan's Avatar
 
Join Date: Apr 2008
Location: BLR
Posts: 8,027
Thanked: 5,325 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

I have also seen the humble M800 car and van go where many others would shudder to try.
for this exact reason if I were to re-attempt the swamp riding and off roading that I used to like to do some years back, then I would choose only a Gypsy or an old Mahindra to do the job because for one thing they have 4WD and are lighter in weight.
Simply on account of its sheer weight, I would disqualify the Scorpio and other similar vehicles from such activities.
with ref to the other points on off roading - about constant momentum and not jamming the accelerator etc I totally agree. Ive burnt my fingers a long time ago, when trying to get out of a slush jam by doing the above and making a further mess of it!
Truth is, whether the vehicle is FWD or RWD, in case the driving wheels get stuck in slush, one is bound to have a nice sized problem on one's hands.


Quote:
Originally Posted by sudev View Post
IMHO on the contrary the FWD has better chance to come out of slush etc. than the RWD.

For one the direction of travel is the direction in which power is being applied.
Two the engine weight acts to improve the wheel grip.

Simply because of one isolated example do not conclude that RWD is better. I have seen so many time 4x4 vehicle stuck where a 2wd guy went past easily. More than anything it is matter of skill first. Ground clearance is the other aspect.

Once your wheel is spinning applying more power become useless and that is where most in-experienced drivers make a mistake. The spinning wheels are more likely to dig you in further.

A steady approach is best and so is keeping momentum. Once stuck you need to use your brains to think a way out rather than accelerate or slip the clutch.

Have been to places in M800 where Jeep's were finding it tough and slippery. Driving control and appropriate power control were the key.

@MODS: I think similar thread existed some where though I do not remember the title.
shankar.balan is offline   Reply With Quote
Old 12th April 2011, 14:22   #8
Senior - BHPian
 
DicKy's Avatar
 
Join Date: Jan 2010
Location: Thiruvanthapuram
Posts: 1,440
Thanked: 607 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

RWD is any day better than FWD in extreme conditions, if 4*4 is not available everytime as it's impractical.
The job of steering and powering should be equally shared among the front and rear wheels.
Especially if in a slope or with heavy weight FWd would have it's wheels spinning helplessly all the time.
there is a reason why most UVs all round the world have RWD.
DicKy is offline   Reply With Quote
Old 12th April 2011, 14:41   #9
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Kolkata
Posts: 3,506
Thanked: 2,072 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

Hi,
For the conditions mentioned, FE FWD anytime anyday.

Though RE RWD too should work, haven't driven a Nano, Beetle (old) or a 911 in any of these conditions! Those who have can comment.

Regards
Sutripta
Sutripta is offline   Reply With Quote
Old 12th April 2011, 14:47   #10
Senior - BHPian
 
Blue Thunder's Avatar
 
Join Date: Jul 2007
Location: Right here .
Posts: 1,632
Thanked: 330 Times
Thumbs up Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

Quote:
Originally Posted by sudev View Post
IMHO on the contrary the FWD has better chance to come out of slush etc. than the RWD.

For one the direction of travel is the direction in which power is being applied.
Two the engine weight acts to improve the wheel grip.

.... More than anything it is matter of skill first. Ground clearance is the other aspect.

Once your wheel is spinning applying more power become useless and that is where most in-experienced drivers make a mistake. The spinning wheels are more likely to dig you in further.

A steady approach is best and so is keeping momentum. Once stuck you need to use your brains to think a way out rather than accelerate or slip the clutch.

Have been to places in M800 where Jeep's were finding it tough and slippery. Driving control and appropriate power control were the key.
....
Pearls of wisdom (highlighted above), sudev .

And repeating the below point, since it is the essence of good (on-road) driving as well as off-roading :

"Driving control and appropriate power control "

.

Last edited by Blue Thunder : 12th April 2011 at 15:02.
Blue Thunder is offline   Reply With Quote
Old 12th April 2011, 14:51   #11
Senior - BHPian
 
shankar.balan's Avatar
 
Join Date: Apr 2008
Location: BLR
Posts: 8,027
Thanked: 5,325 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

a recent Top Gear show I watched - featuring a BMW X6 SUV with Jeremy clarkson trying to get it to drive up a grassy slope and not succeeding at all, while a traditional Range Rover just happily crawled past.

even something as innocuous as grass can be a pain, especially when wet/ damp/ dewy. given a choice in such conditions, I would prefer not to venture onto a grassy slope with either an FWD or RWD or even a normal 4WD softroader type vehicle.

Quote:
Originally Posted by DicKy View Post
RWD is any day better than FWD in extreme conditions, if 4*4 is not available everytime as it's impractical.
The job of steering and powering should be equally shared among the front and rear wheels.
Especially if in a slope or with heavy weight FWd would have it's wheels spinning helplessly all the time.
there is a reason why most UVs all round the world have RWD.
shankar.balan is offline   Reply With Quote
Old 12th April 2011, 14:59   #12
BHPian
 
alexpaul's Avatar
 
Join Date: Apr 2010
Location: London-Kochi
Posts: 71
Thanked: 15 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

I think vehicle with fwd have greater flexibility to move out of slush/mud incase if front wheel is stuck as you can change the direction of wheels using steering wheel to navigate out of the slush/mud. This is where a bit of experience (in offroading) comes into picture.
Incase of rwd, if the rear wheels get stuck in slush/mud, then the rear wheels will keep on spinning in one direction only and you will keep on digging out more mud/slush.
alexpaul is offline   Reply With Quote
Old 12th April 2011, 15:06   #13
Senior - BHPian
 
fine69's Avatar
 
Join Date: Dec 2008
Location: New Delhi
Posts: 1,407
Thanked: 860 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

Quote:
Originally Posted by DicKy View Post
RWD is any day better than FWD in extreme conditions, if 4*4 is not available everytime as it's impractical.
The job of steering and powering should be equally shared among the front and rear wheels.
Especially if in a slope or with heavy weight FWd would have it's wheels spinning helplessly all the time.
there is a reason why most UVs all round the world have RWD.
Could you please elaborate on the reason here, thanks.

I was also reading this but I don't think it concluded if RWD was better over FWD or vice versa.

Quote:
I think vehicle with fwd have greater flexibility to move out of slush/mud incase if front wheel is stuck as you can change the direction of wheels using steering wheel to navigate out of the slush/mud. This is where a bit of experience (in offroading) comes into picture.
Incase of rwd, if the rear wheels get stuck in slush/mud, then the rear wheels will keep on spinning in one direction only and you will keep on digging out more mud/slush.
Great point there.

Last edited by fine69 : 12th April 2011 at 15:07.
fine69 is online now   Reply With Quote
Old 12th April 2011, 15:18   #14
Senior - BHPian
 
shankar.balan's Avatar
 
Join Date: Apr 2008
Location: BLR
Posts: 8,027
Thanked: 5,325 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

nope - it doesnt quite work like that. it is only if the wheels are able to find some purchase/ traction on firmer ground / surface that they can do their job of pulling the vehicle out. Twisting the steering this way and that will cause one to become more deeply entrenched in the mud. Also, if it is a rutted track, fiddling about with the wheel can cost you a broken thumb or hand even.

if one gets deeply stuck in slush - both RWD or FWD and indeed, sometimes even 4WD vehicles, will need external intervention/ help. Just revving the engine, slipping the clutch and twiddling the steering is not going to do anything positive in terms of getting one out.

Typically one digs out the mud from around and under the wheels, creating a channel to try and drain out excess water from the area. Then try and place planks of wood and/or shrubbery under or as near to the tyre bottom surface as possible, in order to try and provide some traction/ grip to them. This method has worked for me in the past but it is really dirty work I can tell you.

In extreme cases the vehicle has to get winched out or pulled out by a tractor. This tractor method also I have taken recourse to in the past when I ve gotten stuck - by far the easier, chilled out way!

Sudev's earlier points about maintaining constant revs and constant momentum when entering slushy muddy and/ or sandy areas are spot on.

Quote:
Originally Posted by alexpaul View Post
I think vehicle with fwd have greater flexibility to move out of slush/mud incase if front wheel is stuck as you can change the direction of wheels using steering wheel to navigate out of the slush/mud. This is where a bit of experience (in offroading) comes into picture.
Incase of rwd, if the rear wheels get stuck in slush/mud, then the rear wheels will keep on spinning in one direction only and you will keep on digging out more mud/slush.
shankar.balan is offline   Reply With Quote
Old 12th April 2011, 16:28   #15
Senior - BHPian
 
DicKy's Avatar
 
Join Date: Jan 2010
Location: Thiruvanthapuram
Posts: 1,440
Thanked: 607 Times
Default Re: Slushy/Sandy/Muddy Trails: FWD or RWD?

Quote:
Originally Posted by fine69 View Post
Could you please elaborate on the reason here, thanks.

I was also reading this but I don't think it concluded if RWD was better over FWD or vice versa.
I said in general RWD is better than FWD.
Agreed that in FWD one can change the direction of the wheels when powering out of a stuck situation,but it stops there.
Going up a slippery slope in a fully loaded FWD is a joke, but as @alexpaul has said in slushy/sandy/mussy trails FWD would work better. It's what the thread is for.
But again, in general,RWD is better.
And @fine69- it's already discussed about in other threads, still RWD format is more robust,balanced and easy on maintenance in the long run ,things which suits UV application more.
DicKy is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
RWD, FWD, AWD-what would you choose? nitroxx Shifting gears 38 30th April 2010 13:41
Can you feel FWD or RWD difference while driving? sbasak Technical Stuff 66 12th November 2007 22:05
converting a FWD to a RWD....POSSIBLE? twister Technical Stuff 21 27th April 2006 03:05


All times are GMT +5.5. The time now is 14:21.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks