Advantages of 4WD on ordinary saloons?
Discussion
Lincsls1 said:
The other consideration when comparing 2wd/4wd/fwd/rwd systems is the differential types used on both axles.
I think its fair to say that (nearly all) FWD and to a lesser extent RWD cars use open diffs which means when the conditions get slippy the car pretty much becomes a 1WD vehicle!
Exactly, my driveway is narrow at the entrance which is 90 degrees to the narrow lane both of which are fairly steep. It's also long, gravelled and mostly in the shade in winter meaning it is difficult to clear when it snows.I think its fair to say that (nearly all) FWD and to a lesser extent RWD cars use open diffs which means when the conditions get slippy the car pretty much becomes a 1WD vehicle!
Couple that with the local council that don't clear the road and all my past RWD cars (none with LSD unfortunately) plus many of my Wife's FWD have done the 1WD trick on many occasions - even a powerfully built 'driving God' can't defy the laws of physics.
I realise winter tyres would help and that all cars without them have the same stopping/turning issues in snow but I don't want the faff of swapping/storing wheels for the few days that it's a problem.
For me the problem is not so much once on the 'open' road as they are generally cleared and driving carefully is sufficient but even with 255 width 'summer' tyres my 4WD car has no problem driving up through a few inches of snow, albeit with a bit of wheel spin and whilst the main reason for me buying an AWD is for more than just traction in the snow, it is also a reason.
Just out of curiosity why do people think that the extra spent on the 4matic/xdrive/quattro vehicles is worth the money over their two wheel drive counterparts but the idea of spending cash on an extra set of wheels with snow tires isn't?
In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
As much as I love the characteristics of RWD, I found myself stranded for about 4 days last year during the winter in my M lite (OK so not a saloon) . I don't live in the sticks or the hills but I've discovered my estate has a small incline that I wasn't aware of in the summer. Working from home a few days wasn't the end of the world and we have a 4x4 for family stuff. Would I want to lose the pleasure of RWD in favour of 4 driven wheels? Probably not, but if we didn't have the 4x4, I'd consider switching to a 4WD car to cope with all demands.
Pica-Pica said:
mwstewart said:
Bragging rights if you can't drive, or you can but are a bit scared.
If you are never scared, you are never pushing yourself, in any aspect of life!Leon R said:
Just out of curiosity why do people think that the extra spent on the 4matic/xdrive/quattro vehicles is worth the money over their two wheel drive counterparts but the idea of spending cash on an extra set of wheels with snow tires isn't?
In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
You asked so..In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
Firstly I am no true fan of pseudo AWD cars that are 2wd until those wheels start to spin. I much prefer permanent awd with an lsd on each axle as well. I don’t like trucks though, as I’m not a builder or farmer.
Secondly, like most people I choose vehicle options within my budget that fit my lifestyle choice.
I can weld, spanner, and build engines, & gearboxes for pleasure, but I really don’t see the need or hassle of storing a second set of winter wheels and swapping them on/off if I don’t have to.
It’s much easier to have one ca in the fleet that stil performs on one single set of non-winter tyres with the added benefit of extra grip on dry days.
My polite return question for you is - what awd car with summer tyres did you drive in the snow, to achieve the limited experience/opinion you speak of?
How many miles did you drive it and what terrain?
300bhp/ton said:
Norfolkandchance said:
They don't have raised ride height and are fitted with ordinary summer tyres so they wouldn't be much better at pulling a horse box out of a field.
They would be massively better in this regard.Having seen a Discovery, with road-biased but still 4x4 tyres, stuck on a virtually level wet grass field, I can very much believe him.
Norfolkandchance said:
I have a friend who works as a design engineer for a 4x4 manufacturer, including a spell working with the algorithms that control the traction control for various different types of terrain. Longish wet grass is, according to him, one of the hardest surfaces to get traction on because as soon as the wheels slip it tears up and the tyres become clogged. Apparently more so than other surfaces. He told me that they had had a presentation from a potential supplier, pleased that their new Haldex equivalent could transfer drive to the rear within half a turn of slip from the front. The consensus of the meeting was that half a turn was fine for most surfaces but too late for wet grass.
Having seen a Discovery, with road-biased but still 4x4 tyres, stuck on a virtually level wet grass field, I can very much believe him.
yes, but 4wd vs 2wd for towing on a slippery surface is still a massive advantage.Having seen a Discovery, with road-biased but still 4x4 tyres, stuck on a virtually level wet grass field, I can very much believe him.
Nanook said:
Polite M135 driver said:
the graph perfectly describes what the poster was talking about.
what's wrong with it? I titled it and I labelled the axes, I even made sure I used the units... I would give it 10/10 as a graph.
what's wrong with it? I titled it and I labelled the axes, I even made sure I used the units... I would give it 10/10 as a graph.
Above 50bhp, that extra power cannot be used. A car with 50bhp can use 50bhp. Once you have more than 50bhp, you can't actually use all of that 50bhp.
My car, for instance, has 300bhp. According to your graph, I can only use about 9bhp of it.
Your graph doesn't appear to consider anything about the car, the type or size of tyres, the gearing, the sort of differential, the mass of the vehicle in question, the speed the vehicle is doing when your graph is 'valid' or a whole host of other things.
1/10. On a good day.
J4CKO said:
The more power you have in a RWD car, the less of if you can use in the wet, and with most BMW's, they are, on normal tyres, helpless if there is any snow.
doesn't make sense.Polite M135 driver said:
how many two-wheel drive motorbikes do you see driving around? Exactly.
The dynamics of steering s driven front wheel on a bike is rather different to a car. Also most bike have a lot of rear weight bias, so the traction conditions are different.That said, AWD motorcycles do exist.
Hol said:
Leon R said:
Just out of curiosity why do people think that the extra spent on the 4matic/xdrive/quattro vehicles is worth the money over their two wheel drive counterparts but the idea of spending cash on an extra set of wheels with snow tires isn't?
In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
You asked so..In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
Firstly I am no true fan of pseudo AWD cars that are 2wd until those wheels start to spin. I much prefer permanent awd with an lsd on each axle as well. I don’t like trucks though, as I’m not a builder or farmer.
Secondly, like most people I choose vehicle options within my budget that fit my lifestyle choice.
I can weld, spanner, and build engines, & gearboxes for pleasure, but I really don’t see the need or hassle of storing a second set of winter wheels and swapping them on/off if I don’t have to.
It’s much easier to have one ca in the fleet that stil performs on one single set of non-winter tyres with the added benefit of extra grip on dry days.
My polite return question for you is - what awd car with summer tyres did you drive in the snow, to achieve the limited experience/opinion you speak of?
How many miles did you drive it and what terrain?
In answer to your question not far at all tbh and it was only on snow covered roads in the UK (southern England) and a small amount of time on a track.
I used to work for Mercedes and 4matic was only available on certain models if you were buying a LHD vehicle. While I was working there during a visit to Brooklands after a discussion about snow and RWD one of the instructors was kind enough to take me out in a c class with winters on as a comparison to a 4matic on summer tires.
J4CKO said:
Hol said:
Leon R said:
Just out of curiosity why do people think that the extra spent on the 4matic/xdrive/quattro vehicles is worth the money over their two wheel drive counterparts but the idea of spending cash on an extra set of wheels with snow tires isn't?
In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
You asked so..In my limited experience of snow driving I would rather take a two wheel drive car with a set of winter rubber on it than a 4wd vehicle on summer tires.
I'm not talking about the guys who have to deal with the extremes of winter as 4wd sounds pretty essential for them.
Firstly I am no true fan of pseudo AWD cars that are 2wd until those wheels start to spin. I much prefer permanent awd with an lsd on each axle as well. I don’t like trucks though, as I’m not a builder or farmer.
Secondly, like most people I choose vehicle options within my budget that fit my lifestyle choice.
I can weld, spanner, and build engines, & gearboxes for pleasure, but I really don’t see the need or hassle of storing a second set of winter wheels and swapping them on/off if I don’t have to.
It’s much easier to have one ca in the fleet that stil performs on one single set of non-winter tyres with the added benefit of extra grip on dry days.
My polite return question for you is - what awd car with summer tyres did you drive in the snow, to achieve the limited experience/opinion you speak of?
How many miles did you drive it and what terrain?
But clearly not Permanent AWD.
Leon R said:
I see how having to swap wheels and store them isn't ideal.
In answer to your question not far at all tbh and it was only on snow covered roads in the UK (southern England) and a small amount of time on a track.
I used to work for Mercedes and 4matic was only available on certain models if you were buying a LHD vehicle. While I was working there during a visit to Brooklands after a discussion about snow and RWD one of the instructors was kind enough to take me out in a c class with winters on as a comparison to a 4matic on summer tires.
Would it be fair of me to summarise your main defining moment as being based on that comparison between 4matic and 2wd winters?In answer to your question not far at all tbh and it was only on snow covered roads in the UK (southern England) and a small amount of time on a track.
I used to work for Mercedes and 4matic was only available on certain models if you were buying a LHD vehicle. While I was working there during a visit to Brooklands after a discussion about snow and RWD one of the instructors was kind enough to take me out in a c class with winters on as a comparison to a 4matic on summer tires.
Because I base mine solely on many years and many miles of 2wd vs Awd on non winters.
Q1. Would winter or snow tyres have made either journey better.
A1. I’m fairly sure it would, but none of those vehicles had them.
Q2. Was i able to drive great distances in an AWD road car, often going out for s
ts and giggles, or to ferry my close neighbors to the remaining shops that still had food.A2: Yes I was.
GravelBen said:
4wd doesn't add lateral grip in constant, steady-state cornering, correct. But splitting the tractive force between 4 contact patches instead of two does reduce the tendency for throttle applications to overwhelm the grip of driven wheels during cornering (which can happen in slippery conditions even with skilled drivers).
Similar with braking, depending on the 4wd system (probably doesn't apply to haldex on-demand stuff) the torque transfer through the drivetrain can resist the tendency for individual wheels to lock on mixed grip surfaces or when they are unloaded. Will it give you a shorter ABS-activated emergency stopping distance? Nope. But it can help you maintain control and stability in difficult conditions.
In both cases the advantage is less about peak steady-state performance and more about a wider envelope in transient states.
Exactly Ben, hence me referring to the need for smoother throttle/braking input in transient states with 2wd (in the traction and braking zones) and for me smoothness of input is far more rewarding than point and squirting, however slow that makes me. Similar with braking, depending on the 4wd system (probably doesn't apply to haldex on-demand stuff) the torque transfer through the drivetrain can resist the tendency for individual wheels to lock on mixed grip surfaces or when they are unloaded. Will it give you a shorter ABS-activated emergency stopping distance? Nope. But it can help you maintain control and stability in difficult conditions.
In both cases the advantage is less about peak steady-state performance and more about a wider envelope in transient states.
Hol said:
Leon R said:
I see how having to swap wheels and store them isn't ideal.
In answer to your question not far at all tbh and it was only on snow covered roads in the UK (southern England) and a small amount of time on a track.
I used to work for Mercedes and 4matic was only available on certain models if you were buying a LHD vehicle. While I was working there during a visit to Brooklands after a discussion about snow and RWD one of the instructors was kind enough to take me out in a c class with winters on as a comparison to a 4matic on summer tires.
Would it be fair of me to summarise your main defining moment as being based on that comparison between 4matic and 2wd winters?In answer to your question not far at all tbh and it was only on snow covered roads in the UK (southern England) and a small amount of time on a track.
I used to work for Mercedes and 4matic was only available on certain models if you were buying a LHD vehicle. While I was working there during a visit to Brooklands after a discussion about snow and RWD one of the instructors was kind enough to take me out in a c class with winters on as a comparison to a 4matic on summer tires.
Gassing Station | General Gassing | Top of Page | What's New | My Stuff