[Closed] 4x4 or 2wd with snow tyres?

Have had a 4x4 for the last ten years up til last spring, bought snow/ winter tyres for the mundano this winter and we haven't ****in had any snow!!!!

Have had a 4x4 for the last ten years up til last spring, bought snow/ winter tyres for the mundano this winter and we haven't **** had any snow!!!!

This actually happened with my other half's car. We had an epic winter (-17, gelled my diesel!) and she decided to invest. Sod all snow ever since.

^^ Can you two buy wet weather tyres next year please?

Sure, I made sure she got rain tyres with her new car but it doesn't seem to have helped. Maybe it's because the snow tyres are still sat on the old car in the drive rotting. I'll palm them off on someone.

(by bringing 2 more contact patches into the mix)

And i would argue that having 4 driven wheels you can use engine braking to provide controled 4 wheel braking and even hill decent if you have a low box. Soon as you touch the brakes going downhill youll slide and 1st gear isnt low enough, ive watched it happen many times while i sit at the top and watch them before engaging low box and letting the engine braking guide me down slowly and safely with no sliding.

I would argue that a 2wd car has the same number of wheels as a 4wd car.

And i would argue that having 4 driven wheels you can use engine braking to provide controled 4 wheel braking

Don't get this. Why is 4wd engine braking any different to the same retarding force applied through the brakes?

Dont do much off roading then,

Going down hill and apply the brakes - youll get weight shift to the front and your bias vslve will send more power to the front brakes and youll lock up once you lock up on ice you will speed up!

First thing i was told when i started off rosding was - if your using your brakes on the course your in the wrong gear. ( trials not comp safari)

Obviously if you have abs and other such driver aids then you may well be ok - although our transit - the only we we could get it to move on snow even on winters was to pull the traction control and abs fuses.

Don't get this. Why is 4wd engine braking any different to the same retarding force applied through the brakes?

As Trail_rat says, if you go for the brakes MOST cars will put 80%+ of the retarding torque through the front wheels. Also, it's usually quite sharply applied as modern cars are generally over-servo'd. Engine braking with a true 4wd it's pretty spectacular what you can maintain control on. Naturally it won't help in an emergency brake situation where you'd not get enough braking from engine braking anyway, but in a "driving around the streets slowly" situation, engine braking is really light years better than just braking. My car has EBD control and that's pretty good but still nothing compared to 4wd engine braking for smooth slow control. MAybe some of the modern ones that just vary pressure rather than applying slip/grip/slip to wheels might be better - not tried them. 4 wheel engine braking is what the hill descent control gadgetry tries to emulate using brakes on modern 4wd's, assuming the driver has no skills.

2WD with snow tyres it is then! Cheers.

The Passat applies the rear brakes in preference, to minimise dive apparently.

If one wheel slips under engine braking, would the other one on that axle not slip if you didn't have diff lock?

What's the difference between hill descent and ABS?

The whole idea behind using engine breaking is to slow in such a way that you dont lose traction.

Ive driven up and down this several times ( i lived at the bottom with no other way in and out) in my land rover on toyo open country m + s road biased ats

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Abs is like repetitive stabbing of the brakes - the hill descent in my parents rr is like dragging the brakes on your push bike.

The Passat applies the rear brakes in preference, to minimise dive apparently.

Seriously? Have you any more info on that as I would doubt that any car would employ a rear wheel braking preference. Are you getting this confused with 'hill descent control' which some vehicles have?

Applying rear brakes instead of front first wouldn't reduce dive, dive is caused by the longitudinal weight transfer set up when the car is decelerated, regardless of which wheels trigger it. Its a suspension design outcome. The only way to reduce dive on an existing car with any particular brake setup is brake less harshly!

If one wheel slips under engine braking, would the other one on that axle not slip if you didn't have diff lock?

Quite the contrary in some respects but with the same net result yes. Open diffs provide equal torque at the wheel outputs. In a powered situation, the wheel that slips sets the torque that the other wheel sees (basically zero) which is why they are not great. In engine braking the same applies, whichever slips first will cause the other to provide very little retarding torque. But the wheels will still tend to be turning at speeds similar to the passing snow/ice so they are more likely to regain traction quickly again. However the point is not to break traction at all, as this is often unrecoverable. Much like when walking down a snowwy slope in slippy shoes, if you stomp down trying to get maximal impact braking from your feet quickly you will tend to slip, if you try to smoothly maximise braking over 10 steps you probably won't slip. Of course you still may run into a tree if it was too close 🙂

ABS waits for traction to be lost, or be about to be lost, then stabs the brakes repeatedly. Hill descent is a much more controlled method and is done different ways by different manufacturers but its aim is to maintain controllable slow descent without ever breaking traction and without large braking inputs.

The big issue is that descent control usually only features on off roaders, whereas gears and engines feature on all cars with similar effect. Of course engine braking is vastly improved if you have 2 axles braking instead of 1, and is even better with snow tyres instead of all season.

Seriously? Have you any more info on that as I would doubt that any car would employ a rear wheel braking preference. Are you getting this confused with 'hill descent control' which some vehicles have?

I read it on a forum, cos usually the rear pads wear more than the fronts apparently. Not entirely sure if it's true but here's [url= http://www.passatworld.com/forums/42-volkswagen-passat-b5-discussion/116970-what-about-rear-brake-bias-passat.html ]some more info/mis-info.[/url]

The whole idea behind using engine breaking is to slow in such a way that you dont lose traction.

Exactly the same aim as ABS, hence my question. From what you've said, if ABS was quick and/or clever enough it would be the same.

No it's not the same as ABS. ABS provides on-off modulation, engine braking provides smooth constant torque. ABS working its bits off is effectively descent control (super fast actuation of each wheel independentl) and is still not as good as proper engine braking on a locked 4wd, but is a close approximation for most uses. However the key difference is that ABS is designed to allow some slip, as that is where best braking lies on tarmac. In snow you absolutely cannot have slip, it's a subtle difference that requires slightly different control algos which is why it needs to be specifically engaged on cars that use it. Incidentally cars that use hdc and have low range available usually combine both for best effectiveness.