This Winter's going to be a corker

[Sysman]

Brake on a front wheel drive car on ice; the rear wheels will lock and you will do a 360 degree spin. Even decelerating can put you in a spin.

Had that with a Morris Minor on the M1 in thickly falling snow.

Most of the traffic was doing just over 30 mph and that felt about right for the conditions. Some idiot in a rear wheel drive Escort came flying past doing about 45 and started spinning in front of me.

I eased off the accelerator, tapped the brakes very lightly and felt the back end starting to go. The only way to straighten up was to restore a light throttle.

Still don't know how I missed the Escort, but miss it I did.

About 15 minutes later the irresponsible twunt came flying past again.

[VectraMan]

Mmmmm.

I've read about that, but most of the cars I've worked on have exactly one pipe going to the rear brakes.

Mine certainly has two. Most modern cars will have an ABS unit under the bonnet somewhere with four pipes coming out of it. The front left - rear right thing was meant to be two independent systems in case one failed, but I'm not sure if that applies anymore.

[Old Hack]

Mmmmm.

I've read about that, but most of the cars I've worked on have exactly one pipe going to the rear brakes.

No, Most cars have them, I know mine does (Merc), and all Audis I have owned do too. You'll find them cross linked, where the FL and RR are on the same circuit.

You'll only ever have one pipe going to each brake.

Found this for you.


Cross-linked brakes - why there are two brake circuits.

In the rendering of the master brake cylinder above, you'll see there are two plungers and two brake circuits. This is the most common design for cars today. It's a form of redundancy in the brake system. The idea is that only two brakes, one front and one rear, are on either of the brake circuits. For four brakes, you therefore need two circuits. But why? Well imagine one of your brake lines springs a leak - for the sake of argument, the front-left brake. If all four brakes were on a single circuit, when the master cylinder began to pressurise the brake system, fluid would spurt out of the broken line and pressure would never build up. In turn, that means none of the brakes would ever come on and you'll sail merrily into the back of the vehicle in front of you.


Read more: Car Bibles : The Brake Bible

[Sysman]

Mmmmm.

I've read about that, but most of the cars I've worked on have exactly one pipe going to the rear brakes.

I remember one of the 2 systems going one day.

The brake pedal suddenly went down a bit further than normal and the car did the kind of lurch you would expect from braking on one front wheel and the opposite rear wheel.

But it did stop.

And it was safe enough to get me home and then to the garage the next morning.

The system works.

[Old Hack]

OH the only reason you know anything is because you just looked it up on the internet to try and seem clever.

Regardless whether that is true or not, I'd rather be an informed person from finding something out, than a cretin who thinks it would be wise fitting winter tyres to the front of his car. I know gods your friend d000hg, but even he cant help you there mate



A god botherer who's ironically also proof of Darwinism - Too funny

[RasputinDude]

We had a discussion on this recently but I can't find it... in a normal FWD car are both braking and drive through the front axle, meaning that you can get away with 2 winter tyres only?

I'm sure that you've worked this out from the other responses, but you definately need four tyres. It's not an unreasonable question to ask really especially if you're not mechanically inclined and I think that some of the responses were a little more unpleasant than they needed to be.

Anyway, I get mine from here Pneus Online: Expert store for tyre selling online and motorized classifieds and if you don't buy another set of rims, then a decent mechanic should fit and balance them for around £45.

[Old Hack]

Er, I wasn't suggesting that brakes are still single circuit, they haven't been since the 60s.

I well remember the joy of brake failure in one of those.

But the dual circuit, non ABS cars I've worked on have all had one circuit operating the front brakes & the other operating the rear brakes.

Only old cats would circuit on the fronts, and on the rears. Sorry, but it would be inherently dangerous. Most cars have an 80-85% front bias; by keeping them on one circuit, you'd effectively have no brakes if they went, and if the rears failed, you'd have a drifting car on your hands.

I remember my dad's Audi 100 being championed for having them, back in the 70's, and they've been the norm pretty much since.

[Old Hack]

I'm sure that you've worked this out from the other responses, but you definately need four tyres. It's not an unreasonable question to ask really especially if you're not mechanically inclined and I think that some of the responses were a little more unpleasant than they needed to be.

It's General, and it was a very stupid question. Very.

[d000hg]

Undecided on the hassle of changing tyres on the same rims and having to get them re-balanced twice versus the expense of having winter and summer wheels like they do in Scandinavia. Their system of having a warehouse who hold your wheels is nice but I don't know if they have that here and storing 4 wheels (or even 2) is a pain.

There are mobile people who come to you, which we looked at when getting new tyres last time, but it's not cheap getting 4 tyres (and maybe rims) - not when the car is cheap to begin with anyway.

[RasputinDude]

Undecided on the hassle of changing tyres on the same rims and having to get them re-balanced twice versus the expense of having winter and summer wheels like they do in Scandinavia. Their system of having a warehouse who hold your wheels is nice but I don't know if they have that here and storing 4 wheels (or even 2) is a pain.

There are mobile people who come to you, which we looked at when getting new tyres last time, but it's not cheap getting 4 tyres (and maybe rims) - not when the car is cheap to begin with anyway.

I don't think that there are tyre hotels in this country. I did think about starting one up a few years ago. If you buy new rims, you don't need (or want) alloys, just some cheap steel ones will do fine. The TyresOnYourDrive lot are pretty pricey, I agree.