Re: Discs & Drums

During JOGLE, we Klubbers had an interesting experience. Four of us

> had to descend a steep 25% hill over two miles, sadly stuck behind an > inconsiderate git in a Civic, who wouldn't let us pass, between 10 > and 20 mph on the brakes all of the time, even in the straight bits. > > Kermit has vented front disc brakes, which I take it are designed to > lose heat nice and quickly, even at low speed. > > The drum brakes, however, I believe are not as efficient at losing > heat. > > So at such a low speed with lots of weight in the back, and with a > reasonably constant pressure, would I be right to assume that the > front discs would have been chucking out lots of heat, but the rear > drums would have probably gotten hotter? > > For what it's worth, the Ford standard non-vented disc braked Ka was > cooking the front brakes at the bottom, but Kermit's braking was just > fine and they didn't even smell bad.

No, the rear brakes don't do nearly as much work as the fronts - in the scenario you describe the fronts would get hotter.

I would not expect you to need to do much braking descending between 10 and

20mph in 1st gear any way.
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Exit
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Agreed, they certainly would do under normal conditions, but does the front disc design allow waste heat to be dumped overboard much more efficiently than the rear drums?

In second gear, using the footbrake, with lots of weight, yeah we were having to use the brakes a lot.

Reply to
DervMan

inconsiderate

Funny thing I regualarly go down a very long steep descent (The Halley Brae) with some very nasty tightening radius curves and the brakes are usually cooler at the bottom than they were at the top -- thats what gears are for.

Reply to
AWM

To a point, however gears are for going and brakes are for slowing. I'll use a low gear for a hill or similar, but these days I use my brakes for slowing rather than deliberately slowing down.

Plus, I have never, ever ever used any brake components in any of my cars lives. :) I've had my own car now for nine years, four of 'em . . .

Reply to
DervMan

But probably much better at high speed ...

I think they're just not as efficient period!

Nah, even with weight in the back, going downhill and braking the fronts will be doing between 60-80% of the work (unless you have a strange suspension set up) so both ends were probably about as warm as each other ...

Reply to
pete boyall

Certainly . . .

This is true, but of course the Ka has a big bias towards the front, so it's not an issue.

Splendid; this is what I'm wanting to read. ;)

Reply to
DervMan

Cool. I drove up to Edinburgh the other day (M1, then A1/A1(M) to the bitter end), and was just thinking what a great idea a motoring holiday would be. One day I'd seriously love to investigate driving to Australia. Ok, so it'd take a while, and require absolutely shit loads of planning, but it's something I'd seriously love to do.

PEter

Reply to
AstraVanMan

How about a drive to the US....

However there are thoughts about a John O'groats - lands end dawn-dusk raid in the future....

Reply to
Tim S Kemp

In your amphibicar I presume ...

Reply to
pete boyall

Yeah, though it's strange; the rear discs on my car are huge, and yet I know that a lot of the street racers replace them with drums to save

16 pounds of weight. So why fit them in the first place?
Reply to
pete boyall

It's not impossible - I reckon we should try it as the ultimate 4x4 challenge - anyone know if there's a shipping company that operates across from Russia to Alaska?

I reckon London to Orlando should only take about 30 days. Need a convoy, two drivers in each vehicle, long range tanks and fuel heaters, look at it as a seriously daft "what's the best 4x4" (or "where did we leave the X5") expedition.

Reply to
Tim S Kemp

I'd be up for that. I managed Edinburgh to Bracknell in 5 1/2 hours last night, along with the worst economy I've ever experienced from the Fiesta :-(

It was either go quickly(!) or be on the road for another 60-90 minutes and risk driving tired.

But for driving at that sort of speed, the 2.5TDI-140 Audi A6 would actually be as good, if not slightly better.

Hmm...let me think, 75bhp 1.8TDi Fiesta, 140bhp 2.5TDi Audi A6.........hmmm......tough one, that!

Peter

Reply to
AstraVanMan

in

Have you seen Kermit's rear wheels? Big chunky rusty brake drums poking out behind alloys. :(

I'd imagine that it's possibly no cheaper to make drums these days than it is to make discs, and if we take a certain range (like the Focus, say), the sportier models have rear disc brakes as part of the package . . . and if Ford are buying ten million rear disc brake sets rather than five million disc sets and five million drum sets, they can squeeze for a higher discount because of volume.

We've a couple of Kas with a rear disc conversion, and whilst a disc looks better behind an alloy wheel, I cannot justify it on brake fade or brake performance grounds. Only on cosmetics, and for the money, it's not worth it.

At least the Ka's spoiler helps prevent water from getting on the rear screen! ;)

Reply to
DervMan

It's more of a challenge in a Ka.

Reply to
DervMan

Well idea should be for two drivers per car, I want to take my ovlov - hopefully brother will have his license back, or I might co-drive a Ka.

Remember - it's not a race....

Reply to
Tim S Kemp

Autocar got a Merc S320TDI to do it on one tank.

Reply to
Tim S Kemp

/Star Wars mode/

He's fast enough for you old man. /looks at Kermit/ This is the Ka that did the York to Forth Road Bridge run in under three hours.

Reply to
DervMan

But the loser gets to lick the winner's Ka klean with their tongue!

Reply to
DervMan

Last time I drove home it took about 11 hours (+ the ferry and a 20 mile drive on the island!!). Watford to Orkney.

Set off at 4 in the morning and arrived in John O Groats around 1500.

Graham

Reply to
Graham

Absolutely, but even on a cruise at 70 I doubt there'd be much difference economy wise between my Fiesta and the Audi. I normally average around

53mpg from the Fiesta, occasionally a bit higher, and twice I've managed around the 60mpg mark. Both times involved a lot of lower speed cruising on country roads (60mph max, but mainly 40-50mph). Even on a long run, sticking to 70 all the way, it'll only do about 52-53mpg. I reckon an A6 TDi-140 would pretty much equal this.

Anyway, if I was to do this now, I'd definitely take the Carlton over the Fiesta, no comparison.

Peter

Reply to
AstraVanMan

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