Mechanical Sympathy.Thing of the past.

Mechanical Sympathy.Thing of the past.

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colonel c

Original Poster:

7,888 posts

238 months

Tuesday 21st August 2018
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Looking at my recent service invoice for my Defender. I see an advice note stating ‘rear brake discs required next pad change’.
Nothing unusual there. However it got me thinking. In forty odd years of motoring I have never had to replace disks before. Very rarely pads and never a clutch. I like to think this is down to some extent of driving with a scene of mechanical Sympathy. Is this another part of driving that will fall by the wayside as EVs and sophisticated hybrids takeover from the conventional internal combustion engine and mechanical power train?

TooMany2cvs

29,008 posts

125 months

Tuesday 21st August 2018
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Discs are a consumable. Always have been, always will be. Work on 2-3 sets of pads to one of discs, and you're probably about right.

If anything, EVs and hybrids will reduce brake wear, because light retardation's done by increasing the regenerative demand, and using the drag of the generator to slow the car. But that might increase disc corrosion...

Ninja59

3,691 posts

111 months

Tuesday 21st August 2018
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Going at the rate I am with my car I will stretch the pads to over 70k, let alone discs!

Either way driving with anticipation allows less heavy braking and reduces wear it does amaze me that some people manage to wear pads out quite quickly, although some cars do seem to start with less meat on the pads anyway.

Haltamer

2,454 posts

79 months

Tuesday 21st August 2018
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It's easier to be sympathetic in an EV, in many ways.
No clutch to ride, or transmission to damage:- Any overheating of motors can be controlled by the vehicle ECU, as in Teslas, Just cutting off the top end of power.

Discs will most likely be corroding:- Regeneration should be enough for regular gentle braking; See the Audi EV Rolling down pikes peak without touching the brakes!

The most unsympathetic thing you can do is mistreat the battery; through lots of extreme (100%) charge cycles.

HustleRussell

24,602 posts

159 months

Tuesday 21st August 2018
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When I do pads I pretty much always change the discs, even if they're within tolerance. They're bloody cheap.

wst

3,494 posts

160 months

Tuesday 21st August 2018
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I am curious to see how long it is before cars no longer require "running" brakes. They'll need something to keep them stationary when parked (and would be a useful "emergency" brake... hmm... sounds like that won't use or need fancy tech) but realistically there's insane amounts of control that can be achieved with a motor. The brake pedal can just become a deceleration request and the car can work out how best to achieve that (given all of the parameters), with no mechanical wear.

Car-Matt

1,923 posts

137 months

Tuesday 21st August 2018
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I got 72k out of my last set of discs/pads on my 320, they weren't down to the bare minimum either but I was going on a big road trip and wanted the car tip top before I went. I was most surprised

otolith

55,899 posts

203 months

Tuesday 21st August 2018
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Clutch wear is largely to do with mechanical sympathy or lack thereof. Braking friction surfaces - more to do with being efficient and / or slow.

bloomen

6,857 posts

158 months

Tuesday 21st August 2018
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You can be as sympathetic as you like but if your terrain doesn't suit things will wear out.

My main driving is up and down goat tracks that require constant cornering and braking and pummels the suspension. I don't cane the car. The countryside certainly does.


anonymous-user

53 months

Tuesday 21st August 2018
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On a defender, the rear discs are more likely to be knackered due to corrosion than actual use..........

Ardennes92

606 posts

79 months

Tuesday 21st August 2018
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Trouble is with modern vehicles the electronic nanny likes using the brakes for esr/tcr/vectoring and acc etc, whereas many humans use feel

RobM77

35,349 posts

233 months

Tuesday 21st August 2018
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It's something I often think of and I'm not sure if it's strictly mechanical sympathy or not... Like I suspect you do, if I'm doing 50mph in a 50 limit and see a 30 limit coming up, I try to judge where I can back off so that I'm doing 30mph when I enter that limit without braking. Likewise, if there's a bend coming up I judge the turn-in speed I want in a similar fashion. Same for junctions, traffic lights (cold or hot etc) etc. I've noticed that most people don't do this, and I've often wondered why. Is it all the cycling I do and how that gives me an appreciation of energy and momentum? Or is it mechanical sympathy? I'm not really sure.

One interesting result of this is that despite driving very quickly, I record pretty high mpg figures. The downside is that when I'm a passenger and people are actively driving their car towards a red light it makes me squirm a bit.

One thing it might be is simply looking and thinking further ahead... Most of the driving problems that certain bad drivers I know have simply boil down to not looking far enough ahead. This also shows on motorways, where I'd hazard I guess you can stick to a speed and flow in and out of lanes appropriately, whereas others seem to be constantly slowing for lorries and then accelerating to pass them - this isn't mechanical sympathy, just thinking ahead.

TooMany2cvs

29,008 posts

125 months

Tuesday 21st August 2018
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Max_Torque said:
On a defender, the rear discs are more likely to be knackered due to corrosion than actual use..........
I did wonder if they might be corroded - especially since they aren't in use for the handbrake.

Reg Local

2,676 posts

207 months

Tuesday 21st August 2018
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RobM77 said:
It's something I often think of and I'm not sure if it's strictly mechanical sympathy or not... Like I suspect you do, if I'm doing 50mph in a 50 limit and see a 30 limit coming up, I try to judge where I can back off so that I'm doing 30mph when I enter that limit without braking. Likewise, if there's a bend coming up I judge the turn-in speed I want in a similar fashion. Same for junctions, traffic lights (cold or hot etc) etc. I've noticed that most people don't do this, and I've often wondered why. Is it all the cycling I do and how that gives me an appreciation of energy and momentum? Or is it mechanical sympathy? I'm not really sure.

One interesting result of this is that despite driving very quickly, I record pretty high mpg figures. The downside is that when I'm a passenger and people are actively driving their car towards a red light it makes me squirm a bit.

One thing it might be is simply looking and thinking further ahead... Most of the driving problems that certain bad drivers I know have simply boil down to not looking far enough ahead. This also shows on motorways, where I'd hazard I guess you can stick to a speed and flow in and out of lanes appropriately, whereas others seem to be constantly slowing for lorries and then accelerating to pass them - this isn't mechanical sympathy, just thinking ahead.
Completely agree.

I’ve been driving for 32 years & well in excess of a million miles & I’ve never had to replace a clutch. I’ve had my current car from almost new - it’s close to 40,000 miles now on it’s first set of brake pads & they’re absolutely nowhere near ready for replacing. And no, I don’t drive it slowly (see my Youtubes!).

A friend has had his car from new & it’s now on 240,000 miles & still on its first clutch.

An anticipatory driving style translates automatically into a mechanically sympathetic driving style (and a more fuel efficient style).

Mrs Local, on the other hand...

kambites

67,462 posts

220 months

Tuesday 21st August 2018
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It depends a lot on the car. Our Octavia has just had what I believe is its second set of pads at about 120k miles. Certainly the first set in the 40k miles we've had it. The Elise is on its fourth set at <50k miles.

I've never replaced a clutch on a road car.

66mpg

648 posts

106 months

Tuesday 21st August 2018
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Another point to consider: since the demise of brake pads with asbestos the friction material wears the disks much faster. We’re all going to be buying more disks than we used to.

spookly

4,011 posts

94 months

Tuesday 21st August 2018
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Driving in a way to conserve brake pads and disks makes Jack a dull boy.

DickyC

49,549 posts

197 months

Tuesday 21st August 2018
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spookly said:
Driving in a way to conserve brake pads and disks makes Jack a dull boy.
When I had an early commute from Newbury to Norbiton I liked to see how far I could get without using the brakes. The rules were, simply, don't piss anyone off. I made it to Kingston Bridge one morning. Fifty miles or so. It's about anticipation and timing. And smoothness. And not pissing anyone else off. Not dull at all. Enjoyed it.

kambites

67,462 posts

220 months

Tuesday 21st August 2018
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I once drove my MGB from somewhere around the top of the M3 to Nottingham with no clutch fluid... that was a lesson in reading the traffic ahead. Especially when I got to Nottingham in the rush hour.

Mave

8,208 posts

214 months

Tuesday 21st August 2018
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66mpg said:
Another point to consider: since the demise of brake pads with asbestos the friction material wears the disks much faster. We’re all going to be buying more disks than we used to.
It's probably been 20 years since they stopped putting asbestos into brake pads so I think we should be used to it by now! :-)