Engine braking / Using 6th gear

[trailZ4]

I've recently become obsessed with slowing my car down with the engine rather than using the brakes... i managed to get to work and back today without hardly using my brakes at all! I can think of one advantage of this is that my brake discs & pads may last a bit longer but are there any down sides to using engine braking all the time? I heard clarkson talking about it on top gear as if it were a good thing but u never know when he's taking the piss :wink:

Also, the Z4 is the first car I've had with a 6th gear and I find the car will comfortably cruise along at 30mph in 6th. This is what I tend to do when i'm driving 'economically' but i'm interested to know if driving at 30mph in 6th is actually that efficient?

All I know is that slowing down to 30 and sticking it in 6th makes me feel a bit less guilty after some 'less-economically' minded driving!!

 

[Z4 Beemer]

On the E89 you get a shift indicator, and at around 30-35 mph it does tell you to put it in 6th. As you say, it will happily sit at 30mph in 6th. Mind you, you get the shift-up indicator as soon as you hit about 2000rpm :?

 

[tomTVR]

brake discs & pads may last a bit longer but are there any down sides to using engine braking all the time? :

Well a clutch is going to cost you more money to replace than brakes.

I think my 3.0i will sit at 30 in 6th but only on a super flat road and it doesnt like acceleration from that speed!

 

[ajs]

IPSGA, Information,Position,Speed,Gear,Acceleration.
Advanced Police Driving teach you to use the brakes to slow and block gear change to suit your speed. IE as above, read the road with information you are receiving, position the vehicle to suit condition, adjust speed with brakes, select appropriate gear, and accelerate away.
All boring stuff, but brakes are for stopping and gears for going.

 

[christhomasleeds]

If you're going to engine brake you need to learn how to heel and toe... :evil: This matches engine speed to road speed and saves you killing your clutch. I would not recommend you practise this on the public roads as it's very easy to get it wrong and end up in the back of someone else or ploughing straight across the first roundabout you get too. If you want to learn get yourself on a trackday and learn safely.

 

[mmm-five]

If you're leaving it in gear then surely you're not wearing the clutch at all, as you're not slipping/riding it. Otherwise simply driving the car at 70mph for 3 hours would burn your clutch out.

There's nothing worse on motorways than people not leaving enough of a gap so they have to brake-accelerate-brake-accelerate. I prefer to simply lift of the throttle and slow down smoothly.

Unless I'm in track/race mode, I simply leave the car is a gear that doesn't strain it with too many nor too little revs, and only change up or down as needs be. If I'm cruising on the motorway in 6th and see the traffic slowing, I won't go down through the gears to get to 30-40mph, I'll simply leave in in 6th and lift off the throttle. If the traffic speed then picks up, I'll dip the clutch, blip the throttle and change into a lower gear for a quicker getaway.

When I need to brake harder than this, then the car stays in gear until I'm starting to come of the brake. If I need to continue braking, then I'll dip the clutch at about 1500rpm and brake to a stop. If it's emergency braking, then the same thing happens, just a lot quicker.

 

[stevedruidstone]

right gear for right engine speed is the most economic, brakes are for slowing, gate the gears as necessary

 

[Z4 Beemer]

If you're leaving it in gear then surely you're not wearing the clutch at all, as you're not slipping/riding it. Otherwise simply driving the car at 70mph for 3 hours would burn your clutch out.

There's nothing worse on motorways than people not leaving enough of a gap so they have to brake-accelerate-brake-accelerate. I prefer to simply lift of the throttle and slow down smoothly.

Yeah, that sounds right to me.

 

[Boogle]

When you're slowing down with the car *in gear* the engine shouldn't be using any fuel - not a drop. It's much better to gently slow down with the engine wherever possible, quite often the road will open up and you only need to accelerate a little bit rather than accelerating a lot (waste of fuel).

 

[trailZ4]

Yeah damaging the clutch was my main concern with engine braking so often, although I'm still not clear if what I'm doing is actually causing any extra wear on the clutch :| . I should point out that most of the time I'm doing this I'm trying to anticipate the traffic ahead and allowing the car to slow down by itself (loss of inertia), it's just when I do need to slow down a bit more I'm changing down, letting the clutch out smoothly and then again into a lower gear if needed. If I'm coming to a stop I might have ended up in 2nd and then I'll use the brakes. Sometimes using the brakes straightaway is unavoidable of course.

On motorways I tend to do the same as mmm-five, although I'm perhaps always a little too eager to change down. Not so much for slowing the car down but for the dramatic acceleration that inevitably follows

 

[Boogle]

Engine braking is unlikely to put much strain on the clutch - afterall it's just the resistance of the engine itself. You'll get more 'pressure' on the clutch when accelerating hard or driving up a hill. It's pretty much moot though, the only time you really get wear on the clutch plates is when they're slipping.

Get a piece of sand paper on a plank of wood, apply pressure and move the paper - the wood should follow the paper around. Notice that the wood is barely harmed. Now apply far less pressure and move the paper over the wood - notice the wood is being abraded. Same thing with the clutch, slipping = wear, not slipping = negligable.

If you're going to change down with engine braking, it's best to rev match to minimise the amount of slip.

 

[tomTVR]

If you're leaving it in gear then surely you're not wearing the clutch at all, as you're not slipping/riding it. Otherwise simply driving the car at 70mph for 3 hours would burn your clutch out.

If you want to maximise fuel efficiency then you need to engine brake through the gears. For example if you are in 50 zone and you see ahead theres a queue of traffic at the lights which clearly means you have to stop. To get the most engine braking you need to go down through the gears.

I am speaking from an MPG point of view rather than about saving the brakes which IMO shouldnt be a concern. Remember just because it's 'in gear' doesnt mean its using no fuel at all e.g if you leave it in one gear to engine brake, there comes a point when the car will stop decelerating and the ECU will start pumping more fuel into the engine to stop it from struggling. I think i read that decelerating in gear above 2000rpm and the car wont use any fuel but i cant verify that so could be wrong. So you really need to work the box to keep it in the sweet spot.

 

[cj10jeeper]

My biggest concern in this is you are likely to get yourself into situations of being in the wrong gear and end up in difficulty, either unable to accelerate away or reduced engine braking by being in too high a gear. As posted above right gear at all times.

The Zed is light and powerful but too high a gear is also uneconomical and strains the engine if it labours.

Just don't become obsessed with this 'game'

 

[Kiowan]

If you're leaving it in gear then surely you're not wearing the clutch at all, as you're not slipping/riding it. Otherwise simply driving the car at 70mph for 3 hours would burn your clutch out.

If you are in too high a gear for your road speed then any acceleration or maintaining speed will labour the engine and put strain on the clutch, if the car feels happy in the gear then it's fine but if in 6th gear at 30mph it struggles to pick up or becomes chuggy in any way then you are in too high a gear. Being in too high a gear does put strain on a clutch, the standard test to check a clutch's condition is to put it in high gear and accelerate, preferably up a hill, this is because at this point in time the clutch is under the most strain.

 

[Z4 Beemer]

Also worth remembering that cars with regenerative braking use the energy generated during engine braking to recharge the battery.

 

[cj10jeeper]

If you're leaving it in gear then surely you're not wearing the clutch at all, as you're not slipping/riding it. Otherwise simply driving the car at 70mph for 3 hours would burn your clutch out.

If you are in too high a gear for your road speed then any acceleration or maintaining speed will labour the engine and put strain on the clutch, if the car feels happy in the gear then it's fine but if in 6th gear at 30mph it struggles to pick up or becomes chuggy in any way then you are in too high a gear. Being in too high a gear does put strain on a clutch, the standard test to check a clutch's condition is to put it in high gear and accelerate, preferably up a hill, this is because at this point in time the clutch is under the most strain.

Nope - disagree. A clutch will never get damaged by simply being in too high a gear. It will get damaged when it slides, which amongst other things like aggressive starts, riding the pedal, slipping it on starts, towing, etc. does.

Sat in a high gear it is not sliding and thus not damaging itself, but if changing gear necessitaes slipping of the clutch to take up the torque it will

I agree that the standard test is to see if a clutch is damaged is to accelerate hard in the high gears.

If you were correct every car driving the length of the m'way in top gear would have a burnt out clutch.

 

[EdButler]

If you're contantly going down 6-5-4-3-2-1 when coming to a stop, thats way OTT in my opinion. 6-4-2 or 5-2 when coming to a stop would be the most for me as every gear shift you make going down will slip the clutch unless you rev-match perfectly.

Your car will likely burn a bit of oil driving like this, as the huge suction pressures of engine braking sucks in a little vapour from the crankcase.

Everything in moderation, but don't let it take over. The more you're concentrating on every gear change, heel-toeing etc, you're taking a little attention off the road

 

[bigshurv]

Driving at 30 mph in 6th sounds alarming to me, mine seems happy at 40,but I'd never take it down to 30. Seems far too slow, I'd worry about damaging the engine driving at very slow speeds in high gears. Labouring an engine does far more damage than revving one.

 

[Z4 Beemer]

Driving at 30 mph in 6th sounds alarming to me, mine seems happy at 40,but I'd never take it down to 30. Seems far too slow, I'd worry about damaging the engine driving at very slow speeds in high gears. Labouring an engine does far more damage than revving one.

Seriously? :?

Maybe its just different gear ratio's, but on mine, and I tested this tonight, I can basically go from just under 4000rpm in 2nd straight into 6th gear doing around 33mph. The car is perfectly happy with this and the engine doesn't struggle at all.

 

[Dav the wheel nut]

I've recently become obsessed with slowing my car down with the engine rather than using the brakes

Why? You haven't explained why you are doing it. It seems a pretty pointless exercise and it must be a real pleasure to be a passenger in a car when you're doing it. :roll: