Engine braking - OK or not OK?

[roxburd]

Hi all,

Do you use engine braking in your motorhome? I find myself using it a little from time to time and I suspect it's frowned upon by HGV instructors... but I've never had any instruction so I'm curious. I'd never driven a big diesel before last month. I've done the IAM motorcycle advanced test and they have a saying - brakes to slow, gears to go. It basically means that you shouldn't use engine braking. They also advise block-changing - changing to the gear you want all in one go, rather than changing one gear at a time and declutching between. And not changing gear at all until you've finished braking. It all depends on circumstance but they are general guidance points.

I try to drive my MH at a very leisurely pace - but I'm still occasionally tempted to use a little engine braking - for example, as I'm entering a roundabout with a little more speed than I'd like to carry round and the gear I want will give some braking.

I realise this might seem a bit 'who cares' to some but I've found myself wondering and so thought I'd see what people think... I suppose the important question is this: can gentle engine braking cause any mechanical issues?? I wouldn't have thought so...

Cheers
(let the disagreements commence)

 

[dunnah01]

Bimbling around the foothills of the Alps in France/Italy at the moment and letting the Comfortmatic decide what gear in the steep downhills. 3k about max with a dab of brakes now and then to try and stop it changing down a gear.

 

[autorouter]

On the other hand, I remember once coming down the Snake Pass in a howling gale, and having to actually accelerate to make any progress down the steep hill sections. That's what comes of driving a Hymer with the aerodynamics of a house brick, I suppose.

 

[denisejoe]

Driven every thing from motorbikes cars to artic lorries always used engine braking never burnt out a clutch.

 

[BouncyBoatFolk]

I suppose the advice on them signs prior to the start of steep declines instructing you to engage a lower gear would have been given heavy consideration before being placed with the litigious nature of society today
Mike.

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[L' Hobo]

I suppose the advice on them signs prior to the start of steep declines instructing you to engage a lower gear would have been given heavy consideration before being placed with the litigious nature of society today
Mike.

Those signs were good advice when some of the first trucks I drove still had crash gearboxes (no synchromesh)

On a steep hill driving an Artic, going up OR down, often the gear you were in was the one you stayed in because, the gearchange was so slow, you either had a downhill runaway truck because the brakes were unable to hold back the load OR, if you were going uphill, you had to stop and, hoping the brakes would hold and the clutch was capable (often both were not) try to start off again in a lower gear.

A couple of times in my early days (before motorways) when A roads were much steeper, I have had to reverse an artic to the bottom of a steep hill,( impeding uphill traffic), before starting again in 1st.
Remember , in those days, often the truck had NO power steering!

Today's truck drivers (nor I) wouldn't stand a chance!

 

[dunnah01]

Modern cars and vans have pretty much the same brakes that were fitted to some 1950s cars so no way would I trust them on a long descent

 

[Burge]

Our Van is Comformatic so don't have a choice

 

[BouncyBoatFolk]

When in Borneo I noted 2 trails of wetness on the very dry dusty roads. After following a heavily loaded timber lorry for a few miles it clicked, water cooled brakes. Those things weren't stopping without that modern addition. Link that to the peculiar road format of dual carriageways downhill, and single carriageway uphill!! Usually, overtaking was taking your life into your hands as the heavy trucks made about half a yard forward movement for every revolution of the driving wheels, not for faint hearted driving there, even though they like us drive on the left. Mandatory signs in red,engage lower gears, and run off zones in the mountain areas,handy if you can make it round the twenty, or thirty hairpin bends before the gravel traps.
Mike.

 

[L' Hobo]

Modern cars and vans have pretty much the same brakes that were fitted to some 1950s cars so no way would I trust them on a long descent

Sorry but that statement could not be further from the truth if you tried.

They may look similar BUT 1950's cars had solid rod operated brakes, no hydraulics only servo assist (if you were lucky)

No discs or pads, all drums and no ABS.

The shoes often included asbestos particles which was inhaled by the mechanic in the dust when he changed the shoes.

There is a lot more but I think that's enough to start with?

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[BouncyBoatFolk]

Yep, disc all round on my Fiat, servo assisted, and anti lock brakes that got a good work out on the way to Cornwall the other week. I rounded a corner on the A303 approaching the Andover Countess services roundabout, to be confronted by the back end of a stationary queue of traffic, the van pulled up straight and true, and the audible sound of the antilocks doing their job was reassuring, we actual stopped with tarmac still to spare, outstanding performance for a 4 ton van. I had new pads and disc's recently, so perhaps that helped as well.
Mike.

 

[Figaro]

I remember the brakes on my first car, a 1966 triumph herald
Brakes have definitely improved massively.

 

[Pausim]

My 9 speed Fiat auto with new 2.2 engine did some serious engine braking a couple of days ago. Clearly the designers think it is the right thing to do. Energy recovery by smart alternators also relies on the wheels pushing the engine to slow the vehicle down.

 

[Carpmart]

It’s one of the my biggest frustrations with my Motorhome. 3.0 Iveco engine, agile gearbox and 7T plus Motorhome the motor just doesn’t have the displacement to provide any meaningful braking.

The theory of engine braking vs real world application with this Motorhome are miles apart! I reckon that 2nd or 3rd gear may give me a tad more retardation BUT, modern lorry’s have good engine braking and me doing 40kph down a Pyrenees decent is likely a recipe for a being rear ended by a 44T truck.

I’ve just replaced the rear pads which were not in a good state and they have clearly gotten too hot on several occasions, despite my judicious cadence braking techniques.

I’ve been looking at retro fitting either an exhaust retarder brake or the selectable magnetic brake that fit on the prop shaft. Neither option is easy or cheap…

 

[Pausim]

My understanding is that a smart alternator adds 3 to 5 BHP to engine braking providing there is room in the battery to take the charge, with or without a gear change down. Anyone know differently?

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[SpeedyDux]

I remember the brakes on my first car, a 1966 triumph herald
Brakes have definitely improved massively.

My cars in the late 1960s and early 70s mostly had drum brakes and no servo assistance or ABS but in an emergency could lock all 4 wheels, so the brakes evidently could overcome the adhesion of the tyres (which were radial).

 

[Carpmart]

My cars in the late 1960s and early 70s mostly had drum brakes and no servo assistance or ABS but in an emergency could lock all 4 wheels, so the brakes evidently could overcome the adhesion of the tyres (which were radial).

- drum brakes vs radial tyres FTW. Shows that drum brakes were ‘good enough’ for the tyres available at that point!

Four locked up tyres ain’t helping the retardation...

 

[The Wino]

My mini had drums all around and adjusting them seemed to make them reasonably effective for about 1500 miles before requiring adjustment again!

 

[Guigsy]

Aren't braking distances about half what they were in the 50s? Even though the average car is far heavier. I know that's down to tyres too. But that implies modern braking systems can turn kinetic energy into heat several times more effectively. And repeatably too.

 

[jerryz]

Some modern motorcycles have the engine ecu and timing designed to massivley reduce or even entirely remove engine braking and also use slipper clutches . Some are aweful to ride , as you approach a corner and shut off throttle and the bike does not slow down unless you use the brakes ,, its horrible and Triumphs Bonneville range is worst offender ... lovely looking bikes but terrible engines .... A few Hondas do the same as do the new HD sportster ..
Slipper clutches can be Ok my2022 kawasaki Z900 and my Daughters Z650 have slipper clutches but still have great engine braking ..
When challenged about this idiotic no engine braking idea the designers and manufacturers say its to help new riders ????? How exactly ?????

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[roxburd]

Some modern motorcycles have the engine ecu and timing designed to massivley reduce or even entirely remove engine braking and also use slipper clutches . Some are aweful to ride , as you approach a corner and shut off throttle and the bike does not slow down unless you use the brakes ,, its horrible and Triumphs Bonneville range is worst offender ... lovely looking bikes but terrible engines .... A few Hondas do the same as do the new HD sportster ..
Slipper clutches can be Ok my2022 kawasaki Z900 and my Daughters Z650 have slipper clutches but still have great engine braking ..
When challenged about this idiotic no engine braking idea the designers and manufacturers say its to help new riders ????? How exactly ?????

Ah, the slipper clutches must be easier to activate on some models than others - I have a 2019 Thruxton 1200 R which has one but the engine braking is fine. A friend also has one and he even managed to bump start it, which I thought a slipper clutch would make impossible!

 

[jerryz]

Ah, the slipper clutches must be easier to activate on some models than others - I have a 2019 Thruxton 1200 R which has one but the engine braking is fine. A friend also has one and he even managed to bump start it, which I thought a slipper clutch would make impossible!

Its not just the slipper clutch its the weird ECU setup on modern bonnies its a deliberate , I tested a Bonny 865 and a 1200 , approached a corner at 60mph dropped to 5th gear ,, nothing happened dropped to 4the gear ,no engine braking , had to use the brakes ,, put me off buying one for sure ...

 

[autorouter]

My cars in the late 1960s and early 70s mostly had drum brakes and no servo assistance or ABS but in an emergency could lock all 4 wheels, so the brakes evidently could overcome the adhesion of the tyres (which were radial).

The theory is that adhesion is best just before they lock and slide. Once they are sliding the adhesion is quite a bit less. So ABS brakes automatically take the tyres to the locking point, then back off and repeat. So if you slam on the brakes you are almost always braking in the optimum point just before locking. Another bonus is that all four wheels keep their maximum grip, if for example the road surface is different under the wheels.

 

[Orion]

When challenged about this idiotic no engine braking idea the designers and manufacturers say its to help new riders ????? How exactly ?????

They wouldn’t get on with my Guzzis then! I can go for many, many miles on the California when I’m in ‘cruising’ mode without having to touch the brakes.

 

[tonyidle]

My understanding is that a smart alternator adds 3 to 5 BHP to engine braking providing there is room in the battery to take the charge, with or without a gear change down. Anyone know differently?

5 BHP absorption would require a 300A+ alternator. 1BHP = 746W.

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[tonyidle]

Our electric car (in common with most others probably) has a switchable regen mode. If that isn't in use throttle off feel is much the same as an ICE car. If it is in use one pedal driving is perfectly effective and can be used to bring the car to a standstill. Drivers who already slow by anticipation would find it completely natural and would only rarely use the brakes.

 

[Guigsy]

Our electric car (in common with most others probably) has a switchable regen mode. If that isn't in use throttle off feel is much the same as an ICE car. If it is in use one pedal driving is perfectly effective and can be used to bring the car to a standstill. Drivers who already slow by anticipation would find it completely natural and would only rarely use the brakes.

I hired a VW iD3 which, despite me expecting to hate it, I actually enjoyed. I quickly adapted to one pedal mode. Even throwing it down some back country roads, one pedal mode provided enough braking to have a bit of fun. It was the most useful in town though. It quickly becomes natural and more convenient that two-foot-coast mode, and it's probably saving a bit more energy too. My annoyance was that the iD3 only slowed to a creep speed. So I still needed to move my foot over to stop at lights and junctions, which just felt a bit awkward and unnecessary, like they were pretending it was an ICE automatic? I'm not sure if there's a technical or safety reason for this choice? As you said, some manufacturers have their cars come to a complete stop in one pedal mode.

 

[tonyidle]

I hired a VW iD3 which, despite me expecting to hate it, I actually enjoyed. I quickly adapted to one pedal mode. Even throwing it down some back country roads, one pedal mode provided enough braking to have a bit of fun. It was the most useful in town though. It quickly becomes natural and more convenient that two-foot-coast mode, and it's probably saving a bit more energy too. My annoyance was that the iD3 only slowed to a creep speed. So I still needed to move my foot over to stop at lights and junctions, which just felt a bit awkward and unnecessary, like they were pretending it was an ICE automatic? I'm not sure if there's a technical or safety reason for this choice? As you said, some manufacturers have their cars come to a complete stop in one pedal mode.

Don't think there's any technical reason. Creep can be useful for manoeuvring in confined spaces (ours doesn’t). It might be configurable and buried in the menus.

 

[jerryz]

They wouldn’t get on with my Guzzis then! I can go for many, many miles on the California when I’m in ‘cruising’ mode without having to touch the brakes.

Cali 850 1980 is my favoute Guzzi.. quite like the new 850 V7s .

 

[cyberyacht]

Using brakes wastes fuel. As the Daleks would say, 'Anticipate, anticipate'.

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[Orion]

Cali 850 1980 is my favoute Guzzi.. quite like the new 850 V7s .

Son currently has his eye on one of those, either the Stone Ten or the Special Edition. I’m more semi-old skool with a 1997 Cali EV, LM1000, project Dr John LM1100 replica 1985 AMA Endurance racer, and this beast: