Driving Style & Engine braking

[McGreggor]

Hi,

I do like the auto box in my car, but like most auto drivers, I miss the control of a manual now and then. Thankfull its not that often, certainly not enough to warrant any "go buy a manual" remarks thanks! I'm just wondering if its safe enough to manually drop the auto box down a couple of gears when needed, or is this a no-no?
I generally use this in one of two situations:
1). To engine brake, slowing from 40 to a red light, I may select 2nd to slow up, works very well!
2). In advance of hooning it out of a corner, selecting 3rd say and then giving it some. More stress to the car with this one, though i'd best check on here!

 

[mark.t]

i do it

I sometimes use the gears to engine break mines a diesel though...I do use the box sometimes just for overtaking and have a bit of a play..I hold it in gear mainly to give it a good blow out ....I also do it in my dads 180k auto but use the tip box on that if i'm buggering anything up someone on here will let us know

 

[IanA2]

That's the way I've been driving for years..........

 

[Ian B Walker]

My advice for whats it worth is not to select 2nd gear while travelling. Read that somewhere, possibly in a manual for my ex 190.

 

[Dieselman]

The electronic boxes won't let you do anything that's bad for the car. You can choose which ever gear you like, if it's going to over rev the engine it won't change into that gear.
I personally wouldn't use the gears for braking as the more changes a box makes the more it wears and it's a lot cheaper to replace pads and disks than a gearbox.
Occasionally I will use engine braking and boy does it work in a diesel.

 

[Simon]

It's a lot cheaper to replace pads and disks than a gearbox.

Spot on.

 

[mercmanuk]

brakes or gearbox

sorry gents,check with the STEALERS gearbox £4000.00 brake pads £50

 

[nickmann]

If you're driving up or down a big long hill then there is a case for using the 'box to make life easier, either in terms of avoiding constant up and down changes when travelling uphill, or in terms of avoiding brake fade when going downhill. I humbly suggest that these conditions are far more likely to be encountered in the Alps than in the High Street, and if you live in those environments then you have to accept a shorter 'box life.

Note that the 'box ECU will ignore any selection that would cause damage, ie you can select 1st at 100mph if you like, and nothing will happen. It will physically prevent you by lockout from selecting R or P as well.

 

[calum]

One obvious comment: given the twats that drive so close behind, slowing down without any brake lights on might not be the best thing to do, so perhaps brake *and* change down...?
Not that the scrotes will pay any attention, anyway.

 

[McGreggor]

Thanks for the advise, all taken on board.

Glad to know you can never knock it in to reverse on the motorway by mistake, I did wonder if that was possible....

Nice to know I can keep it in 2nd around the tight twisty lanes of Lewes, this gives me better control I feel at lower speeds. This morning on my usualy route, I wasn't manually selecting gears, and pulled away from lights on a steep hill, got going in to 2nd, and then had to let off in advance of another junction. Just as I let off, the box changed to 3rd and the car slightly lurched forwards, though probably just seemed to lurch as the engine braking was suddenly removed and I was on a slight downhill slope.

 

[se97mlm]

I know for a fact that the overrun deceleration on modern CDI engines is controlled by the ECU so it's definately ok. This is needed because the severe engine braking effect on a diesel could cause the vehicle to become unstable if it was uncontrolled.

I have been optimising this particular map today at work for a new chinese engine.

 

[nickmann]

Thanks for the advise, all taken on board.

Glad to know you can never knock it in to reverse on the motorway by mistake, I did wonder if that was possible....

QUOTE]

It's both clever and simple - you can move the lever into 1st and nothing will happen as the ECU will simply ignore your "Request" This is because 1st-4th are electronic switch settings on the lever mechanism. Selecting 1st is an electrical impulse that can be overridden to protect the car from the driver.

PRN&D are physical, mechanical settings on the lever mechanism, this means if the lever is moved in these positions, big oily things move because they are on the end of the lever. This means if you put the lever in R on the motorway then the box will select R. HOWEVER, the car will prevent you from moving the lever by physically locking off the gate. This is done using the cable mechanism that holds the gate in P when the ignition is off and the footbrake not applied. This failsafe kicks in at about 10mph, no doubt using the same trigger as the auto-door locking

This means on the motorway, shifts into 1st are ignored, and shifts into R are prevented.

Interestingly, if you are coming to a halt and you select R **just** as the speed falls below threshold the gear goes in but throttle is ignored. Also you are going backwards and select D before you stop then the gear is selected smoothly but any throttle pedal movement is ignored. (unless you are in 'W'-mode when the anti-rollback thingy stops the car dead and you end up in the back seat!!).

So, MBs not much good for auto-testing then

 

[Flyer]

Interestingly, if you are coming to a halt and you select R **just** as the speed falls below threshold the gear goes in but throttle is ignored.

I did that once in mine, gearbox may have been engaged, but brain certainly wasn't . I was in a car park and spotted a space. Still moving forward, for some inexplicable reason, I shifted into reverse, before stopping. Probably moving about 5mph ... The gearbox made a *very* loud clicking noise, but did shift. Not had any adverse effects luckily, but did spook me.

My excuse is that it was after a long drive upto Fort William and I was tired and it was raining and .....

 

[Thmsshaun]

Had a similar clicking sound when I for some reason moved it into park just before stopping. Never done it since

 

[portzy]

Had a similar clicking sound when I for some reason moved it into park just before stopping. Never done it since

I get a clunk when I go straight from R to P but strangely not when I go straight from D or N and THROUGH R to P without stopping .

Portzy.

 

[ixy]

This is slightly related I think . . .
My C180K is the first AUTO I've had. My question is how long is it OK to leave in 'Drive' with brake on, i.e waiting for red lights, etc. If it's going to be a while then best to change to N to save wear on clutch, is this right?

 

[BonzoDog]

Nickman seems to have it right. Most of the time I can't be bothered doing any manual changing as the automatic is so good but I have noted that with my new diesel, engine braking is far better. This is reassuring.
Last year, coming down an Austrian pass with my wife driving our automatic, petrol Saab, even with engine braking, the discs got so hot that they started smoking, at which point my wife's casual comment, "The brakes don't seem to be working too well" resulted in a few heart stopping moments until we could safely pull in.
The revs on the petrol Saab are so high as to make engine braking almost ineffective. this is not a problem in our Murky B. We have to tackle the same pass in the summer again but this time I will drive.

 

[Dieselman]

This is slightly related I think . . .
My C180K is the first AUTO I've had. My question is how long is it OK to leave in 'Drive' with brake on, i.e waiting for red lights, etc. If it's going to be a while then best to change to N to save wear on clutch, is this right?

Just leave it in D. The torque converter isn't affected by slippage.

 

[Dieselman]

Last year, coming down an Austrian pass with my wife driving our automatic, petrol Saab, even with engine braking, the discs got so hot that they started smoking, at which point my wife's casual comment, "The brakes don't seem to be working too well" resulted in a few heart stopping moments until we could safely pull in.

It would have been the pads overheating causing the smoke. The pads are not too much to worry about, it's the brake fluid that's the real problem. Air bubbles and hydraulics don't go together.
Wifey was going too fast and using the brakes too much.

 

[fwb44]

Thanks for the advise, all taken on board.

Glad to know you can never knock it in to reverse on the motorway by mistake, I did wonder if that was possible....

QUOTE]

It's both clever and simple - you can move the lever into 1st and nothing will happen as the ECU will simply ignore your "Request" This is because 1st-4th are electronic switch settings on the lever mechanism. Selecting 1st is an electrical impulse that can be overridden to protect the car from the driver.

PRN&D are physical, mechanical settings on the lever mechanism, this means if the lever is moved in these positions, big oily things move because they are on the end of the lever. This means if you put the lever in R on the motorway then the box will select R. HOWEVER, the car will prevent you from moving the lever by physically locking off the gate. This is done using the cable mechanism that holds the gate in P when the ignition is off and the footbrake not applied. This failsafe kicks in at about 10mph, no doubt using the same trigger as the auto-door locking

This means on the motorway, shifts into 1st are ignored, and shifts into R are prevented.

Interestingly, if you are coming to a halt and you select R **just** as the speed falls below threshold the gear goes in but throttle is ignored. Also you are going backwards and select D before you stop then the gear is selected smoothly but any throttle pedal movement is ignored. (unless you are in 'W'-mode when the anti-rollback thingy stops the car dead and you end up in the back seat!!).

So, MBs not much good for auto-testing then

I never knew it was that clever. Impressed