Mikko

I have a question and some ponderings. I recently was dealt a blow at a driving school I am attending, as it seems my shifting/braking style is not permitted to use on the road test. My instructor, and later I found out, my friends, too all use their 'proper' technique, which is to engine brake to the fullest extent possible before using the vehicle brakes.

My habit/technique is to, whenever a more severe slow-down is required (even a planned one), simply clutch to disconnect the enginge and use the brakes with my right foot. Once I have stopped enough or at least slowed down to desired speed, I engage whatever gear that is most appropriate, usually second gear. It is all a very smooth operation, never any jerks of any kind, and the least wear and tear on the gearbox synchros and clutch.

Whenever I downshift or upshift, I rev-match. My driving instructor and friends don't do it, and if i want to pass the road test, I'm not allowed to.

Their way of doing it is - engine braking as much as one can instead of using the brakes. So approaching a slow turn or stop, right foot on brake, clutch with left, move stick to one gear lower, use drag mode on clutch to engine brake appropriately. Approach stop/turn in second gear, at very very low RPM's (verge of stalling). Ugh.

The way I see it, their way has these negatives:

* A lot of wear on the synchros (from trying to mate it when being perhaps 2000rpm off what it should be)

* Extensive wear on the clutch

* The roughest way of braking (due to using the transmission and different gears + clutch)

* The hardest way (balancing a clutch for braking is hardly easier than balancing the brake pedal)

* Provides unbalanced braking due to FWD or RWD. Imagine doing this on black ice in a RWD, heh.

* Brake discs will rust if only lightly used

* Not using the brake pedal will result in no brake lights coming on, confusing nearby traffic


What about the positives for their way? I can't see any. Not a single one.

How do you do it? What are your thoughts on it? I will be forced to do it their way, but as soon as I'm all done with this stuff, I'm going back to my own way unless someone can give me very good reasons to engine brake all the time instead of normal braking.

xviper

"Normal" deceleration: I prefer to rev match down shift immediately and if engine braking is enough, I'll continue down shifting till I eventually need to stop. If I need to slow down more than engine braking, I'll throw in brake useable as much as needed, continuing downshifting.
"Severe" braking: clutch in, use brakes. Worry about gear position when things calm down.
I put up a vid here showing my downshifting method:
https://www.s2ki.com/forums/showthread.php?...threadid=110562

Mikko

I do your 'severe' braking method all the time personally, or put in neutral and use the brakes.

The method the school wants me to use is to NOT rev-match, but holding the right foot hovering on the brakes all the time, and forcing (by riding the clutch) the lower gear in at the wrong revs, which causes some pretty nutty engine braking on older cars. On the A3 Turbo which is my student car (heheh), it hardly engine brakes at all. Feels like an auto throttle. I'm suspecting the ECU's in some new cars are simply programmed not to provide engine braking.

xviper

It is engine compression and gearing that provides engine braking. The ECU can't control this. If you shut the engine off at that moment, your car will still engine brake.
Diesels excluded.

Mikko

Shutting the engine off would of course result in it. But in this Audi A3, which is a normal manual transmission, there simply isn't any engine braking. Only some very very slight deceleration from the wind and tire roll resistance.

I'm at a loss.

xviper

I'm not saying to go and compare by shutting off the engine as this will most likely NOT be good for it but I'm thinking that is just the nature of the compression and gearing of the A3. The only way the ECU can hamper engine braking is to dump fuel in while you have your foot off the gas. Then you would see that in your idle speed. My '98 Grand Cherokee did something like this.
What is that car's compression ratio? And what sort of final gearing does it have? This might give you a clue as to why it is a lousy engine braking car.

Mikko

Here are the specs, if anyone can get wise on it:

Audi A3 1.8T (turbo)
Power: 150hp at 5700rpm
Torque: 155ft-lbs at 1750rpm
Compression Ratio: 9.5:1

I cannot find out the gearing, unfortunately, but it seems to be rather low. It can easily take off without using the gas pedal even in a slight uphill.. nutty. Torquey?

xviper

With that kind of compression, I would think that your car would have quite nice engine braking. Are you perhaps not downshifting while your rpm is still moderate? If you wait till your revs are quite low, then after the downshift, your revs will still be relatively low and hence, not get the kind of sensation that I get.
What rpm are you waiting for before downshifting. If I'm using engine braking, I don't let the revs get much below 4000 rpm to downshift (so just less than half of your max revs).

Mikko

That isn't my car, that is the student car the school has.

I did the downshifts from mainly third gear while RPM's were very low, then quickly stuck it into second gear with pretty much no jerking, with rpms quicky going up a bit (due to being forced into the lower gear).

I didn't get a chance to rev it very high nor to experiment. These things are expensive, 65-70 USD for a 1 hour and 10 minute session. Ugh. I'll be going back to many of those though.

I will not ever downshift in that car until rpm's at the current (higher) gear reaches closer to 1200rpms or so. I guess the rather overall low RPM's explains it to some extent. But even at 2000-3000 it didn't seem to engine brake at all, only the usual that comes even when coasting.

xviper

I believe you have just diagnosed the reason why you never experienced minimal engine braking.