DECELERATION - Clutch ENGAGED or NOT?

[crisp]

Thought I'd see what responses I'd get... if the question were posed on clutch engagement practice under deceleration.

Whatever the state... as argument relative "engine braking" or "stability drag"... how do YOU load your drivetrain in the midst of the various deceleration scenarios you experience with your car... and WHY?:icon_bigg




-crisp

 

[modmonster2008]

clutch in and put in neutral, using the power of 4-wheel disc brakes haha

 

[tekdeus]

clutch in and put in neutral, using the power of 4-wheel disc brakes haha

Same here. Except when I'm doing repeated hard stops I'll use engine braking to put a little less heat on my brakes.

 

[Poodles]

I remember being taught in driver's ed. here that's it's illegal to coast in neutral or with the clutch in.

Not that they could possibly know you were doing it, but it all depends on the type of stop I'm doing.

 

[IJ.]

ALWAYS use engine braking, doesn't add much in a Mk3 due to the weights,3.0L low comp engine but it's nice having the engine loaded in case I need to accelerate again. (might have something to do with I'm on the same set of brake pads that I fitted when I did the BBK back in 2002, I know the AP Callipers have thick pads to start off with but I haven't even hit 50% yet)

Even now I'm auto I have a failrly agressive downshift map programmed in to the controller.

 

[jetjock]

Great. Yet another thread where we see people who think they know how to drive versus those that really do...

 

[Dirgle]

I prefer to keep the drivetrain engaged as much as possible encase I need it. Besides, the engine cuts fuel on decel so I can get a few extra miles out of the tank.

 

[SupaMan]

Engine braking always, sometimes down shifting.

If im coming to a light i might go down a gear and then let that drop all the way out and when its almost at idle push the clutch in.

I very recently just heel-toe'd the supra for the first time, I could do it in my omni because the pedals were so close but i couldnt quite get it in the supra.

 

[Jayhall]

My clutch goes in only for gear changes. Rev matching with the "heal-toe" is the only way I downshift. I say it like "that" because my foot covers enough of both pedals to operate them the way I want when slowing down

 

[thedave925]

Jetjock: Generally its the people that don't focus on the road who get into accidents which makes them the ones that can't drive
And i hate people that weave through traffic!!

Crisp: Decelerating is all about what i'm doing in the car moment to moment.
If I'm hotrodding around town enjoying myself, i'll heel-toe rev-match through the gears till second, just to hear the obnoxiously loud exhaust and show off that it's a manual gearbox. The car turns head anyways, why not give them more reason to stare lol
In the end I prefer going to neutral and applying the appropriate brake pedal pressure for a smooth stop to the chosen point, over engine braking. Something about fuel conservation, conserve, conservative

 

[Dirgle]

Umm.... The engine cuts fuel when you use it to decel via engine braking. If you put it in neutral it continues to idle and consume fuel. Taking it out of gear is counterproductive to conserving fuel. But is I suppose fuel conservation is weak ground to establish a point with these cars anyways anyway.

 

[thedave925]

LOL I suppose is a half-full half-empty perspective thing. I drive her easy but lay into the throttle lots anyways.
I just don't like to be all loud with the exhaust if i can help it.

 

[supramk3speed]

I use the idle and downshifts depending on what i feel like. I usually downshift if im slowing down to make a turn but i generally put it in nuetral at stop lights because i don't want to sit there holding in the clutch. That would just be a pain.

 

[Dirgle]

LOL I suppose is a half-full half-empty perspective thing. I drive her easy but lay into the throttle lots anyways.
I just don't like to be all loud with the exhaust if i can help it.

Yeah I'm the other way around, Brakes are a necessary from of waisting energy. They take the kinetic energy of a moving vehicle and convert through friction into heat, which is then dissipated into the atmosphere. It is a waste of energy, though they have to be used. So I use them only as necessary. Engine braking is a more efficient (if only slightly) means of decelerating.

 

[thedave925]

I've got crappy fast fading pads that need the assistance of engine braking if i'm going from illegal velocity to dead-stop ASAP. A serious downshift will buy me a couple lengths off the total stop distance, these cars can STOP.

It would make sense the engine stops sending fuel during engine braking, using cylinder compression to slow the vehicle.

 

[fixitman04]

its an auto.....therefore it does what it wants!

normally i leave the cluch in, and engine brake

 

[Flateric]

It depends on how I'm driving and what mood or situation I am in. If I'm taking it real easy and I obviously won't be accelerating I prefer to clutch in. My thinking is that brakes are far cheaper then powertrain parts. Also much easier to replace. If there is a chance I'm going to need to accelerate but I'm not ripping around aggressively I'll still be sure to match the given speed to the appropriate gear so that it is a simple matter of dropping the clutch back into gear and rev match.

 

[crisp]

ALWAYS use engine braking, doesn't add much in a Mk3 due to the weights,3.0L low comp engine but it's nice having the engine loaded in case I need to accelerate again. (might have something to do with I'm on the same set of brake pads that I fitted when I did the BBK back in 2002, I know the AP Callipers have thick pads to start off with but I haven't even hit 50% yet)

Even now I'm auto I have a failrly agressive downshift map programmed in to the controller.

My philosophy as well. I was always "taught" to maintain engine/drivetrain "engagement" with the exception of slow-roll situations. My motorcycling experiences are similar philosophy, even though you are pushing a MUCH higher compression and delivering substantial backlash through the system. The biggest reason engagement is preferred for me is not the effect of DECELERATION provided as "engine braking", but DRAG that provides stabilization... not unlike the tail of a kite or rudder on a ship. Free-wheeling, especially from VERY HIGH speeds can be extremely unstable... particularly at the transition point from ON throttle hard to OFF throttle accompanied by DIS-engaging the clutch! Very pad pizza for control... if a lot less "stress" on the system.

So... my primary point in asking was FIRST to stir up a bit of banter and see where others experience and logic would take the discussion, and SECOND, to see what people had to say about it relative two SPECIFIC scenarios:

1) FULL THROTTLE RUN on DYNO DRUM

My thoughts are that this is an "exception" scenario to leaving the clutch ENGAGED on decel, and I would/do DIS-engage the clutch and BLIP THROTTLE to take the load off the system as driven by the drum and "feather" the motor to introduce varied lubrication and coolant circulation for cooling, etc... after the heavy loading from the pull.

2) FULL THROTTLE RUN in UPPER/TOP gear to VERY HIGH SPEEDS... then off throttle

My thoughts here are that I maintain ENGAGEMENT in this case, as I DON'T want to be "coasting" at buck-and-a-half speeds and down, but I DO wonder about the lash/strain from such higher velocities to off-throttle. Never had an issue to speak of, but it's always been a point of some concern to me when doing an all-out run. Any thoughts on this scenario?

Great. Yet another thread where we see people who think they know how to drive versus those that really do...

So... I'm actually quite pleased that you chimed in! Hopefully, you have some words of wisdom to counter those in the "THINK" camp and better arm those of us who lack the resource and/or experience to know better by our own accord.:1zhelp:


-crisp

 

[nick88]

Double clutch and engine brake.

 

[RazoE]

in the 92, I just clutch in and brake, I used to engine-brake but I don't really feel the need..

in my 89, since I'm running an atmospheric BOV (which I'm going to recirculate, just waiting on the fittings, hopefully they arrive this week), I engine brake inorder to prevent stalling, plus it sounds bad ass with my exhaust system (yes, ricer, I know, that's why I'm changing my entire set-up to be much quieter, hence recirculating BOV)...

In the 86.5, it's either, as it's NA but it has a nice exhaust on it, so I like to engine brake a bit to hear it...