My GTZ really lacks compression braking....

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Postby RomanV » Wed Sep 27, 2006 11:17 am

Say you're coming through a decreasing radius right hand corner in 4th gear, which slows down and links to an increasing radius 3rd gear left hand corner.

Even if you dont use the engine to brake at all, you've still got to get the car into third gear, to start accellerating through the left hand corner.
If you dont rev match at this point, you'll probably have some unwanted consequences.
Last edited by RomanV on Wed Sep 27, 2006 11:24 am, edited 1 time in total.
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Postby RomanV » Wed Sep 27, 2006 11:23 am

Chickenman wrote:
It was a totally theoretical situation.. if you aren't supposed to use your engine to brake (as someone else stated in this thread) then you wouldn't be changing down anyway and cruising around in 5th.


That's a load of bollocks, why wouldnt you change down gear at all? Do you take off from the lights in fifth?


As soon as you change down whilst slowing you are initiating engine braking.

But at some stage, usually the apex of a corner, you stop slowing down, and start accellerating again. Which usually necessitates a drop in gear or two. Now it's entirely possible to NOT use engine braking at all up until this point... And still have heel/toe as a technique to get the car in gear, to start accellerating.

So to drive without using engine braking you would have to put it in neutral/hold the clutch in and brake into the corner... where you would spinout as you tried to put it in gear to continue.

Unless you heel toe, but apparently that's impossible if you dont engine brake. :roll:

FFS, can't anyone use their brain these days.


Apparently not. :o
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Postby Chickenman » Wed Sep 27, 2006 11:49 am

Unless you heel toe, but apparently that's impossible if you dont engine brake. :roll:



Heel toeing shouldn't be done just to match revs... it would only be a viable alternative to changing gear if you were slowing down (your toes are on the brake pedal = slowing down or "braking") hence asking the engine to take some of the load at the same time (concurrently) as the brakes. So it's obvious that it wouldn't be required at all if you weren't slowing down.

I know you've been to a track day and you are now a fully fledged expert though so let me just say one or two more words.


I concur

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Postby Crucible » Wed Sep 27, 2006 2:07 pm

DB4G63 wrote:Hi All

My only gripe is living in hilly Dunedin when driving down a hill, changing gears to slow down does well.... bugger all. Even knocking her into second just makes her growl and well not really slow down much. Changing down in traffic is about as pointless, I feel myself overusing the brakes like (dare I say it ).... a dirty auto...


Dont forget even though the throttle is closed on gze's the intercooler, piping and blower etc is under continuous vacuum as its all after the throttle plate, a small leak at a joint etc would give the same result as a partially open throttle, may not be the case but could be a possibility.

thats why when front mount coolers are fitted on gze's they take a while after the throttle is closed to return to idle, just something to think about anyways 8)
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Postby Santa'sBoostinSleigh » Wed Sep 27, 2006 4:30 pm

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Postby AE85coupe » Wed Sep 27, 2006 6:47 pm

i just always figured brake pads are cheap

gearboxes/drivetrains are not

so i won't engine brake too much, don't see the point, obviously you will need to in some situations though
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Postby DB4G63 » Wed Sep 27, 2006 8:30 pm

It used to be magic when I was coming down lookout point in my old galant, I could just sit in 3rd and brake every 10 or so seconds, it barely sped up at all.

I guess compression braking doesnt work so good with lower compression. Apologies it is my first forced induction car.

I dont fully use engine braking to stop, just to keep speed constant or slow down a little. It usually complements real braking.

Engine braking is the ONLY solution to some hills in Dunedin. I travelled down from Highgate down through the town belt to the exchange in my old lancer and had alot of fade near the bottom.... was a bit freaky!
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Postby deaf_rattle » Wed Sep 27, 2006 9:12 pm

DB4G63 wrote:My only gripe is living in hilly Dunedin

yep, silly small town nz

RomanV wrote:
beeker wrote:I suggest you research your topics prior to making such statements. I've been on so many courses over the years and every professional instructors states such.

I've been surfing at beaches like Piha and Bethels for several years, and you can tell who does, and doesnt engine brake; by who's brakes are on fire by the time they get to the bottom of the hill.
Do you suggest that they dont drive down hills, as it obviously "isnt designed for that"?


i quite often get comments of, why dont your brakes smell as bad as mine etc when going out to bethels. engine braking is key.

driving out to bethels, i have to do that again soon, its been too long
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Postby AE85coupe » Wed Sep 27, 2006 9:14 pm

deaf_rattle wrote:yep, silly small town nz



its a city
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Postby deaf_rattle » Wed Sep 27, 2006 9:20 pm

i know, but anything south of the bombays and north of orewa is small town nz in my books :lol:
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Postby Dell'Orto » Thu Sep 28, 2006 12:18 am

AE85coupe wrote:i just always figured brake pads are cheap

gearboxes/drivetrains are not


Too bloody right...my step dad always told me I should use the engine more than the brakes, and that was always my reply.
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Postby RomanV » Thu Sep 28, 2006 9:39 am

Mmm, Boost wrote:
AE85coupe wrote:i just always figured brake pads are cheap

gearboxes/drivetrains are not


Too bloody right...my step dad always told me I should use the engine more than the brakes, and that was always my reply.


Says the guy with 4Ks and K50s :lol:

Getting an engine for half a pack of ciggarettes isnt what I'd call expensive.

I dont understand on what basis you guys think that engine braking is bad for your car.
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Postby fivebob » Thu Sep 28, 2006 9:44 am

RomanV wrote:I dont understand on what basis you guys think that engine braking is bad for your car.

Because gearboxes are designed to drive the car not the reverse. The loads are totally different when the car drive the gearbox. I've seen a few examples of a gearbox failures due to excessive engine breaking, usually in the lower gears.

Not that I'm saying engine breaking in itself is bad, but too much of it can be. Brakes are for stopping, engines are for going ;)
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Postby RomanV » Thu Sep 28, 2006 10:55 am

Fivebob you more than likely have the priviledge of driving cars that are more than well equipped in the braking department. (Maybe not the dirty holdens you have to drive? hehe)

I do too, with my MR2 it doesnt matter if I engine brake or not, I dont have any brake fade, etc.
Which is great!

However many other cars that I've driven, the only way it's possible to get to certain places, without having dangerously little control over your brakes, is to engine brake.

I've never had a problem doing this, as well as everyone else I can think of.

How do you know that the gearboxes were damaged by engine braking?
I could understand that intentionally shock loading the gearbox (for the sake of compression locking etc) in the opposite direction could make bad things happen, and I wouldnt be surprised if a gearbox or two blew up doing this.
However engine braking in a sensible manner, not dumping the clutch out etc, I dont see how it could cause problems, and in my personal experience (including everyone I know, pretty much) it hasnt caused any problems.

Also, some trucks are designed with engine braking in mind. How would the gearbox design differ, to a regular car etc? Not being a smart ass, just curious.
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Postby fivebob » Thu Sep 28, 2006 11:17 am

RomanV wrote:How do you know that the gearboxes were damaged by engine braking?

By the nature of the damage.
I could understand that intentionally shock loading the gearbox (for the sake of compression locking etc) in the opposite direction could make bad things happen, and I wouldnt be surprised if a gearbox or two blew up doing this.
However engine braking in a sensible manner, not dumping the clutch out etc, I dont see how it could cause problems, and in my personal experience (including everyone I know, pretty much) it hasnt caused any problems.

In a sensible manner it's ok, but a lot of people overdo it. It's not only bad for the gearbox, it's also not good for the engine. I'm not saying you'd notice the difference in most cases, and there's nothing overly bad in using some engine braking. In fact some engine braking is good for handling (why I don't like autos), but I wouldn't use it as an alternative to brakes (even in the Holden).

Also, some trucks are designed with engine braking in mind. How would the gearbox design differ, to a regular car etc? Not being a smart ass, just curious.

Ever seen the inside of a truck gearbox...they're heavy for a reason ;)
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Postby Adamal » Thu Sep 28, 2006 3:31 pm

Most of the replies in this thread come across as if you're saying you should ONLY use the brakes or ONLY use the engine.

Use BOTH people, BOTH :P
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Postby Silent Knight » Thu Sep 28, 2006 3:41 pm

Pffffttt you are all pussies.

All I have is a whole next to the drivers seat and thick metal rod I push hard against the road when I need to brake. 8)
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Postby RomanV » Thu Sep 28, 2006 4:01 pm

Yes but you also use a rudder to steer that thing, we're talking about cars here.
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Postby AE85coupe » Thu Sep 28, 2006 6:30 pm

RomanV wrote:Yes but you also use a rudder to steer that thing, we're talking about cars here.


oh man, thats gold!
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Postby Dell'Orto » Thu Sep 28, 2006 8:09 pm

RomanV wrote:
Mmm, Boost wrote:
AE85coupe wrote:i just always figured brake pads are cheap

gearboxes/drivetrains are not


Too bloody right...my step dad always told me I should use the engine more than the brakes, and that was always my reply.


Says the guy with 4Ks and K50s :lol:

Getting an engine for half a pack of ciggarettes isnt what I'd call expensive.


Actually, the last one I was offered was for a tinny :lol: Also Lucas brake pads from work = $12 :lol:
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