Lingo help!

[sfr rob]

hey guys, help me out here....
i need a few things explained.

what is a Stall Converter.... and what does it do?


DIFF RATIO's.
I have been reading heaps about it on the forums... but can someone explain to me how changeing the DIFF ratiios helps performance?
i think it has something to do with smaller gear cogs yeah?
ah.... i forgot al my other questions...
so i might ask more later.. butyeah if you can explain that for me it would be ACE!
thanks
rob :

[bathurst77]

taller diff ration (low number to one) means higher top speed. more kmh per rpm, so also lower fuel consumption on highway
shorter diff ratio (higher nuber to one) means less kmh per rpm but peppier acceleration

[bathurst77]

btw..love your avatar

[Casper]

Originally Posted by sfr rob

hey guys, help me out here....
i need a few things explained.

what is a Stall Converter.... and what does it do?

This should explain it for you:
http://www.gnttype.org/techarea/tran...onverters.html
DIFF RATIO's.

Originally Posted by sfr rob

I have been reading heaps about it on the forums... but can someone explain to me how changeing the DIFF ratiios helps performance?
i think it has something to do with smaller gear cogs yeah?
ah.... i forgot al my other questions...
so i might ask more later.. butyeah if you can explain that for me it would be ACE!
thanks
rob :

Easiest way to explain the diff ratio is to think back to the old 10 speed push bikes. If you had a tall ratio (the little cog at the back wheel) it was harder to get moving but you could get up quite some speed for very little rpm (of your legs). If you used the short ratio (biggest cog at the rear wheel) you could launch like a demon but couldnt go very fast before your legs could no longer keep up. They did not effect your overall power (your legs were the same strength for both) but one was certainly better for fast launches and one for high speed cruising.
Same rules apply for a car. Tall diff (lower number:1) is sluggish off the line but uses little effort (rpm) to cruise at a higher speed. Short ratio (higher number:1) will blast you off the line but you need a lot more rpm to get the same cruise speed.

Hope this helps.

[sfr rob]

Originally Posted by Casper

what is a Stall Converter.... and what does it do?

This should explain it for you:
http://www.gnttype.org/techarea/tran...onverters.html
DIFF RATIO's.


Easiest way to explain the diff ratio is to think back to the old 10 speed push bikes. If you had a tall ratio (the little cog at the back wheel) it was harder to get moving but you could get up quite some speed for very little rpm (of your legs). If you used the short ratio (biggest cog at the rear wheel) you could launch like a demon but couldnt go very fast before your legs could no longer keep up. They did not effect your overall power (your legs were the same strength for both) but one was certainly better for fast launches and one for high speed cruising.
Same rules apply for a car. Tall diff (lower number:1) is sluggish off the line but uses little effort (rpm) to cruise at a higher speed. Short ratio (higher number:1) will blast you off the line but you need a lot more rpm to get the same cruise speed.

Hope this helps.

thanks i now understand the diff ratio thing...

but the converter link...... well i still dont GET IT! ! ! ! !
dont know why.... hahaha

What is the best way to go with the Diff Ratio's?
i am guessing in the middle would be good... but i guess that is what is probably already standard?
tall gears would mean slow shitty acceleration, better fuel economy.
Short gears would mean... very touchy at low speeds and responsive. crap at higher speeds and more fuel consumption.
Would there be a way to have short first 3 gears... then a tall 4th for "over drive" ??
it:

[sfr rob]

Originally Posted by bathurst77

btw..love your avatar

thanks...
i made it my self!
haha nah..

[dogbreath_48]

Originally Posted by sfr rob

What is the best way to go with the Diff Ratio's?
i am guessing in the middle would be good... but i guess that is what is probably already standard?
tall gears would mean slow shitty acceleration, better fuel economy.
Short gears would mean... very touchy at low speeds and responsive. crap at higher speeds and more fuel consumption.
Would there be a way to have short first 3 gears... then a tall 4th for "over drive" ??
it:

If you had a Hollinger race gearbox you could do almost whatever you want - but short of a 20 thousand dollar 'box, theres not alot you can do apart from change your differential ratio (the gears in the rear axle). There are only certain ratios available - you'd neet to let us know what you drive for us to recommomend what to put in it!

[sfr rob]

hahah sorry... i am a dip shit... really... hahaha

AU FALCON 6 cyl...
is it actually really worth doing?

[Dodge]

3.5 is a good all round ratio for a falcon NA 4 speed , 4.11 is good for the new 6 speed cars as its hard to hit 6th cog with a 3.5 on normal roads.
hi stall converters are used in drag racing , 2500 stall is good for a hotted up V8 , some new cars have a lock up converter which is like a extra gear when it locks in.

[pauljh74]

The torque converter in an auto tranny is there to let the engine get a little bit of revs on board otherwise if you try to get a car moving with only a few hundred revs on board. the engine will stall - there's no grunt down that low. So manufacturers set the "stall" speed of the torque converter to suit the engine it is matched with. Then with aftermarket ones aimed at performance, the aim of them is to let you build up more revs before locking up the transmission and turning your revs into drive. So higher stall speeds effectively lets you get your engine to a point where it produces more power before trying to transmit that power through the gearbox and therefore the wheels. This enables a quicker launch. Higher stall speeds are really only necessary mainly for drag racing and burnout cars. But with a manual, your left leg can set the "stall" speed for every situation

But if you get a converter with too high a stall speed, it will result in slipping of the converter while driving on the highway perhaps.

The car companies spend time and money getting the compromise right with these and with things like diff ratios and gear ratios, so unless you can see a clear advantage of changing one of these to suit your goals, leave it alone.

If you change your diff ratio to a shorter one, sure it may take off quicker, but then you could be stuck with a car that revs higher at highway speeds, causing excessive noise in the cabin. If you go longer in the diff ratio, you'll use less juice on the long hauls, but may leave your car sluggish - just look at the 6 speed mated to the Gen 3 in the SS Commodore, I think it did about 1500-1600 RPM at 100 km/h in 6th. It was criticised as you needed to drop it at least 2 cogs to get any decent acceleration for overtaking on the open roads. That had a 3.08:1 gearing and a TALL top gear. Whereas the new XR6 turbo with the 6 speed has a much shorter 3.73:1 diff and the XR8/GT with 6 speed has a 3.45:1. Then again, alot of older cars with 3 speed autos have something around a 2.7:1 diff. So the combination of the gearbox ratios need to be looked at first to pick the correct diff ratio

[sfr rob]

thanks paul, your a good man! thanks for taking the time mate!

So from what i understand, the stall converter is pretty much your engine revs yeah? i have noticed some AU falcons at the lights that when they take there foot off the brake pedal there car does not budge an inch... but on mine the car creeps forwards if you even let the brake out a bit.... guessing the higher the engine revs in idle the quicker it will rev higher??!
out:

[Pilch]

Originally Posted by sfr rob

what is a Stall Converter.... and what does it do?

okay, this explanation is very simple and will have a heap of flaws in it but it is my basic concept of how they work.....

The stall convertor sets the level of rpm required to start the vehicle moving forward. If you have a 1500rpm stall convertor, the car won't go anywhere until you get the rpm up to 1500. If the stall convertor was for 3000rpm, that vehicle would not start moving until the revs reached 3000.

The convertor is designed to slip against the force of the engine and not allow power to pass to the driveline (wheels).

this is very simplistic and not entirely correct, but is the basic concept of how a stall convertor works.

in the real world, the convertor will allow some level of force be translated from the engine to the wheels, although not directly translating the entire force of the engine until the stall speed is reached.

can someone confirm my understanding is correct? fill in any holes i have left...

[pauljh74]

Originally Posted by sfr rob

thanks paul, your a good man! thanks for taking the time mate!

So from what i understand, the stall converter is pretty much your engine revs yeah? i have noticed some AU falcons at the lights that when they take there foot off the brake pedal there car does not budge an inch... but on mine the car creeps forwards if you even let the brake out a bit.... guessing the higher the engine revs in idle the quicker it will rev higher??!
out:

The stall converter is a part in the transmission that dictates when the clutches in the auto transmission take up drive. In a road car, raising the stall converter speed may result in your car rolling backwards if you lift off the brake on a hill, so you have to consider things like that as well before changing the converter stall speed.

[4.9 EF Futura]

Much more to torque converters than what meets the eye... good article here:

http://auto.howstuffworks.com/torque-converter.htm