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Discussion Starter #1
Ok, let me start off by saying Rear ends and torque converter's really stump me....

As most of you know I'm doing a DOHC swap in my 97 and as most of us know Early DOHC motors suck on the low end.

So I would like to add a larger than stock torque converter and maybe install some 3.55's or 3.73's to replace my 3.27's...

This is the part I don't understand.

What is the job of the torque converter and why do they stall?

What are name names of the items I'm looking for to swap my car from a 3.27 Open to a 3.73 Locking?

I think I need a gear set the the items that look like photo 1 but what other info do I need like number of teeth, length brand ???

Next photos two what is that thing called and what do I need to know about it???

Thanks all for your help...

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This is how I understand it - I am by no means an expert and I only have a very basic understanding of them. The torque converter basically functions as a clutch between the engine and transmission. It functions by spinning transmission fluid at one end. The spinning motion of the transmission fluid then passes over the other end and turns it - think of a metal rod at the bottom of a dish; use a propeller to spin the water above the rod and eventually the rod starts to turn with the water.

The stall rating is basically how fast one end of the TC (the engine side) can be spinning before the pressure inside (that spinning motion of the transmission fluid) forces the other end to start spinning if it's being held still. IE, when it locks up. A higher stall means the engine is producing more torque when you let off the brakes for a good, strong launch.
 

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A torque converter is a fluid coupling. It's like a clutch that's only active above a certain speed.

A torque converter is a type of fluid coupling, which allows the engine to spin somewhat independently of the transmission. If the engine is turning slowly, such as when the car is idling at a stoplight, the amount of torque passed through the torque converter is very small, so keeping the car still requires only a light pressure on the brake pedal.

If you were to step on the gas pedal while the car is stopped, you would have to press harder on the brake to keep the car from moving. This is because when you step on the gas, the engine speeds up and pumps more fluid into the torque converter, causing more torque to be transmitted to the wheels.
Stall is the point at which the torque converter is at full capacity. An easy way to determine stall is to do a power brake, stomp the brake and slowly ease on the gas. The RPM where the rear tires start to spin is the stall point.

So, dragstrip race MK VIIIs are running 4000RPM Stall converters and silly things like that so that they launch already well into their powerband-- of course, I could be wrong.

Reference:

http://auto.howstuffworks.com/auto-parts/towing/towing-capacity/information/torque-converter1.htm

As for differentials,

What is a Differential?

The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed.
For more, visit
http://auto.howstuffworks.com/differential1.htm
 

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An over-simplified explanation of a torque converter:

Imagine two fans facing each other. One fan has electricity applied causing it to blow at the other fan. The other fan begins to spin from the air flowing through it. Now imagine it is ATF instead of air. So one fan (the one hooked up to electricity) is the engine, the other is the transmission.
 

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An easy way to determine stall is to do a power brake, stomp the brake and slowly ease on the gas. The RPM where the rear tires start to spin is the stall point.
This never works. The tires will break loose way before the true stall is reached. What you can get here by holding the brake and mashing the loud pedal is what's known as the "flash" stall.
The stall is dependant on several things...vehicle weight being but one of them. A heavier vehicle "stalls" the convertor higher than the same convertor in a lighter vehicle.

Misconception #2: Although it wasn't yet stated but rather somewhat implied, and is constantly misunderstood everywhere anyway, a "4k stall" does not mean that the car will not move in gear until 4k is on the tach.
 

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Discussion Starter #8
Ok, I have a good idea of what the torque converter is for, how do I know what one would be good for my setup?

What about the photos, what kind of info do I need on what rearend parts are needed for the housings in are cars?
 

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Discussion Starter #9
Wait Wait Wait I may have what I need to know about the torque converter....

If I'm understanding every one the inside of the T.C. turns and over the RPM range it fills with Fluid at lets say 3000 rpm it hit's max and dumps it off to start the process all over for the next gear???

So the higher RPM T.C. you buy the longer you can keep the car in lower gear in turn using higher RPM's intern getting more power?

I.D.K. It sounded good in my head but as I typed it the less I know.
 

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This never works. The tires will break loose way before the true stall is reached. What you can get here by holding the brake and mashing the loud pedal is what's known as the "flash" stall.
The stall is dependant on several things...vehicle weight being but one of them. A heavier vehicle "stalls" the convertor higher than the same convertor in a lighter vehicle.

Misconception #2: Although it wasn't yet stated but rather somewhat implied, and is constantly misunderstood everywhere anyway, a "4k stall" does not mean that the car will not move in gear until 4k is on the tach.
Well, I said I could be wrong ;)

@dirtydog
No, ridiculous would be 4.55 or higher.

I dunno, I don't understand the 4k stall thing.
 

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Discussion Starter #12
Well I have had really good luck with the 3.73's in my Charger and the 3.55's when I had a 96 SS. So I think I want a to install 3.73's in my 97 Cougar that I'm doing my DOHC swap into.

Could I use the factory Mark VIII T.C., Rebuild my Trans with a nice J-MOD, installing 3.73 Trac-Loc gears and maybe have some shift options done in my dyno tune and still get a nice low end feeling with my stock 97 Mark motor?
 

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Could I use the factory Mark VIII T.C., Rebuild my Trans with a nice J-MOD, installing 3.73 Trac-Loc gears and maybe have some shift options done in my dyno tune and still get a nice low end feeling with my stock 97 Mark motor?
If you plan to hit high RPMs, (and you do... :) ) I would talk to DirtyD0g about a converter. That's my plan, and current savings goal. :D

The mark converter is good, the 04+ marauder is better, but Alan doesn't make cheap OEM quality converters like the factory ones, either... :)

Search for photos of some of his work here... I was pretty inspired.
 

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For an old "B" head 4V Modular-4.30 minimum gear and a 4000 rpm converter. Otherwise-you just wasted your money.
JL
 

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To answer your questions about the photos:

The first one has many names, but most common is "ring and pinion". You can count the teeth, but its not necessary really. usually the ratio is stamped on the end of the pinion. (my 3.73's were delievered just hours ago, the two things I was looking for were there.. "373" and the Ford logo.)

The second pic is the differential itself. Again there are many different types and brands. Some are limited slip such as the popular trac-loc (ford) and positrac (GM). They send power to both rear wheels under most conditions but do allow for some slippage to allow the wheels to travel at different speeds when needed (I.E. going around corners). The types go up from there allowing less and less slipping, keeping the rear wheels locked. Nope, can't tell you what type of diff is in the pic.

You'll want gears and diff built for Fords 8.8" rear end.

Believe it or not, you can learn a lot of the basic stuff by reading the online catalogs such as Jegs, or Summit.
 
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