Tech Tuesday: Clutches

[mikey_d05]

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Welcome to Tech Tuesday. The way this works is simple. I bring up a topic related to off roading in some way, ask questions, get feedback, basically interview you guys. If you have something useful to say, add it, if not, just read.

Clutches

What is a clutch?
What does it do?
What are all the different parts of the clutch assembly and what do they do?
What different types of pressure plates and friction materials are there?
I keep hearing the term "hydro clutch", what does that mean?
How hard is it to install one?
What is a clutch alignment tool and what does it look like?
What parts do I need?


Links

[38377k5]

Originally Posted by mikey_d05

What is a clutch?
What does it do?
What are all the different parts of the clutch assembly and what do they do?

All answered here:

HowStuffWorks "Fly Wheels, Clutch Plates and Friction"

Originally Posted by mikey_d05

I keep hearing the term "hydro clutch", what does that mean?

Later model (say, 80's up or so) cars and trucks use hydraulics (a master cylinder and slave cylinder) to actuate the clutch. Older vehicles use some form of mechanical linkage or cable to actuate the clutch.

The biggest advantage to hydraulic linkage is the packaging; its very easy to route a hose and small slave cylinder wherever you want.

AFAIK, all clutch master cylinders are non-power-assist so there should be very minimal difference in pedal effort between hydraulic and mechanical linkages; hydraulics are kind of a different way to gain mechanical advantage, just like a lever arm in a mechanical setup.

Originally Posted by mikey_d05

How hard is it to install one?

It depends on the vehicle but its generally pretty easy. You will have to remove the engine or the transmission and transfer case (if 4WD).

Originally Posted by mikey_d05

What is a clutch alignment tool and what does it look like?

Its a cheap, plastic splined rod that aligns the clutch with the crankshaft so that everything will go back together correctly during reassembly. It looks like the pieces here.

Originally Posted by mikey_d05

What parts do I need?

Clutch plate, pressure plate and throwout bearing. Always use a new flywheel or have the old one resurfaced.

[5280k5]

Lots of good info here too:
Clutch U
Chapter 4 - Automotive Clutches, Transmissions, And Transaxles

Here's a typical mechanical clutch system

Here's an exploded view of a diaphragm style pressure plate:


Borg & Beck style pressure plate


Long style

Typically the diaphraghm style is the softest or easiest to depress but still delivers the same holding power.

Partial list of clutch manufacturers:
LuK Automotive Systems - Original equipment automotive clutch and flywheel aftermarket supplier
Centerforce Clutches
Hays Clutches :: Performance and Racing Clutches
RAM Clutches Online
McLeod Industries: Performance Engineered Drivetrain Components
ZOOM Performance Products Homepage

Stay away from anything that says it's a reman clutch IMO, way too much work to risk getting a poorly remanned part.

[filo]

Yep, what they said.

The only thing I can add is: I always replace the pilot bushing even if it doesn't look bad. It's only a few bucks, but is a lot of work to pull everything apart just to replace it later........