84 FJ1100 Clutch

[AppleJack]

I've replaced the clutch slave and have questions about a couple of things.  Should I be able to physically push the rod that the slave cylinder would normally push, by hand? 

I'm pushing on the rod as hard as I can and it doesn't seem to want to move, should it?  It's been sitting for six years.  Please don't tell me the clutch is locked up and won't engage! 

I haven't got to the point where I can start the engine and try to drive it yet, so just wondering how much pressure is required to move the clutch rod.

That's all - thanks... 

[ribbert]

Should I be able to physically push the rod that the slave cylinder would normally push, by hand? 

I'm pushing on the rod as hard as I can and it doesn't seem to want to move, should it? 

No

Noel

[FJmonkey]

If you could push the rod by hand, your clutch would be slipping so bad you would think it was missing.

[4everFJ]

Not unless you are Superman (or woman)... 

[CutterBill]

...so just wondering how much pressure is required to move the clutch rod...

Interesting question.  Hmmm... How much force does it take to pull back the clutch lever?  Let's call it 10 pounds.

The distance from the clutch lever pivot to the center of the grip area is about 5 inches.  From the pivot to the center of the arm that pushes on the master cylinder piston is about 1.2 inches, for a ratio of 4.17.  So a 10 pound pull would generate 41.7 pounds of force against the piston.

The diameter of the master cylinder is .625 inches, which gives us an area of .306 square inches.  The diameter of the slave cylinder is about 1.5 inches, so call it 1.77 square inches there.  Comparing areas we get a ratio of 5.77.

So the 41.7 pounds exerted on the master piston would result in about 240 pounds required to move the slave piston (and the clutch pushrod.)  And that's why you can't push it with your thumb. 
Bill

[Arnie]

What !?  Are we now going to use that "science" and "math" stuff to decide things here?
Who let thils guy in? 

[fj johnnie]

 

[FJmonkey]

What !?  Are we now going to use that "science" and "math" stuff to decide things here?
Who let thils guy in? 

I vote to keep him, saved me the time and trouble to explain it... I just want to ride.

[krusty]

CutterBill  AKA Sheldon Cooper?

[CutterBill]

CutterBill  AKA Sheldon Cooper?

Guilty as charged!   

[Pat Conlon]

Thanks Bill, I enjoyed the mental exercise. I've always wondered about how the numbers world line up....

Pat