Clutch Change guide - no engine removal 1982 720 King Cab 4x4.

[720_Daniel]

Hi all, 

I'm changing the clutch on my 1982 720 king cab 4x4. I'll use this thread to describe what I've done in case it helps anyone in the future. 

My transmission is 31.5" 

 

1. I drove the truck up on ramps. 

2. Disconnect the battery (negative first, positive second). 

3. Drain transmission fluid (makes it easier to bench press and a good time to change it out). 

4. Remove the front differential support. This allows the diff to shift left and right about 10 degrees either way, giving you more flexibility to move things around. 

5. Remove the transmission support (crosses the frame under the tranny). This took some wiggling to get out.

6. Remove the exhaust at the downpipes from the manifold (I need to get the exhaust repaired, so I pulled the whole thing. The exhaust is supported by the transmission support mount and it made life easier just to get rid of it. 

7. Remove the starter - Uuuuugh. This sucks. I pulled the front right wheel to access one bolt. It was a hex head and took lots of time to remove. The other side was easier, even though I couldn't see it. Update - a couple of long (~16" total) wobble extensions will let you get there with enough clearance. 

8. Unbolt the short drivetrain axle behind the transmission (This has 4 bolts that you can only access from the driver side. I needed to jack the back up and rotate a wheel to get to both sides of the axle. This won't come all the way out until you've loosened the transmission and can angle the transmission with the rear end pointing towards the back, driver side. Then the axle slides out. 

9. Unbolt the transmission. 4 bolts on the bell housing. one of mine was 17mm for some reason. The rest were 14. There is a bolt at top dead center that requires a wrench and patience. I was able to use a closed end wrench with a bend on the handle to get it. Others have reported that a crow's foot works. I couldn't get a crow's foot to work. I came at it from the passenger side of the engine compartment.  

10. Shift the angle of the transmission to remove the axle. 

11. Push the transmission up and back (bench press style). Be ready for extra drips.

12. Remove the 6 bolts from the pressure plate. You'll need to muscle the flywheel around to get to them all. 

13a. Have a look at how the arm is attached to the collar before removing it. Maybe take a picture ( I didn't

13b. Remove the clutch arm by releasing the wire clip (a narrow bladed flathead worked well for me). 

14. Remove the throwout bearing and collar.

15. Clean everything. 

16. Inspect the flywheel as described by Mr. Mike below. Remove and have machined if needed (mine was in good shape surprisingly). 

17. Remove the flywheel and replace the pilot bearing as described below. 

Grease up parts described below and reassemble. 

.... 

 

 

Edited May 2, 2022 by 720_Daniel
Added some steps and clarified

[datzenmike]

Most DEFINITELY replace the release bearing. Don't cheap out they are hard to get at.

 

Clean out the old grease and replace the following with Lithium grease..... the small cavity inside the release bearing collar, the pivot ball the clutch arm seats on and both ends of the push rod connecting it to the clutch slave cylinder.

 

If you drag your fingernail over the flywheel surface and it catches on any roughness you really should have it machined. If it seems ok use some 180 grit emery cloth on a small block of wood and with circular motion sand away the glaze.

 

Replace the pilot bushing in the end of the crankshaft, they are only $5. It's very soft sintered bronze. I use a small screwdriver and hammer it down the length in 2 or 3 places slitting it open. Bend them in and pull the pieces out. Tap the new one in using a block of wood and and a hammer. 

 

 

 

Time to inspect for oil leaks. Rear engine seal is easy enough to get at with the flywheel removed. You can still get the front seal for the transmission under the cover plate. If removing the cover plate, take the bolts out and reach through the clutch arm hole and hit the clutch arm pivot ball with a socket extension.

 

 

 

 

The pilot bushing is made of bronze powder subjected to extreme pressure in a die, then the porous bushing is heated to just barely melt the particles together and soaked it oil to permanently lubricate it for life. Do not grease this part.  

[720_Daniel]

Thanks so much! 

Do you know if these engines have return springs on the clutch arm? The arm seems so floppy. 

[datzenmike]

No return springs on these. They were used on the 510 and 521 back in the early '70s.

[datzenmike]

Floppy? Is the clutch master cylinder full?

[720_Daniel]

My whole motivation for this job was that the clutch got really soft. I bled and bled and bled and it only got worse. No loss of fluid though. The master and slave were replaced by the previous owner (new rust on the slave). The truck has like 300k miles, so I figured I had to bite the bullet. 

[720_Daniel]

Any idea what the torque specs on the pressure plate bolts are? 

[datzenmike]

16-22 ft. lbs.

[bottomwatcher]

You can remove the pilot bearing by packing with grease, finding a bolt or dowel that barely fits then whacking with a hammer. Are you keeping the truck a while? If so pull the flywheel and have it machined. These need a 2 stage grind. Good luck 

[EDM620]

There is also a tool to get the pilot bushing out, it threads into the old pilot and has a grease gun fitting - you pump it full and the hydraulic effect forces the pilot out. Less risk of damage. The soft clutch is possibly due to worn out pressure plate fingers.

[EDM620]

This is the tool. Lisle 55600, about $10

[Logical1]

Just my 2 cents but I find it incredibly easier to pull the engine and transmission out as a unit, rather than wrestle it past the torsions bars if that is even possible or remove the torsion bars. I have heard it is possible to reach up and swap the clutch after pulling the transmission back, but uhg!

[datzenmike]

1 hour ago, bottomwatcher said:

You can remove the pilot bearing by packing with grease, finding a bolt or dowel that barely fits then whacking with a hammer. Are you keeping the truck a while? If so pull the flywheel and have it machined. These need a 2 stage grind. Good luck 

 

Very messy. Have you tried soft white bread? Just keep packing it in and tapping the dowel. Still you have to find a tight fitting dowel whereas everyone has a screwdriver handy.

[720_Daniel]

I have an unsatisfying update. The clutch is still soft as a baby's bottom. I should've replaced all of the hydraulic parts first, but the clutch was worn, so at least that's good for a while. The next step is the master, slave, and the small flexible tubing where the metal line hooks up to the slave. Thanks all for the help, especially Mr. Mike. 

[datzenmike]

What does 'soft' mean? The clutch either works or it slips.

[720_Daniel]

By soft, I mean that the pedal is very easy to push and I can't get it into gear. The slave piston moves between 1/4" and 3/4". When I bought the truck, I needed a little effort to get it into gear. I checked the gear oil. It was fine. I bled the system and filled it with quality brake fluid. It seemed okay, but then I got in the truck after it sat for a week and the pedal was just soft. I jumped to the clutch because I figured an old neglected truck likely hadn't had the clutch changed in a long while. 

 

So, my next question is probably obvious. 

What brand master and slave components would you recommend? 

[datzenmike]

Slave travel is 1.18" so that's wrong right there. Probably grinds like hell going into reverse. Sounds like air still in the system.

 

OR....

 

Pedal play... push on the clutch pedal pad with thumb. Should be 1/16" to 1/8" of looseness before there is resistance. You say master was replaced? Probably master push rod at the pedal was never adjusted.

[720_Daniel]

The master push rod is wound all the way out. The clutch safety switch is missing, so I can't accurately gauge the play in the pedal, but I'm sure it's too much. 

[bottomwatcher]

I prefer excedy stuff but even with them not all comes from Japan anymore. Lots of counterfeit crap out there that doesn't help. Anything made in Japan is better.

[NC85ST]

That sounds like an aftermarket master cylinder. The rod that connects to the pedal is, most likely, to short and that’s why you can’t full range of motion at the slave cylinder. Need to figure out a way to extend the rod, so you can adjust the pedal properly. I haven’t figured out the best way to do that yet.

[banzai510(hainz)]

I always notice the MC rods are actually too long and have to be cut.

 

was the same T/O bearing colloar used if the cluctch was swapped out. I alwasy comepare the 2 before install.

Most kits have the just the bearing as one uses the old collar so the length would not be changing.