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Transmission grinding issues.


cooprasupra

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Nice job on taking pictures for us.    They looks "normal" to me, but a lot of clutch adjustment is by feel.

 

Clearance between the ball on the slave cylinder push rod and the throwout lever should be 2 to 3 MM.  This is without the pedal being pressed and no fluid pressure.  To make sure you have no fluid pressure crack open the bleed valve on the slave cylinder.  Loosen the lock nut on the slave cylinder push rod, and hold the ball nut with a wrench.  Using a screwdriver, in the slot in the end of the push rod, turn the push rod to take up all clearance.  it is easy to go too far, because the clutch will start to disengage, stop before that.  When you are at zero clearance, loosen the push rod 1 and 3/4 turns.  Tighten the lock nut.

 

Go into the cab.  With your hand, lightly push the clutch pedal down.  You should feel just the pedal return spring resistance, for a slight bit of pedal movement.  Then you should feel a slight increase of pressure, as the clutch master cylinder starts to move fluid, but takes up the slave cylinder free play, and finally the pedal pressure should increase a lot as the clutch starts to disengage.

 

The transmission makes no difference, providing you keep the same throwout collar, that holds the throwout bearing, that is used with the pressure plate on the engine.

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qztjNyU.jpg
 
Has the removable oil pan just like that used in the 521/early 620/510/610/710/A10 so not a 71B or dogleg. The adjustable push rod was only used on the 521 and 510 L16s

 

Later slaves are self adjusting for clutch wear.

 

 

 

clutch-disc-japanparts-df107-1.jpg

Clutch disc shown with transmission side up. If you reverse it, the splined nose hits the end of the crankshaft before the disc material is against the flywheel surface. If you place the pressure plate over it, the bolts won't reach within a 1/2 inch of the flywheel. 

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Length of rod I have coming out or master cylinder to pedal.

Ku9vL0h.jpg

It looks to me like the threaded rod is actually hitting the pedal arm. If this is the case, you may not be depressing the clutch far enough which would not disengage the clutch disc, which would explain the grinding.

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when one get a aftermarket slave or blake master the rods need to be adjuted so when you install them to the fire wall they dont already push IN the cylinder fluid.

that rod is hiiting back of pedal is a sign you did it wrong. Well you didnt know. Its a learned thing.

 

if you have the old rod you can size it up . then new rod put the nut on and screw it on the rthreaded rod then cut off what you dont need and then unscrew the nut to clean the threads up. install to fire wall and then see how it fits in there and make slight ajustment.

 

 

also the slave adjustment is about 16 in , or just a little off tension before you push the clutch fork in.

 

oplus it dont take mush to disengage a clutch. 1in would be more than enough maybe a half is all that needed

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Some updates.

 

All I have done today was adjust the rod from the master cylinder to the pedal and bleed it a bit more.

 

The rod trick seems to have worked a bit. On the jack stands I started it up. I was able to properly shift into first with the motor running, reverse still grinds.

 

Strange thing is though when I dropped the truck back to the ground I am unable to shift into first or second. Reverse still grinds. First or second do not grind, I am just physically unable to push the shifter into the gear. Third seems to get the truck rolling a little bit.

 

I am confused  :confused:

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Remember, the synchro has to match the rear wheel speed with the engine speed. In the air the synchro (basically a small clutch) can spin the drive shaft and tires up to engine RPM. When on the ground they would be trying to move the truck forward.

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when one get a aftermarket slave or blake master the rods need to be adjuted so when you install them to the fire wall they dont already push IN the cylinder fluid.

that rod is hiiting back of pedal is a sign you did it wrong. Well you didnt know. Its a learned thing.

 

if you have the old rod you can size it up . then new rod put the nut on and screw it on the rthreaded rod then cut off what you dont need and then unscrew the nut to clean the threads up. install to fire wall and then see how it fits in there and make slight ajustment.

 

 

also the slave adjustment is about 16 in , or just a little off tension before you push the clutch fork in.

 

oplus it dont take mush to disengage a clutch. 1in would be more than enough maybe a half is all that needed

Often the new master comes with a rod that is not the same length as the old one. I measure from the two bolt mounting face of the master to the back of the clevis. Apply that same measurement to the new rod.

 

I have also seen rods that are too long and hit the pedal as shown in the OP's pic. Those need to be trimmed.

 

You have to be careful when swapping actuating rods between masters. Some of the rounded tips are different and when installed, can actually keep the master from returning completely. This can keep pressure on the master, even if you have free play at the pedal.

 

Though I've mentioned this a few times, it doesn't seem to have caught on here, but if the slave is applying constant force on the clutch, that wipes the engine thrust bearing dry and can actually wear out the thrust bearing and eventually the crank.  Free play at the pedal AND slave is super critical.

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Never hurts to check the fluid level, indeed it should be changed every 30K miles... and seldom is.

 

Grinding means there is spinning parts in the transmission when there should be nothing moving if the clutch is working properly.

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Strange thing is though when I dropped the truck back to the ground I am unable to shift into first or second. Reverse still grinds. First or second do not grind, I am just physically unable to push the shifter into the gear. Third seems to get the truck rolling a little bit.

 

I am confused  :confused:

Maybe someone asked and I missed it, but can you shift through all gears when the engine is not running?

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Noob question. Got a 70 521 here with an L16 and stock transmission. Have a rebuilt motor that has no clicking sounds from the transmission. After doing quite a bit of searching on the subject here I am a bit at of a stopping point after trying all that was suggested. When motor is running I am getting grinding in all gears when clutch pedal is depressed. It does shift freely when motor is off.

 

I went ahead and replaced the clutch master and slave cylinders to no avail. I have bled the system dozens of times to ensure that all air is out. The issue still persists.

 

The slave cylinder is only moving the clutch fork about 3/4 of an inch and from what I have read an inch and an 8th seem to be normal. With the slave cylinder removed the clutch fork does have some play, is this normal?

 

Still keep bleeding it with no luck. At this point I am thinking my only option is dropping the transmission and replacing the clutch, pressure plate, and throw out bearing. Sadly I have no information from the previous owner whether the transmission was working prior to purchasing. 

 

Do y'all think this is a transmission or hydraulic issue? Any help would be greatly appreciated.

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Got some pics.

 

Slave cylinder at rest.

qztjNyU.jpg

 

Slave with clutch pedal in.

3cifDwe.jpg

 

Clutch pedal at rest.

uwo62JU.jpg

 

Clutch pedal in.

C9Ryjj6.jpg

 

Length of rod I have coming out or master cylinder to pedal.

Ku9vL0h.jpg

The last picture of the master cylinder pushrod looks way out of adjustment.Is it threaded all the way in ?

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OK, as mentioned I almost always switch the old clutch master cylinder push rod to the new clutch master cylinder if the push rods are different lengths, but if they are not transferable then I modify the one it came with, I have had to cut quite a bit off the rod before to make it work so it doesn't hit the pedal arm as mentioned also, but I also have found that if the rod hit, I could not install it anyway.

That said I believe that you might try adjusting the push rod into the clutch master more if the slave cylinder push rod has play without the spring connected, this is the way I would go now, keep adjusting the rod in on the pedal assembly till the slave cylinder rod on the transmission has no play anymore, then go back it off till it does have a 1/16th inch play, then tighten everything up and it should be good.

Now doing this may get you the slave rod travel needed before you get to having no play between the clutch arm and rod without the spring connected, you may not have to go all the way to having no play.

All this said I like having the arm closer to the slave than yours is, first I would ask if when the clutch pedal is all the way pushed in(too the floor), is the rear of the clutch arm hitting the transmission case, if it is hitting the case, then you likely have the wrong throw out bearing collar, and that will mean you need to drop the transmission.

I do not have the 521 clutch slave anymore on any of my rigs, I don't have an adjustable rod, if I need a longer rod, I make one out of a bolt, I don't have a spring either.

Here is what my slave cylinder setup looks like, my slave push rod is much shorter than yours and I have the clutch arm rubber gasket in place so it doesn't show the hole the clutch arm comes out of very well, sorry but I don't want to remove it as it is cold outside and I want to stay clean.

DSCN6198_zps9fm3ka0t.jpg

As I wrote, adjust the clutch pedal push rod farther into the clutch master right now and keep checking for the 1/16th inch play needed without the spring connected, that spring has to be removed.

There is another issue that may need to be addressed, slave rod adjustment, if the slave starts leaking fluid, or the pedal goes to the floor and stays there or has no resistance anymore, then that would mean the clutch slave piston came out of its hole/bore, this would likely be because the slave rod is out of adjustment, or you have the wrong throw out bearing collar installed, but we will deal with that if it comes to that.

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Just a crazy question, but can you actually start the thing in gear, clutch pedal pushed, and wheels on the ground, without the truck trying to move?

 

Have you EVER been able to? 

 

If no to both of those, how long has it been sitting undriven?  I've had a fair number of these that the clutch plate rusted to the flywheel and/or pressure plate after sitting for long periods.  But I've also had clutch plates delaminate (won't disengage), as well as have the wrong throwout collar.  And plenty of times the hydraulics failed- including the hose bulge out.

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