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Need Help...SM456 Binding

A

AC130Ghostrider

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I've searched on here and found a few threads that talked about this, but I don't know enough about this trans to follow very well.

The problem started after doing some light wheelin. Flexed the front a little and heard a couple pops/thuds. I don't think that had anything to do with it, but then it would not shift in or out of gear. I shut it off and could shift it fine. I made it home with minimal problems. Now when it's not running I can shift it fine, but as soon as I crank it, I can't even get it out of gear. Nothing is visually broke and all fluids are good.

Don't know if makes any difference, but I'm running 1 tons, np 205 twin stick, and 39.5s.

Just noticed I mistyped, it's an SM465, but I'm sure you guys know what I meant.
 
Is it mechanical or hydro linkage? If mechanical you may have tweaked, bent or broken something when it twisted, thus not allowing the clutch to fully disengage.
 
Well, that is where my lack of knowledge comes in. I don't know which it is. My guess would be mechanical. How can I tell. I traded a car for it and haven't had it very long.
 
Hydro meaning hydraulic, mechanical being a metal rod going from the clutch pedal down through the floor (inside the truck) to a pivot on the frame then a rod going to a lever sticking out of the bell housing. When you push the clutch pedal the rod goes down, moves the pivot and then pushes in the lever to disengage the clutch. Hydro is done by fluid pressure so there would be a hose going to a slave cylinder attached to the bell housing.
 
It's hydro then. It's an 89 model. Will I have to pull the trans to really know what's wrong? If so, what would I look for?
 
I hate giving advice when I don't know what I'm talking about, but it never stopped me before................

I have worked on a couple of hydraulic clutch setups, and the basics are all the same.
You should have two master cylinders. Probably on the firewall. The big one with all the lines, is the brake.
The small one with one line is the clutch. Check to make sure its full of fluid. If its low, do not put anything in it until you ask here.
I'm not sure what that model truck takes.

It could be brake fluid, or hydraulic fluid and its real bad to mix those two.

If its full, chock the wheels!!

Then slide under, following that single line. It should go to a small slave cylinder on the bell housing with a rod sticking out that pushes a rod coming out of the bell housing.

Look for something loose. The cylinder could be loose, or the rod might have an adjustment on it that has backed out.

If you don't see anything obvious, get someone to push the clutch pedal while you watch the cylinder to see how it works and if you see anything that does not look right.

Make darn sure the wheels are chocked so the truck cannot roll over on you. If the clutch works when pressed, the transmission will no longer hold the truck in place.

Post back what you find.
 
Just checked underneath. Nothing seemed to be loose or broken. Had someone work the clutch in and out. Everything seemed to be ok. The slave cylinder rod did not look like it had any adjustment.

The rod coming out of the trans has a boot around it with an open end as the rod comes out. With the clutch out the rod is in the center of the boot. With the clutch pushed in the rod goes all the way to the rear of the boot opening.

Looked good to me unless the rod is supposed to go all the way to the front of the boot when the clutch is out.

The clutch fluid is a little low. The haynes/chilton says use brake fluid, but I don't know what's in it now.
 
Well, that ain't good. I was really hoping for something simple.
It sounds like the clutch is not quite releasing all the way.

Unfortunately, I am rapidly running out of specific advice due to my unfamilarity with that setup.
I have seen three different types of hydraulic clutch adjustments over the years. I'm sure there are others, and some may not have any.

On one, the slave cylinder rod was adjustable, another, the cylinder its self would move on the bell housing, and the third had an adjustable rod and pivot on the pedal.

If the rod coming out of the bell housing is moving all the way, then the hydraulics are doing their job.
If you cannot see an adjustment, if there is any way to get something between the slave cylinder rod and the rod coming out of the bell housing to make the clutch rod move farther, that might tell if its an adjustment problem.

If it is not, then its going to be a clutch problem inside the bell housing. Not sure if there is an expection plate.
If there is, you need to look and see what is going on.

It has the symptoms of a worn out throwout bearing, but they usually make noise when you push in the clutch.

Hopefully someone else will chime in who is more knowledgable about your setup than mine.

I have seen what you have caused by a couple different things over the years.

A frozen pilot bearing, bad throwout, faulty clutch disk binding on the transmission shaft.

I have also seen the clutch disk soak up water and swell up.

Look for an inspection plate on the bottom of the bell housing.
 
Brake fluid is correct.

Does the master cylinder and slave cylinder function correctly?
Put the truck in first gear, push the clutch in, and then start it. If the truck moves forward while you are starting it, then the master/slave/hydraulic line are faulty. Or the throwout bearing came off the fork, or the clutch is shot.
 
It doesn't move forward when I'm cranking it but it does rock forward slightly. Sorta like putting an auto in drive. Never really noticed it doing that till now.
 
Well it sounds like the trans will have to come out to figure this out. Any recommendations on a clutch or where to buy from...if that turns out to be the issue.

Generally I tear things apart only to find out that wasn't the issue, so I'll troubleshoot a little more first.
 
Dustin, I'm not familiar with that tranny, is there any kind of inspection plate or cover?
It really sounds like a throwout bearing, or worn pivot, but it would be nice if he could see what is going on in there before he pulls it all out.

Or maybe a borescope would work if you took the rubber boot off the clutch lever....
 
There is a cover, you can't see past the flywheel though. Removing the rubber boot will allow you to see in there with a pen light . I didn't read the whole thread... do the gears grind when trying to go in? The throwout bearing may be out of wack from the clutch fork I suppose, don't think the stud would just $hit the bed all of the sudden.
 
I'm guessing from the post that the syncros are not letting it shift. Like I say, I don't know that transmission, so I don't know if it has an unsyncroed gear.
Maybe reverse?

It sounds like the clutch is just barely not disengaging.
Which is why I was wondering about an adjustment. Most of the time, when a throwout starts going bad, it will squall when you push in the clutch.

It just seems strange that it would do it suddenly like that, unless it has been almost worn enough to hand the transmission for a while, and finally went just too far.

He could knock the transfer case out of gear, and that would let the transmission shift with the engine running if its the clutch.

Would not fix the problem, of course. Just help confirm its the clutch. Not sure what else it could be though if it shifts without the engine running and not when it is.....
 
I would expect some squeeling as well before the bearing goes. The bearing retainer tab on my fork snapped off, not sure how though. Unfortunately it sounds like he's gonna have to drop and check things out. Bad clutch? Bearing came off fork? Etc... = dropping it.
 
There has not been any squealing or any other noises. It was shifting pretty good before this. Sometimes it would crunch a little into 2nd, espacially after it got warm. If I pull the trans, can I leave the t case bolted up and drop them together?
 
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