48 Chevy Pickup Wont shift into gear

[weltertm]

I bought a non running 48 Chevy Pickup, 1/2 ton. Got the motor running. It wouldn't shift into gear. So i replaced the clutch in the 4 speed transmission. I tested it on jack stands. Worked fine except for reverse. While in neutral the back tires spin. I took the truck off of the jack stands and now it is like before and will not shift into gear. Does anybody have any ideas? I adjusted the clutch pedal and it doesnt affect it.

[maxwedge]

Originally Posted by weltertm

I bought a non running 48 Chevy Pickup, 1/2 ton. Got the motor running. It wouldn't shift into gear. So i replaced the clutch in the 4 speed transmission. I tested it on jack stands. Worked fine except for reverse. While in neutral the back tires spin. I took the truck off of the jack stands and now it is like before and will not shift into gear. Does anybody have any ideas? I adjusted the clutch pedal and it doesnt affect it.

Tires spin in neutral, of course it will not shift. I assume you can shift, engine not running. Something is locked up in the trans, check shifter forks, see if the sliders are moving, should be taken apart.

[weltertm]

With the truck on jack stands and engine running, the transmission shifts fine except for reverse. When the truck is on the ground with engine running, it will not shift into any gear.

[maxwedge]

Originally Posted by weltertm

With the truck on jack stands and engine running, the transmission shifts fine except for reverse. When the truck is on the ground with engine running, it will not shift into any gear.

Can you hold the rear wheels from turning in neutral, clutch out, by stepping on the brakes? ( on the jack stands)

[weltertm]

Yes i can stop the rear wheels with the clutch out on jack stands with the brakes or with my hands. I opened the top of the transmission and the sliders move and the gears look fine. I took the dust cover off of the clutch and when the clutch is pushed in it disengages the clutch(on jackstands) I havent tried that yet with the truck on the ground.

[maxwedge]

You really shouldn't get much or any power to the wheels in neutral, just the friction of the oil. So this may be a problem once the wheels are stopped on the ground, the parts that are causing the wheels to turn are now stopped and could be preventing normal engagement, not a vacuum shifter, right?

[weltertm]

It is not a vacuum shifter. I will probably lower it to the ground today and see if the clutch will disengage. Just dont know why it is different on jack stands and on the ground. Seems like something may be binding. Could it be the pilot bushing?

[maxwedge]

Originally Posted by weltertm

It is not a vacuum shifter. I will probably lower it to the ground today and see if the clutch will disengage. Just dont know why it is different on jack stands and on the ground. Seems like something may be binding. Could it be the pilot bushing?

Yes for sure, if you depress the clutch, the input shaft should stop, there is some friction there but shouldn't be enough to drive the trans.

[weltertm]

I will try to look at that today. i know that on the jack stands yesterday, the shaft was spinning with the clutch engaged and disengaged. How would i fix the pilot bushing? would i have to replace it? Or could it be that the clutch is not disengaging all the way? How could i check that?

[maxwedge]

I'd pull the trans again and see if the inputshaft is binding in the pilot, misalignment can cause this also. The problem here is whether this in fact is the issue, remember to engage the gears in a nonsynchro trans ( is it?), the input shaft must not turn, clutch in.

[weltertm]

Im not sure if it is a non synchro transmission. How can I tell? What do you mean i should engage the gears? When I install the tranny again?

[maxwedge]

Look for a synchro ring between the gears that the shift forks engage, hard to explain, maybe google synchros. Engage the gears meaning shift to first second or 3rd the idea of the clutch is to mechanically disconnect the engine from the trans ( you knew that, don't take wrong).

[weltertm]

The manual says that it is synchromesh action in 2,3,4, gears. Are you talking about the 2 sliders that fit into separate gears that have a groove around the circumference?

[weltertm]

So with the truck on or off the jack stands, the clutch engaged or disengaged, the transmission shaft is spinning. With the clutch disengaged, motor off, there is enough room to stick a flathead screwdriver in between the pressure plate and clutch. Is that enough room for the clutch to be fully disengaged? With the truck in the air, I can shift into gear with the motor running. With the truck on the ground I cannot shift into gear. I dont know if it is the clutch or the pilot bearing.

[maxwedge]

Originally Posted by weltertm

So with the truck on or off the jack stands, the clutch engaged or disengaged, the transmission shaft is spinning. With the clutch disengaged, motor off, there is enough room to stick a flathead screwdriver in between the pressure plate and clutch. Is that enough room for the clutch to be fully disengaged? With the truck in the air, I can shift into gear with the motor running. With the truck on the ground I cannot shift into gear. I dont know if it is the clutch or the pilot bearing.

Make sure the clutch disc is disengaged from the flywheel as well as the pressure plate, with clutch in and in neutral you should be able to spin the driveshaft over, with the car in gear, clutch in, you should be able to turn the driveshaft, but more force is needed to turn the trans gears. ( engine off here, of course)