The Stovebolt Site Forums The Shop Area Engine Shop HELP! Mysterious Gear Jam Has Me In A Jam

Who hasn't had a gear jam in a 50's Chevy truck? I get 'em every now and again. But each time I've jammed the gears, it's taken a quick upward jerk of the 1st gear rod to get me running again. And the culprit is always the gear shifter box on the column.

Today I was adjusting the length of the clutch pedal travel and took it out for a test when the gears jammed in 1st (per usual). This time, it's serious. They won't come un-jammed.

I tried the upward jerk. Wouldn't budge. I returned the clutch pedal travel to where it had been & stepped on the pedal. That didn't help. I unhooked the 1st gear rod to free the clutch lever (on the side cover), but found that the 1st gear only moves forward a small amount and the 2-3 gear lever won't move at all. So I am pretty convinced the solution is not to be found in the gear shifter box (which in the past has proven to be a formidable foe).

Rocking the truck back and forth didn't help. Having a friend step on the clutch pedal to disengage didn't help. It's stuck.

Any tips on how to un-stick it? This is my only vehicle. Thanks!

Mandrew

PS: I am planning on replacing the clutch over the weekend. That's what precipitated this situation to begin with.

I would pull the side cover off the tranny and realign the shifter forks. They may be worn and need to be replaced. While your at it I would also look at replacing that 60 year old linkage.

I ran into a similar problem years ago at the strip. I had locked a Muncie into both 1st and 3rd. Tried forcing it to no avail, then an old time buddy stopped by to check on me. Lifted the rearend off the ground to release the tension on the thing and it popped out of gear in both places. Might want to try it if you haven't already.

Devin

Well, while draining the oil from the tranny case, a handful of ball bearings dropped out the bottom. Turns out the main input bearing had disintegrated (hence my 2nd gear woes and the locking up of the gears). Found a new bearing after an exhaustive search, cleaned the tranny up, replaced the clutch and reinstalled the tranny. It all went together fine, but now I have way too much free pedal travel. I originally reconnected the fork to the pull rod where it had been with the old clutch (which worked fine), and I practically had to floor the clutch pedal before the throwout bearing would make contact. So I started readjusting the length of that linkage. Now the fork is set at the very end of the rod (closest to the rear) so I can't adjust it back any further, yet I still have 2-3 inches of travel before contact is made.

All I can think of is that the shifter fork isn't seated properly on the ball and maybe there's too much play in the mechanism. Gonna try working the fork onto the ball a little better and see what happens.

Anyone have any other thoughts?

There are two different lengths of throwout bearing carriers. if you replaced the TO bearing with the clutch, as most people do, it's possible you switched a short bearing for the long one that was there to begin with. It's also possible the pressure plate you installed needs a different length bearing carrier to work properly.
Jerry

Hi Jerry,

Thanks for the info. It turns out that the fork was fine, so the pressure plate/throwout bearing was my next guess.

Unless the bolts to the pressure plate can be torqued down too tight (can they?) the only logical thought is that the clutch cover is not as tall as the old one, or that (as you say) the throwout bearing is shorter. Or both. I still have the old throwout bearing just in case, but would rather install a new one.

I also found a crack in my tranny housing :-(

Nope, there's no way to overtighten the pressure plate bolts, short of twisting them off. I believe those bolts are 3/8" X 16 thread, which would take about 35 ft/lb torque. They might be 5/16 X 18, which would need only 20 ft/lb or so. The 3/8" bolt will have a 9/16" head, while the 5/16" bolt will have a 1/2" wrench size.

Try disconnecting all the linkage and moving the throwout bearing into contact with the pressure plate fingers with the fork. The area where the fork meets the bearing should be approximately parallel with the back of the pressure plate if the right bearing is installed.
Jerry

There are 2 different pressure plates available. Each uses a different length TO brg. The older style has the fingers around the center of the plate, parallel to the surface. It uses the long TO brg. The newer style has the fingers protruding out to the outer edge of the cover, commonly called a beehive clutch. It uses the short TO brg.

Well, the pressure plate is definitely the older style, with the fingers pointing all to the middle. I'll have to look at the fork/bearing relationship and see what that is. However I am pretty certain that the bearing is the shorter style, based on what I have read here.

Thanks for the help guys!