VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 53 Chevrolet 1/2 ton truck, sticks in 1st gear

53 Chevrolet 1/2 ton truck with stock 3-speed on the column. It likes to jam in first gear (not every time, but often enough). I have replaced all the bushings on the shift linkage and I believe I have everything adjusted like it shows in the shop manual.

What is happening is, the pawl on the shift lever is jumping out of the R-1 fork inside the shift box on the column. The picture below shows what it looks like inside the shift box, when it is stuck in 1st gear.



The lever at the top of the picture is R-1, the lever on the bottom is 2-3. You can see that 1st gear is engaged (top fork moved to the left), but the pawl has engaged with the bottom (2-3) fork. So, no way to get out of first, unless I stop on a level place, kill the engine, and manually move the R-1 lever into neutral.

I understand it may be possible to adjust endplay on one or both of the shafts which support the forks, but for the life of me I can't see how. Any ideas or advice? Thanks

It was commom years ago for this to happen. The surface on the pot metal lower box and cover wear allowing the levers to lock. In other words when bolted together the openings are too large. File down the surface on the top cover for a tighter fit. If this dosen't help I have an after market "shift neutralizer" kit that will cure it. It prevents it from going into two gear positions at once.

Thanks, I'll try to grind a thousandth or so off the top casting and go from there. Meanwhile, I would be interested in the shift neutralizer, sounds like something that may prevent a real disaster. I appreciate your taking the time to post.

To make an improvement it will be necessay to take off probably .010 or .020"......You could lay a shim on either side of the opening and see if that helps (on the wearing surface) I had a friend that cut up a beer can and made shim material of of it.

I am not familiar with these shift mechanism but a similar type without the box was used down here and had the same problem. I found that by adjusting the 1/R lever so that the linkage rod travelled slightly further towards R before the shift would move into the 2/3 lever was a improvement. The other thing I did was to make sure I moved the lever fully into the nuetral position before allowing it to move towards the 2/3 slot (definite square movement). Some floor shift gearboxes required the same square movement.
I would put the shim (I think Don mentioned)between the lower selector lever an the housing on the inside to lift that lever towards the lever.
Tony

"The other thing I did was to make sure I moved the lever fully into the nuetral position before allowing it to move towards the 2/3 slot (definite square movement). Some floor shift gearboxes required the same square movement".
The best explanation of the proper way to shift these cars that I have seen. So many problems occure when folks try to short cut the shift pattern.

Here is a little better picture.



You can see the transmission is in 1st gear, but the pawl has slipped down to the 2-3 fork, making it impossible to shift out of 1st. With the cover in place and tight, I measured .015" of radial play between the rod and the box, but no axial play to speak of.

Bruce,
That is a fantastic photo, illustrating the problem.

Bruce --

I had the same problem with my 49 when I was a kid, but it only happened when bang shifting it when running against Fords. Not saying that you are doing this though!!

It looks like too much clearance between the shift forks allowing the dog to drop down into 2nd/3rd when going into low.
Do the shift forks line up properly when in neutral position?? Does this problem occur if you are in low, step on it, then let up on it quickly, or does it jump out of low when doing this??

Just wondering, as perhaps selector lever adjustment for low/reverse might be part of the problem. Just thinking aloud here.

Jim.

Jim, it will hang in 1st gear at any time, but usually after I've been driving for a few minutes. It doesn't jump out of gear - the problem is that I can't get it out of gear.

When I originally set up the linkage, I adjusted to neutral (creating the "gate" between the two forks, which allows the pawl to move between them when in neutral). I have adjusted the rods/levers at the shift box up and down a number of times, and that has seemed to make no difference - the problem is still there.

I agree, it looks like too much clearance between the forks is causing the problem, or maybe there is too much axial movement (0.015") between the selector rod and the case of the box. So, I think I'll try to find another shift box and see if I can make that one work.

Thanks for getting back to me. Don't think I'll be racing any Fords in this dinosaur!

One more think here. The dog should ride directly on the lower fork when either in low or reverse as the spring will put pressure on the dog to go downward. If, and I say if, the low/reverse fork isn't going far enough in either direction, than the dog has a better chance of dropping into 2nd/3rd fork before it should. Not being critical of your work, but what would happen if you adjusted the selector rod a bit and see what happens. If it would move the fork further either way without screwing up 2nd/3rd, it may help. Just a thought.

Jim.

Another possibility I see is even though the clearance between forks is close the dog is dropping into 2/3 but as it does so 1/r lever drops back into gear. Try adjusting the 1/r rod so that it travels slightly past nuetral (towards R but not actually selecting) position before the dog will fall into 2/3 fork.
Shimming the 2/3 fork closer to the 1/r fork and shift lever.
Tony

Fixed!

Tony, you were exactly right - the gap between the forks was too big, and the corners of the forks had work to a radius, allowing the pawl to slip out of 1st gear. So, my friends at the VCCA found me a NOS shift box:



You can see in the picture, how crisp the forks look in the new box compared to the one I took out. I put the new box in yesterday, and today the truck shifts like new (no more hanging up, no more sloppy feel to the shifter).

Thanks to everyone for the help and advice.

Glad to see the problem sorted.
I would be cleaning the old 1 up putting a .010" or .015" shim under the lower lever to close the gap between the 2. The lower lever most likely has worn the housing allowing it to drop away.
If the levers and dog have rounded off severely they can be welded up and filed back into shape.
I would still adjust the levers so that the 1/r lever sits about 1/32" below the 2/3 lever which will allow for wear in the future.
Tony

Does anyone know where I can either get a new NOS box, or a neutralizer kit? Both are described in this string.

Any help will be appreciated.

I found one on ebay.