Popping out of gear

[70cst10]

Hey guys, what's up? Well, I've had a little problem lately. My truck (68 c10 with a 3 on the tree) has started popping out of gear into neutral on the interstate at higher speeds lately. Any ideas of what this could be? I suspect the shifter fork or something. I don't really have much experience with manual transmissions and I have very little time to fix/diagnose the problem (being in the military), so I'd like an idea of what could be wrong before I start digging. Thanks!

[Joachim]

Originally posted by 70cst10
...this is more fun than a barrel of beer . . .

Seems to me that you have held on to the wires too long.

My 68/L6 seems to do the same thing, only from second to neutral. On the steering column just after it comes out of the firewall, is a pair crescent shaped spacers with a nib inbetween. Ultimately these work the shift linkage to the transmission. The nib is worn down, and or the bushing(s) that keep these spacers/nib in alignment is worn. Supposed to be a "fix kit" for it. I'll be looking at the Food Lion Auto Fair this weekend (Apr 3,4,5&6) Charlotte NC. Will keep in touch if I find what we need.

(formaly: RM2)
USS Lexington/USS Little Rock

Joe

[O'l Buck]

normally when they pop out of direct, it's a misalignment problem. Possibly the input shaft has worn the pilot bushing or the input bearing is getting bad.

[Project1970]

Here's a stab in the dark - it could be low on fluid. Probably not if it hasn't been leaking...but my girlfriend's Opel started doing it about halfway home from Santa Monica to Phoenix...it ended up the tranny leaked like a sieve and had almost no gear oil in it! Filling it up and sealing it off has almost completely fixed it (almost, since running it that far with that little had to have done some damage...)

[70cst10]

Those little pieces are pretty worn down on my linkage as well. I have to hold the shifter toward my chest when I go to neutral from first or reverse or won't shift. I don't think I've ever seen a replacement piece for that though..

[SCOTI]

If you figure this out let me know as this just started happening to me as well on a recent road trip. Below or @ 60 is no prob . . ....but get over 65 & it started coming out of gear pretty often. VERY annoying.

[jhow66]

Worn synchronizers--teeth on gear and synchronizer rings are rounded --only way to fix is replace.

[70cst10]

It's just as well, I guess. I want to put a muncie m20 in it anyway. Is there anything I should look for? I have a 250I6 in the truck now, but I'll be swapping to a sbc or maybe a big block soon. How do I know which tranny to buy? Is the swap difficult?

[Class of 69]

Since you have a 3 speed now, going to a 4 speed is very easy. The trans will bolt right in. You just need to make a hole in the floor for the shifter. The input shaft on an M20 will have two grooves around it, the M21 has one. The output shaft on both of these will be the same size, and spine count as the 3 speed, therfeore the yoke on the drive shaft will interchange. There are some 1st gear ratio differences between them.. the m20 has a lower gear ratio in first giving you a wider spread between 1st, and 2nd .. the m21 has the same percentage of ratio change between all gears, and are some times called close ratio muncies

[alta-aj]

chances are that if you go to a 4 spped you have to change the hump cover to a high one and possibly replace the carpet.