Holding my 3-speed in 3rd gear or pops out

[Harveybacon]

Have been just holding third down for a couple years now. No trouble other than it progressively getting worse. Use to go 65 before would pop out, now soon as I put it in 3rd (around 35mph) when accelerating. Had reman'd tranny 6 years ago. I have been told it's just my drive shaft (bearings). I have checked my springs and forks and shifters, and all seems in order. I took it to Aamco today for free inspection, and we'll see what they say. But I am hoping that I can fix it without dropping tranny.

update-
I took it to Aamco today and he straight told me the problem was IN the tranny. And swore that I had to pay 400 bucks for him to look at it. This is not the first tranny ppl I have taken it to. Transmission mechanics are a shame. I will NEVER have anybody else do work on my tranny again (after owning a 99 Mazda and rebuilding it twice), lol.

One person on other thread said:

Originally Posted by andyh1956

i think you will find a broken / lose / missing snapper on the main shaft. this is a super common problem & there is a fixit kit that can be installed from the top side after the shift top is removed. call jackson powertrain at 601 932 3159 & john will fix u up!
andy

I am not familiar with this, but I assume it is either like that, detention, bearings, OR the 2/3rd gear is worn. Any help on this would be great!

[Harveybacon]

it's a 3-on-the-tree Muncie 219 or 319 from what I remember. 4-bolt on side.

[68gmsee]

re. transmission mechanics: One thing to remember is that most of the cost is labor these days. A good transmission mechanic can diagnose the problem or problems fairly quickly. If you can do the removal and reinstallation yourself by renting the tools needed you save a couple of hours or more of labor.

I had a car once that used to pop out of gear but mine turned out to be a bad motor mount. It would pop as the engine lifted with the torque of the drive shaft. Only way I found it was by lifting the motor with a jack.

[Harveybacon]

well, I would gladly do the work, but I live downtown, and park in the street. The fine would equal out the labor, lol. I was quoted 4.5 hours labor to pull it apart and rebuild. My problem was that it already has been rebuilt and I don't understand how it should be internal when Aamco "rebuilds them for life". So I am really hoping to not have to pay anyone else to "diagnose" a problem. Every mechanic I have talked to tries to get me to pay them to pull the tranny and let them dismantle it. I have been down that road and rebuilt a tranny twice. So I am looking for insight into something I can fix (even temporarily) that I can work on here in the street and not worry too much about cost. Otherwise, my truck is for sale and I will just let the next owner worry about it.

[dwcsr]

Originally Posted by Harveybacon

it's a 3-on-the-tree Muncie 219 or 319 from what I remember. 4-bolt on side.

SM 319 is an over drive 3 speed tranny, You should have and SM 318. Popping out of third is most likely cuased by the 2nd/third shift fork being worn or the 2nd third syncro slider being bad or the input shaft bearing being bad. Could be all three. But it does have to come apart to find out.

$400 should get you a complete rebuild provided the broken parts are available and not major components.

[Harveybacon]

Originally Posted by dwcsr

SM 319 is an over drive 3 speed tranny, You should have and SM 318. Popping out of third is most likely cuased by the 2nd/third shift fork being worn or the 2nd third syncro slider being bad or the input shaft bearing being bad. Could be all three. But it does have to come apart to find out.

$400 should get you a complete rebuild provided the broken parts are available and not major components.

Thanks, that sounds right, SM 318 .

Not the fork, I've check it out, pulled off side casing (4-bolts). I don't think the syncro is the case, there's no syncro on first, but I have read threads that explain that issue, pops out when letting OFF the gas. Mine pops out from vibration during acceleration, so I'm still leaning towards bearings. Is input the same as drive shaft? I originally thought that it was the 2/3rd gear being worn, but I don't know if it's the syncro.

Can I fix input bearings without tear down? Thanks!

[usmcchevy]

Have you tried adjusting the linkage? When I got my 70 I had to hold it in reverse because the adjustment was way off.

http://67-72chevytrucks.com/vboard/s...d.php?t=215307

[Harveybacon]

Originally Posted by usmcchevy

Have you tried adjusting the linkage? When I got my 70 I had to hold it in reverse because the adjustment was way off.

http://67-72chevytrucks.com/vboard/s...d.php?t=215307

yeah, I've adjusted it, it was a little tighter, but then threw off my 2nd, so I put it back, IMO best place for it, but I don't think that's an issue. Thanks.

[vince1]

I can remember one such transmission that had been run like that with it slipping out of gear for so long that the gear teeth were actually worn with a taper to them.