Keeps jumping out of first gear... need help please.

[Airstrike]

I have a 78 CJ AMC 304 with a 3 speed. I have been having problems with it grinding first and jumping out of gear when taking off in first. It will even jump out of gear when I let off the gas at any rpm in first and high rpm in 2nd. So I decided to change the dogs in it thinking it wasn't getting good position when moving the shifter around.










Well needless to say it shifts alot tighter into gear. Doesn't seem to want to dive out of first upon take off, BUT... soon as I left off the gas in first it dives straight into neutral.

Please help!!!! Any ideas?

 

[gert]

I have heard that it means your syncros are shot, which means a rebuild

 

[Jimbos76cj]

I have heard that it means your syncros are shot, which means a rebuild

Ive never heard of synchros causing a Transmission to jump out of gear. Not saying that it couldnt but never heard of that, unless its not completely engaging. Synchros really only help keep the gears from grinding when shifting. Look for an expanded view of your Transmission . you may have a bad detent ball or spring. When the Transmission is shifted into gear these balls and springs are what lock the shaft into position. My AX-15 I bought came cheap because the PO did his own rebuild and after it would throw it self out of gear and would grind a little. My Transmission guy pulled it appart and found out when he put it back together he never tightened the detent spring plugs. Tthe Transmission jumping out of gear messed up the synchros again.

| Repair Guides | Understanding The Manual Transmission | T-150 3-speed Transmission Overhaul | AutoZone.com

Look at the diagram of the top cover.. see the springs and the balls? Id start there. easy to get to and cheap to fix.. If thats not it take it to a shop and have it rebuilt. you dont want to destroy your gears.

 

[Jimbos76cj]

OR if you have the 176

Interlock pin T176 ..... Whats it do? - JeepForum.com

numbers 14 and 15 in the diagram

 

[Saddle Tramp]

It could be a lot of things. Too much end play in the transmission shaft, bad motor mounts, bad transmission mount or lack of torque stud at the mount (the stud that attaches to the skid plate and the bracket at the between the tranny mount and the bottom of the tranny), miss aligned clutch, and the list goes on. I would start by checking the motor mounts as that can be done without pulling the transmission. I’m not a transmission guru so if it is something inside the box others will need to say.

 

[Airstrike]

It could be a lot of things. Too much end play in the transmission shaft, bad motor mounts, bad transmission mount or lack of torque stud at the mount (the stud that attaches to the skid plate and the bracket at the between the tranny mount and the bottom of the tranny), miss aligned clutch, and the list goes on. I would start by checking the motor mounts as that can be done without pulling the transmission. I’m not a transmission guru so if it is something inside the box others will need to say.

That sad part is I understand about 1/4 of why any of the reasons you stated could be the issue. Looks like I need to do some more reading!

Thanks to all that responded to date!!

 

[Saddle Tramp]

That sad part is I understand about 1/4 of why any of the reasons you stated could be the issue. Looks like I need to do some more reading!

Thanks to all that responded to date!!

I dug up the whole list:

 

[thiswontbetooexpensive]

I dug up the whole list:

Thats a good page to have there. Nice find!

 

[Airstrike]

I dug up the whole list:

See, just when I thought I had a good high school education this information comes along and I wonder, "How can any good American school not have a class called Jeepin' 101."