Popping Out Of 1st Gear

I have a 73 cj-5 with the 304 and a t-15 trany.Occasionally it will pop out of 1st gear as I'm taking off anyone have any ideas?

 

On the T-90, it will pop out of 2nd when you back off the throttle becasue of wear on the inside diameter of 2nd gear. This wear allows the gear to turn slightly sideways, forcing the clutch ring (sliding ring) to be pushed off the dogs on the end of the gear. Something similar could happen with 1st on the T-15, since the design of 1st on the T-15 (ie a synchomeshed gear) is similar to 2nd on the T-90.

You mentioned that it pops out when accelerating though. This would suggest to me that the clutch ring is not sliding all the way over the end of the gear. Could be a problem with the shifter top, or with the gear, synchro hub, or clutch ring. There's also some detents that put some pressure on the clutch ring to hold it in place. There are springs (that look like snap rings) that vcould be weak or broken, allowing the clutch ring to slide off the gear.

I recall Nickmil saying that parts are getting hard to get for the T-15 ... if you have a problem, it might be worthwhile to look around for a spare transmission or two. T-15s are strong, but they don't seem very popular - everybody wants a truck-style 4-speed. Might also be worthwhile to freshen it up with new blocking rings, small parts and maybe bearings. They aren't hard to work on, and they are light enough that you can R&R them without heavy rigging.

 

to start I would check motor mounts, trans mount,maybe even body mounts just to make sure everything is good and tight, not moving around on you. I would also check the floorboard to shift lever clearance, to verify the body is not hitting the tower and/or lever.
If all that appears normal and okay, it might be wise to just remove the shift lever/trans tower, inspect the forks, maybe drain the oil to peek inside the trans and make sure all appears normal.
As Tim suggests above, it could be worn synchros or even a bad front/rear bearing that is allowing too much end play in the mainshaft.
A little detective work and observation might save having to pull the trans out.

 

Well said Jim. I was thinking "start with the obvious stuff" also.

We sure are lucky to have Tim here, the guy is a wealth of knowledge!

(Actually, this is the best board I have found for pre YJ Jeeps!)

 

I know this was posted a little while ago...but anytime I've seen a gear pop out it has usually been atributed to the sincros in the trans. 2cd and so on work fine right...? Probably the sincros.

 

While you're at it, make sure that the bolts that secure the transfer case to the transmission are tight. Loose bolts here could allow excessive endplay in the mainshaft. Although if they were loose, I would think that you would be leaking oil there.