Transmission keeps jumping out of first gear

Transmission keeps jumping out of first gear


Senior Jeeper
Mystic, CT
1979 CJ7 304 T-150 D20 D30 AMC20
2000 Subaru Outback Limited
When ever I am decelerating down an incline the transmisson will kick the shifter out of first gear. The only way to stop it is to force it back and hold it in place which is a challenge to keep there. My Jeep has a 304 with a T-15 transmission. Any ideas what the problem could be and how to fix it?
Sounds like it's time for a rebuild.
Mine does it in second gear, and also has a whine in first gear
If stock (1979) the transmission should be a T-150 not a T-15. I’m not a transmission guru but a lot of things not inside the box can be related to popping out of gear from shot motor mounts, lack of a good transmission mount, and a missing or bad torque stud; could even be clutch misalignment. I would look at mounts or torque stud first before yanking the transmission.
Sounds like in both of those cases its a bad synchronizer, that's the part that allows you to shift between gears with no grinding.
Like the other person said , rebuild time.
Is a rebuild someone with a decent tech manual and some mechanical knowlege can do on his own or should I drop it and take it to a pro?

In answer to your question,Yes anyone that has common since and the ability to comprehend detailed instructions along with following the proper order of assembly can make it happen.
The only thing that may hold you up is time, and having some special tools, like pullers, a press and bearing drivers. If you have access to these things again by all means go for it, but don't use some backyard tools or approach to your rebuild that will come back to haunt you.
I had my T-15 rebuilt, and it still pops out of reverse often.

I like checking what Saddle Tramp suggested before jumping into a rebuild.

These T-15's are very strong tranny's.

and yes internally pretty simple.

After having mine professionally done, I seen the gear sets, and shafts, and kicked myself for not going ahead on my own. (especially since it did not solve the problems. (but my input shaft bearing was toast and balls missing so it did need attention)

~ JR
also the T-15 is a common swap to stock T-150's.

T-15's "should" have only been stock options behind v-8's (but occational stock upgrades behind 6's) from 71-75.

Our Info section (BusaDave's Post):
Novak: The Borg-Warner T15 Jeep Transmission - Novak Conversions

Which reads:
Borg-Warner T-15 Transmission

The Borg-Warner T-15 is a medium-to-heavy-duty, three-speed transmission, introduced in the 1971 Jeeps. It was offered in Jeeps up through 1975. The T-15 was primarily found behind the AMC V8 engines as the base transmission, but was also found behind the AMC 232 and 258 I6 engines as an upgrade option over the T14. The upgrade to the T-15 transmission was the Jeep T18 four-speed."

Though anything with these fun jeeps is possible :cool:
~ JR

Did they replace the Reverse Idler gear in the rebuild?

Did they replace the Reverse Idler gear in the rebuild?

To tell the truth I'm neither sure if they replaced the reverse idler gear or even where it is :p Though I could find a blown up pic of T-15 pretty easy to see.

But they replaced the whole gear-set inside with another T-15's guts, said they were in "better" condition.

Guess thats what you get when you call all around town for the cheapest bench rebuild price :D

I just deal with it for now, but mentioned it for OP as a suggestion that it may be easier than a full re-build, and then again, it is quite possible it may need it as well...

~ JR
He should like others have said check all the mounts Etc, and it its not that will then pull out the tranny and take it apart.
On yours that 1st/Reverse sliding gear engages with the reverse Idler in the bottom rear of that case, and a lot of times guy knock the corners off of those gears from jamming it into reverse before it gets to a stop..........I've done it before also. when the gears are right the driven force keeps the gear in there and when the corners are worn they sometimes pop out. Could also be the top loaded shiftier as those rods and spring loaded detente balls sometimes go away.

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