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post #1 of (permalink) Old 10-27-2002, 07:25 PM Thread Starter
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tranny pops out of first

AAAARGH!!! OK, after replacing the broken T-150 (2 broken teeth on 2nd gear) with another used one, all seems fine except now it pops out of first gear when deccelerating. For normal driving it's fine, can go 1-2-3 with no problem, but if I take my foot off the gas while in 1st it pops into neutral, and if I try to hold it in 1st it grinds, unless I pull really hard. I really hope somebody can tell me it's something stupid and I won't have to pull it again, but I'm not all that optimistic. The internals looked OK when I had it open. Any ideas?

-Dana

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post #2 of (permalink) Old 10-27-2002, 08:07 PM
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Re: tranny pops out of first

I like your optomism....
unfortunately, unless the shifter is hitting the body tub , it sounds like you got a bad tranny.
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post #3 of (permalink) Old 10-27-2002, 09:56 PM
 
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Re: tranny pops out of first

actually it sounds like the synchros are worn for the first and reverse gearnot a bad fix but you do have to pull it again or you could live with it i did in my cj5 for about 5 years now i am building a 7 with a different tranny [img]images/graemlins/wink.gif[/img]
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post #4 of (permalink) Old 10-28-2002, 06:27 AM
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Re: tranny pops out of first

When examining a used transmission, always take a screwdriver and pry each gear forward and aft on its shaft. Any more than a miniscule amount of end play can result in the transmission popping out of a gear.

If you want to be scientific about it, there are specs on end play in the shop manuals. The problem is that even with end play within tolerance, it could still pop out if the engagement parts are worn, too.

The gears are engaged by a splined sleeve that pushes the synchronizer ring onto the gear, to match speeds, and then slips over spline teeth on the gear, locking the sleeve to the gear. The sleeve is splined to the output shaft, and that gets the power out.

Under power, the angled cut of the gear teeth pushes the gear toward the sleeve, and it stays engaged. When you back off, the gear is pulled the other way and the spline teeth pop out of the sleeve.

By trying to hold it in gear with the lever, you're causing wear to the shift fork and the groove in the sleeve that it rides in.

There's another possible cause. The engagement points on the gear and in the sleeve could be worn, because the synchro wore out and the transmission was repeatedly 'ground' into gear. In that case it would probably be prone to popping out under power, too.

In either case, the transmission will need to be opened up and examined. Sorry.
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post #5 of (permalink) Old 10-28-2002, 05:25 PM Thread Starter
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Re: tranny pops out of first

That's what I was afraid of. [img]images/graemlins/frown.gif[/img] Though I'm not looking forward to repeating the exercise right now, so I guess I can live with it for awhile.

One thing I forgot to mention: When I put the tranny in, I used the top cover / shift rail assembly from my old tranny instead of the one which came with the new (used) one (popping out of gear was not a problem with the old one). Are they matched; could that be the problem?

The synchro seems OK because I can downshift into first with no problem without grinding.

-Dana

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post #6 of (permalink) Old 10-29-2002, 06:03 AM
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Re: tranny pops out of first

You might help yourself by changing covers. Probably not, but it's a lot easier than swapping boxes. Give it a try.

Even if it does help, the transmission is still worn and will need attention before too long.
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