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T150 Jumping Out Of First *still*

Discussion in 'Intermediate CJ-5/6/7/8' started by 78blue5er, Mar 5, 2019.

  1. Mar 5, 2019
    78blue5er

    78blue5er New Member

    Texas
    Joined:
    Feb 27, 2019
    Messages:
    4
    Well hi everyone, I am having a pretty disappointing issue with my jeep. Me and my dad acquired a 78 CJ5 with a 258/t150/d20 and the po had the everything out. They said the trans needed synchros because it was jumping out of first, so we ordered a rebuild kit. We didn't notice the anything about the synchros wore so we were wondering why they said thats what it needed. After rebuilding it by the book, we decided to take the bellhousing off, and gosh it was messy. The clutch had fallen apart! So we ordered a new one and installed it.

    We get everything back together and get the jeep running. I get in and put it in first and all seems well, but as I start to get going the trans jumps out of first. The jeep won't do it as bad if you hold down on shifter, and it only happens in first. After driving it some we put it in first and listened and it kinda sounded like the gear may have a flat spot in it, because you can hear a thump as you have the clutch in at a stop.

    Sorry for the long post but we would like to know for sure what it could be. Thank you all for reading and have a good day
     
  2. Mar 5, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    First post - welcome from Boston!

    First thing I would look at - is it assembled correctly? I don't know much about the T-150, but these 3-speeds stay in gear by the synchro collar sliding over the teeth (not the gear teeth - the ones that match up with the blocking ring teeth) on the end of the gear. They should stay in gear without much force holding them together, ie the force from the detent balls in the shifter and the synchronizer inserts does not need to forcibly hold the hub and gear together. If there is too much end play (ie left out parts or wrong parts in some location) the teeth and hub can move apart and the transmission will come out of gear. Look for excess wear on the synchro hubs and the gear teeth that match with the blocking ring teeth. You should also look for excess wear on the interior bores of the gears. Typically there is a bushing on the inside of the gears that rides on the mainshaft. If the gear flops around on the shaft, it will come out of gear when loading skews the gear on the shaft.

    The TSM may help Jeep® 1976 TSM online page 6-3

    The T-150 is a Ford transmission so parts should be easy to source.
     
  3. Mar 6, 2019
    78blue5er

    78blue5er New Member

    Texas
    Joined:
    Feb 27, 2019
    Messages:
    4
    timgr,
    We do have the TSM and that's what we followed when we put it back together. There didn't seem to be any play at all and we had no leftover parts and they all went in with no trouble at all. Nothing seemed to have any excessive wear, but then again we could've missed some stuff. The gear is stout on the mainshaft, not floppy at all. I was reading on another forum (or maybe this one I've lost count:rofl:) that the first reverse shift work could cause it by being wore down. It did have some wear so we went ahead and ordered it. If that does not fix it the trans comes back out:banghead:
     
  4. Mar 6, 2019
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
    Messages:
    12,529
    Take a close look at the inside of the 1st gear synchronizer sleeve for wear where it engages the dog teeth on first gear. Common wear point people miss. Also check the teeth on first gear where the sleeve engages as they wear as well. Also as you've noted pay attention to the shift fork and check the sleeve where the fork engages. Common for these to wear when people rest their hand and arm on the shifter when driving. Big no-no. It can not allow the sleeve to move far enough to fully engage the gear teeth. Also make sure the poppet (detent) in the top is firm to hold the fork into first gear.
     
  5. Mar 7, 2019
    78blue5er

    78blue5er New Member

    Texas
    Joined:
    Feb 27, 2019
    Messages:
    4
    Nickmil,
    The shift for will be here Saturday but we won’t have a chance to install till Sunday. If that doesn’t fix it then we will pull the transmission back out and look for all the wear points you and timgr listed. Thank you both for the help!
     
  6. Mar 21, 2019
    78blue5er

    78blue5er New Member

    Texas
    Joined:
    Feb 27, 2019
    Messages:
    4
    Hello all, still having problems with the t150 in our jeep. We had the cover off the top to take the shift fork off for first-reverse. While it was off we decided to take it around the block to see what may have been causing it to jump out of gear. We slotted it into first and it was working flawlessly. We could never once recreate it jumping out of gear with the cover off. So we knew it had to be the shift fork not putting it in gear enough. Everything gets put back together and all seems well on the test drive but it jumps out of first again. We have no idea what the issue is, it never once jumped out of gear while the cover was off, but with a new shift fork it still does it.

    If you are careful you can slowly let the clutch out while holding down on the shifter and it will go into gear a little more. After doing this it will not pop back out. It did this before replacing the fork and still does.

    We figure our last option is to tear it back down and inspect the gears. What should we look for on the gears when doing this? If anyone knows what it could be it would be greatly appreciated if you could help out. TIA
     
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