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Thread: CJ-3B Transmission Problem - Shift lever not shifting the gears

  1. #1
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    CJ-3B Transmission Problem - Shift lever not shifting the gears

    Hello Jeep Friends,

    I have discovered I have a new problem to tackle. I recently got my fuel pump overhauled and now have my 4-134-F engine quite nicely. Since I had two flat tires anyway I decided to put the CJ up on jack stands and take off all wheels. I thought it would give me an opportunity shift through the gears. I immediately found that although I can move the shift lever freely left and right in neutral, I can't even budge it in a forward / aft direction to try to get into reverse or first gear. I can't make it go into second or third either. I took the trans mission cover off the floor board to get access to the inspection port. I took that cover off also and watched when I pressed the clutch pedal. I think it worked correctly because when I put pressure on the pedal i noticed that the clutch plate would stop rotating. I was never able to get it to shift. Someone told me to spray plenty of penetrating oil down the shift lever area. I did that but I have plenty of oil.

    I am assuming this is a T90 but I am unfamiliar with these transmissions. I have a tendency to want to remove the four bolts on the top of the tranny and just pull the shift mechanism out and figure out what's going on. I would like to find good disassemble / assemble instructions so that I will know how to proceed. I haven't gone through all the tech data on the blog yet. I will continue with digging through.

    Any suggestions / tips / tricks will be much appreciated.

    Thanks for your patience with me long wordy posts.

    Chuck

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    I tried to post this yesterday but I must have not completed the post or something.

    I have been digging in the Tech section and found the maintenance manual. I noticed that the very first thing that is done when removing the transmission is to remove the shift lever cover. It is probably a safe bet to pull the 6 bolts and take a look inside. I want to see if the detent shaft is froze up or something.

    Chuck

  3. #3
    Super Moderator gmwillys's Avatar
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    The biggest thing with these transmissions are rust from storage/sitting. If the Jeep was left outside then water will make it's way down the shifter, and into the transmission. If the Jeep was covered up or protected from the elements, then condensation from the atmosphere will attack the transmission parts that are not submerged in oil. Pull the six bolts for the sifter assembly and clean up the action in the shifter. Next look at the gears to ensure that there is not any corrosion on the shafts. slide the gears back and forth to ensure that they move properly. This would prevent the gears from being shifted as well.

  4. #4
    Super Moderator bmorgil's Avatar
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    Chuck, I am thinking it is a pretty safe thing to do, pull off the shift cover. For sure don't force things. The fact that it is in neutral makes this even easier. The Universal Manual that KW sells has an excellent tear down rebuild for the T90. In fact it is more correct than anything I have found on the Internet. The service manual oldfireguy posted in the Tech Section also does a stellar job.

    Take the cover off and do a few things. Disassemble it, and thoroughly clean it up. Replace all the poppet springs. They break ALL the time. This is a great thing to do on any old transmission. Those old springs do some very important things. A broken spring can allow a transmission to lock up the shifter and/or go into two gears at the same time. Two gears at the same time causes "spontaneous disassembly" of the transmission (kaboom). It is not uncommon to find them broken from age. You will need new seals for the shift rails and, possibly some new freeze plugs and maybe even a rail or two. I would take it off, take it apart and see what was needed. You can clean up most of the parts to satisfactory results. For sure new springs. I am guessing it has a frozen shift rail or two, or three. Water notoriously poured down the shifter on these if the boot wasn't on and functional. The rails can rust and seize and often do. It is best to repair it rather than work it loose. You also need to be sure the trans isn't full of water. This is often a blessing in disguise saving you from future heartache if it were to jump into two gears at once. If it has a busted spring in the interlock or rails, it can be tricky to get apart. Nothing requires a great deal of force unless the rails are frozen. Soak it for sure if it is frozen up. Remove the inter lock plunger first.

    If the cover is free and shifts fine off the trans on the bench. The shift collar (clutch sleeve) may be frozen on the clutch hub. Try to use a pry bar or large screw driver to shift the trans by sliding the clutch sleeve forward to third gear or rearward to second gear. If that will go, put the sleeve back to neutral and try to slide the 1st reverse sliding gear. You may have to rotate the gears a little to get things to line up. I am still betting the cover is frozen up or has a busted spring.

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    Thanks Guys, great advice as usual. I did find the online version of the manual you mentioned. Still want the hard copy though. I don't remember if I explained this, but I actually have two Jeep CJ-3B's, only one engine though. I have been wanting to pull the trans that has no engine attached for some time. Looks like now may be a good time.

    Thank You Jeep Friends.

    Chuck

  6. #6
    Super Moderator gmwillys's Avatar
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    Bench refresh the engine-less transmission, then swap out the problem child in the running 3B. You'll be better off if you do have water contamination plaguing your primary trans. Needle bearings do not like rust, and will probably give you head aches if not gone through.

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    Hello Jeep Friends:

    Ok Guys, It's been a busy morning. I was able to pull the shift lever cover in CJ with the engine. I was pleasantly surprised to see happy gears swimming in a bath of thick smelly gear oil. It had that heavy gear oil smell that we all would recognize. I can't tell if it is water contaminated or not so let me know how to test or what to look for. See T90-P1. When I inspected the forks and rails, the forks seem happy as well but the rails look like they may have picked up a little corrosion from the condensation or maybe there might be a little water in there. They are still locked up and need a little love. See T90-P2. On the other hand however, the engine-less tranny looked very unhappy. At some point it looks like all the oil leaked but it had plenty of water. The forks and rails are in bad shape too. See T90-P3 and T90-P4. I will go through this one and hopefully return it to great shape. To keep with my phased restoration plan, I think I will remove as much oil as I can, take a close look at the gears and see if I can get them to move. I will fill with fresh oil and see if I can get the drive train rolling again.

    Please let me know what you think. Your comments are very helpful to me.

    Thanks

    Chuck
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    Super Moderator bmorgil's Avatar
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    Chuck,I do not like the color of the lube in the trans. Looks more like mud. Let it set for a bit and the water will settle to the bottom. If it has water in it it will be the first thing out of the drain plug. I would take the opportunity to drain the trans and transfer case. They share the same lube, and the lube you have in there is nasty looking. I would fill the gear train back up with cheep light weight engine oil, spin everything up and drain it out, maybe twice. Then I would run what ever gear oil you choose. There is a discussion on the correct lube in the tech section.

    It looks like you have your work cut out for you on the cover. Soak it for a few days in a good rust solvent.

    Between the two covers I am sure you have the parts you will need. The poor trans in the 3rd photo... oh my. Probably a good gear case. It would be worth a tear down to see what made it. I am thinking not much.
    Last edited by bmorgil; 08-31-2020 at 07:13 PM.

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    Sorry, I'm not familiar with that term "Rust Solvent". My first thought would be penetrating oil, but that is usually a spray. What should I use. "Marvels Miracle Oil" maybe?

  10. #10
    Super Moderator gmwillys's Avatar
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    After you drain the sludge out, I would use kerosene to flush out the remaining crud. Then you can put Marvel's around the gears and synchro. Rustoleum makes a rust converter liquid, but I would be sure to have read the label to make sure it is safe on brass. Clean out drain, rince and repeat.

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