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Thread: 61 CJ5: a few small issues to resolve

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    Junior Member oblvnnwtnjhn's Avatar
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    61 CJ5: a few small issues to resolve

    Let me preface for those not familiar with my Introduction. All systems were rebuilt/replaced by the seller minus the T90 and rear end, an auto engineer with a major manufacturer, I trust his skills, he was forthright with all the quirks or systems he did repair, he provided a photo library of the 5 year build. He advised the previous owner told him he rebuilt the T90, he inspected early in the 5 year build process, saw no issue. He inspected the rear end, check lash etc, no issue.

    With that said, a few small issues to address:

    1. Usual pops out of 2nd gear on decel. Reading threads, watched Stivers YouTube videos, a few culprits. Current thought is, since a Saturn OD is planned, may has well rebuild the box to be certain to remove any unknowns

    2. Heat soak on new Daytona Universal carb. I saw a thread where a gent made a spacer to alleviate. Idle is good, noticing a flat/dip going into 2nd, no tach yet, unsure of RPM. Seems to get more noticeable as engine heats up in this hot humid weather as of late. I know this carb has some additional jet settings vs stock.
    Side note: is the Weber worthwhile for an improvement in overall drive-ability? Also considering looking into the Sniper 1100. This is my daily ride, the previous/owner built it to be daily/reliable thus not all stock in some errors such as Pertronix electronic ignition, alternator etc.

    3. Fuel gauge is off. New gauge, new tank, new sender, new wiring harness etc. I talked with seller, he said he spent some time setting up the sender but says he never let it get below a 1/4 before filling. I ran out of fuel the other day at 1/4. Filled, it reads past FULL, I assume time to break out the multi-meter and test the sender, adjust as needed per thread https://willysjeepforum.kaiserwillys...ght=fuel+gauge? Also noticed the speedo is off, I do have BFG KM3 7.5r16. GPS said 46 at 40, but speedo does bounce a little. New cable, perhaps gear is worn/slack?


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    Senior Member 5JeepsAz's Avatar
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    There's one video where he positions the top of the case certainly and it helps with the 2nd gear pop out. Thought that was interesting since he also shows synchro width adjustment in anither video. Interested to watch your build!

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    Super Moderator bmorgil's Avatar
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    ob, lots of stuff there. Transmissions of the type the T90 is hop out of gear under load or hard deceleration for one reason. Worn clutching teeth on the gear or the clutching collar or both. The shift rails and detents can contribute to a "hopping" out of gear at certain times, but it is important to note if that is the case it would probably be missing, broken, or worn springs and/or detent balls. Worn shift rails that are allowing the trans to slip out could also be a culprit. If it is not popping out under load or deceleration, it is not being pushed out of gear. These are two different scenarios with similar results.

    Focusing on second gear in the T90 there are three sets of teeth to look at. As the shift is made the clutch fork pushes the clutch collar into the Brass sychronizer ring. The teeth on the sychro ring lock to the clutching collar and the fork continues to move the collar forward. As the inside of the brass ring contacts the machined cone of the gear, the ring "clutches" against the gear and spins it up to match the speeds of the spinning gears. The clutch collar continues to move forward and as soon as the teeth on the gear speeds match the collar slips forward, engages the collar to the clutching teeth on the gear itself and the shift is made. The most import aspect of those clutching teeth is their surface area and approach angles of the teeth as cut. As those clutching teeth wear the load applied by the engine or drivetrain can cause the gear to "spit out". Surprisingly you do not have to lose much tooth to get it to spit out. I would say this is one of the things that student tech's had the most trouble with, determining if a gear should or should not be used. If the tips of the tooth profile are chipped or visibly worn away, I always advise replacement. The alternative is you put it back together and it spits out of gear. I really don't accept much wear here on a rebuild. The comeback is too expensive.

    If the brass synchronizer ring or the synchronizer assembly is bad, or their surfaces are glazed from heat or the wrong lube, the shift will be difficult to make without grinding or forcing the shift. The grinding or clashing of teeth from a worn or bad sycro or, speed shifting will cause the clutching teeth on the collar and the gear to wear. As they loose surface area and profile the gear will begin to have difficulty staying engaged. It is the torque applied to the clutching teeth that hold it in gear under forward and reverse loads. It is the shifter cover mechanism that holds it in gear under no load situations. When the teeth get worn enough there will be sufficient torque generated to push the collar off the gear. This first begins on deceleration. When you get on and then off the gas hard in second gear, and use the engine to slow you rapidly, a hard downshift, it spits out of gear. As the wear increases it will begin to happen more frequently and then on acceleration. Once it starts on acceleration it is over. Trying to hold it in gear will quickly wear out the shift forks. When it gets bad enough it simply wont stay in gear no matter what you do.

    Assuming the shift cover is in proper working order, a solid click when shifted from gear position to gear position, and the shift forks are not worn out (full shifts are occurring, levers are free to move completely) here is what to look for as the clutching teeth wear.

    Grinding during shift or difficult shift = usually sychro's worn or a broken synchronizer assembly or wrong lube
    Hops out of gear when rolling down rough road with the clutch in or when shifting no detent clicks = check the cover assembly (springs, rails, balls etc)
    Hops out of gear when decelerating in gear or when accelerating in gear = worn gear and or clutching collar teeth

    I would try to find a Carter Carb for it like the original. They run like a clock with the original carb set up. A sniper would be cool! Stay away from replacement universal carburetors.

    Check the heat stove under the carb in the exhaust manifold. They are notorious for sticking and frying the carburetor.

    It sounds like you are definitely going to have to adjust the gauge. Welcome to the club, it seems like we all wish the gauge would tell the truth!

  4. #4
    Senior Member 5JeepsAz's Avatar
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    Bmorgil, thank you for the better answer. So... why (actual mechanical reason) do some advocate shaving or notching the 2nd gear? Ive seen stuff said about it, but I dont know the first thing. I am installing change to floor shift eventually that will be rebuilt, just to what degree and which if any mods is the question. Shave or notch gears on a rebuild? Thoughts?

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    Super Moderator bmorgil's Avatar
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    Az I am assuming a lot about ob's transmission below. It sounds like it is not making any noises and it works well in all the gears except the second gear hop out. It is not grinding or having trouble shifting into second gear. I am not sure what is meant by "Notching" or "Shaving". The T90 should be rebuilt as specified in the repair manual. Back in the day or if high performance gear sets for drag racing weren't available, a modification to improve shifting speed and the ability to shift under power without the clutch, led to the removal of some of the clutching gear teeth. The best place for shift modifications like this however, is the shift collar and the race track of old.

    I would definitely not notch or shave anything. Some of the information you hear can be very misleading. Some things are meant to shore up a worn transmission or not following rebuild specifications for wear. When a transmission is loose or sloppy, you can expect all kinds of shifting problems and noise in more than one gear. The engineering of the transmission is such that as it wears out it has a tendency to take parts with it. In other words as the gears wear and bearings wear and things start wobbling the clutching teeth will quickly wipe out their profile. So it is the chicken and the egg, in the end the clutching teeth will be bad if the gears and bearings are worn bad enough to wobble. Many people believe the detents and springs in the cover hold the trans in gear. If you have ever seen a shifter tied to the dash, and the transmission bend it (the shifter) spitting it out of gear, you learn quickly that no shifter detent spring will hold it in gear if the clutching teeth profile is worn bad enough!

    I have seen some wild stuff on the You Tube. Some of it probably has the gear engineers rolling. Often great mechanics who can rebuild it in their sleep, may not have gotten the engineering explanation on how it actually works. I would not recommend any transmission modifications without a good engineering look over. There is a lot more science in there than you would think!

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    Super Moderator gmwillys's Avatar
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    If I were a gambler, I would put money on the fuel tank float is bent down too far, causing the sensor to read over full, and at empty, it's reading at 1/4 tank at empty.

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    Junior Member oblvnnwtnjhn's Avatar
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    Quote Originally Posted by bmorgil View Post
    Az I am assuming a lot about ob's transmission below. It sounds like it is not making any noises and it works well in all the gears except the second gear hop out. It is not grinding or having trouble shifting into second gear. I am not sure what is meant by "Notching" or "Shaving". The T90 should be rebuilt as specified in the repair manual. Back in the day or if high performance gear sets for drag racing weren't available, a modification to improve shifting speed and the ability to shift under power without the clutch, led to the removal of some of the clutching gear teeth. The best place for shift modifications like this however, is the shift collar and the race track of old.

    I would definitely not notch or shave anything. Some of the information you hear can be very misleading. Some things are meant to shore up a worn transmission or not following rebuild specifications for wear. When a transmission is loose or sloppy, you can expect all kinds of shifting problems and noise in more than one gear. The engineering of the transmission is such that as it wears out it has a tendency to take parts with it. In other words as the gears wear and bearings wear and things start wobbling the clutching teeth will quickly wipe out their profile. So it is the chicken and the egg, in the end the clutching teeth will be bad if the gears and bearings are worn bad enough to wobble. Many people believe the detents and springs in the cover hold the trans in gear. If you have ever seen a shifter tied to the dash, and the transmission bend it (the shifter) spitting it out of gear, you learn quickly that no shifter detent spring will hold it in gear if the clutching teeth profile is worn bad enough!

    I have seen some wild stuff on the You Tube. Some of it probably has the gear engineers rolling. Often great mechanics who can rebuild it in their sleep, may not have gotten the engineering explanation on how it actually works. I would not recommend any transmission modifications without a good engineering look over. There is a lot more science in there than you would think!
    Well, it works well cold (minus random jump out on decel in 2nd), but as it heats up, I am getting some light grinding shifting into the gears that I am starting to notice. I ordered a gallon of Sta-Lube GL-4 to the local NAPA, no one stocks it here. I am noticing Charlie (the CJ5) marking his territory so I am sure it's low, will check that tomorrow. I can say I am able to hold (more like gently ride my hand atop the knob) the cane in 2nd, I never feel it try to force itself out or find myself man handling to keep it in. Only pops out on decel if my hand is off the cane.

    I have a brand new in the box Novak transfer case billet pan with heavy duty gasket the seller included to install. I may wait or install this week. The seller purchased in hopes to A. increase capacity B. stop the weeping.

    Lucked out, found a Carter YF ready for a rebuild kit nearby. But will it also suffer from heat soak, is that inherent to the design? I see the earlier models, 41-53 had a heat riser valve to prevent such? Shame not to use the current carb, the seller spent $400 on the Daytona Universal, it has the upgraded ethanol resistant rubber. It's brand new, less than 7500 miles on it.
    Last edited by oblvnnwtnjhn; 08-29-2021 at 08:46 PM.

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    Junior Member oblvnnwtnjhn's Avatar
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    Quote Originally Posted by gmwillys View Post
    If I were a gambler, I would put money on the fuel tank float is bent down too far, causing the sensor to read over full, and at empty, it's reading at 1/4 tank at empty.
    I'll take that bet! Low hanging fruit at the moment, but on the list. I need a new whiteboard for the Jeep so I can start addressing/marking off the small annoyances. Overall, I am really happy with the purchase. The seller, like myself and my MGB GT, put his heart and soul in the build. It shows, I know it was hard for him/family to part with it.

  9. #9
    Senior Member 5JeepsAz's Avatar
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    This is the general idea.... (and possibly the worst idea because not meant to solve gear pop)

    The article "The Process of Gear Shaving" appeared in the January/February 1986 issue of Gear Technology.

    Summary
    Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of the gear teeth. Its purpose is to correct errors in index, helical angle, tooth profile and eccentricity. The process can also improve tooth surface finish and eliminate, by crowned tooth forms, the danger of tooth end load concentrations in service. Shaving provides for form modifications that reduce gear noise. These modifications can also increase the gear's load carrying capacity, its factor of safety and its service life.

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