T90 Partial Disassembly

Discussion in 'Flat Fender Tech' started by william_cj3b, Mar 13, 2017.

  1. Mar 13, 2017
    william_cj3b

    william_cj3b Sponsor Sponsor

    Milton, FL
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    I want to change the sychro blocking rings in my T90 while it's out. It's been clashing a little when shifting into second and occasionally into third. No other noises or jumping out of gear. No abnormal play in the counter shaft or mainshaft. The brass rings are just worn out.

    I've read conflicting reports as to whether the mainshaft can be removed without dropping the counter gear out of the way. More say you can't, or more specifically don't say that you can. Although, most writeups are geared towards a full rebuild.

    It looks like I should be able to get it out if I remove the rear bearing adapter. Anyone here ever try this?
     
  2. Mar 13, 2017
    jackdog

    jackdog Member

    Finger Lakes NY
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    I have rebuilt T90s in the past and used a dummy shaft the same length as the inside of the T90 case to push the counter gear shaft out and allows you to drop the gear to bottom of the case to allow the main shaft removal. The dummy shaft keeps the needle bearings and thrust washers in place. After you put the main shaft back raise up the counter gear and slide the shaft back thru forcing the dummy shaft out. I think I heard PVC pipe will work for the dummy shaft.
     
  3. Mar 14, 2017
    spm1us

    spm1us New Member

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    Also, be careful, when raising the cluster gear into the position during re-assembly to keep the tangs on the front and rear thrust washers, located at each end of the cluster gear, aligned with their corresponding slots in the T90 case. Try to locate and install blocking rings "Made in the USA" - they can be had from some of the military vendors like Peter DeBella and others. Inspect your 2nd gear closely for wear and also your synchronizer components, too. Sometimes easier to just install a complete NOS Synchronizer assembly and 2nd gear. Good luck with your project, Sam
     
  4. Mar 15, 2017
    toolman_ar

    toolman_ar New Member

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    "You can do it"

    Separate the T-90 from the transfer case.

    Make sure the cluster gear and reverse idler gear retaing plate is not in the way.

    Shift the 2nd / 3rd slider into 3rd gear.

    Tap out the bearing retainer plate and lift out the main shaft.

    If you leave the trany mount on the T-90. It will cause the transmission to tilt forward and you should be able to keep all of the bearings, from falling into the bottom of the case.

    toolman_ar
     
  5. Mar 15, 2017
    william_cj3b

    william_cj3b Sponsor Sponsor

    Milton, FL
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    And indeed you can do this. I finally got some time to go out to the garage after work. Entire operation took about 90 seconds, about half of which was removing the bubba-made custom lock plate.

    Everything in the trans is in great condition beyond the worn sychro rings and dogs. I just finished ordering the parts from Novak.
     
  6. Mar 18, 2017
    william_cj3b

    william_cj3b Sponsor Sponsor

    Milton, FL
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    Here's some pics...

    [​IMG]

    [​IMG]

    Notice there's no gap between the blocking ring and the second gear clutch hub. Also, the clutch dogs aren't putting sufficient pressure on the blocking ring. The clutch sleeve is in good shape but the groove in the dogs is worn out such that the sleeve slips across them too easily.

    My transmission and transfer case parts will be here Monday. I've already checked out the overdrive and put it back together. Hopefully, I'll have the gearboxes buttoned up by the middle of the week.
     
  7. Mar 18, 2017
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Dang
    Do you ever back up ?
    Reverse idler and low and reverse gears look perfect.
     
  8. Mar 18, 2017
    william_cj3b

    william_cj3b Sponsor Sponsor

    Milton, FL
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    Yes. I am very carefull to avoid gear clash. My grandfather 'made' me rebuild the transaxle in his Cub Cadet 86 garden tractor when I was 9 after I managed to break a gear. In reality, he wasn't punishing me. He was doing me a great service, not only teaching me valuable skills, but spending his time with me. He could have done the job in an afternoon. It took me three days with his help. It's one of my fondest memories of the man. He's been gone about eight years now and I still miss him every day.

    I still have the Cub. I cry damn near every time I crank it up and cut a little grass with it.

    [​IMG]

    Excuse me a moment, please. Gotta go dry my eyes.
     
    Glenn likes this.
  9. Mar 18, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    Funny, I noticed that too. I always thought they were supposed to be chewed up on the end. :coffee::)
     
  10. Mar 18, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    Just wondering, are you absolutely confident the cluster gear shaft/bearings/ thrust washer are good to go? No better time to check them out. ;)
     
  11. Mar 18, 2017
    william_cj3b

    william_cj3b Sponsor Sponsor

    Milton, FL
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    Yep. End play is about 7/1000ths. Radial is two at the front and three at the reverse gear end.

    I'm pretty sure this trans was rebuilt with new gears in the 70's or 80's. There is some wear on the main shaft pilot that would prompt me to replace it if I was doing a full rebuild. That said, I'm not and I bet I can get tens of thousands of miles out of this trans before it needs a total overhaul.
     
  12. Mar 18, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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  13. Mar 19, 2017
    3b a runnin

    3b a runnin Sponsor Sponsor

    virginia
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    perfect time for a sealed front bearing, to help stop the leaks:shock:
     
  14. Mar 19, 2017
    Walt Couch

    Walt Couch sidehill Cordele, Ga. Sponsor

    cordele, Ga.
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    So how badly worn is the pilot bearing. Too much wobble in the input shaft can enhance gear clash.
     
  15. Mar 19, 2017
    william_cj3b

    william_cj3b Sponsor Sponsor

    Milton, FL
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    Minimal. Just some visible scoring in one spot like a piece of grit ran through the rollers at some point. It will get new rollers when it goes back together.
     
  16. Apr 10, 2017
    Keys5a

    Keys5a Sponsor Sponsor

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    Dryfit your mainshaft and input shaft with your new rollers. If there is very little to no slop, you will be fine. If you have too much play at these bearings, you will be pulling it back apart after a short time. The input ball bearing will also suffer, and the combination can cause these transmissions to jump out of second gear on decelleration. Both the snout of the mainshaft, and the corresponding recess of the input shaft are prone to wear, and fresh rollers don't always "fix" the wear.
    -Donny
     
  17. Apr 10, 2017
    william_cj3b

    william_cj3b Sponsor Sponsor

    Milton, FL
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    Thanks Donny, I did just that yesterday. Dry fit was nice and tight. The T90 and the tcase are assembled and ready to go.

    When I disassembled the transmission, I found that the blocking rings slid too far up on the second gear and main drive gear. No gap between the gears and the rings. There wasn't any noticeable wear in the inside of the rings. Only some minor scuffing on the ends where they were contacting the gears. This makes me think they are poorly made reproduction parts. The new rings from Novak fit well!
     
  18. Apr 13, 2017
    Keys5a

    Keys5a Sponsor Sponsor

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    Good to hear that your tolerances are good on the mainshaft/input shaft. Get some "made-in-USA" blocking rings that have good margins on the taper, and you will have a nice-shifting trans. Be sure the countershaft thrust washer clearance is good too.
    -Donny
     

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