1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

T90 Issues - Time To Rebuild?

Discussion in 'Early CJ5 and CJ6 Tech' started by kenb, Sep 13, 2020.

  1. Sep 17, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    I talked to Novak today about their kit. They said it's not labeled where the needle bearings come from. The second gear and some other parts come from India. They charge a lot for that kit and I'm not sure what separates it from the cheaper ones on the market.
     
  2. Sep 17, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    I hesitate to suggest Herm, because there have been some negative comments about him lately. www.hermtheoverdriveguy.com

    However - all second hand info - previously it was reported here that Herm went through the suppliers of these parts, bought some sample, and tested them for size, hardness etc. If you want more info, I also hear he is very talkative if you reach him on the phone. Not so great by email. He sells kits with the parts that he found were of the best quality.

    You don't have to buy a kit per se. You can buy the individual parts that need replacing and meet your standards. It will require more research on your part. How many miles do you expect to put on this Jeep? This is why I brought up repair vs. rebuild. You can inspect the parts and replace what's worn. Is a hardened countershaft better than the original countershaft, if it's in good condition? Maybe you only want the hardened countershaft, in comparison to the usual soft aftermarket replacements. Pull the countershaft, use a micrometer and measure it.
     
    Last edited: Sep 17, 2020
  3. Dec 4, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    Now that winter is here I had time to pull my transmission yesterday. I got it on the bench and looked it over. Second gear doesn't seem to have much if any slop on the shaft. It will be interesting to compare it with the new one when it arrives. I ordered the rebuild kit from Herm and they claim it's a made in India gear.

    As far as the end play I found the main shaft was tight however the input shaft had a fair bit of end play. I think I will need to look into shimming that as per Donny's discussion.

    The other issue I found was that one of the thrust washers for the cluster gear spun. The tab had broken off. I think it was the rear one. It scored the case a bit but not very deep. So it's probably good I took this apart before that got worse.

    After I get these parts washed I'll take apart the transfer case and see if I have any surprises there.
     
    jeepstar likes this.
  4. Dec 4, 2020
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

    USA
    Joined:
    Oct 25, 2006
    Messages:
    5,798
  5. Dec 5, 2020
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

    I live South of...
    Joined:
    Dec 2, 2014
    Messages:
    1,725
    Lots of good info on this thread, Thanks Guys. I put a full rebuild kit in my T 90, then I put a Kovak kit in my D18 made all the difference in the world. Took all the slop and noise out of the drive train. I notice it the most when decelerating down hill, no more strange noise's.
     
    Keys5a and Jonbbrew like this.
  6. Dec 6, 2020
    Jonbbrew

    Jonbbrew Member

    Paso Robles, CA
    Joined:
    Mar 14, 2015
    Messages:
    739
    Novak for the T90 kit as well? So both?
     
  7. Jan 14, 2021
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    I finally got the parts I needed so I could put the transmission back together. I wound up using a new case, new (used) main shaft and new second gear along with bearings and synchronizer assembly. So I suspect whatever end play measurement I had before is pretty meaningless now.

    I assembled the transmission and dry fit the transfer case without a gasket. The mainshaft gear was installed and nut tightened. I tried to measure a gap as described between the mainshaft and bearing spacer however there appears to be no gap. It appears the mainshaft gear holds the bearing tight. Perhaps I misunderstood how that measurement works?

    What I did do is measure end play of the shaft with a dial indicator with the gear installed. That gave me .010". When I reassembled the case with a gasket and sealant that gave .020". So it appears the end play is driven by the movement of the bearing between the rear bearing adapter and the transfer case.
    Am I interpreting this correctly? Should I shim this somehow? I have some .010 shim stock that I could make a shim with. I was thinking maybe between the bearing and the transfer case to replace the space created by the gasket?

    Some other considerations are that the input shaft does not appear to have significant end play. Also I have an overdrive. My concern is that if I shim the bearing I would reduce engagement of the overdrive.
     
    Ol Fogie likes this.
  8. Jan 14, 2021
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

    Southern...
    Joined:
    Nov 24, 2019
    Messages:
    1,765
    Kenb, I think you are on the right track. After rereading my prior post I realize that the way I tried to explain the problem and the repair could be a bit misleading. It is very hard to put in words exactly what I need and want to say. Also remember that it has been 35 years since I worked on a T-90 and I could easily have missed something I needed to say.
    So here goes I will try to clarify some of my statements.
    -First of all reread Keys5a and nickmil's post, they are spot on.
    -What you needing to accomplish is eliminating any back and forth movement (in and out movement) between the rear of the main drive gear and the front end of rear main shaft (where the needle brgs are). This is accomplished by adding shims as Keys5a (Donny) explains in his post. His suggestion pushes the main drive farther toward the rear by placinging shims (or an extra oil slinger) between the front main drive ball bearing and the gear face on the main drive gear.
    - Now if that does not remove all of the in and out play between the two shafts an additional shim can be placed between the spacer (#22 in the diagram) and the boss where the low-reverse gear slides. Just enough shim to eliminate all in and out movement between the two shafts except for about .003 to .005 .
    - You can place this shim on either side of the #22 spacer- on the bearing side or the gear slide boss side, it will work either way. By adding this shim you are forcing the rear main shaft forward/away from the rear bearing and closer to the front main drive gear again helping to eliminate any excess in and out movement between the two shafts.
    -Keep in mind that the front main bearing cap has a recess in side to properly position the front main bearing in the transmission case and must be installed with gasket and torqued to determine the in and out play adjustment.
    -Also the transfer case has a recess machined into it to properly position the rear main shaft bearing as well. You cannot shim the bearing in the transfer case recess as that would misalign your overdrive gear to intermediate transfer case gear mesh.
    -Remember that adding the shim between your rear main shaft bearing and low and reverse spline boss forces the rear main shaft forward (helping fix your original problem) but will keep your rear main bearing and your transfer case (or overdrive) gear in their original positions and in proper alignment.
    -Also remember that the transfer case must be bolted up to the trans with the gasket and transfer case gear in place to check the in and out shaft play.
    - Note the bearing retainer (#15 in the diagram) is a slip fit into the rear of the main transmission case and I think also serves as a oil slinger or barrier to help slow down oil transfer between trans and transfer case. Also note that that the shim you use with your spacer need to be the same outside diameter so that they both can slip thru the bearing retainer shaft bore.
    Hopefully Keys5a and Nickmil can help with this as I could be easily missing something important.
     
New Posts