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Gearbox jumping out of third

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  • Gearbox jumping out of third

    Some novice, preliminary questions: I haven't opened anything up yet and still need to check the box suffix (it's non-synchro).

    Rover jumps out of third on deceleration under mild load (e.g. slight downhill). The frequency is increasing over the past few weeks. It always pops out gracefully into neutral with no crunching. All other gears operate fine with no unusual noises. I've read this problem could be as simple as those detent springs, but have also read this is the beginning of the end and I might as well plan to pull the transmission.

    Thoughts before I dive in? Is this a don't-fix-until-it's-broke situation or do I risk damage? All new stuff for me so thanks in advance.
    Last edited by worldofinflation; 05-22-2021, 09:18 AM.

  • #2
    Hello from Brisbane.

    It's a reasonably common fault with the Series boxes - there are plenty of clips on Youtube that will explain what is likely to be going on. Also a few that cover the repair ranging from basic to difficult in situ to complete removal and strip down of the box.

    Whatever the final repair option is selected make sure that you chase down NOS parts - no matter how expensive they appear - the cheaper aftermarket stuff is likely to be a quickly acquired source of grief.


    Last edited by S3ute; 05-22-2021, 06:33 AM.


    • #3
      I’ve had this on my truck a couple time now. The first time I was able to solve it by removing the top selector linkage plate and adjust the 3/4 shift fork so it was pushing towards 3rd gear fully when you select 3rd. It’s been fine for the last 5 years but has started doing it again on overrun. I tried adjusting the fork again and it didn’t seem to work this time so I’m beginning to suspect my 3/4 syncro is wearing out.



      • #4
        If you pull the transfer case isn't there an adjustment screw on the back of the trans for 3rd gear engagement?


        • #5
          Thanks for the input, everyone. Will keep this updated.

          Neil, that's a great video resource, thank you. Talk about fastidious!


          • #6
            Originally posted by worldofinflation View Post

            ..., that's a great video resource....
            Hello again from Brisbane.

            Yes, while there are lots of clips floating about covering Land Rover repairs I've generally found (Kiwi) Geoffrey Croker's postings to be among the best. Nice presentation style and gets to the nub of it pretty succinctly.

            To be honest until I saw that particular clip I didn't have a clue about how a gearbox worked other than the fairly superficial view that there were lots of gears inside and how mechanical advantage works. Pulling mine apart was a definite no-go area, despite a few old hands suggesting that I just get on with it and have a go. I'm still to do just that, but having watched the clip a few times and read the manuals I'm now fairly relaxed at the prospect - just rounding up a few hard to source OEM/NOS parts for now.

            Still on the topic of YouTube clips, another good set to watch is a troika on overhauling a Series 3 gearbox by Steam Wally from the UK.


            One of the useful aspects of Steam Wally's clip is that his truck is a well used ex-MOD 109" and he goes over the wear on most of the parts in his gearbox. The gearbox in Geoffrey Croker's truck had been rebuilt a couple of years before and he was largely focused on a couple of broken parts.


            Last edited by S3ute; 05-24-2021, 03:35 PM.


            • #7
              Geoffrey is awesome. I've recommended his channel a couple times on this forum. He is a funny guy, and his videos are well done. My only complaint is he doesn't put out enough videos. I could watch him everyday!

              A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.


              • #8
                Mine just started doing this. Mildly entertaining to be engine braking down a long trail descent, or at least think I am engine braking in third gear, and find myself picking up speed because it is actually in neutral. I guess it is time to drain the gearbox oil to look for glitter (bushing bits) and pull the overdrive to check the main layshaft nut- or something like that after I look in the shop manual. I know it is pointing toward pulling the transmission. Any other words of advice before I go that far?

                1963 109 3-door