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Caterham 6speed semi rebuild

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  • Caterham 6speed semi rebuild

    I wasn't planning on rebuilding my tranny, but I had some time waiting for the last few pieces of my swap to come along. Since I had ordered the bearing and gasket kit already when I broke my speedo gear, I said what the hell...

    I've done only 2 other transmissions in the past and I'd recommend a very good set of internal, external and horseshoe shapped pliers to remove all the various sizes of snap rings, retaining rings and circlips. A good strong set is crucial as the type 9 is filled with them. I used a generic 3 arm bearing/gear puller to help me get the bearing and gears off. Also, keep everything clean, neat and organized with many trays and labels for all the different parts. Take lots of pictures to help you remember where it goes in case you forget later.

    You can order pretty much all the parts you need from here:

    I used these PDF’s as a reference guide

    Now let's gets started:

    Here’s a quick overview of the different parts inside and out:

    Remove tranny from engine, bell housing and drain fluid.

    If you haven't already done so or if you have one, carefully remove the speedo sensor and back up switch sitting on the lower right side. The speed sensor on mine unscrews at the brass portion and then very slowly pull out the quill that is connected to the speedo gear. Then using a flat head, you can pry out the cover on the opposite end. Once the cover is off, you can push the speedo gear through and out on the left side.

    Remove the small rectangular breather plate on the top rear of the tranny.

    At the top left corner on the left side of the main case, unscrew the allen plug, spring and plunger.

    Put it in first gear and then remove shifter. Make sure you also remove the black plastic saddle that the shifter fork sits on. Putting it in first gear allows you to access the drift pin that keeps the selector rail connected to the main selector shaft. I use a small punch pin with the correct size to tap it out.

    Lightly tap the rear cover plate out from the inside and remove the selector rail and drift pin.

    Remove the 6 bolts on the top lid of the main case. Looking inside from front to back, you’ll see the brass 5-6th gear selector, and the 1-2nd gear selector. The 3-4th gear selector is on the back end.

    Last edited by vstryker; July 8, 2016, 03:47 PM.

  • #2
    Remove the other 6 long bolts connecting the tail end to the main case. By tapping the rear end with a rubber mallet, pulling and wiggling you should be able to remove the rear case revealing the rest of the gears.

    To remove the gear selectors and shaft, punch out the drift pin that is on the arm and pin as seen here. Once this drift pin is out, pull the selector shaft back towards the rear and remove the 5-6th selector along with the 1-2nd selector. You can’t remove the 3-4th selector yet until you slide off 3-4th gear later on.

    Looking at the main shaft, at the rearmost is the speedo worm gear. Mark the exact location of the worm gear before pulling it out with your gear puller as it has to be pressed back in the same spot.

    On the main shaft, remove the circlips, external rings, and sliding out the rear bearing.

    Continue by removing 3rd gear, and syncro rings. Now you can finally remove the 3-4th gear selector by sliding it to the rear and out.

    In order to remove the rest of the gears on the main shaft, you now have to start working on the layshaft bearing and layshaft 3-4 gears on the bottom.

    Once you have removed the 26mm bolt on the layshaft, use your bearing puller to pull out the rear layshaft bearing, along with 3rd and 4th layshaft gears and it’s spacer in between. The 26mm was pretty tight at around 90-110ftlbs so it will take vise or a second set of hands to secure the tranny and a long extension to break it loose.

    On the layshaft, remove the circlip, then bearing in the center of the spacer plate by sliding the bearing to the rear.


    • #3
      Back on the main shaft, remove circlip slide off 3-4th inner and outter hub, needle roller bearings, and 4th gear. When you slide off the syncro inner and outter hubs, try to remove it as a single unit at first, then later on you can disassemble it but you must keep track of the inner clips on the hub plate as they are different sizes for different sets.

      Remove front cover and layshaft stub bearing, then the 2 circlips and input bearing at the front.

      You can now remove the mainshaft/inputshaft together with the gears and spacer plate as a whole unit. Takes some force, again a bit of pulling, wiggling and it’ll eventually come out.

      To continue disassembling the gears of the main shaft, remove the big circlip and mainshaft bearing on the center plate. Once the center plate is off, the rest of the gears, syncros, and hubs will be easily accessible.

      To be continued…


      • #4

        This is great, the links to the pdf files are't working for me.



        • #5
          Links should work now