1975 Norton Commando Mk3 restoration Part 4, Rebuilding the Mk3 transmission
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- เผยแพร่เมื่อ 7 ก.ย. 2024
- In this video we take the fully disassembled transmission and put it back together again. Along the way we replace bearings and seals and gaskets.
Excellent guys! Thank you!
With a layshaft roller bearing fitted it’s important to measure the end float on the end of the kickstart shaft and control it with shims to 0.005” - 0.010”
Kudos on your detailed explanation on why it's important to properly line up the clutch cable lever with the clutch cable mounting hole in the outer gearbox cover. Most videos forget about protecting the oil seals by covering the splines of the shafts with either electrical tape or a plastic baggie. Well done!
Well I am happy you are rebuilding a MK3, I just completed a MK1 and have purchased a disassembled MK3 that needs a new main shaft in the gearbox. I have a long road trip to get the bike and will not start my build until the fall/winter 23. I Enjoy your channel.
Thanks for the great comment, and good luck with your build and enjoy.
Hi i am restoring a mk3 so this gearbox video was so usefull as i am just about to rebuild my box great detail,far better than any manual,will look forward to the primary side being put together, I bought this bike as a pile of parts so no reference to go by. Keep up the great work. Dave. (From the UK)
Thanks for the great comment glad to help
When dealing with a "parts basket" motorcycle, it is best to obtain the parts catalog, as well as the factory workshop manual. The exploded views in the parts catalog will show you what parts you need, and what order they are assembled in.
The dreaded Norton hairspring adjustment !
[4:40] An easy way to check if you have the shift quadrant timed correctly, is to install the shift detent plunger, as you did, the put the cam plate into the notch for 3rd gear. Temporarily install the gearbox inner cover. You don't need to bolt it down. Now shift into 4th and 1st gears. If the timing is correct, you will be able to engage the notches in the cam plate for both 1st and 4th gears. If you have it wrong, the quadrant will hit either the top or bottom of the rectangular window in the inner cover, prior to getting the plunger into the notch for that gear. [17:40] You are partially incorrect. There was only one Made in Portugal bearing in the Norton gearbox. It's on the left side of the lay-shaft, NOT the main-shaft. When the bearing would first start to fail, the warning symptom was that when the engine was started, the kick-start lever would go down all by itself. If you ignored this obvious warning that something was not right inside the gearbox and drove it in that condition, then you could "blow up" the gearbox. [14:50] Great tip of using an ohmmeter to test the neutral light switch and set it correctly. FYI, I often see the switch button [P/N 06.5388] with a groove cut in it from the neutral switch. Replacement buttons are available, but I prefer to simply weld up the groove and dress it down with a file. The welded area is now much harder than original and won't wear. I would prefer that the contact pin in the switch wear out, rather than the button. You can replace the switch externally. Rather than totally disassembling the gearbox to replace the button. Much easier and cheaper repair.
Been trying to get that Spring aligned it's a nightmare. Been watching your videos on how to install that Spring and still can't get first gear. This is my 5th day and I finally gave up and order another spring. Am I doing something wrong?
That spring is got to be right.
Dog leg down towards the bottom of transmission they don't usually just work out of the package new. They need to be bent or slightly bowed. When the spring is in place the pawl must sit straight and not contact the spring on ether side and needs to have equal gap on both sides this gap needs to be around 0.010" it needs to be very close and equal on both side of the shift pawl. To test it you must move the pawl arm and the pawl must start to turn just as it contacts the spring when you move it. It must do this in both directions. If the gap is too wide it will turn to late and miss the ratchet tooth and won't shift into gear correctly. If the gap is to tight or close or touching. The pawl won't center correctly when released then gears might only shift one way but not the other or nothing at all.
I hope this helps in the video I show the testing for both directons and how it just starts to move in either direction.
Thanks, I finally got it to work. I'm keeping this video.