Friday, March 18, 2011
Norton gearbox strip down
Last Saturday I went to John Taylor-Leigh's house (well garage mostly) and he helped me pull the guts out of the Norton's gearbox. I met John through the Norton Owners Club here, he has an 850 same year as mine ('74) and he's owned it since new. It's the only bike he owns and he rides it daily! Anyway one of the big problems I had been having with the Norton was that when I'm accelerating out from a standstill, so in 1st gear, the kickstart was pulling itself down. I'd been riding around like this until I heard that it's a sure sign your gearbox is about to seize! Which would leave me in a bloody mess on the side of the road somewhere. The theory was, from a few different guys I talked to, that it would be a collapsed bearing on the layshaft... hence the bike not being ridden for ages, and now this — a complete strip down of the gearbox.
I took photos of the process as a reminder and thought I'd put em up here. This (above) is the gearbox with the outer cover removed. I'd done this much before, but hadn't ever gotten in any deeper than this before now.
The kickstarter pawl is pretty worn and I will replace it, but nothing to do with the problem according to John.
So this is the gearbox empty, and with all bearings looking just fine!?
Second and third gear have a bit of wear on them and we will replace these as well, but still haven't found anything that would obviously be causing the problem?
To get the mainshaft out we had to also pull the clutch basket out from the primary chain case. I've done a lot of work on this clutch but haven't had to remove the basket before. I've just been pulling plates out and cleaning them and whatnot. To get the basket out we had to remove the front sprockets, the alternator and everything.
That's the basket. I had the clutch center replaced about a year ago. I asked for a hardened steel center, but John seems to think this one might not be hardened?
There she is empty! One thing we found on this side that was 'odd', according to John, was a rubber o-ring on the mainshaft. He reckons that shouldn't be there, and looking through the exploded diagram of this area I sure don't see any o-rings there either. Could this be my problem? We won't know til we put it all back together. Which is the plan now... rebuild it to original spec, while replacing some worn parts (since we're in here now it makes sense), and then road-test it.
We're currently waiting on some parts to arrive from Norvil in the UK. And then as soon as they're here I'll be back to John's garage to put it all back together. Which I'm thinking will be a much bigger learning curve than pulling it apart! It's fuckin great that John's into this. Originally I thought he'd just take the bike, fix it and I'd get it back. it wasn't until after I'd dropped it with him that I asked if I could come back and actually go through it with him. I thought he'd tell me to bugger off, but actually he was stoked I was interested to see how to do it for myself. Great guy! I'm slightly worried about my bike being up on that workbench while we are having all these bloody earthquakes, but apart from that I'm pretty stoked to be getting my hands dirty again, but with some expert help this time.