gearbox rebuild question

The teardown continues. I've got the gearbox completely disassembled now and it will be ready to put back together once I buy a few new parts.

But there's a problem. I need to replace several of the brass bushes, notably the one that's inside the kickstart shaft, the sleeve gear bushes, and the bush that's inside the first gear-lay.

I read in some earlier posts about cutting threads in the kickstart bush and using a bolt to draw it out. But what about the other ones? As a test, I applied heat to the lay gear and tried to tap the bush out with a socket. It didn't budge. I didn't try the sleeve gear bushes but they look to be equally difficult.

I'll probably look for a professional to do this job for me, but I was wondering how these things are normally extracted. And more importantly, how do you install the new ones without destroying them? As you know, the bushes are very thin and very brittle.

thanks,
Debby

Hi Debby,

You can remove the bushes by cutting a groove down them (right through) with a Dremel or similar tool, then the bush can easily be removed.

I'm all ears for the "proper" technique.

My installation technique left allot to be desired. I did get them in, with a fair amount of force and a lot of cringing- the trick is to drive them in straight as humanly possible...

A note on gearbox reassembly- Page 106 of the Clymer manual states"

5. Line up the upper edge of the quadrant arm with the top front case stud (figure 57) ...

Click to expand...

On my gearbox the stud does not line up like the photo - if that is the case with yours, err on the high side (a little above the stud). If you go low, you won't be able to shift into first when you install the inner cover and the quadrant arm hits the bottom of the "window".

On all but the one in the Kickstart I just use the new bushes to drive the old ones out with no heat required, may not work nowadays if the new bushes are pattern but has always worked for me with genuine parts.

Debby,

Hmmm... the bushings that weren't obliterated in my gearbox slid off like nothing.

If there's anything I can add, its the following:

First, spend the $200 on the Norvil gearbox rebuild kit: Norvil P/N 085002

It includes all the consumables in one tidy package:
1 x 1st gear bush, 1 x 2nd gear bush, 1 x 3rd gear bush, 2 x sleeve gear bushes, 1 x layshaft bush, 1 x sleeve gear bearing, 1 x UPGRADE layshaft superblend bearing, 1 x mainshaft bearing, 1 x kickstart spring, 1 x kickstart pawl spring, 1 x gear lever return spring, 1 x gear lever ratchet spring, 1 x inner cover gasket, 1 x outer cover gasket, 1 x inspection gasket 1 x gear lever o- ring, 1 x kick start o- ring, 1 x ratchet spindle o- ring & 2 x quadrant o- rings

Second, have the layshaft bearing seat machined to accept the upgraded bearing. Fred's pretty cheap. Matt at CNW might offer the service as well.

Might be worth a few bucks to have Matt or another local Nort'n wrench help with the last bits of the teardown. I freely admit that I did most of mine with Fred at Old Britts - and paid him for the shop time. It was worth it to do the work with someone who's made all the special little tools and knows all the tricks.

Debby,

You might want to consult the gearbox teardown video by the late John Hudson. I have the engine video with John and it is quite informative to see someone else do it first!
http://www.nortonownersclub.org/merchandise/videogear_detail.html

There is a new engine strip video featuring Mick Hemmings. http://www.nortonownersclub.org/merchandise/videoengine_detail.html
If any one has any feedback on these I would be interested in your impression.

You should press, not whack, the bushes in, but you can whack the old ones out!. You can use a drill press as a light duty arbor press, however, if it needs more pressure, take it to someone with a hydraulic press and press blocks or drifts to get it into place. Check the fit afterward and internal lap or ream to fit.