Tranny spline gear

Hi all,
Am reconditioning a transmission bought of flea_bay with a few gears missing etc. Looks to be in ok condition otherwise i.e. no cracks in the housing etc.
I intend to replace the missing gears in pairs main and lay first gears and replace all bearings, bushes and seals.
The question I have is regarding the main shaft spline gear - gear teeth look ok, bushes are ok, but it has a brownish ring around the base indicating some overheating at some point. It also has some mild pitting at the end of the spline. Pics attached.
Would you use reuse this gear?

It looks as though the marks have come from a bearing overheating. If that's all it is, I'd re-use it. Before doing so, however, I'd clean it up and measure the contact area to ensure that the marks haven't in fact come from a complete bearing seizure and thus resulted in material being rubbed away.

That appears to be fretting from being run with the sprocket retaining nut loose. Measure it, report back.

OD varies from 1.247 to 1.248 inches

... maybe someone can put a mic or even a caliper on an undamaged one, post it up.

concours said:

... maybe someone can put a mic or even a caliper on an undamaged one, post it up.

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It appears to be a thousandth small (a new one being 1.249ish and the bearing inner at 1.250) and has spun in the bearing. Whether the sleeve gear is bad or not, I would surely replace the bearing.

Thanks for the replies, a new bearing will be installed along with this gear.

freefly103 said:

Thanks for the replies, a new bearing will be installed along with this gear.

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FF
I would replace these bushes in the spline gear if you don't know the history (try to get the Mk 111 longer type x2) or order three 040062 + the first gear Layshaft bush 06-6664. These tend to be the bushes that break down most frequently. 04-0131 Sleeve gear sprocket seal usually gets a groove where the seal rides and should be changed if you want it oil tight.

Check the kickstart pawl as well.
Cheers,
Thomas
CNN

My observation, have never seen a Commando gearbox that didn't have pitted gears. This AMC gearbox was designed for machines with up to 25 HP. Norton started using it in '57 on all models. Two of my passed machines a '57 model 50 and '61 ES2 had beautiful looking gears. For all of the Commandos I've owned, this pitting has not been a problem. Bushes, bearings and seals are what have needed replacing. I am cautious when considering replacing gear sets as I'm not convinced of the quality of what is available.

illf8ed said:

I am cautious when considering replacing gear sets as I'm not convinced of the quality of what is available.

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illf8ed,
I am with you on that. As far as I know, you want to see "AH" stamped on all the gear sets. Sometimes it is hard to see because the stamping is so light, but look at the sleeve gear on the area between the dogs. Opposite side of the sprocket. freefly103 If you don't see the AH then suspect it to be pattern parts of unknown quality.
Cheers,
Thomas
CNN

Well, one thing after another. I replaced the bushes on the mainshaft spline gear. I had ordered a new main shaft as the old one showed some wear on it. I also had ordered a new main shaft first gear. The new main shaft first gear would not fit on the shaft. Back they both went last week, and today, the replacements arrived. Main shaft first gear fits ok on the new main shaft, but fitting the spine gear with new bushes (all from the same supplier) is a tight fit.

The new bushes for the cam plate and quadrant are not a push fit i.e. I can push them in by hand. The layshaft bearing is the same, while the main bearing is ok i.e. will require the case to be heated.

I intend to use a smidge of locktite on the loose fitting bushes and lay gear bearing to secure them in the case.

All this looks much easier when Mick Hemmings assembles the tranny on his DVD.