small bore" a" series primary gears-different profiles

[814CWE]

im building up my "refreshed" mg 1100 engine onto the early 846 type 4 sync box,

ive got a new old stock primary gear but the teeth seem a bit fatter than my original which has scored bronze bushes

gone through my pile of small bore primaries to find some have a sharper flank on the teeth than others which are like my new old stock item..

obviously the a plus one is totally different and im not regarding these here...

are the onews with sharper teeth "worn?"

will i get more transmission noise fitting a new old stock primary gear?

[guru_1071]

im building up my "refreshed" mg 1100 engine onto the early 846 type 4 sync box,

ive got a new old stock primary gear but the teeth seem a bit fatter than my original which has scored bronze bushes

gone through my pile of small bore primaries to find some have a sharper flank on the teeth than others which are like my new old stock item..

obviously the a plus one is totally different and im not regarding these here...

are the onews with sharper teeth "worn?"

will i get more transmission noise fitting a new old stock primary gear?

a series and a plus have different tooth forms

the easy way to tell them apart is to count the teeth

a series = 24 tooth

a plus = 29 tooth

[814CWE]

rich..these are all a series primaries..it seems some have fatter teeth than others though both mesh correctly and have same number of teeth

[KA2S4]

Is this an "A" type and "B" type gears thing, or was that just the 'box gears?

J

[Spider]

There were only the two factory profiles, A and A+.

I think it fair to say that any non-factory drop gear would be straight cut, although I do recall that JKD did (do?) a helical set, but I'm pretty sure these were non-stock ratios. I'm not sure what the tooth profile on the JKD gears was.

When these teeth wear, they do look rather ratty as they have a hardened surface, which is only around 0.008" deep. If you look towards the top of the teeth on the gear, you'll see what worn teeth look like

[814CWE]

the difference must be the new and old teeth then-
ill take a pic today and post some pics up of the comparison in the next day or two

[Spider]

I have actually just been informed from a reliable source that there was in fact a different tooth profile on the very early drop gears. I'm not sure what years these covered, but I'll be back with the low down.

[guru_1071]

I have actually just been informed from a reliable source that there was in fact a different tooth profile on the very early drop gears. I'm not sure what years these covered, but I'll be back with the low down.

the very early thin tail primary was different internally (to suit the crank), but i think the tooth form was the same, if it had been different, there would have had to have been another number for the idler gear and the input gear, which there isnt (according to my akm2)

we need to see a photo!

[Spider]

I have actually just been informed from a reliable source that there was in fact a different tooth profile on the very early drop gears. I'm not sure what years these covered, but I'll be back with the low down.

the very early thin tail primary was different internally (to suit the crank), but i think the tooth form was the same, if it had been different, there would have had to have been another number for the idler gear and the input gear, which there isnt (according to my akm2)

we need to see a photo!

I was working from the parts book and that's also what it tells me, however a college let me know his 60 850 not only has the thin tail crank but that the drop gear tooth profile is also different. He's going to find them and send me a pic (could be a couple of days).