Gearbox parts...

pjmcburney · Post by **pjmcburney** » Tue Mar 10, 2009 7:57 pm

What's the general consensus on mixing and matching gearbox parts?

I have about five gearboxes at home, all in varying degrees of serviceability.
Some gears are too far gone (teeth/case hardening wise, dogs badly worn) and will be discarded, but others look pretty good.

I want to put together a gearbox from the best bits I have - is there a big problem matching, say, a driven gear from one box with a drive gear from another, taking into account that they're a 'matching' (the right number of teeth) set?
I have to make sure I've got the right 'series' of gear sets as well obviously, as I have early 'boxes and late 'boxes...

I know some sets are supposed to be matched i.e. weren't there paint dots on factory-matched sets that meshed with the kick-start shaft at one stage?

Thanks
Paul

parksie · Post by **parksie** » Wed Mar 11, 2009 12:21 am

No problems.. Sometimes they're mismatched and whine a bit under load but other than that you can go ahead.. New gears are preferable when you can get them.

rngdng · Post by **rngdng** » Thu Mar 12, 2009 8:04 pm

I'd mix and match them (I have done it before). Shouldn't be a problem.

Lane

jkevinlilly · Post by **jkevinlilly** » Thu Mar 12, 2009 8:08 pm

I've never mixed the gears, but I have used the top half of the crancase off one 550, and the bottom half off another, without a problem.

Kevin

pjmcburney · Post by **pjmcburney** » Thu Mar 12, 2009 8:51 pm

Thanks for the info...

The next $64 question is, how do I tell how good an individual gear is?

What I mean is, apart from obvious wear on the the face of the teeth and the edge of the dogs, should there be any particular marking or lack of marking I should look for?

And, how bad can the dogs get before they're too bad to use?

I'll take some pics of some examples and post 'em tonight...

Cheers
Paul

H2RICK · Post by **H2RICK** » Thu Mar 12, 2009 10:06 pm

Well, for my first H2 rebuild and not being used to early Kwakker stroker gearboxes, I was trying to decide whether or not to buy new gears or go through my other stuff to find a better set than what was in that particular engine. That bottom end had never been apart so I knew everything was original. To MY eyes, 1st, 2nd and 3rd all had problems on the gear faces....severe load marks on the drive faces of all 3 gear combos.
So.....I took the whole thing to the local H2 dragster guru for his opinion....and he's been doing it for at least 20 years. He looked at the gearsets and shafts and then asked me if I'd be willing to sell everything to him. I asked for confirmation about the condition. He said put her all back together and run her with gear oil in the tranny and don't worry.
I took his advice and he was right. Shifts and sound okay....no funny noises at all. Soooo....looks CAN be deceiving....at least in Kwakker strokers.

parksie · Post by **parksie** » Fri Mar 13, 2009 12:35 am

Unless there is pitting on the gear face they SHOULD be OK.

bighole · Post by **bighole** » Fri Mar 13, 2009 8:46 am

I have personally mixed and matched gears and cases with no ill effects as long as the parts you are using are in good condition. One factor to keep in mind is with the case of most of us, many of these bikes were ridden for less than 30k miles and parked, typically leaving the transmissions in a low wear condition. When it comes to mixing case halves I have heard that they were line bored to match from the factory. I have mixed them up and never had problems.
my 2 cents.
-John

Post by **Suzsmokeyallan** » Fri Mar 13, 2009 11:07 am

The main issues here for the gears themselves are the condition of the teeth faces, the holes, and of course the undercuts.
Obviously something looking scored or badly grooved is not the best candidate so you need to look carefully at the ones you have and make a rational decision between the gears of similiar type
Also,,, selector forks are a big no-no if you see any sort of gouging on the faces where they contact the gear, dont even attempt to use them as the box will jam.
Since these gearboxes are fit into horizontally split cases you can easily place the assy into the lower half and measure all the end clearances to see how they compare with each other and to the specs in the manual.
Some simple turning of the gear by hand will allow you feel any problem spots, ifthey are any..
Straight cut gears do whine anyways so its not like they are silent like the helical type.

Post by **oldjapanesebikes** » Fri Mar 13, 2009 11:57 am

As others have commented, I've mixed and matched after discarding the bits that had obvious damage. I have tried to observe the colour code on the gears and crank cases on the GT750's only because it is specifically mentioned in the factory manual, although to be honest, when I've looked at them I couldn't really see any measurable difference with the gauge I had.

So far, no problems.

kmil · Post by **kmil** » Fri Mar 13, 2009 6:57 pm

Not trying to steal the thread here, but I to have been looking at two different gear clusters trying to find the best of the two and I have found that one of the gearboxes has all steel gears and the other has some of the gears that look like bronze (or are a bronze color). Does anyone know if there is a difference between the two and why a different color? Thanks.

kmil

H2RICK · Post by **H2RICK** » Sat Mar 14, 2009 9:51 pm

Kmil:
WAG here, but I've seen that too. It seems to be that the gears are either:

AA) from a different heat treat/material lot or

BB) the bronze coloured ones have been severely abused/overheated...and the evidence of this will show up in other places as well.

If the bronze coloured ones appear to be in good shape with the faces all nice with no pits or scoring and the dog/slot corners are all nice and square, I'd say it's a heat treat thing. No worries in that case.

Post by **Suzsmokeyallan** » Sun Mar 15, 2009 6:55 am

The bronze colour is something ive come across a few times. It appears to be a suppliers finish on the gears since some have it and some dont.

tz375 · Post by **tz375** » Sun Mar 15, 2009 11:12 pm

Pure speculation, but copper is used on parts where the manufacturer wants a face to be hardened and other parts to remain soft. Think of the way conrods are copper plated so that only the inner races are hardened.

Well, it's possible that the faces were copper plated so that the faces of teh dogs could be case hardened without making the whole dog harder and more brittle.

Ease possie bull yes? No?

pjmcburney · Post by **pjmcburney** » Mon Mar 16, 2009 1:23 am

Well...

This is one of the 'boxes I have and looks to me, to be not too bad.

I'm not too sure if these pics will show too much, my camera has a decent macro, but it was focusing incorrectly.
I was trying to get a shot of the leading edges of the dogs, so that's kind of where you should see a sharp focus.

See what y'all think...

Cheers
Paul