Toying with idea of taller Metro 5th gear (to go with the already taller final drive)

[MetroMPG]

Just posting this for posterity...

2nd gear set (1.8947 ratio)

19 teeth - input shaft cog
36 teeth - output shaft cog

5th gear set (0.7576 ratio)

33 teeth - input shaft cog
25 teeth - output shaft cog

[Wonderboy]

If you need another suzukiclone, I've taken full notes on what's at each junkyard around here (the one closest to me is chock full of them now... probably 3 or 4 older and 5 or 6 newer), and the guy I bought my civic HB shell from has about 6 metros, all of varying quality, and all of shich he's willing to sell. I don't think he's into spellunking or selling parts - if he's going to sell it will be the whole thing, but it will be reasonable. That's still pretty far from where you live.... but you could always move here for a while Little rust belt cities like mine are beginning to get awesome - not just because of an abundance of metros.

[MetroMPG]

Thanks, Will. Noted.

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Somewhat discouraging news after a visit with the machinist friend this afternoon: he's not really equipped to do the work on the gears.

The issue is primarily around removing the material from the centers of the 2nd gear cogs to modify them to receive the hubs from the original 5th gear cogs.

He said for best accuracy (and likely lowest labour) this should be done with an electrical discharge machine (EDM), which he doesn't have. Particularly because the gears are hardened steel.

Also, he's not equipped to mill gears from scratch.

If you've looked at the well-documented web site about the manufacture, results and ultimate failure of the Ford ZX2 custom 5th gear set made out of a 2nd gear set, you'll see that EDM was used for that job.

So unless I happen to find someone with an EDM machine who isn't going to charge crazy beans, it's curtains for this particular project.

Now... do I put that Blackfly transmission back together before I forget how it came apart, or wait in case some other opportunity comes up...

[Daox]

Unfortunately, EDM is a slow process which always means $$$.

Also, you don't mill gears, you hob them. :P

[Christ]

Put it back together, so you don't lose any parts. IF another opportunity comes up, you can always pull it back apart, and this time, you already know how.

If you want to experiment with gearing, you could always have some straight gears milled, which would increase noise, but at least they'd give you an idea of your optimal ratios.

Not that I'd recommend it, but you could actually mill short-term use gears by hand (with a lathe and files). I say short term use, because you don't have the proper equipment to harden them and such... you'd be using them for a tank at most, and then you'd have to take them out for inspection, which may be more work than you want to get into.

[Daox]

Next project, high flow EGR!

[ZeroFuel]

D

We have a contact that makes gears for the Indy cars, assuming high cost & long build time, will try to get a quote & let you know.

[RobertSmalls]

I could live without a 2nd gear. Can you just swap the 2nd gear input and output gears, and shift in a 1-3-4-5-2 pattern? Or would that be a 1-lug-****-3-4-5-cringe-2 pattern?

[MetroMPG]

Originally Posted by Christ

Not that I'd recommend it, but you could actually mill short-term use gears by hand (with a lathe and files).

The difficult part though are the gear hubs. Splined on the output shaft cog, and freewheeling on the input side, with the synchro & sliding collar that have to fit the shifter fork. I suspect the actual making of the teeth for a "proof of concept" gear set is the easy part! Getting them on the shafts and making them "shift-able" is the challenge.

The other thing to consider in that arrangement is that if the test set of gears start to wear and shed filings into the oil, it'll accelerate wear through the rest of the transaxle.

Zero: sure, wouldn't hurt to ask. I've seen prices everywhere from $2k to $500-800.

Robert: the gears aren't simply swappable. EG: the small cog of the current 2nd gear set is actually integral to the input shaft. I would have sacrificed the input shaft to do the surgery to put the 5th gear hubs into the 2nd gears.

[MetroMPG]

Was going to put the transaxle back together this weekend, but I just talked to my brother and he knows a couple of other local machine shop owners. He's going to ask them about this project next week.

EDIT: already heard back from one of the shop owners who wants to test cut one of the gears to check for hardness - same concern as the first machinist.

I'm assuming the best case would be if this stuff is case hardened. Once you cut through the outer wear-resistant "skin" you reach metal that's more easily worked, so it's more practical to machine the old fashioned way (non EDM).