I've noticed recently a "sudden" interest in Econo transmissions, and Econo gearing. I myself was looking for an Econo transmission for my son's car, when my research started revealing how really "rare" these things are!

I got to thinking that if we're only talking about 2 gears, the 4th gear and the axle gear, why not just get some replacement (swap) gears made? In my business, I already have a couple of gear cutters in my supplier base, and can get short orders of gears cut to spec and hardened.

This would be in comparison to having gears forged or broached, which would be cost prohibitive for small lots.

This begs the question "Could it be that simple"?

What I'm looking for as feedback from the PFF "experts" out there are answers to:

• Will cut and hardened gears work (as opposed to forged)?
  
• Does anyone have a set (or destroyed transmission) for use to reverse engineer the gears?
  
• Would there be interest in such an item (other than myself)?
  
• Am I glossing over other details with my simplified solutions?

Inputs anyone?

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Marc in sunny Titusville, FL

• 84 SE son's car, loaded
  
• 85 Coup w/V6 transplant
  
• 85 GT newly on the road
  
• 86 SE/GT conversion just bought - big plans!

I'm no expert, but no, it is not that simple.

The output for the ring gear, is part of the output shaft itself, which includes 1st and 2nd.

The fourth gear, is part of the input shaft, which includes both 3rd and 4th, and the input splines. I can try to down load the exploded picture of the tranny, if it would make more sense.

Kevin

If they could be made for around $400. I think you could sell as many as you wanted to.....

quote Originally posted by Lambo nut: I'm no expert, but no, it is not that simple. The output for the ring gear, is part of the output shaft itself, which includes 1st and 2nd. The fourth gear, is part of the input shaft, which includes both 3rd and 4th, and the input splines. I can try to down load the exploded picture of the tranny, if it would make more sense. Kevin

This is backwards.
The ring gear is just a spur gear with a bolt circle.
The pinion is on a shaft, but it's only a little more complicated than the pinion for a Ford 9 inch or other rear axle.
4th gear output splines onto the output shaft. On the V6 transmission, 3rd and 4th output are on a single cluster. However, on the 4 cylinder gearboxes, they are independent parts.

The 1-2 synchro assembly is the same as the 3-4 synchro assembly. Both spline to their shafts with 1.500 x 35 splines. The 3rd & 4th outputs spline onto a 1.290 x 30 spline on the output shaft.

I got mixed up trying to decipher the digram in my 84 service manual.

Go with what Will said.

I figured it couldn't be too easy, or it would have been done by now.

Kevin

the gears are used in other car tooo
semi rare in Fieros
but more common in other cars

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Question wonder and be wierd
are you kind?

It would be great if we could regear these 4 and 5 speed transmissions to better suit our needs depending on use and engine swaps.
I had always wondered if it were possible.
Steve

the thing that makes the "econo" 4-spd what it is, is the final gearing. 3.33. the final gearing of a 4-spd trans, or "ring & pinion" from the "old school" is NOT easy to swap. the "pinion" is part of the gear shaft. the ring is super easy - its just mounted on the spider gear cage.

the "easy" appraoch is to use larger diameter tires. you accomplish the same thing. you raise the final drive ratio. but, you lose your speedo, unless you do the math to adjust. 2 places to adjust, 3 if you swap to a 7730 ECM. 1> speedo gear in the trans, 2> speedo crystal in the speedo, 3> with 7730 ECM, and ECM wired to control the VSS line - you can adjust the ratio in the ECM.

Well I certainly appreciate these inputs. Here's what I see at this point:

quote by Will on 1-28-2008 4th gear output splines onto the output shaft. On the V6 transmission, 3rd and 4th output are on a single cluster. However, on the 4 cylinder gearboxes, they are independent parts.

My initial research focused on the gears in the original 84 trannys. In these the 4th gear is separate, so making a replacement with different aspect gearing would not be complicated. Right now I need to understand what provides the 4th gear "input"? If it's another gear, than making a replacement gear "set" is again, not a show stopper as I see it at this point. If it's a shaft, that will add some cost. My current understanding is that all the gears are "live" and synchronizers lock the desired gear when we shift?

quote by Will on 1-28-2008 The pinion is on a shaft, but it's only a little more complicated than the pinion for a Ford 9 inch or other rear axle.

Now directing attention to the differential, this is my understanding too. It may mean making the pinion gear and the side spiders, but also I believe the Citation 4 speeds had a 3.32 axle ratio (just not the "high" 4th gear) so it might not be necessary to actually "make" the diffy gears. Also the 85-88 5 spds had a 3.35 axle ratio which is pretty doggone close!

Another possibility would just be dropping the upgraded gear set (with 84 shaft etc) into an 85/86 4 speed. Those had an axle ratio of 3.65 which would give a final drive ratio of 2.66. That's not quite as good as the Isuzu 5 spd 2.479, or Getrag 5 spd 2.599, but it's "way" better than the 84 perf ratio of 3.32! and only slighly worse than the 84 Econo 2.42?

I have an 86 4 spd, and if all I needed was a bone yard 84 4 spd (I've seen tons on car-parts.com) near me for a $100 bill, and a new set of gears to take my axle ratio from 2.95 to 2.66 in 4th, I'd do it in a heart beat. I'm turning 3k+ on expressway runs, and I'd sure like to get that down to the mid 2's if possible.

At first blush, it looks like just making the 4th gear input and output set might be the ticket. This presupposes you're starting with 4 speed box, so you have the shaft and other internals to swap, and/or maybe a junk Citation tranny for the diffy?

If that's true:

quote by Mark A Klein on 1-28-2008 If they could be made for around $400. I think you could sell as many as you wanted to.....

and:

quote by Will on 1-28-2008 The cost wouldn't come down to $400 unless he made hundreds or even thousands... which he won't be able to sell.

I see $400 as infinately doable, and if you read the first part of my post, going to cut and hardened gears, small lots are easily cost effective.

As to the market, well, who knows. I do know a bunch of swap guys would like to have this combination, and just like with my son's car, boosting the MPG for highway driving for those who don't need "performance", is also attractive.

Quite frankly, I tend not worry about the market first. I like to see if it's doable and cost effective first, and usually the market takes care of itself.

Case in point: We recently introduced an EGR Adapter plate with the help of Darthfiero and others, and I expected that to be a relatively limited market. I was wrong with that guess. We've made 3 runs of these so far, and we're still accepting orders. I'm not trying to be the next Fiero Store, just trying to contribute to the Fiero community!

Having said all that, while I continue to research, in the end I will still need either a set of gears to reverse engineer, or borrow a trashed Econo tranny in order to pull the gears to reverse engineer.

Keep those cards and letters coming!

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Marc in sunny Titusville, FL

• 84 SE son's car, loaded
  
• 85 Coup w/V6 transplant
  
• 85 GT newly on the road
  
• 86 SE/GT conversion just bought - big plans!

quote Originally posted by ray b: the gears are used in other car tooo semi rare in Fieros but more common in other cars

all except the 4th gear, it was exclusive to the 4 cylinder fiero

Why use the 4 speed at all? Just use an Isuzu 5 speed. Can be had for under $100 if you break one, but unlikely if you're driving for milage. New ones are still available, ( not necessarily for Fiero, some other applications have other gear ratios, look on Ebay) Uses later model slave cylinders which are superior to the earlier models.

Final drive ratio is 3.35:1

1st: 3.73
2nd: 2.04
3rd: 1.45
4th: 1.03
5th: .74

With 215-60-15 ties, 60 mph = ~2100

quote Originally posted by niemann99: Just use an Isuzu 5 speed.

Weak.

Kevin

quote Weak.

That's really only a consideration if you're using a higher power engine.

If we're talking about backing the Duke, it's irrelevent.

I'm totally interested in this. If it can be done, awesome.

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Spent my days with a woman unkind Smoked my stuff and drank all my wine...

quote Originally posted by joeveto: That's really only a consideration if you're using a higher power engine. If we're talking about backing the Duke, it's irrelevent. I'm totally interested in this. If it can be done, awesome.

Yes, if going behind a duke, it is irrelevent.

But now matter how you consider it, it is weaker compared to the four speeds. At least there are many threads on here that say so.

Kevin