What gearset is this?

[eclipsh]

I've got two M/T AWD transaxles apart on my work bench. The one I have pictures of looks like it was recently rebuilt before I got it. The bearings are German made, not Japanese (stamped on housing) and the seals look new. It looks like it has a brand new 3/4 shift fork. My guess is it, or a spider gear in the center differential broke and was the cause of a rebuild (there is some scaring in the aluminum near the center differential area and the center diff has writing indicating it was opened up). This transaxle looks to be the better of the two units but I'm concerned about the wear on the teeth of the 1/2 sleeve and I'm not sure if the keys are in good shape. I have a pile of pictures in high resolution if anyone wants a better look.

Here's what I've got:

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Any knowledgeable thoughts on what parts are good and what should be replaced are appreciated.

EDIT: On second thought, the engagement teeth on second gear look pretty worn. The other gear set has a better second gear. The synchro's on both are equally good. The engagement teeth on first gear of the other set is little more worn though. I may end up mixing and matching some parts (keeping gears paired of course). Still not sure about the keys though.

REEDIT: So it looks like the engagement teeth on 2nd gear were intentionally cut, not worn down. I was comparing with my other gear set and checking out Jackstransmissions.com and made the connection. I also took measurements of third and fourth gear diameters on the intermediate shaft. Both gears are slightly narrower on the rebuilt transmission. The gap in the synchronizer sleeve where the fork goes in is also narrower on the rebuilt unit. You can see it in the bottom four pictures. The number of cuts in the tip of the teeth on 3/4 are also different. I'm thinking I may have something interesting here but I don't know what.

And more differences:

5th gear, one on the right is from rebuilt unit:

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Input shafts, on on right is from rebuilt:

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Also, the new 3/4 shift fork has two guide holes instead of three.

 

[JackM]

Looks like the rebuilt unit has a 90 gear set in it. It's a good and strong gear set, but the synchros are a little smaller. I would at least replace the synchro rings from what I can see in the pictures.

I would use the rebuilt trans gear set, because that gear set has the HD 3-4 setup in it which is a plus for strength and looks to be in good shape.

I wouldn't worry about the 1-2 sleeve. Those are the reverse gear teeth and the marks don't bother anything. The engagement teeth that I could see on the sleeve in the pics for 2nd look prestine! That is a rare find on a used trans as people always seem to chew them up. I would reuse that sleeve.

Jack

 

[eclipsh]

Thanks Jack, I appreciate your help. 5th gear looks like it has some funny wear patterns on the teeth. I may use the 5th gear set from the non-rebuilt unit along with the synchros. I'll give you a call and get some parts ordered.

EDIT: Got your email, I will tear down both sets first and then order off the website.

 

[eclipsh]

So now that I've got both sets of gears pulled apart here's a follow up. Which shafts and gears are the best (other than 3/4 as you've state those are stronger on the earlier set). It looks like I need to use the 90 intermediate shaft due to the 3/4 combo but what about input shafts? Any big difference in the rest of the gears? I can see 1st gear has weaker looking engagement teeth in the 90 unit (much the same as 5th gear). Thanks again for any help you can offer. I'll see about taking a bunch more pictures in case others would like to see these differences.

 

[bastarddsm]

So now that I've got both sets of gears pulled apart here's a follow up. Which shafts and gears are the best (other than 3/4 as you've state those are stronger on the earlier set). It looks like I need to use the 90 intermediate shaft due to the 3/4 combo but what about input shafts? Any big difference in the rest of the gears? I can see 1st gear has weaker looking engagement teeth in the 90 unit (much the same as 5th gear). Thanks again for any help you can offer. I'll see about taking a bunch more pictures in case others would like to see these differences.

I've played with these a bit. Few tips.

1. 3rd gear, intermediate shaft and center diff lower housing need to stay together. Because of the different tooth profile.
2. I don't think that the engagement teeth on first matter. Usually you will strip 3rd/center diff before anything else happens.
3. I would at least try to sharpen up the engagement teeth on second.
4. Get the upper torrington bearing mod done.

Now I don't have first hand experience with this, but I think that the actual gear for the late style third is stronger than the early style gear. It is just the hub and slider that is weaker on the latest (93+) trannys. So you could just locate a used 91 3rd gear (from tre for like $30) put that on your rebuilt input shaft, with your late style intermediate shaft and center diff housing, and have the best (strongest) gear set.


I wish someone could chime in on the strength of the 90 3rd gear, and list out the specific differences between each gearset. I believe that there is also another variation of the gear set that is for like 89/early 90.

 

[eclipsh]

Well I got the tripod out and took some shots of both gear sets disassembled and side by side. Some of these I'm just posting up for the general knowledge base.

Newer style first gear.

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Older style first gear.

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Second gears, both are newer style.

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However, the engagement teeth on the one below have been cut down

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Third Gears, older style on the left.

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Fourth Gears, older on left.

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For those who haven't seen it this is the difference between older and newer style synchros (besides size). The old syncrhos used felt liners for the synchro friction surface rather than the metal ridges on the newer style.

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Here are the intermediate shafts with the older one in back. Not a whole lot of difference.

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There was damage to the newer style input shaft in the fifth/reverse synchro splines. My guess would be the damage came from the nut being loose but I can't be sure. I'll have to take a close look at the syncrho assembly to see if there is any damage to it.

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Given all of this I think I'll use the newer style 1st gear simply because it has a good synchro and will save me $30. If one is stronger than the other I'll go with it. I'm not sure which second gear to use. From Jack's response I should use the older 3/4 gears but with new synchros that don't use felt pads. I'll also probably use the newer 5th gear. EDIT: no I wont. 5th gear inner ring for the synchro has the same wear and damage as the input shaft. Bummer.

 

[eclipsh]

After a lot of reading through TRE and Jack's websites, staring at gear clusters and synchronizer hubs I've come up with some answers for myself.

The 1/2 hubs off both transmissions have a lot of wear. I'll need a new one.

The 90 first gear has worn engagement teeth while the newer first gear is pristine. Unfortunately the newer input shaft is torn up (see picture above). I'm going to try mating the good input shaft with the good first gear, dot some paint on the teeth and see how they mate up. Otherwise it's $200 for a new (matched?) pair.

I'm still not sure what the deal with the cut engagement teeth on one second gear is. The other second gear looks perfect though so I'll probably run it.

The teeth on 90 third gear and synchronizer sleeve are both worn. The newer 3/4 set and are in great shape as are their synchros and sleeve. I'll be running the newer set. TRE suggests they are no weaker than the "HD" 90 set. From what I can gather it is the hub/slider that is stronger on the earlier units. I don't know why/if this is actually correct.

I'll use the older style 5th set as the hub is fine and I'll just need a newer synchro ($27 vs. $105 for a new hub)

I'm debating on sending my 1st gear out for machining for a set of double synchros. Both sets I have look pretty good to my inexperienced eyes. The teeth don't look worn and when they are squished down there is still some space between the outer synchro and the face of the gear.

Also, thanks badtarddsm for the reminder about 3rd/input/center diff. I've got that in my notes for how this is all going together now.

 

[eclipsh]

I realized I haven't done my follow up. I got everything back from TRE shot peened and reassembled. Apparently the early model year front differentials used better quality spider gears and the one I sent out was one of them.

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[TSIfreek]

What year gears/slider assemblys did you end up using??

 

[twicks69]

Looks like 93-99 parts based upon the 1st gear, the bi-directional dog engagement teeth on the double synchro 2nd gear (93-94), the 93-99 3rd and 4th large-synchro gears and hub/slider, and an intermediate shaft from late 91-99.

 

[eclipsh]

Looks like 93-99 parts based upon the 1st gear, the bi-directional dog engagement teeth on the double synchro 2nd gear (93-94), the 93-99 3rd and 4th large-synchro gears and hub/slider, and an intermediate shaft from late 91-99.

That is exactly right. I ended up ordering a new later model 5-R synchro hub assembly based on the advice of Jon @ TRE.

For anyone who doesn't know what the shot peening does from what I gather it essentially forges the surfaces of what you put in. Jon estimates it makes the gears at least 20% stronger. He went into a lot of depth on it and quickly had me convinced that once a car is nearing the 400+ hp/tq mark this really extends the life of the tranny for not much money.

Things I had shot peened:

Input & Intermediate shafts
First - Fourth gears (forgot to send fifth but it doesn't get much abuse anyway)
Early stronger front diff and output
Center Diff

Before doing any of it he magnafluxed all the gears to make sure I didn't have any nasty surprises hiding in wait for me. I also got the torington bearing upgrade on the center diff. When I rebuilt the tranny on my now gone '90 Talon the area where this bearing goes was completely chewed up so I wanted to make sure this didn't happen to my new rebuild. I also replaced all the non-reusables. I'll be putting the whole thing back together today.

On a side note: I'd actually sent both second gears to Jon. Either would have worked fine but because I'd taken everything apart and hadn't packed things as well as I should have the other 2nd gear got dinged up and Jon suggested not using it. For anyone else doing their own rebuild he STRONGLY suggests leaving the gear clusters in one piece and shipping them out to him that way. It is safer for the gears and a lot smaller package that is easier to pack.

 

[twicks69]

I fully agree with Jon in the use of shot-peening, as well as the use of cryogenic treatment on select parts.

As well, I do agree with Jon regarding the shipment of gearsets. It is easier to pack up a complete gear cluster by just bubble-wrapping the hell out of it and boxing it up. Normally, if the parts are new, then I have each part seperately double-bubble-wrapped and have the box it is shipped in double-boxxed and packed full of protective packing materials.