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Discussion Starter · #1 · (Edited)
I have started to tear down the DONOR trans for my winter rebuild. I've never rebuilt an Alfa trans and didn't want to go in blind and I hoped that the donor would yeild enough good parts to resolve my 2nd gear grind.

So far, so good. The trans has come apart quite easily and it is in very good shape inside. Yes, the 2nd gear dog gear is shot and 3rd is worn but everything else is very nice and between the 2, I should get the trans working like new.

I will continue to post pics and impressions as I move along. Next is to get an understanding of how it all works and then press apart the main shaft so I can get the bad dog gears off. I am thinking about lightening 1st gear some by having it drilled. I'm not sure if this will give me a longer lasting 2nd gear syncro/dog gear but I will post so you can follow along.



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Off to the gargage to pull the lay shaft and see just how this thing really works.
 

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I can't tell how excited I am about this thread!

Going to learn a ton!

Thanks!

Vin
 

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Many of us are not "gearologists" and what goes on in an Alfa transmission is a mystery. I only rebuild them if forced by circumstance for fear I will mess up somewhere. This is a very valuable thread, not just for transmission first-timers, but for all of us that just need that little extra nudge. Sort of like the rubber/plastic mallet!
Thanks!
 

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This is great and timely, I have torn apart and rebuilt a few Alfa transaxles, but I will be doing my first Spider transmission in a few months and this is answering a lot of questions I have about the differences. Please keep posting the picks and the comments, they are priceless!!!
 

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Discussion Starter · #9 · (Edited)
Thanks for all of the kind words.

I'm no trans expert, just a guy that is fearless with decent mechanical skills and a curiosity about all things mechanical :)

OK, so here is a short video of what is goping on insdie of your spider transmission. Shot with my crappy garage only digital camera. It does get the message across tho. ZZ Top supplying the background music.

Click the image to open a new window and start the video.




Just how it all works is still a bit of a mystery but I'm closing in on a good explanation.

Now some additional pictures from the fist step of the tear down.














If you have a part you specifically want to see, just ask. I'll try to get it up for you.

Next I will work on showing the actual path of power from the clutch to the Guibo.
 

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Those are the old-style non-molly synchro rings. You can replace with the newer ones. Stronger, a bit more friction as they start to engage, so less grunching.

You'll need an amazingly strong circlip pliers to disassemble the syncro parts, and to pull the dog teeth set.

It takes some care and a a gear puller or bearing splitter, but you can pull the dog teeth of the donor fifth gear and use it to replace the damages 2nd gear dogs. Same for the synchro shift sleeves. Go find my thread on "First gear grunch" to see how to fix the annoying first gear issue. Pull a second dog set from the fourth gear to use on the first gear.

There are two shims - one in the input shaft to space the fourth gear, and the other in the rear shaft. These are critical to tx life and good shifting. The factory manual has good directions on how to measure these.

Robert
 

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A question. The synchro ring shown has grooves just as my non-moly synchro Alfa GTA transmission. The Moly synchro's from both my Ferrari Transaxle, and (in theory) from your 2L transmission should have a non grooved, rough, black surface, with moly rings, correct? You cannot mix and match moly and older non-moly components, and as the non-moly components are no longer available, or easily found in good used shape, it is preferred to convert older non-moly synchro's to the newer moly style. Have I missed something here?
 

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Robert, you have answered the question. Technically, to convert a non-moly box to all moly, I understand all the synchro components need to be changed to the later parts, correct?
 

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And you really should not "flip" the synchros. The other side works too. The synchro ring engages the slider and " acts as a clutch" against the synchro dog teeth. If you flip the synchro, you are loosing tension and the rebuild won't last very long. With the old style synchros ( with grooves) transmission, you need to replace all the synchros if using new( 67 and later) Moly synchros. I change all the dog teeth and inner bits when converting to late style Moly synchros on a race or high performance gearbox. The dog teeth are a bit fifferent between moly and non-moly so I just don't want any issues. On a street gearbox, just change all the inner straps and quadrants when converting.
Another item to check out closly is the diameter of the output shaft. It should fit into the bushing at the front of the short driveshaft piece with no slop. The output shaft should be a nice round ball, with no signs of being flat. The worn out shaft will cause a vibration that is very difficult to find. And sometimes cause the bellhousing to crack.
 

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Thanks Karen!
 

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It's been a while since I've been inside a synchro, but here's what I recall:

You need to use the molly synchro ring and the matching sleeve. Inside the big circlip there are four parts - two different shaped steel block like wedges, one top one bottom - and two semi circle thick springs. The wedges are the same for moly or non- (AFAIR), but the spring arcs are slightly different length for the moly ones - they are longer. they are not really different; the longer piece just makes the syncro radial forces larger, which makes the synchro work better. You can use the old bits, you just do not get all the benefits of the better moly design. The moly ring itself (correctly described above) is 'slicker' in that it slides on the sleeve, but the roughness helps it engage faster. The moly spring arcs provide more force to make the syncro even faster, and the slicker engagement prevents the greater radial force (from the longer arcs) from making shifting too hard.

There are different parts in the first gear - different wedges and only one spring arc, but you want to change that anyway so that all gears are identical with four pieces and all the same wedges. That's one of the reasons for pulling the dog teeth off a higher gear to use in the first - 1st has a slot milled in it for the different internal bits, and you don't need the slot.

Robert
 

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Discussion Starter · #17 ·
Those are the old-style non-molly synchro rings. You can replace with the newer ones. Stronger, a bit more friction as they start to engage, so less grunching.

You'll need an amazingly strong circlip pliers to disassemble the syncro parts, and to pull the dog teeth set.

It takes some care and a a gear puller or bearing splitter, but you can pull the dog teeth of the donor fifth gear and use it to replace the damages 2nd gear dogs. Same for the synchro shift sleeves. Go find my thread on "First gear grunch" to see how to fix the annoying first gear issue. Pull a second dog set from the fourth gear to use on the first gear.

There are two shims - one in the input shaft to space the fourth gear, and the other in the rear shaft. These are critical to tx life and good shifting. The factory manual has good directions on how to measure these.

Robert
I have a press and a bearing puller/plate for pressing off the dog gears and associated parts.

The syncro ring and sleeve is an extra that I was given with the trans and didn't know there were different styles until I pull the cover off of this gear box to see what you are calling "moly" syncro rings. this is whay I'm doing this; Live and Learn!!

I have printed your thread on the first gear mod and will be doing that to my trans.
 
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