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Although you can't be really sure about the condition of a transaxle, there are a few things you can do to get a rough idea of its condition:
-- Check the case for leaks, obvious cracks, etc.
-- Drain the lube and look at its color, condition, etc. Also check the magnet on the inside of the drain plug. Some fine shavings are normal, but big chunks are bad news.
-- Clean all the grease out of the inner driver 'cups' (assuming this isn't an older trans with the rubber-donut inner drivers) and feel the inside edges of the slots. Often you'll be able to feel a groove where the roller has pressed against the slot through long wear. This can cause vibration when you accelerate; an easy fix is to swap the drivers side-for-side.
-- Grab the drivers and rotate them in the opposite directions. The amount of play gives you a rough idea of how loose the ring-and-pinion is. I can't give you a rule of thumb for how much is OK vs. not OK, but in general the less the better. My "good" spare transaxle has about 1/4 inch of back-and-forth play.
-- You can shift the gears by grabbing the rod that comes out of the top cover. It twists front to back and also slides in and out. When you do this, you're moving a "finger" that goes into the shift forks inside the top. It's pretty stiff, but you can shift it if you've got a good grip. Shift into the various gears and spin the input shaft, feeling and listening for any roughness or rumble.
If you want to go farther...
-- Split the front and back sections of the transaxle by removing the bolts around its "waist." (I think you also need to remove the freewheel selector if your car has a working freewheel.) Carefully pull the bellhousing part off. This will let you see the ring and pinion. You can look for rust, chipped teeth, etc. You may also want to try grabbing the pinion gear and wiggling it; if you can wiggle it any significant amount, it suggests that the bearings are worn.
-- Take off the flat top cover, the one with the shift rod coming out of it. This will let you see the shift forks and the gears themselves. Again, look for rust, chipped teeth, debris, etc. You can also see the synchro rings; if their teeth are worn down to sharp little points, your synchros have a lot of wear.
This is as far as you can go without getting into scary disassembly. For example, DO NOT remove the rear end cover (the one with the rear motor mount in it.) The very important rear bearings are under this cover, so it would be nice to be able to look at them... but once it's off, you can't put it back together correctly without making dial-indicator measurements, cutting shims, etc., etc. That's farther than you probably want to go for a simple bench-top evaluation!
I did go farther than that when I took my spare transaxle apart; I think I went as far into it as you can go without actually pulling out the gear shafts (which is very difficult if you don't have the special Saab fixture.) I've got some pictures on my website that show the whole process, so you can see what you'd be getting into. Click the link below for a peek.
Good luck and have fun!
posted by 204.76.113...
Go here, then click the 'Transaxle Autopsy' link at left
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