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Today I went to see a 1983 C900, it has a bad transmission but the engine starts and runs. The car has been sitting for five years. The owner is asking $200 for it, and says that last time the car was in the shop (5 years ago) they told him it needs new synchros, new clutch, etc. Basically it needs a new transmission. The owner says many of the gears won't stay in, and he can't remember if the car will move under its own power now. We didn't try because three of the tires were flat.

I intend to come back on Tuesday with a tire pump, air up the tires and see if the car moves. It will still need a transmission, however.

I am going to call around a few places here to see if I can find a transmission for this car, my questions are: 1) what year transmissions fit this C900, 2) How easy (or not) is it to change the transmission on the car? I have access to a full shop I can use to do the work myself, with car lifts, transmission lifts and all tools. 3) How much of a basket case is this? More questions to come.
 

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c900 trannys are pretty much "all same, make fit". I'd shoot for an 85 or newer trans. simply because they center internally instead of the spring set up that's on the shift rod in your 83. Whole engine/trans must be pulled as a unit and split outside the car, but if you have access to a full shop it comes out pretty easy.
 

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Delorean or Paul will know the details, but I think post 87 cars had a diff shifter mechanizm and some small modifications have to be done to make them work.
 

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Today I went to see a 1983 C900, it has a bad transmission but the engine starts and runs. The car has been sitting for five years. The owner is asking $200 for it, and says that last time the car was in the shop (5 years ago) they told him it needs new synchros, new clutch, etc. Basically it needs a new transmission. The owner says many of the gears won't stay in, and he can't remember if the car will move under its own power now. We didn't try because three of the tires were flat.

I intend to come back on Tuesday with a tire pump, air up the tires and see if the car moves. It will still need a transmission, however.

I am going to call around a few places here to see if I can find a transmission for this car, my questions are: 1) what year transmissions fit this C900, 2) How easy (or not) is it to change the transmission on the car? I have access to a full shop I can use to do the work myself, with car lifts, transmission lifts and all tools. 3) How much of a basket case is this? More questions to come.
It's hard to say if the hear-say is accurate. I've worked on many transmissions and have yet to find one where it needed more than one syncro (not that it doesn't happen, just not that likely on a stock 8 valve, turbo or not). Even then, what is often blamed on synchros is something else such as a bent selector fork, which can cause 2 gears to suddenly not fully engage. Another common cause of these problems is the rubber linkage between the shifter rod and the selector shaft on the transmission. It starts to separate causing 1st and 3rd to be difficult to fully engage. The self centering mechanism could also have lost it's spring, which makes positive engagement of gears a bit difficult as well. The motor mounts and transmission mount are almost certainly failed and will also make shifting in all gears difficult. I find all those problems far more often than several bad synchros (or even one bad synchro).

I remember my first 900, an '83, would jump out of 3rd and I was told by a mechanic that the synchro was bad. Within 1000 miles, the pinion bearing blew up and cracked the transmission case. This was back when they still made c900s, so a transmission was around $3500 used and beyond what a college student could afford. I now believe (after rebuilding many c900 transmissions) that the pinion bearing was the cause, not the synchro. The most common synchro failure I come accross in a stock Saab is a broken syncro spring on 5th gear. If the transmission were dismantled, I'd suspect that most of it will be in mostly good order and more minor problems discovered and bearings needing replaced.

My opinion is that you will be replacing many things outside of the transmission, so unless you are willing to spend something along the lines of $500 on other parts you should get it as a parts car or not buy it at all. It's been sitting a long time and it would not be shocking if it needed considerable suspension work, it will almost certainly need brakes after not being used for a while, the head gaskets don't seem to age well without use, the condition of timing components is unknown, the cooling system may or may not be in good shape particularly given your location, etc., etc. I'd only go through the trouble if it's a REALLY nice car otherwise.

c900 trannys are pretty much "all same, make fit". I'd shoot for an 85 or newer trans. simply because they center internally instead of the spring set up that's on the shift rod in your 83. Whole engine/trans must be pulled as a unit and split outside the car, but if you have access to a full shop it comes out pretty easy.
'85 is still external self centering, but possibly late '85s switched over. '86 or newer would guarantee internal self centering.

Delorean or Paul will know the details, but I think post 87 cars had a diff shifter mechanizm and some small modifications have to be done to make them work.
They are all the same and can be interchanged right up to '94 verts, including the 4 speeds. The main difference is self centering internal or external and primary gears which have no effect on installation, just driveability and durability (some 4 speeds are actually gears and not chain driven). The external self centering can be eliminated by removing the rollers that detent onto the linkage just before the shaft exits the cabin of the car, under the center console IIRC (been a while since I've seen one). The selector shaft on the transmission itself, which goes in and moves the selector forks, is the same on the outside of the transmission for all years. The difference in self centering or not, late model or early model is entirely internal. There are differences in performance as well, but nothing would prevent a person from installing any transmission into any car provided the self centering is dealt with (added or subtracted depending on application). From the outside, you wouldn't be able to tell one from the other without checking the label for a model number.

As to what is practical, an '87 or newer will likely have type 7 primaries vs. type 6 for earlier models (even my '86 SPG has type 6). '85/'86/'87 have a smaller pinion bearing housing, but they are the chillcast variety (pinion housing only, not transmission case). '88 has smaller bearings as well, but not sure if the pinion housing is chillcast still. '89-'93 ('94 vert) are some of the best transmissions. All of them had the enlarged rear pinion bearing. '89/'90 have a gear set more like the older transmissions while the '91-'93 have a different selector fork configuration and gears of a different design (not sure if they are really any better than the early ones). Personally, I'd shoot for an '89/'90 all else being equal. If not go even later. If nothing late model is available, then go '87/'88.
 

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I remember my first 900, an '83, would jump out of 3rd and I was told by a mechanic that the synchro was bad. Within 1000 miles, the pinion bearing blew up and cracked the transmission case. This was back when they still made c900s, so a transmission was around $3500 used and beyond what a college student could afford. I now believe (after rebuilding many c900 transmissions) that the pinion bearing was the cause, not the synchro.
My dad had an '82 8v that did the same thing. He bought it like that and 60k later the pinion bearings were still quiet.
 
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