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Discussion Starter · #1 ·
Thought some of you guys would like to see what went wrong with my transmission. were here it is, the main failure point. this trans was a recently rebuilt unit, good working condition before the failure. I guess 20 PSI boost was just too much for casting...
 

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1981 8v c900 sedan, 1990 2.0 9k carlsson, 1992 21 c900 sedan
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Ewww! That's nasty. Ben Wells in Tasmania (the guy behind Snaab) has chatted with me in email about transmissions and mentioned a lot of useful info about how the standard manual transmissions are not up to standard with performance-enhanced turbo Saab 900's.

His recommendation is to fit a post-1991 manual transmission if I want a stock one to replace the auto transmission my car has at the moment, but my cars are all equipped with 8V engines so I don't know if the 8V and 16 V C900 engines can both mount on exactly the same transmissions without any problems. Does anyone know if they're all inter-changable regardless of which model of engine is bolted to the top of the transmission?

Ben is apparently looking at getting one of the rebuilt Saab 4-speed transmissions from a Saab 99 which are produced by someone in Europe, but there's a big waiting list supposedly! Given that the transmissions are the main bugbear with C900's, I'm not surprised there is so much interest. I got in touch with the guys at Three Trolls and they confirmed that the wait-time for rebuild manual transmissions out of Europe is very long!

Craig.
 

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c900 said:
His recommendation is to fit a post-1991 manual transmission if I want a stock one to replace the auto transmission my car has at the moment, but my cars are all equipped with 8V engines so I don't know if the 8V and 16 V C900 engines can both mount on exactly the same transmissions without any problems. Does anyone know if they're all inter-changable regardless of which model of engine is bolted to the top of the transmission?
the 91+ transmissions are the strongest ones that were made, actually the 89-90 units arent too bad either since the main failure point- the pinion bearing is larger and therefore stronger, its just that the 91+ ones also have thicker gears apparently.

as for the transmissions bolting up, yes all 900 trannys and most later 99 trannys (including the 4 speeds from the 99 turbos wich are the strong ones) will bolt right up to both the 8v's and the 16v's, turbo or not. i belive that there is a small issue with the older cars (up to 84 i think?) with the inner CV joints being a different size (bigger on the newer cars) but that can be fixed by simply swapping in the axles from a later car.

Paul
 

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Discussion Starter · #4 ·
yep, the trans to use is an 89-93 C-900 manual trans. they have the larger pinion bearing and a slightly larger gearset on the 91-93. This one that blew up was from an 87 I think... the main reason for failure was not high output, but the fact that 1/2 the roller bearings had failed...

all the other comments I see Paul answered, as usual he has it right. the only thing I should mention is the guy who builds the 4 speeds (erricson I think) charges quite frankly an insane amount of money, and takes forever to build a trans. IMHO, it's worth saving yourself $5000 and buying an entire 1978 saab 99 turbo / 4 spd. that's about the best trans saab ever used. 91-93 5 spds are not bad, but the shifter forks and the synchros are just as bad as any saab trans, and in-fact, the 91-93 has some of the worst forks yet! reason being that they had to make them thinner to accomidate the larger gearset. I have a trans from a 94 vert in mine, synchors are gone, and it blows out of gears. Everything else works fine though…
 

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owch man

i need a 5speed bad now i wana do the swap for my auto so if any one knows where i can get one free / cheap im on a budget im only 17
 

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the main reason to go to a 4speed is the stronger case so if you are cracking the case then go to 4speed but if you are stripping gears then get 90+
 

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For the fun aspect of it, I'd pick the 4 speed. That thing is a blast. But I hardly ever drive on highways. Nothing better than this short run I have from edgehill rd. turning onto terwood rd., here in PA, with a 4 speed. It has a tight right down a short steep hill, straight stretch of rolling hills for speed, then a good jump right into another turn, then it's a few more good turns till it ends. Short but fun to do over and over.
 
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