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Tranmission Noise & Massive Boost

1191 Views 45 Replies 6 Participants Last post by  Cornbinder89
Hi All, I thought that I could modulate the additional boost from a modded APC and higher flow injectors in order to avoid damaging my gearbox, but seemingly no such luck. When the boost kicked on in second gear I could hear what sounded like a light knock that at first I thought was engine pre-ignition, but now think that maybe it was the sound of bearings hitting shafts in the transmission. There's now a mild whirring noise under light or more throttle while driving, and to me that's a bad pinion shaft bearing. Who here did this too, and can advise me. If it is in fact a transmission failure, are the parts still available these days? I have rebuilt Alfa transaxles & Porsche transaxles, so I think that a Saab should be doable as well, hopefully...
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Almost no parts can be found new, in terms of "hard parts" gears shafts etc. Bearings some are some are proprietary
Stop driving until you determine what has failed. Assume you are going to have to buy a good used..
 

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Discussion Starter · #4 ·
Almost no parts can be found new, in terms of "hard parts" gears shafts etc. Bearings some are some are proprietary
Stop driving until you determine what has failed. Assume you are going to have to buy a good used..
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Funny enough I had bought a good used transmission from back east, hoping to just swap it in, and sadly it arrived mashed and cracked from UPS dropping it.
 

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Discussion Starter · #8 ·
That SUCKS.

There are sort of four generations of c900 transmission, and most parts swap within a generation. Compare the G/GM numbers on the primary housing.

@mylesc can rebuild one for you for a very reasonable cost.
Thanks for the info! Is the G/GM number visible with the transmission in the car? I seem to either be blind or not looking hard enough.
 

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Thanks for the info! Is the G/GM number visible with the transmission in the car? I seem to either be blind or not looking hard enough.
yes, it is on the top of the primary chain case, On a turbo you may have to move, look under one of the pipes for the turbo/intercooler.
There are a number of small changes, and some big ones. Hopefully if your present case hasn't yet cracked, you can transfer all the parts from the one with the broken case.
 

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Pinion bearings make a 'singing' noise; one unchanging note.You'll first hear the noise in 5th gear: ON with any throttle, OFF when you let off the gas or shift to 4th. As it gets worse, it will do the same in 4th, 3rd....
Other whines, clicks, and whirs are probably not pinion bearings. Boost won't break the transmission, it's usually the sudden engagement of the clutch or the sudden stop of the pinion when bearings shatter.
 

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Discussion Starter · #12 ·
Pinion bearings make a 'singing' noise; one unchanging note.You'll first hear the noise in 5th gear: ON with any throttle, OFF when you let off the gas or shift to 4th. As it gets worse, it will do the same in 4th, 3rd....
Other whines, clicks, and whirs are probably not pinion bearings. Boost won't break the transmission, it's usually the sudden engagement of the clutch or the sudden stop of the pinion when bearings shatter.
Yes, that sounds like the symptom and progression, thank you.
 

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Goodluck getting those spineless bass tards to take responsibility for their actions. After the 2nd time they broke my rare saab parts i filed a claim & all that became of it was nothing but excuses
 

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There should be more numbers, should be something like GM45606 and GM 55610 or something.
Changes between the 45 and 55 series, depending on the whole number. external vs internal centering, shift fork size pinion bearing and ring/pinion ratio. We need to know the complete trans model number.
Even with that you can't be 100% sure it is what the tag says after all these years.
 

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Discussion Starter · #16 ·
There should be more numbers, should be something like GM45606 and GM 55610 or something.
Changes between the 45 and 55 series, depending on the whole number. external vs internal centering, shift fork size pinion bearing and ring/pinion ratio. We need to know the complete trans model number.
Even with that you can't be 100% sure it is what the tag says after all these years.
Understood, thank you. The full numbers are: GM 457 12 and GM 556 02.
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I think, but have not seen it in Saab official literature that 55 series boxes are internal and 45 series are external centering. I know both my 45 series boxes are external.
The 5 spd tech manual (available above in the "sticky's") goes by year and not trans number on the updates.
At one point the ring and pinion was changed, which changes the effective gear ratios of the different primary choices. In other words, an old 6 set of primaries has a different final ratio than a new 6 set will because of the ratio change on the ring and pinion.
Somewhere I have seen a list by trans number but it wasn't from Saab, it was someone's best observations put to paper.
I would first pull what you have and look for what failed and any damage the failure caused.
There are still good used transmission to be had but it will take some looking, and may be a road trip rather than shipping it.
 

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I think you're thinking of the twinsaabs site, which sadly seems to be no more.

Oh, but there is also 900aero - forgot about that!


In any case, both are externally centering, but one is an earlier small pinion bearing 3.67 final drive and the other a later big pinion bearing 3.89 final drive box. I don't think there is anything useful compatible between the two. If the 3.89 box is just broken, maybe you can find good case?

It's a real pretty car. I would personally give the $1700 to Chris and get a rebuilt gearbox. Maybe he'd want the other two for cores which might offset the pain a bit.

It's funny, because back in the '80s $2k or $3k for an Ericksson box seemed like an insane amount of money when $1k would buy a manual gearbox for most cars. These days, Chris's $1700 is pretty competitive compared to what you'd pay for a manual transmission. You'll pay $1500+ for a used F40!
 

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Discussion Starter · #19 ·
I think you're thinking of the twinsaabs site, which sadly seems to be no more.

Oh, but there is also 900aero - forgot about that!


In any case, both are externally centering, but one is an earlier small pinion bearing 3.67 final drive and the other a later big pinion bearing 3.89 final drive box. I don't think there is anything useful compatible between the two. If the 3.89 box is just broken, maybe you can find good case?

It's a real pretty car. I would personally give the $1700 to Chris and get a rebuilt gearbox. Maybe he'd want the other two for cores which might offset the pain a bit.

It's funny, because back in the '80s $2k or $3k for an Ericksson box seemed like an insane amount of money when $1k would buy a manual gearbox for most cars. These days, Chris's $1700 is pretty competitive compared to what you'd pay for a manual transmission. You'll pay $1500+ for a used F40!
Thanks for the info! I think the 3.89 box is my preference moving forward, so finding a good case would be nice.
 

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The real question before him is are the cases interchangeable? As long as the main case is not damaged on the present trans and the guts of the damaged case are still good, could one be made from two?
I would be interested in what differs between the 55 series transmission and the 45 and why they were run at the same time in production?
There was a member on Cape Cod that was selling off his collection of transmissions, and the guy in Conn that I bought mine from had a few others. Most were epoxied around the oil drain and later boxes, There is also a place in Upstate NY that is closing and selling off what they have (Saab Parts Pro).
There are options, none that are very convenient, but a lot cheaper.
 
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