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Performance Modifications for the NG900 / Old 9-3 This forum contains PERFORMANCE related Q&A's for the NG900 and 9-3. This may also include suspension.

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Old 10-31-2017, 10:20 AM   #1
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Improving F25 manual gearbox

Hey guys I had a gear whine noise for a couple weeks now, most audible when going about 20 - 30mph. It's in every gear and even with the trans out of gear and changes with vehicle speed only, so it must be differential related.

Car is a 1998 9-3 B204 with TD04 swap that I T5-suited to stage 1.

Changed transmission fluid but that didn't help. Most prolly the diff didn't like the extra power.

Now the clutch started slipping in 4th, so there's no way around removing the transmission from the car.

I found a used FM55 505 with 100k miles locally for like 300 bucks, the same trans that is in the car already.

As long as I have it sitting on my work bench I might as well freshen it up before I put it in the car. So I spent the last couple hours reading through the Interweb on that topic.

Here's what I came up with so far:

- install transmission upgrade kit, Saab no. 5440516

- replace differential bushings with new ones, Saab part no. 8733230

- replace crush sleeve with uprated version, Saab part no. 55352125


Any small bits and pieces that I'l need and that aren't included in no. 5540516?

Also what about the clutch slave cylinder, should I just put in a new one? The one in the car seems fine after ~200k miles.

I want to upgrade to the Viggen clutch and pp for obvious reasons, anyone happen to have the part # for that? Will I have to buy the throwout bearing seperately or does it come with the clutch?

I have no plans to go beyond stage 1 at the moment as this is my daily, so I'm not about to rebild this thing into an all out race transmission. Just want to freshen it up to make it last longer.

Btw is there some kind of manual for rebuilding the F25 transmission like this one:

I rebuilt a Toploader a couple years ago and it really was no big deal with these instructions and a kit from David Kee.

I already found excellent instructions for the clutch swap:

Also some general Saab gearbox info that is helpful:

-Chris
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Old 10-31-2017, 10:22 AM   #2
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Looks like I'm not allowed to post links...ignore the last part of my 1st post lol
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Old 10-31-2017, 05:03 PM   #3
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Unless you're really committed or happen to have a large variety of pullers and press fittings and willing to buy a few other strange tools I'd just run the replacement box that you have, or get one with a warranty from a yard somewhere.

There are quite a few special tools needed to rebuild these boxes. Setting the bearing pre-loads requires shims and calibrated torque procedures. It's not impossible to do obviously, but to build one that'll last a bunch of miles is difficult.

WIS has the procedure in it. It's also worthwhile to look up the F35 rebuild procedure for the Saturn Ion Redline and Cobalt SS. There are some alternate procedures in there that work pretty well and use slightly different tools, like to split the case and pull the 5th gear at the same time.
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Old 11-01-2017, 02:32 AM   #4
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Thanks for your reply. I watched the youtube video tutorials on the F23 and F35 and it should be possible with the instructions from the WIS.

Do you by chance happen to have these and are willing to share them?

Also it looks like the gear whine is actually caused by the crush sleeve loosing tension, so at least I know now what's wrong with the transmission in my car...
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Old 11-01-2017, 02:34 AM   #5
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Btw the Viggen pressure plate is #5023718, clutch disc #51 74 933, t/o bearing - slave cylinder #8743197 just in case someone is looking for the part numbers for the Viggen clutch conversion
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Old 11-01-2017, 05:32 AM   #6
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Here's a little bit of info: https://www.cobaltss.net/forums/how-...ission-286806/

There are copies of WIS around, maybe someone can chime in and help? I purchased a copy of the official GM manual for the Ion Redline as .pdf, (it's for their "MU3" variant, NOT the Getrag manual transmission) and there's a procedure in there for it--that's where the line art in the CobaltSS link came from. Unfortunately, I didn't record where I purchased it from, sorry.

Let me emphasize, the difficult part is not taking it apart, it is setting the preloads correctly during rebuild--which requires shims and special tools. Beyond shims, you have to rotate things with a drill and multiple points, checking things with a dial gauge, there are equations and a special degree-socket to tighten the output shaft nut correctly. If you re-shim the differential bearings, you need "a 10KG weight" lol. There's a reason why not too many shops mess with these.

There are also varying amounts of 'rebuilding'. If you pull it apart to the point where you can just replace the crush sleeve, keeping everything clean, and put it back together that's not too bad. As you go further and start disassembly of the input and output shafts it starts to be really time consuming and it gets like exponentially easier to make a mistake and mess things up the further you go lol.

I'd highly recommend getting both versions of the manual, reviewing them carefully, and look specifically at the tools needed for each step before launching into it.
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Old 11-01-2017, 07:18 AM   #7
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A member posted some videos a while back on tearing one down. I put together a quick playlist: https://www.youtube.com/playlist?lis...8eRO6acy-pDWKj

WIS/EPC Info: http://www.saabcentral.com/forums/sh...d.php?t=622081
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Old 11-01-2017, 08:11 AM   #8
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Wow thanks a bunch to both of you, that's far more than I expected! Great info, didn't know that was available online.

I'm familiar with transmission and differential work and I have a small shop at home with some assorted tools Also I can borrow tools from work if I don't have them.

Building my own engines (mostly V8 stuff) and racing them, so I'm pretty confident I can tackle the F25 job as well.

Thanks again, really appreciate it!
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Old 11-01-2017, 06:52 PM   #9
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Stop back and update on your progress. Good luck!
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