V1 Hoping you guys can help with a transmission question

[cegan09]

Hey everyone. I'm chasing a transmission question, and this community seems to have some decent knowledge on the subject. I run a saab 9-5 in the 24 hours of lemons, and recently installed the transmission ventilation mod. We're trying to figure out how we want to approach the repair. We have a spare Saab F35, and we've talked about putting an LSD in it. However it looks like the parts kits for doing that are not available any more from any source I used to know. Even the shop we'd talked to about doing the install was weary of being able to get parts. So I've been trying to figure out what approach to take, between just throwing in another open diff F35, trying to actually find the parts we'd need for an LSD install, or trans swapping it. This is where I was hoping some of you might have some technical knowledge to share.

First, since the F35 was used in some other chevy applications, are there still decent resources I don't know about for getting the install kits? (bearings, crush sleeves, pinion locknut, gaskets, etc). I only really knew the saab sources and am now trying to search others. I think I can piece together something piecewise, but I've had no luck finding the pinion locknut specifically (PN 12755195, unsure if that's a cross over with the chevy applications or not).

Second option for me is to figure out if I can trans swap. I'd love a solution that still has good junkyard spares options, which the saab trans does not. There is apparently a super rare F40 that bolts up, but it only came on some silly small production number diesel version of a saab, so not a good option. It looks like this community has had success with the F23. The biggest hurdle there would obviously be making it bolt up, but if I could I'd feel a lot better about future spares. So a few questions related to the F23. First, I found this forum thanks to a thread a couple years ago about some brand new saab F35 transmissions that were being sold. If these were a valid option for you guys, what are the chances there is overlap in the engine bolt pattern with other transmissions like the F23? I have preemptively assumed little chance and will be pleasantly surprised if I'm wrong.

Next question, does there exist a version of the F23 with the starter on the same side of the motor as the diff, instead of the opposite side as I see most are? I can wrap my head around an adapter plate to solve a mounting hole misalignment, but I don't think I can move the starter to the opposite side of the engine in our car, that space is taken up by a turbo and downpipe, which is already competing for space with radiator fans.

Last piece of the puzzle will be axles, since I know the F23 and F35 don't share input shaft sizes. But I figure that solving the axle problem is the easy part if I just go sit in front of a catalog to find something with the right lengths and splines. I'd love to keep the intermediate shaft on the passenger side, but I saw in other threads that there might be an answer in different Isuzu vehicles.

I hope it was ok jumping in here with questions. Appreciate any answers you might be able to share.

 

[Rauq]

Not a problem, welcome! I'll try to be clear about what I know vs what is speculation.

Real quick: What year is your 9-5 and what motor does it have?

Confident in my understanding:
For Cobalt applications, the F23 and F35 are pretty much bolt-in replacements for each other. I am working on such a swap and a few others have successfully completed it. There are no factory LSD options for the F23. There is an OBX helical LSD which has a questionable reputation for longevity, some of which is rectified by replacing the hardware in it. There is a supplier of a kit of this hardware to which I can direct you if you'd like. There is a Quaife LSD which is much more expensive and hard to find. There are also LSD inserts which are honestly probably not worth the money but allegedly not completely ineffective, just partially.

Fairly confident in my understanding:
An LSD swap in an F23 is a reasonable task for a DIY-er, while the F35 swap is not. I believe DF Kit Car was doing them for a while as they invested in the research and the tooling fabrication to be able to set and measure bearing preloads and such.

Not confident in my understanding:
I read at one point but can't find the source again that there were several different engine-side case halves for the F23 transmission. Something like early J-body, late J-body/Delta, Theta platforms had different cases? I researched for a time using a Saturn Vue 4.41 final drive trans and I seem to recall my conclusion was that it was a simple case-half swap away from being a bolt in for the Cobalt platform. Perhaps there is an F23 configuration that allows you to use your starter configuration, but I'm not sure.

Speculation:
The F35 -> F23 swap is less straightforward for an LNF Cobalt vs any other, as they use different wheel bearing/hubs, so there is not a Cobalt axle set for the application like there is for other Cobalts (where base model Cobalt axles are used). You may be able to identify other GM models with similar wheel hub splines that also use an F23 transmission and work backwards from there to find a fit.


I'm not sure how much clearer things are after my braindump but I've tried to avoid speculation presented as fact as is so common online. If you have any other questions or particular clarifications you're after, just post up. I feel like I'm at least as good as anyone and finding information online and I appreciate the challenge and opportunity to learn new things and help folks out.

 

[cegan09]

That is amazingly helpful, thank you. You're right I forgot to mention the saab details. We're a 2008 9-5Aero with the B235R.

I didn't realize from what I'd read so far that the inserts for the F23 are not "real" lsd inserts, so that alone is helpful and makes it a less appealing option as a replacement.

I'm going to assume still that the F35 used in the cobalt uses a different case half, so I will not get lucky on bolt patterns. I'd hoped to be wrong here, again based on the thread of some DF kits using the saab version F35. But I am just not familiar enough with the Chevy drivetrains to know what lines up and what doesn't. Sometimes you get lucky and can piece together some weird stuff (did you know what if you use the MA5 from a Soltice/sky, with the bellhousing from a 1994/5 dakota 4 cylinder, you can bolt it directly to an 80's Chrysler 2.2/2.5 turbo? I do, because that's something I apparently needed to figure out....)

Again, thank you, appreciate the data dump.

 

[Desert Sasqwatch]

The B235 engine is a Triumph based engine - iron block, aluminum head from what I've read - and I cannot find anything that defines if the bolt pattern is a match to the I4 Ecotec engine. This being the case, it's quite probable the F35 (FM55 Saab indentifier) used on the B235 engine has a different bolt pattern than the GM F35 transmissions that are used on the Ecotec engine family. As you stated, a housing swap to the B235 bolt pattern would most likely be needed to use a stateside GM F35.

OR, get an Ecotec to replace the B235?

 

[Rauq]

Sometimes you get lucky and can piece together some weird stuff (did you know what if you use the MA5 from a Soltice/sky, with the bellhousing from a 1994/5 dakota 4 cylinder, you can bolt it directly to an 80's Chrysler 2.2/2.5 turbo?

I came across a guy putting a 2J into a Dakota, not sure if this was the exact setup but a quick search puts me on this path... Toyota W58 bellhousing, Colorado tailshaft housing/transfer case I want to say?

For what it's worth, small clarification according to my understanding... I don't think folks are referring to a Saab version of the F35, rather that the LSJ + F35 combo is very similar to the Saab B207R + F35 setup. But I think the B207R and B235 are different enough that the comparison is a bit off.

 

[Tinkles]

F23s were available in 00-05 J-bodies(Cavaliers and Sunfires) and had 3 different bell housings. 00-02 2.2L OHV(same bell housing as GM's 60* V-6 engines), 00-02 2.4L(GM Quad 4 bell housing), and 02-05 2.2L Ecotec(an 02 Ecotec car is not that common).

 

[cegan09]

I meant this thread, if it clarifies anything. But looking closer they must be for the ecotech based engine that was going into the 9-3 in the 2000s. I see cable shift, not rod linkage shift as the 9-5 uses. I forgot the F35 went in those as well, was thinking they were all F40.

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Regardless, all of this is helpful, much appreciated. I'm not looking to change the engine, the B235r is fantastic for what we're doing. Darn near indestructible so far, and the right power level for endurance racing. The trans is just now the limiting factor if we can't find parts.

edit: didn't realize I'd trip your profanity trigger, changed it.

 

[Lonny]

There is an f35 that comes from a Saab that uses the same internals as the f35 from a Cobalt.

The only difference is the Saab bell housing is much deeper to allow for a different flywheel. I think the Saab uses a dual-mass flywheel but I am not positive.

I have used Saab internals to repair F35s for our Goblins.

Now as far as bolt patterns go I have no idea if the Saab f35 will bolt to your engine but I do know all of our starters are always located on the forward side of the engine.