Another one bites the dust. Cruising on the hwy, downshifted to 4th to pass a car, rolled into the throttle about 50% and then went to shift to 5th and it said FU. Started whining in 4th and then identified as neutral. Luckily after 4th broke I was able to limp it to work in 3rd gear.

So, the F35 is going into the trash pile where it belongs. I've read guys having nothing but problems with these, there's no aftermarket support and they're a million dollars from the JY. So the F23 is the logical choice. I'm familiar with the trans as a friend of mine has has one in his 600hp 3800 fiero since ~09 and I've seen the beatings it's taken, so I know it'll be plenty strong for whatever I throw at it. (<450hp)

I plan on running the 4.17 final drive as it looks like it'll have a pretty ok split for street use. The info on the 3.94/3.63/3.84 trans is plentiful, but I'm not able to make heads or tails on the 4.17 application. From what I've seen the 05-07 HHR supposedly is what has the 4.17 final drive, but I've yet to find an M86 trans breakdown that lists any parts for the 4.17 transmission.

It's easier to find a low mileage 09/10 f23, so if I could do that then swap the final drive and rear shaft to a 4.17 that'd be ideal. All the breakdowns have part numbers for everything but the 4.17 that I've seen, so anyone that has additional information it'd be appreciated.

It doesn't appear to me that a "swap" tutorial has been done yet, so hopefully in the next couple weeks I can document everything I've done to do this swap including part numbers for the next guy that has their F35 inevitably grenade.

Appreciate any input!

 

IMO, there isn't a large enough difference between the 3.94 and the 4.17 to justify the time required sourcing parts and doing the R&R. The MPH difference at 7000 rpm is negligible in basically every gear. 5% difference in speed. Not even a 10 mph difference in 4th gear.

There's a Transmission Gear Ratio spreadsheet in the Technical Articles forum: https://www.cobaltss.net/forums/tech...dsheet-329296/

 

F23 >>

 

How’s the tutorial going. I wanted to swap from my f35 lnf to a f23 but like you said, there isn’t much on “how to”

 

Well, it's funny you ask..

The car has ~200k on it so I decided it was probably as good a time as ever to put a ZFR/TR10 on it.... I also did the timing chain and walnut blasted the intake.

I've been passively working on the car in between other projects and actually got the car back together last week. I found out my RR caliper is locked up and been waiting on the replacement from RA since Thanksgiving...however I did take the car around the block and all my gears do gear things. I'm not going to ever track this car and it's more of a quick DD, so I did a budget build... I think if you were looking for best setup it would be better to investigate what some others did with the equal length axle setups. Here's what I ended up doing for the swap, along with install notes. I'll update more once I get some time on the car.



Thanks F35.. 4th gear let go on the hwy. The only positive about the F35 is that it stayed together long enough for me to get to work 5mi after it broke.

Started with the filthiest F23 I could out of an 09 G5 (3.63 FD)

Nothing some oven cleaner, simple green/dawn and a pressure washer can't fix.

Tough to see, but F35 reverse light switch is mounted on the top of the trans

F23 Reverse light switch is on the back of the trans next to the diff.

Had an old LS1 knock sensor harness laying around that happened to be the correct female plug to extend the factory wiring. It's probably easier for most to cut the wires on the factory harness then extend them with butt connectors. I happened to have the correct connectors so I opted to make an extension harness.

Used some SCL to mold the harness to route it on the outside of the trans and up.

F23 has 'lil guy bolts here, F35 are M10. I opted to drill and tap the F23. I think there was another couple holes that also needed to be drilled and tapped to the M10 bolts, but I can't recall. It'll be obvious when you try putting on the F23 mounts reusing the F35 hardware.

F23 has a different tooth count (F35=85, F23=29) on the VSS reluctor. The vss pulses per value listed above is if you're using factory tires (225/40ZR18). This value is the tire diameter multiplied by the vss reluctor tooth count. (Tire Diameter[mm] * 29) so it would need to change if you're not running factor sized tires.


You'll need the following from a JY 2.2L Cobalt:

Upper, Front and rear trans mount
Clutch line from master to trans
Shift cables
Shifter

I opted to purchase new GM mounts since there was a bit of time where there wasn't any manual trans cobalts in the local JY. I also opted to rebuild the F23 shifter and add an OTTP short shifter. I replaced the axle seals too since it was easy to get to and cheap. Here's what I ended up with for parts



I've got a lot of faith in the F23 after seeing the abuse it's gone through in my buddies car, so this thing with 3/4 the tq that he's running should be a walk in the park. Time will tell.

Feel free to ask any questions.

Hope this helps

 

this helps puts a lot thanks man

 

I’m looking to swap an f23 for my 2010 lnf because my 5th gear blew up on the highway. I bought a f23 in good condition as well as followed your guide on rockauto for other parts. They were sold out of the right cv axle so I bought one from a manual transmission 2000s grand am hoping it will fit. What did you do about the mounts, did you have to drill new holes in the frame to make em fit? I’m getting a shop to do the swap for me so I just want to be as clear as I can with them so there’s no surprises along the way you know?







QUOTE=blacksaleen95;7753162]Another one bites the dust. Cruising on the hwy, downshifted to 4th to pass a car, rolled into the throttle about 50% and then went to shift to 5th and it said FU. Started whining in 4th and then identified as neutral. Luckily after 4th broke I was able to limp it to work in 3rd gear.

So, the F35 is going into the trash pile where it belongs. I've read guys having nothing but problems with these, there's no aftermarket support and they're a million dollars from the JY. So the F23 is the logical choice. I'm familiar with the trans as a friend of mine has has one in his 600hp 3800 fiero since ~09 and I've seen the beatings it's taken, so I know it'll be plenty strong for whatever I throw at it. (<450hp)

I plan on running the 4.17 final drive as it looks like it'll have a pretty ok split for street use. The info on the 3.94/3.63/3.84 trans is plentiful, but I'm not able to make heads or tails on the 4.17 application. From what I've seen the 05-07 HHR supposedly is what has the 4.17 final drive, but I've yet to find an M86 trans breakdown that lists any parts for the 4.17 transmission.

It's easier to find a low mileage 09/10 f23, so if I could do that then swap the final drive and rear shaft to a 4.17 that'd be ideal. All the breakdowns have part numbers for everything but the 4.17 that I've seen, so anyone that has additional information it'd be appreciated.

It doesn't appear to me that a "swap" tutorial has been done yet, so hopefully in the next couple weeks I can document everything I've done to do this swap including part numbers for the next guy that has their F35 inevitably grenade.

Appreciate any input![/QUOTE]