LTBALTBMX

I have been doing some reading out of interest on swapping the F23 into the LNF. My understanding is that the tranny will bolt up to the LNF block and clutch, while the F23 mounts and shifter cables should be used.

The only missing piece of the puzzle is what to do about the axles? I know the stronger lnf axles do not insert into the F23. I see two potential solutions:

1. Use the F23 axles, and swap the F23 hubs into the FE5 knuckles.
2. Use the F35 axles, but swap the CV cup on the transmission end with one from the F23 axles.

Option 2 seems like the stronger option, but I have no idea if it will work. I know the F23 has been bolted in place of the F35 on LSJ/LNFs before but information is not readily available.

63 Nova SS

iTrader: (3)

Several guys on Facebook have made the swap, most go with aftermarket axels. F23 Transmissions are cheap to buy but the conversion and decent axel cost don't make it as attractive unless you think you will be going through several of them. LnfwagonSS is supposed to have found a way to make f-35's last a great deal longer but it's not cheap and he is backed up building them currently.

jdbaugh1

iTrader: (1)

I don't think you can swap out the splined portion of the differential to use F35 axles. The F23 axles should work fine for you as long as you don't do a bunch of hard launches. People have had luck with regular old Napa stock replacement F23 CV shafts.

tomj77

iTrader: (2)

ottp f40 is another option

royce777

iTrader: (29)

I think most guys want the cheap availability of the f23. But OTTP now offers a f40 swap, im waiting to see some guys run this

Tdubbs

Same here. I read into it more after I missed it the first time, that price OTTP gives for the kit includes a trans as well. Without the lsd and dss axles it's ~2.5k for a 6 speed swap if you do it yourself.

armcclure

iTrader: (2)

I work for zzp and still prefer the f23 for a high hp lsj/lnf. my 3.63 final XFE trans on junkyard axles held 600whp all summer. she is starting to get a little noisy though.

ECaulk

iTrader: (6)

Time to spend another $3-500 on the next junkyard transmission

armcclure

iTrader: (2)

there's another 3 miles away for $250

ECaulk

iTrader: (6)

Nice

goblin

so to convert to the f23 what is different with the mounts? I thought the castings were identical??

Slowbalt2000

iTrader: (1)

cw383

iTrader: (6)

Then they dont really do a rotated mount for these? How bout an LSD? I'm wondering if these really are more robust then the F35. I hate my 1st gear. Hate it.

ECaulk

iTrader: (6)

F23 first gear isnt much better

cw383

iTrader: (6)

But the compounding of that 3.63 final ratio has to make a huge dif

Slowbalt2000

iTrader: (1)

cw383

iTrader: (6)

Did that already. No assumptions here. 1st ratio on my 4.45 F35 is 3.38 x 4.45=15.04 to 1. The F23 would be 3.58 x 3.84, or 13.78 to 1. And of course not everyone has 4.45's, but it seems the purpose of using F23 as an alternative to using the deep gears in an F35. And cost. Another benefit is using 24" tires at 60 MPH the F23 RPM's would be around 2200,while the F35 with 4.45's would be 2600 RPM. Nothing huge on both ends, but it is something.

Sharkey

iTrader: (1)

the f23 1st gear is ever so slightly shorter than the f35, when comparing a 3.84 f23 and a 4.05 f35 they are nearly identical overall ratios. the one benefit of the f23 ratio wise is 2nd gear, its not as tall so the gear split between 1st and 2nd is less. trying to compare the 2 when talking about a 4.45 final drive f35 to a 3.84 f23 is kinda hard, its 2 opposite ends of the spectrum, but i get why your trying to. the whole "run a 4.45 to keep the trans from breaking" always seemed a little problematic to me, its such a compromise of driveability. if you have a gear ratio that works well and the trans isnt strong enough to take the power there has to be a better option.

Slowbalt2000

iTrader: (1)

Wasnt thinking about 4.45, not many people have them. In that case basically any 3.84 or lower FD in an f23 would benefit you. 4.17 would be about the same as your 4.45, and a 4.41 f23 would be useless

arubenstein

Any feedback on whether or not the F40 is a better/stronger/more durable option than F23?

Slowbalt2000

iTrader: (1)

F40 is stronger 'allegedly' but exponentially more expensive.

Kamerica

How did you calibrate the speedometer? Mine is swapped and it only goes to 20 mph. I have used hp tuners to try to change the pss setting but the results are the same. Used the wheel/tire tool in hp tuners as well. No luck. Still stuck at 20 mph at 60 mph+ real world speed. Any help would be appreciated.

Kamerica

Okay. I figured it out. THIS IS THE FIX FOR 07 Cobalt Computers:
In HP Tuners go to advanced view. Change the following under Speedometer:
Hardware: VSS Pulses Per Rev 29.0000
Gear Ratio & Tire Size :
Final Drive:
Ratio : 1.00:1
Ratio: Error 3.05:1
Sensor Calibration:
VSS Tire Revs Per:
DIst 786.97
Dist- Err 828.81

PCM Output Calibration
Pulses Per
Mile 23,421

That is the fix.
Hope this helps someone.
Still trying to find fix for 5th gear cruise control not working issue.
Cruise works in all other gears 2-4.
Jason

slapbetcommissioner

iTrader: (3)

The f40 guys have the cruise control issue as well. I’m pretty sure it’s a calculated load issue preventing lugging the engine. Taller top gear is dropping the rpm a bit too low for whet the computers load limits are set to. For example with your old trans if you started to go up an incline in top gear with cruise it would eventually kick it off once the load gets too high. Not sure if there is a fix for this. As far as I’ve ever read this isn’t a perameter that can be altered through hpt.

just out of curiosity does it work if you were say going 10-20mph faster? (Obv speeding)
But putting the rpm back into the acceptable load range?