Requirements for a f40 (Page 1/1)
Josh86gt FEB 07, 12:31 PM
I believe I've decided the first thing I'm going to do to my car is keep the stock engine and do a little bit of performance mods to it maybe even a turbo but while I'm in there I would like to swap it over to a f40 transmission I'm curious if anyone knows everything I would need to do that and keep the stock engine
cartercarbaficionado FEB 07, 12:43 PM

quote
Originally posted by Josh86gt:

I believe I've decided the first thing I'm going to do to my car is keep the stock engine and do a little bit of performance mods to it maybe even a turbo but while I'm in there I would like to swap it over to a f40 transmission I'm curious if anyone knows everything I would need to do that and keep the stock engine


an f40 swap is expensive. why do you think its needed currently?
Josh86gt FEB 07, 12:51 PM

quote
Originally posted by cartercarbaficionado:

an f40 swap is expensive. why do you think its needed currently?



3000 rpm at 70 mph and I plan to use it for a future swap where I put a 3800 in it I just don't want to go there yet the price of it really isn't an issue I can buy a new one for $1,200 I'm just looking for how much the parts to install it would be
fieroguru FEB 07, 09:10 PM
Plan for about $3,500 + transmission:

Custom Clutch/Flywheel - (if you had an 88, you could use the G6/F40 flywheel and clutch) - bellhousing is about 1" deeper than Fiero transmission and the input shaft ends about 1" from the bellhousing face. All this means you need a flywheel thicker than stock fiero. Transmission has a 1" 23 spline, which is also different from stock Fiero transmissions.
Custom Axles (Passenger Side, Intermediate shaft, drivers axle) - 27 splines @ differential and the F40 shifts the differential 1" to the driver side, so Fiero axles won't work.
Custom intermediate shaft bearing support
Custom Shifter bracket, cables and reverse lockout
Clutch Line connector & bleeder assembly
Dakota digital signal converter for VSS
Custom Transmission mounts
Josh86gt FEB 07, 09:17 PM

quote
Originally posted by fieroguru:

Plan for about $3,500 + transmission:

Custom Clutch/Flywheel - (if you had an 88, you could use the G6/F40 flywheel and clutch) - bellhousing is about 1" deeper than Fiero transmission and the input shaft ends about 1" from the bellhousing face. All this means you need a flywheel thicker than stock fiero. Transmission has a 1" 23 spline, which is also different from stock Fiero transmissions.
Custom Axles (Passenger Side, Intermediate shaft, drivers axle) - 27 splines @ differential and the F40 shifts the differential 1" to the driver side, so Fiero axles won't work.
Custom intermediate shaft bearing support
Custom Shifter bracket, cables and reverse lockout
Clutch Line connector & bleeder assembly
Dakota digital signal converter for VSS
Custom Transmission mounts



Thanks a lot that is all I need
cartercarbaficionado FEB 08, 04:53 PM

quote
Originally posted by Josh86gt:


3000 rpm at 70 mph and I plan to use it for a future swap where I put a 3800 in it I just don't want to go there yet the price of it really isn't an issue I can buy a new one for $1,200 I'm just looking for how much the parts to install it would be


my gt does 3k at 90.. whats up with yours? then again our 4 speed car did 3k at 79.
honestly the f40 isnt really the best trans either. it depends on what your doing and what you want out of it. it sounds like you want better durability and a higher ratio which that will do. or you can find a fwd getrag that has a different final drive and swap just the final drive and output shaft over to have a better cruise ratio.
if your doing a 3800sc and plan on beating it hard then a f40 is the way to go. cruiser can be anything honestly.
ive honestly had horrible luck with all the transmissions that can go into a fiero so far. im getting some billet gears made since i keep breaking the 3rd in my getrag (its my fault)
fieroguru FEB 08, 05:29 PM

quote
Originally posted by cartercarbaficionado:
honestly the f40 isnt really the best trans either. it depends on what your doing and what you want out of it. it sounds like you want better durability and a higher ratio which that will do. or you can find a fwd getrag that has a different final drive and swap just the final drive and output shaft over to have a better cruise ratio. if your doing a 3800sc and plan on beating it hard then a f40 is the way to go.



The F40 is the only 1990+ GM FWD transmission where you can swap out the final drive to get numerically lower ratios (G6 is 3.545, others available are 3.348 & 3.091). The 3.091 is an awesome match with high torque swaps and allows you to cruise at 80 mph at 2100 rpm with a 24.8" rear tire.