Transmission Swap ?

WE3RX7 · 01-11-2009, 08:53 PM

I'm 99.9% sure that a 12A trans from an '84 FB will bolt up to a GSL-SE 13B. I know the driveshafts interchange, the bolt pattern is the same, etc so I'm pretty clear on all that.

What I'm not clear on, if using a 12A transmission (5spd) on a 13B GSLSE, which flywheel do you need to use - the 13B one right? I cant recall if the splines on the clutch/flywheel assembly from a 13B work with the input shaft on the 12A trans and I dont have the parts here to check..

Any insight would be appreciated... thanks.

PercentSevenC · 01-11-2009, 09:09 PM

You need the 13B flywheel because it also acts as the counterweight. The splines on the input shafts are the same, so you can mix and match the clutch discs and pressure plates since they're all 225mm.

Rotarydave · 01-11-2009, 09:44 PM

If you look up the clutch from any parts store ie Mazda trix you will find out that both cars use the same clutch there for your spline question would be moot, as for the tranny question they are interchangeable the only issue you will see could be related to rear end gear ratio as some SEs have a different ratio than the 12a cars, You do not need to change the flywheel of your engine because you are using this tranny.

WE3RX7 · 01-11-2009, 10:21 PM

Sweet.

My buddy ripped his trans out at summit point two weekends ago. He was hoping it was just the throwout bearing, but turned out it was a failed transmission. This helps. Thanks guys!

I'm still learning more about FBs each time!

01-11-2009, 08:53 PM	#1
WE3RX7 RCC Addict Join Date: Feb 2008 Location: VA Posts: 1,812 Rep Power: 19	Transmission Swap ? I'm 99.9% sure that a 12A trans from an '84 FB will bolt up to a GSL-SE 13B. I know the driveshafts interchange, the bolt pattern is the same, etc so I'm pretty clear on all that. What I'm not clear on, if using a 12A transmission (5spd) on a 13B GSLSE, which flywheel do you need to use - the 13B one right? I cant recall if the splines on the clutch/flywheel assembly from a 13B work with the input shaft on the 12A trans and I dont have the parts here to check.. Any insight would be appreciated... thanks.

01-11-2009, 09:44 PM	#3
Rotarydave Rotary Nut Case Join Date: Jan 2009 Location: Cibolo, TX Posts: 273 Rep Power: 17	If you look up the clutch from any parts store ie Mazda trix you will find out that both cars use the same clutch there for your spline question would be moot, as for the tranny question they are interchangeable the only issue you will see could be related to rear end gear ratio as some SEs have a different ratio than the 12a cars, You do not need to change the flywheel of your engine because you are using this tranny.

01-11-2009, 10:21 PM	#4
WE3RX7 RCC Addict Join Date: Feb 2008 Location: VA Posts: 1,812 Rep Power: 19	Sweet. My buddy ripped his trans out at summit point two weekends ago. He was hoping it was just the throwout bearing, but turned out it was a failed transmission. This helps. Thanks guys! I'm still learning more about FBs each time!