I recently installed a MFactory LSD into my hydro b16 trans and I installed the final drive out of my hydro LS to get a little longer gear set. I know that there are the same number of teeth on the countershaft gear that connects to th FD, so my question is will this setup be ok? Only part that is LS is the final drive. I've got it all back together and it spins and shifts fine as well.

 

So you just swapped the ring gear and not the counter shaft?

 

Yea. I only put in the LS Final Drive. I meant to say the gears on both the B16 and LS countershafts have the same number of teeth.

 

I know everyone always says to swap countershaft gears when swapping final drives but I just looked it up and the 99 Civic SI and 95 LS (the two transmissions I have) both have the same exact countershaft gears. They are the same part number 23421-p21-000. So either final drive should work with either countershaft gear right?

 

The 99 Si has a countershaft with p/n 23221-P21-020. The 95 LS has a countershaft with p/n 23221-P21-E02. Your p/n is for 1st gear.

The countershafts have to differ slightly to accommodate the rings gears with different teeth.

 

I see now! I was looking at the countershaft low gear. So the actual countershaft is what drives the final drive? I was thinking it was that low gear.

 

The countershaft is part 1 in the diagram.



1999 Civic Si

1995 Integra LS 5sp

 

So does the whole gearset just slide off the B16 and onto the LS? Does anything have to be replaced or changed?

 

My understanding is that the countershaft and final drive are a set and the gears on the countershaft can be swapped.

 

Ok sounds good! Thanks!