I have a 91 crx that I use for stage rally. It has a dohc zc motor and trans. a couple of years back, I put in a quaife helical differential. In the last rally(Sandblast 2013) the clutch blew apart and I had to pull the motor. While I was there, I decide to bite the bullet, and purchase mfactory's 4.9 final drive to make my dream tranny. I swapped ring gears and transferred gears onto the mfactory counter shaft. I reinstalled this into the case, and everything seemed OK, ie- it shifted good, everything lined up, used the original bearings and shims which seem to be in very good shape. I did notice some very close close clearance with the ring gear and the case. the problem is this- I bolt the case together and now the input shaft is harder to rotate with a seemingly lack of backlash and it does not want to shift much( out of the car still, shifting with a screwdriver through the bitch pin hole). Is the ring gear rubbing? does the case need a little die grinding? Is this just a case of new gear interface that is causing the resistance? I have the original 250k mile d series trans that came with the car to use in comparison, and much more free spinning. Does anyone out there have experience with using this d series final drive? Replies greatly appreciated.

 

You shouldn't need to grind the case and it shouldn't be harder to turn the shaft or shift the gears with the new FD set installed.

What is the part number of the FD set you are installing?

MFactory makes two different D series 4.9 FD sets, one for the cable 88-91 L3 trans and another for the Hydro S20 and S40 92-00.

 

The part number MF-TRS-02D49C, and is listed for d15/d16 88-91 Honda civic.

 

That is the correct part for your trans. I suggest taking it back apart and checking it again to see what is binding up. Feel free to call me when you get it open and I will do my best to help out.

 

You will need to grind the case for ring gear clearance. Mark it with machinist paint or a Sharpie and put the diff in and rotate it and you'll see where it needs clearance at.