Rotary Car Club - View Single Post - FD Differential Remove and Replace

jkstill · 04-17-2010, 01:35 PM

After deciding to replace the stock 4.10 FD gears with a set of 4.77 gears, I also purchased a Carbonetics Carbon Limited Slip Differential at the same time. ( free plug - Great deal, thanks Rishie! )

I would be remiss if I didn't also mention the smokin' deal I got on the gearset from Dial8 - thanks again. It included a Greddy diff cover (which is what made it such a great deal), which about doubles the volume of the differential so that it can hold 2 liters of diff oil, as well as all the seals and bearings needed to replace the differential.

I haven't got around to installing the Diff cover yet, waiting until I decide how to setup an oil cooler for it.

If you are simply taking your diff appart to replace the gears or the diff with another set of the stock variety, this job is probably a lot simpler. I know someone that replaced his Miata diff with another Mazda diff - it all simply bolted right up.

Using a non-Mazda gearset and/or an after market differential will create more work. It isn't too likely that the spacers will be correct for the new setup.

Changing the gears also requires removing the pinion, possibly replacing the pinion spacer, definitely replacing the crush collar and then setting the pinion bearing preload.

If you are reading this for entertainment, curiousity or are just bored at work, forge on head and read all of this.

If you are planning to do this job yourself, I cannot overstress the need to read the Differential section in the repair manual. Read it and study until you can almost quote it. Some of you may be old hands at this and will find nothing new here. I am not an old hand at it, and had I better studied the manual, could have saved some time and work.

The first time I re-installed the diff, I ran the car through the gears on the jackstands (very solid jackstands I might add) and didn't like the sound of the diff. It sounded rough. Had I paid more attention to the pinion bearing preload setup I could have avoided that.

Taking it all apart the 2nd time and re-doing all the setup was a bit easier than the 1st, as I already had pretty good idea of how to do it.

Next: The Documentation

04-17-2010, 01:35 PM	#1
jkstill Rotary Fan in Training Join Date: Mar 2008 Posts: 93 Rep Power: 18	FD Differential Remove and Replace - Writeup After deciding to replace the stock 4.10 FD gears with a set of 4.77 gears, I also purchased a Carbonetics Carbon Limited Slip Differential at the same time. ( free plug - Great deal, thanks Rishie! ) I would be remiss if I didn't also mention the smokin' deal I got on the gearset from Dial8 - thanks again. It included a Greddy diff cover (which is what made it such a great deal), which about doubles the volume of the differential so that it can hold 2 liters of diff oil, as well as all the seals and bearings needed to replace the differential. I haven't got around to installing the Diff cover yet, waiting until I decide how to setup an oil cooler for it. If you are simply taking your diff appart to replace the gears or the diff with another set of the stock variety, this job is probably a lot simpler. I know someone that replaced his Miata diff with another Mazda diff - it all simply bolted right up. Using a non-Mazda gearset and/or an after market differential will create more work. It isn't too likely that the spacers will be correct for the new setup. Changing the gears also requires removing the pinion, possibly replacing the pinion spacer, definitely replacing the crush collar and then setting the pinion bearing preload. If you are reading this for entertainment, curiousity or are just bored at work, forge on head and read all of this. If you are planning to do this job yourself, I cannot overstress the need to read the Differential section in the repair manual. Read it and study until you can almost quote it. Some of you may be old hands at this and will find nothing new here. I am not an old hand at it, and had I better studied the manual, could have saved some time and work. The first time I re-installed the diff, I ran the car through the gears on the jackstands (very solid jackstands I might add) and didn't like the sound of the diff. It sounded rough. Had I paid more attention to the pinion bearing preload setup I could have avoided that. Taking it all apart the 2nd time and re-doing all the setup was a bit easier than the 1st, as I already had pretty good idea of how to do it. Next: The Documentation Last edited by jkstill; 04-17-2010 at 01:56 PM.