Nissan 370Z Forum - View Single Post - 2017 to 2009 6MT Diff Swap

ecoplunge · 08-27-2018, 02:03 PM

I've been living with a bad side bearing on my diff for about a year now. Mileage is now about 95k. Since used diffs go for about $500-600 for a 40k unit I decided I would let it ride and just replace the whole pumpkin. Ended up getting a 5k 2017 unit for $900 shipped. More than I wanted to spend but for being essentially brand new it seemed like a good way to go.

Since I had already pulled my diff for mount bushing replacement before, all the bolts were pretty easy and the job was quick - not the case the first time I pulled it. That **** is torqued down tight!

Everything was smooth until I realized the output shafts (stub shafts) changed in 2011. They flipped the threads from the drive shafts to the output shafts. Had to pull the unit again and swap the output shafts from my old unit. A note on the swap: The short shaft is retained by a circlip. Removal required a deadblow with a sledge and a large wood block. Long shaft did not have a retainer and was easier with just a carefully placed pry bar to free up. Another note on the sensor wires: They changed at some point, don't know the year. They now use different sized plugs left to right so that they can't be cross plugged. Swapped for my old ones and all was well.

Result of the swap was definitely good. The bearing hum/roar is gone and the clunky slop from the diff is gone. (FYI, I replaced the wheel bearings on this car because I suspected that over a diff side bearing. Very hard to tell apart since I have the urethane diff mounts.) However, I still have slack in the driveline. I plan on replacing the short shafts then going after the drive shaft and transmission for issues.

Synchro rev match seems off. Revs are about 200 rpm below a matched shift. I thought all years' manual transmission sport had the 3.69 gears. Maybe they changed ratios in '11 with the other changes?

Tools:
Most bolts are pretty large, I'd suggest:
Spray all bolts with penetrant several hours before
Large 3/8 and 1/2 breaker bar
Sockets and gear wrenches 12, 14, 15 and 17mm (from memory)
Extensions
Sledge and large wood block for output shafts
Jack with strap
Jack stands
Friend for jacking/installing diff

Removal notes:
Order is exhaust pipe rear section, v-shaped chassis brace, sway bar, drive shaft, short shafts (inside only), diff
Wheels can stay on.
Expect to shear off exhaust bolts, grind and drill studs, replace bolts
Muffler can stay in place and can be forced out of the way to remove the exhaust section.
Short shaft bolts need to be loosened with the brake set for half of them, unset brake, spin shaft 180, set brake, remove remaining.
Hang your short shafts with bungees. Don't dangle!
Drive shaft can be supported on the aluminum shield by placing a wrench across it under the shaft.
Drive shaft can be manipulated out of the way when removing the diff - may be easier to fully remove shaft.
Replace your diff mounts while it's off the car!!!! Optional: get a better LSD, change your gear ratio, swap your gear oil.

See the great DIY thread on here about replacing the mounts. Warning: It's a bitch to do the rear mount!

It think that's all the stuff I wish I had known!

08-27-2018, 02:03 PM	#1 (permalink)
ecoplunge Base Member Join Date: Mar 2012 Location: Orlando Posts: 45 Drives: 370z TS M6 Rep Power: 13	2017 to 2009 6MT Diff Swap - Install Notes I've been living with a bad side bearing on my diff for about a year now. Mileage is now about 95k. Since used diffs go for about $500-600 for a 40k unit I decided I would let it ride and just replace the whole pumpkin. Ended up getting a 5k 2017 unit for $900 shipped. More than I wanted to spend but for being essentially brand new it seemed like a good way to go. Since I had already pulled my diff for mount bushing replacement before, all the bolts were pretty easy and the job was quick - not the case the first time I pulled it. That **** is torqued down tight! Everything was smooth until I realized the output shafts (stub shafts) changed in 2011. They flipped the threads from the drive shafts to the output shafts. Had to pull the unit again and swap the output shafts from my old unit. A note on the swap: The short shaft is retained by a circlip. Removal required a deadblow with a sledge and a large wood block. Long shaft did not have a retainer and was easier with just a carefully placed pry bar to free up. Another note on the sensor wires: They changed at some point, don't know the year. They now use different sized plugs left to right so that they can't be cross plugged. Swapped for my old ones and all was well. Result of the swap was definitely good. The bearing hum/roar is gone and the clunky slop from the diff is gone. (FYI, I replaced the wheel bearings on this car because I suspected that over a diff side bearing. Very hard to tell apart since I have the urethane diff mounts.) However, I still have slack in the driveline. I plan on replacing the short shafts then going after the drive shaft and transmission for issues. Synchro rev match seems off. Revs are about 200 rpm below a matched shift. I thought all years' manual transmission sport had the 3.69 gears. Maybe they changed ratios in '11 with the other changes? Tools: Most bolts are pretty large, I'd suggest: Spray all bolts with penetrant several hours before Large 3/8 and 1/2 breaker bar Sockets and gear wrenches 12, 14, 15 and 17mm (from memory) Extensions Sledge and large wood block for output shafts Jack with strap Jack stands Friend for jacking/installing diff Removal notes: Order is exhaust pipe rear section, v-shaped chassis brace, sway bar, drive shaft, short shafts (inside only), diff Wheels can stay on. Expect to shear off exhaust bolts, grind and drill studs, replace bolts Muffler can stay in place and can be forced out of the way to remove the exhaust section. Short shaft bolts need to be loosened with the brake set for half of them, unset brake, spin shaft 180, set brake, remove remaining. Hang your short shafts with bungees. Don't dangle! Drive shaft can be supported on the aluminum shield by placing a wrench across it under the shaft. Drive shaft can be manipulated out of the way when removing the diff - may be easier to fully remove shaft. Replace your diff mounts while it's off the car!!!! Optional: get a better LSD, change your gear ratio, swap your gear oil. See the great DIY thread on here about replacing the mounts. Warning: It's a bitch to do the rear mount! It think that's all the stuff I wish I had known!