NissanDiff

Nissan Diff replacement

*click any picture for a full sized version*

Over the 20 years that I have owned my TR6 I have replaced the diff 2 times. The first time was 15 years ago when the original diff started whining loudly at 50MPH. I had a spare diff from the parts car I used in the rebuild so I has that diff professionally rebuilt and then I installed it in my garage. After 10 years that diff started to whine a lot as well so I found another second-hand diff and rebuilt that myself with the help of the local triumph club (ISOA). That diff was installed in the spring of 2011 and I found it to be very quiet. However, at the end of the driving season (September) that diff also had major problems when the castle nut that hold the front flange on came loose allowing the pinion pre-load to go completely off. Whether that was a mistake in my rebuild process of a failure that was not my fault I'll never know but the freshly rebuilt diff was now noisy and questionable so it was time for yet another diff. This time I opted for installing a Nissan R200 LSD diff along with Richard Good's conversion kit. These Nissan diffs are supposed to be nearly indestructible so I'm hoping this is the last time I have to do a diff swap.

The first step was, of course, to find a suitable candidate diff for the swap. Richard Good sells used diffs so, that was an option but I decided to search around myself a bit first. Surprisingly, I found a diff down on the south-side of Chicago out if a '99 Infiniti Q45 with only 58,000 miles on it. Seemed perfect for what I needed. A local ISOA member once again stepped up and agreed to make the 10 minute drive to the junkyard to pick up the diff. I would then meet him at the monthly meeting and bring it home.

Here's a pic of the diff as it came from the junkyard. Covered in light rust but not too shabby for a diff that has lived in Chicago its entire life.

The process of prepping an R200 diff for installation in a TR6 is well documented both by Richard's instructions and on Bob Danielson's TR6 site. The short version is as follows:

• • Remove the input flange and send it off for machining. I used Rick Patton as he's done this many times before.

  • Replace the front oil seal

  • Drive out the old mounting bushings

  • Replace the input flange

  • Acquire a new drive shaft and have it shortened by 2" at a local driveshaft shop

  • Clean and paint the diff

All of this was pretty easily accomplished. Getting the old mounting bush out was a challenge that eventually required the use of a dremel to cut the bush out but the rest was mostly a case of following instructions.

Here's a pic of the diff after having been gone over with a wire brush on a drill to remove the surface rust as well as a pic of the diff all cleaned up and painted ready to go into the car along with RIchard's conversion kit.

With the diff all cleaned up and painted, the flange machined and reinstalled and the driveshaft shortened, all that remained was to drop out the old diff and pit the new one in. The exhaust system needed to be removed and,. being 20 years old, it was destroyed in the process. Since I was rebuilding the rear suspension as well, that was all removed as part of the process.

Dropping the old diff is a simple matter of disconnecting the driveshaft and the half-shafts from the diff, putting a floor jack with a wooden cradle attached to it under the diff and then removing the 4 nuts the hold the diff in place. With that done, the diff literally just drops out of the car when the jack is lowered. Here's the old diff on the cradle as it came out from under the car.

With the old diff out of the car, Richard's kit was bolted loosely to the new diff, the new diff was placed on the diff cradle and then jacked into position. Once it was in position, it was just a matter of attaching the various bolts and torquing them to the proper specs. Attaching the driveshaft proved to be a challenge in the the Nissan diff is slightly longer than the stock diff so there was no room to get finger or a wrench in there to get the bolts through the flanges. The was solved by putting together a long series of extensions with the proper socket and threading the whole mess through from in front of the frame T-Shirt.\

Here's the diff ready to go under the car as well as a shot of my pit crew working to hook things back up.

Overall I'm pleased with the results. The diff is much quieter than the old one though not completely silent as I expected. There were some issues where I failed to properly torque the nut on the input flange so that could be a contributing factor in the noise but, overall, it was a pretty straightforward swap.