Whiteline Rear Differential Bushing Review
 

Before I bought my Z I knew it had a bad rear diff bushing (what Z doesn't?) The fluid leaked out, so I knew when I got it I would have to change it out.

Before I changed it, the shifts were ok, but I noticed that it wasn't that smooth in the lower gears you could feel the diff moving from load>unload>load. Ok enough of that

Install: This was a royal PITA. No joke, I knew it wasn't going to be easy, I used a 32mm socket and was able to remove one of the stock bushing. The other did not want to come out. So I took the drill to it, and then the saw-zall. If you are doing this just once you can buy a cheap Harbor Freight Rep-saw, it will work fine. I did this all outside of the car so those 2 (front ear) bushings weren't hard, they went in easy so I was happy about that. The hard part came doing the rear bushing. I knew it was going to be a pain to get out, I had no idea it would be a pain to get back in. I am not going into how to take the old one out there are plenty of how to's.

Rear Diff Bushing: The instructions say to put the bushing on the differential, and then put it in. I did NOT do this, well I tried but the bushing is tight and there was no way to push it in with the differential. So I took the differential out and put in the bushing without the diff. Again I ran into issues. The bushing would not go in straight which sucks. If you do this make sure to hammer it all the way in till it is flush with the front of the subframe, if it does go in crooked its ok. Once you get the front 2 bolts for the diff the rear will center itself, just make sure you can get the rear stud into the hole.

Once it was all done took it for a drive, Feels 100x better than before, shifts feel better, clutch is easier to modulate, same with downshifts. Is it worth it? Yes. But if I were to do it again I would just do the SPL solid bushings. Would be MUCH easier. If you have a worn (read:ripped) rear bushing I would change it out.

This is the bushing kit I got, Mods if links aren't allowed please remove.
http://www.b2autodesigns.com/product...oducts_id=5307

Did you try freezing them?

No but that probably would have been a good idea. LOL

Bringing this back, anybody have any "long term" reviews of whiteline bushings for the diff? My rear is blown so I'm looking at this over the spl solid since I Street mine.... Although I don't drive it much since I walk to work.... Just wondering if anyone has had their kit warp or anything.

I've had mine in my car for maybe 2 years, always driven hard and they are still perfect. There is no reason a hard urethane bushing will fail in this application. The aluminum would work just as well but it's really up to your preference.

Ok thanks! I'm likely gonna go with the whiteline poly kit

I will go solid next time around. Really no reason not to. I have poly bushings in now and there's still a chance for a little bit of play. Solid bushings will have no play whatsoever

yea I've been contemplating the two, but at 50% more cost ($150 for SPL vs $98 for Whiteline), and the fact that my car is driven a few days a week (I walk to work) and I plan to track maybe 2-3 times max per season, I feel the Whiteline would serve me best. I've pm'd some vendors here so I'll see if there's any deals I can get in a package with other bushings (looking at suspension bushings eg. control arms, shocks).

btw, I just realized that the OP here said next time he'd go for SPL bushings as they'd be easier to install, I thought the poly ones would be easier to install from what I read due to the shape and material (can freeze it to slightly shrink it? I've had a few friends who's shop did this prior to installing it on their cars). I'll be paying a shop to do the removal/install, haven't called around to see if they'd charge different for poly vs solid though, if that made a difference that would def weigh in on which route I choose to go.

I like that rear bushing having a bit of compliance, it absorbs a ton of torque and considering that people have snapped the stud off the diff cover, I feel better knowing it's not metal on metal fighting for superiority. If the poly gives ever so slightly, it's far superior to the stock voided rubber hydraulic bushing (mine blew out on the street with fairly aggressive driving) while being not too harsh in my opinion.

I know lots of guys run the aluminum ones just fine and I would too on certain cars and applications, I feel it's not necessary for a street driven 350z diff bushing.

I agree that the whiteline is superior to stock, but if youre trying to avoid shearing the diff stud any amount of play I think would create a stress riser on the stud that will still lead to increased chance of failure.

No, play isn't what breaks it, but resistance to movement. If you get the car wheelhopping, which isn't hard to do on a stock suspension car, the diff bouncing up and down can snap the stud clean off. If the stock bushing is there you have a lot of play but this can result in a rebound motion that makes the hopping worse and can make the impact sharper. In a poly bushing the stud isn't fixed solid but can't move around very much. This is the safest and it will largely eliminate hopping without being rigid but still absorb some movement/vibrations. A solid bushing would theoretically eliminate any hopping motion at the diff but if the wheels are bouncing the force could easily snap off the stud since it can't move at all.

In practice this happens very rarely, also if you are not getting the rear tires hopping it's pretty much a moot point. Only that drastic shock load could snap off that large mounting bolt, it's not like it's a little piece.

With a solid diff bushing the diff isnt "bouncing up and down"...it is fixed. The axles move up and down with the suspension and rotate during a launch. The solid bushing serves to mitigate (more effectively than a poly bushing):

1)the loading of extraneous forces on the diff pumpkin as forces from launch are sent through the driveline (the tendency for it to want to twist and rotate)
2)the creation of angles that can act as a stress riser on the stud (caused by deflection of the diff itself)

If the shock load is strong enough to snap the stud as you say I think it will do it with or without a solid diff bushing. Agree to disagree.

I'm with you on the fact that it's really a non-issue, a firmer mounting isn't going to break anything or prevent anything from breaking, it's the whole drivetrain dynamic movement that causes problems. Either bushing is just fine for street use, the aluminum is more positive but in reality nobody on the street will notice a difference.

Solid bushing is no cake-walk. I cracked the sleve on my subframe trying to put the round peg in the almost round hole.

I love my whiteline diff bushings!

I went the opposite direction, from SPL to Whiteline, because of the extra NVH i got from the SPL. For a DD i prefer the whiteline much better.

Prothane rear differential bushing
 

Rear differential bushing install was easy. I obtained various bushing remover tools from Ebay, that were meant for other make dealerships, visually gauging the size compared to screw assembly. Ignoring the horror story about "spitting out a Energy Suspension bushing", I'm very satisfied with my Prothane rear differential bushing. Car handles better, no more clunking, and no extra drive line noise. The only cutting was through rubber to separate inner sleeve before burning off residue.

^Nice 1st post!!!

That removal tool looks like it'd make the job really easy. Where did you get it?