THE SPOTTEDGECKGO BLOG

New DIFF!

Updated 01-28-10

Hi there again and welcome to another exciting episode of Marty's Blog.

Today I'm here to tell you about what a DIFFerence a new rear differential can do for your car. The difference is like night and day. The car has more traction at the wheels on takeoffs which means better launches and lower track times! For those of you driving on the street, you also have better control when accellerating out of corners and higher lateral G forces. Drifters already know that a new differential is essential to the sport, so no point in mentioning that. Combined with my 275/40R18 tires, the car is sticky as dried stains, you know the kind I'm talking about.

So basically, what we are looking at here is an install for a Quaife Limited Slip Differential on a base model 2007 350Z. The whole process takes between 4 and 12 hours depending on what kind of tools you have, how comfortable you are with the swap, whether you are rushing or taking your time to get stuff right, and how timid you are with a hammer. Mine took the max alloted time due to lots of breaks for thinking, drinking, and smoking, food, and with 8 hours of sleep plus the whole going to bed and waking up thing, my car was up on blocks for about 22 hours.

The picture at the top of the page is what my diff looked like when I got it, aside from the plastic bag it was wrapped in. No bearings, no ring gear, just the diff, which runs 1420 dollars at mynismo.com plus shipping. All in all, look to spend 1600-1700 for a Quaife diff. They are expensive because they are great, both at the track and on the street. You get a nearly 50/50 wheel power balance off the line and great traction control, without all those noisy clutches that are in most LSDs and wear out over time. The Quaife also comes with a lifetime guarantee and they don't care if you are racing on it or not. Just like a zippo lighter! On with the show.

Step one was to get the bearings installed properly. Don't F*** around on this and get it done right! I went to the dealership and they pressed the bearings on for about 60 bucks. The bearings themselves were about 70 each but I bought them from the nissan dealership, part number 38440 if you want to know, and you can probably get a better deal from an auto parts store, but I'll spend the extra couple bucks to make sure that I'm getting exactly the right part. Pressing bearings on the diff... I'm not going to lie to you. The quaife is made so that they will only slide on as far as they need to and with a rubber mallet, some kind of soft punch, and some skill you can probably DIY, but why take the risk?

Now that the bearings are on (and I got an extra day off work), I started the install, around 6pm last night. Did a lot of thinking, a lot of prep, and printed out pages 17, 18, 24, 25, and 26 from the Factory Service Manual. Oh yea, you need to get that cause it has all the torques and you ain't going to find them in your Chiltons, sorry. For my car I did a google search and went straight to the download. My buddy's G8 on the other hand, not a whisper. Make sure that you get your hands on that manual. If all else fails go to the dealership, put up some dough, and make them order you one. If they give you any crap smack 'em in the face and tell them again to get you one!

With a new socket set and torque wrench I went to work pulling bolts, disconnect the drive shafts and the transaxle. Theres a little hose on top of the diff that you need to disconnect and it's the biggest pain in the butt of the whole install. It's reccommended that you also take off your sway bar, but one the 2007 base model Z I didn't need to. I wedged my way around it. Make sure you put a wire or something on the axle bars, don't just let them hang there as they can be damaged really easily. A little bailing wire or aluminum fence wire works great. They arent real heavy, I think I used 18 ga wire and it worked fine. Also if you have ABS or traction control sensors you need to take them off, as well as the speedometer sensors that are attached to the back of the pumpkin. One bolt and pull them out, that easy on the speedometer, just remember that there are two of them, one on each axle.

Oooh, I forgot. You need a bench vice for later on to get the bolts on and off of the old diff, unless you order one with a ring gear already installed, which mine obviously doesn't have. I bought a cheep on and threw it on one of my benches real quick but this is definitely NOT the right tool for the job. I needed help untorquing the gear from the old diff and getting torque on the bolts for the new one was damn near IMPOSSIBLE. Spend the 80-100 bucks at harbor freight and get a good vice that's big enough, more on that later. Here's me installing the vice...

All that crap out of the way, time to get the car up on blocks and take off all the bolts, the ones mentioned a minute ago as well as the three mounting bolts. There are two on the transmission side that are vertical as well as one in the back that is horizontal and attached right to the pumpkin.

Took a lot of wiggling and wobbling and some attention to get the pumpkin out around the sway bar, but WILL come out without damaging anything if you are careful. Always, on trannys and rear ends, use a friggin jack for support when you lower these things out, they are heavy. I can carry my pumpkin by myself when it's full of fluid (I did it) but that doesn't mean that I want it dropping on my head when I'm under the car. Be careful, darn it!

So next thing's next. Take off the eight bolts on the back of the pumpkin and open her up. I got Chris started scraping on the old gel gasket material with a razor blade and we cleaned up the edges for the new gasket. Then you have to take out those bloody attachments that go to the drive axels. A little convincing with a rubber mallet works just fine. Just be careful when they start moving b/c they come out real easy once they get out of their seats. Luckily that is one lesson I didn't have to learn the hard way! Also, don't take off the case cover with a screwdriver, use your head. A couple of medium blows around the edge with a rubber mallet works just fine for freeing it once the bolts are out... Some people's children!

So what's next? You see that gear there? It needs to come out! This is the open diff for the base model 350z and it has the ring gear attached with red loctite. So there's four big bolts that hold that puppy in, 17mm. Pop them loose. Also keep all the left side stuff with left side stuff and all the right side stuff together. They are different! If you don't have the right shims and whatnot you are taking a risk putting in a diff too. I'm not responsible if you f it up! This post is just for entertainment purposes only, and not meant to be instructions! Those are in the FSM! So you get those two little clampy things out and pop the diff loose. It takes some convincing. We did it with a mallet and a socket extention. I found out this morning that you can also put a wrench on one of the ring gear bolts and put some torque on it, it will come out that way too. The proper tool is a slide hammer thingy that you can probably get from the dealership.

Now the fun part. Breaking those loctited bolts off. I think if you heat them to 500 degrees the bond is supposed to come loose, but we're men so for us muscling up on it was the best. ...and a long cheater bar, lol.

The ring gear is off, putting it back together is the same thing. Mount the gear on the new diff, pop it back in the pumpkin, seal the case with a silicone gasket, fill her up with diff fluid and put it back under the car. Easy right??? This is where shims are supposedly important and heaven help you if you screw up and put the wrong torque on or forget your loctite where it is needed. Leaking gaskets are never good either, and you need to check to make sure that you don't have any backlash. Backlash is best described something like this... You have two gears spinning together one way. Then you stop and try to turn one the other way. The amount of movement required to reingage the gears is backlash, and you need less than 0.2mm if I'm not mistaken. Maybe it was 0.02, no I think 0.2. I'm not looking at the manual right now, sue me. Or no, don't. LOL. Here's some more pics. Hope you had fun and remember, do you racing at the track and wear your seatbelt and go the speed limit and that kind of junk.

Oh yea, one last note before I go. The car is no longer acting like a peg leg (thank god, or um, whatever), it hugs corners like a dream under accelleration, drifts are much more controllable, and with the 10" tires on the rear end this car handles, takes off, and corners like a dream!!!! Hopefully I don't wake up. Road testing it was a blast and I can say that I love this part, so I want to thank QUAIFE for making it and send a shoutout. I'll be driving for y'all one day! This thing is an awesome part and anyone thinking about getting one, it is a great investment. Worth every friggin penny and every drop of sweat, every cut from untorquing high torque bolts, even worth dropping stuff on my foot! Till next time...