Hi guys, so the time has come for my rear bushing to go bad after 7 years and 75k miles. I have a 2012 RWD Sedan Journey 7AT, and I think I will do the replacement and upgrade all by myself since the shops cost me an arm and a leg for the labor cost. However, there are something that I would like to ask everyone about:

1. Should I buy Z1 bushing removal tool to remove the rear diff bushing or use a hack saw or a reciprocating saw to remove the bushing?
2. What is the easiest way to install the rear diff bushing? I heard that people will put them into the freezer over night, so it can be a little bit smaller by the time they install it. is it true?
3. My car is a 7AT sedan, should I upgrade the final drive to 3.69 or 3.9 or even 4.0.8? I believe the 2012 RWD 7AT sedan has a final drive is 3.35?!?

I don't track my car; I only daily drive it. Sometimes, I will do some small pulls with friends, and I also do some spirit drivings around the mountains maybe like 2 or 3 times a year for about 15 miles long each time. Not like I'm trying to race everyone on everyday lol. Just drive to work and home and around the city. This car has 75k miles on it now, and I want to keep it for up to 200k miles since I really love the car though.

My mods on my car right now: Stillen Gen 3 CAI, J2 Engineering Catback Exhaust and up coming High Flow Cat (not sure what brand yet) and tune at the end. I hope to make 300whp, and that is enough for me already.

Here are the link of stuff that I may buy to do the job:
The upgrade kit with final drive upgrade: https://www.z1motorsports.com/oils-a...37-p-8928.html
The differential kit upgrade without final drive: https://www.z1motorsports.com/z1-pro...it-p-8914.html
The removal tool: https://www.z1motorsports.com/transm...7-p-11086.html

Thank you everyone. Please feel free to let me know what you guys think about it.

 

1. do both, the sawzall will make getting it out faster, but you will need some kind of bushing tool to get the new one back in..you can mess around with bolts and washers and drilled out metal plates from home depot to make your own tool for a few bucks or get the Z1 tool
2. freezing seems to help... I think most people do it cause it doesn't cost anything.. I t seemed to help a bit for poly from my own experience probably moreso for solid
3. yes upgrade to a 3.69...get an LSD too if you can while you're at it if you don;t mind doing a bit more work and paying a bit more, but definitly at least get the bigger gears ..you may not notice the LSD depending on your driving style but you'll notice the 3.69 right away...3.69's are cheap and easy to find getting one with an LSD may take bit more effort and cost a bit more ...look for one with the letters "KG" stamped on it....you may need to modify your pinion and swap the flange to do this mod too so good idea to get under your car and see what flange you have (3 bolt with the long pinion or 4 bolt with short pinion) and try to match it with what you are shopping for...check the many many thread on this on here for more info

Edit: I just noticed you linked to Z1 Kits with internal gears...I was referring to getting used OEM pumpkins which can be done for a few hundred dollars....if you are going to install fresh gearing, consider a fully built one by Z1 https://www.z1motorsports.com/transm...l-p-11644.html

 

Thank you for your information. I just saw a video on Youtube where a guy use a drill to remove the center of the old bushing, and he used a long bolt, a few washers and a metal stick with a hole on it to screw in the new bushing. Look like I don't need the Z1 tool though. Also, I've been searching around the internet, and I saw most people like the 3.9 and up. Do you think it is over-killed for what I use my car for? And yes, your link with the Z1 fully built diff is very helpful; I didn't know they have it though. I was searching all over the place on the internet about the information of the diff bearing and seals, and how to install the new ones correctly LOL. Thanks though.

 

I don't think 3.9 is overkill at all, I've heard some ppl say 3.69 is the best for streetability, but some people run 4.1 gears on the street and seem to like it fine, IMO, 3.9 is worth it especially if you're buying a built unit or getting new internal gearing done and is probably the size I'd go with if it were me...

BTW, I'm not sure if it is your intention, but I don't recommend doing internal gearing work on the diff as a DIY as it require some skill in measuring and setting the lash on the gears and preload on the crush collar and requires shims and measuring tools etc., generally speaking its not the same kind of work as just bolting up the diff that you can follow a you tube video for and even a lot of mechanics send this type of work out to specialists unless they have learned this skill themselves and have the equipment to do it, so unless you really want to learn a new skill and buy some new specialized equipment, getting a built unit and installing it yourself is a much better way to go...(if you do want the challenge of learning how to do this definitely go for it, I'm all about that myself)

Seals are easy though, you just need a cheap pick/puller to get the seals out and the bearings just bolt up at the sides and the front one can be pulled out..to get it all back together you can rent seal install tools from auto stores for free...they basically tap in but you'll want to use a tool to tap them in evenly...the seals and bearing themselves don't cost a lot..anyways if you get the built unit, the 3.9 with even the oem lsd will be a very good upgrade for what you're looking to do with it.....

 

The gear ratio you select should take your current or planned tire size into consideration...A tire/gear ratio calculator could help like the one here: https://tiresize.com/gear-ratio-calculator/.
Good luck with your swap...Subbed for updates.

 

I see. Thank you very much. I think it's best for me to buy the Z1 built diff and swap it in, and yes I really want to go with the 3.0 ratio though . Thanks again.

 

Thank you very much. I will let you know how everything turns out.

 

Autozone rents bushing tool for free. Save yourself some headaches and put a little dish soap on new bushings to help slide in dont use wd40 or lube

 

Here is the quickest (20 minutes) easiest fix for the G35/G37 diff bushing:
$20 Differential Bushing Fix: Motorvate's DIY Garage Ep.23

and a 1 year update:
1 Year Later… $20 Differential Bushing Fix: Motorvate's DIY Garage Ep.33

 

I bought the Z1 bushing tool and snapped the 3/4 acne rod trying to push the metal sleeve out. I ended up using an air hammer with the chisel and flat head bit to get it out. I got the upgrade kit without the LSD but I now regret it because this viscous fluid is trash when it’s hot. Wavetrac or Quaife should be sufficient for your needs.