Welcome to Zclub - Australia's Largest Nissan 370Z and Nissan 350Z Forum
Register for FREE to gain access to all of our features. Once registered and logged in, you will be able to create topics, post replies to existing topics, give reputation to other members, get your own private messenger, post status updates, manage your profile and so much more. This message will be removed once you have signed in.


Sign in to follow this  
Followers 0

Diff rebuild

14 posts in this topic

Posted · Report post

Hi guys, does anyone here have any experience rebuild a diff (bearings/seals)?

I've had a drone (abd more recently a faint grinding) coming out of the rear since January, but the wheel bearing seems fine (no movement). I'd suspected the diff, but couldn't say what exactly.

After a recent tune (finally) I asked them to have a listen and see if they could tell where the noise was coming from. They think it's the side bearing on the diff, but can't say for sure without pulling it apart.

If it is the diff, it'll be a good opportunity to replace the diff bushes, particularly the rear bush which has deteriorated and leaked some time ago.

Any input would be great.

Share this post


Link to post
Share on other sites


Posted · Report post

The side and front bearings, the front crush washer and all seals cost $250 USD

You need to send the diff to a workshop that can correctly set the pre-load and mesh - they will charge $200~$250 in labour

Getting the shop to remove and re-install the diff will cost $280

 

The trouble with this scenario is you could open the diff and find a number of secondary problems
With the side bearing going, the pinion to ring gear mesh could be impacted and caused nasty wear

If you were at all interested in a low ratio diff for greater acceleration now is a good time to consider this option

The 3.7 ratio can give up to 10% more acceleration and is a great option for a daily drive,

the 4.08 ratio could give 15% more acceleration but RPM, noise and fuel consumption while cruising over 100kmph may displease you

Doing this replaces the pinion and ring gear with new items solving any damage, cost $500~$600 USD 

 

Whiteline sell a good diff bushing set for $124 (getting a little rare now)

 

You will need new oil - depending on what you choice could be $50 to $100

 

You could get a finned rear housing cover for a little extra cooling $120 USD - very optional for a daily drive

 

(I'm not going to mention a decent LSD due to cost)

 

Clearly you'll be spending over $1,000 

 

Another approach is to get a lower km diff from a wrecker costing $750~$800

Then $280 for the shop to install and you still need the new oil and bushes

Share this post


Link to post
Share on other sites

Posted · Report post

Potentially your wheel bearings also. It's hard to isolate sounds when you're under the car as the reverberate all over the place. I'm parting my car out soon and will probably be selling my diff with Cusco RS 1.5-way, 3.7 final drive and Nismo finned rear cover if you're interested.

Share this post


Link to post
Share on other sites

Posted · Report post

Thanks guys.

 

@MartinZ- I'd come across the bearing and seal set while I was researching and I've had my eye on the Whiteline set for some time now. I'd just been putting it off, but this is obviously a good opportunity to replace them.

 

I'd not considered changing the final drive until now. Haha, just when you think you've got a handle on your spending...

 

@Kammo- Thanks as well. I've PM'd you about your diff.

Share this post


Link to post
Share on other sites

Posted · Report post

Hmmm, it just occurred to me- Having just had the car dyno tuned (UpRev), if I was to change the final drive, would you need to or should you have the car tuned again?

 

Also, is it definitely a 3.7 final drive? I'm seeing 3.9 referenced in most places.

Share this post


Link to post
Share on other sites

Posted · Report post

No need to retune the ECU/Engine

 

There are numerous ratios available 3.9/4.08/4.36

3.9 is a good option for daily street usage

 

(I've heard the rear wheels of a few 350Z's clicking and squeaking - that's the rear CV joints)

Share this post


Link to post
Share on other sites

Posted · Report post

3.9 and 4.08 are aftermarket gears. The 3.7 final drive is actually made by Nissan (or is OEM at least) and can be found in one of the V35 variants, not quite sure which one though.

Share this post


Link to post
Share on other sites

Posted · Report post

3.7 ratio is the standard 6MT 370Z diff - also used in the V35 (370GT) or G37 Infiniti

 

The 4.08:1 ratio is Nissan OEM from the Frontier truck in the USA (actually the Navara here).  I suspect that the 4.36:1 is also a US truck ratio.

Share this post


Link to post
Share on other sites

Posted · Report post

Right, thanks for the clarification guys.

Share this post


Link to post
Share on other sites

Posted · Report post

Okay, so I've got the diff out at the moment to change the bushings. While I've got it out, are there any tell-tale signs I could look at that would point towards the diff bearings? Would there be lateral movement in the output shafts/spindle (whatever you call them)?

 

If I try and turn the outputs in opposite directions, there's maybe a millimetre play between them, but I figured that's probably normal/acceptable.

 

Cheers

Share this post


Link to post
Share on other sites

Posted · Report post

You really need engineer's blue or other similar products

Have a look at the teeth on the diff - if nothing obvious it's probably ok

Share this post


Link to post
Share on other sites

Posted · Report post

Given my time schedule over the weekend (and the fact that I'd only changed the diff oil about a month ago) I bailed on taking the diff cover off.

 

I did have success with installing new diff bushes and sway bars (thanks Kammo).

 

I really wasn't looking forward to removing the rear diff bush as everywhere I'd read described how much of a pain is. Well, it wasn't an easy job, but I found the front diff bushes much more taxing, even with the limited working space under the car. The deterioration of the rear diff bush played a large part in the ease of its removal- it was bone dry. The front bushes on the other hand looked like they would last another 10 years. MEGA pain in the ass to destroy. I ended up drilling into parts of the housing (slightly) trying to tear them up. Cracked a saw blade too...

 

Sawed up rear bush:

/monthly_11_2014/post-6936-0-00207700-1415620878.jpg" rel="external nofollow">post-6936-0-00207700-1415620878_thumb.jp

/monthly_11_2014/post-6936-0-00266300-1415620896.jpg" rel="external nofollow">post-6936-0-00266300-1415620896_thumb.jp

 

Pulling the new bush in was a piece of cake with a steel plate, an open-ended ratchet/socket, a nut, bolt and some washers:

/monthly_11_2014/post-6936-0-89956000-1415620962.jpg" rel="external nofollow">post-6936-0-89956000-1415620962_thumb.jp

/monthly_11_2014/post-6936-0-48396900-1415621061.jpg" rel="external nofollow">post-6936-0-48396900-1415621061_thumb.jp

/monthly_11_2014/post-6936-0-18228800-1415621137.jpg" rel="external nofollow">post-6936-0-18228800-1415621137_thumb.jp

 

Installed!

/monthly_11_2014/post-6936-0-19935200-1415621156.jpg" rel="external nofollow">post-6936-0-19935200-1415621156_thumb.jp

 

Useless apprentice:

/monthly_11_2014/post-6936-0-58187100-1415621175.jpg" rel="external nofollow">post-6936-0-58187100-1415621175_thumb.jp

/monthly_11_2014/post-6936-0-71388400-1415621215.jpg" rel="external nofollow">post-6936-0-71388400-1415621215_thumb.jp

 

This is where I noticed there could be sign of bearing/sealing failure. You can see the right side sensor rotor teeth are fairly clean:

/monthly_11_2014/post-6936-0-49796700-1415621242.jpg" rel="external nofollow">post-6936-0-49796700-1415621242_thumb.jp

 

The left side teeth are covered in gunk. I'm thinking sealing failure and possibly related to my drone from the rear end. I'll find out soon enough when I take it to a specialist.

/monthly_11_2014/post-6936-0-10775000-1415621266.jpg" rel="external nofollow">post-6936-0-10775000-1415621266_thumb.jp

post-6936-0-00207700-1415620878_thumb.jp

post-6936-0-00266300-1415620896_thumb.jp

post-6936-0-89956000-1415620962_thumb.jp

post-6936-0-48396900-1415621061_thumb.jp

post-6936-0-18228800-1415621137_thumb.jp

post-6936-0-19935200-1415621156_thumb.jp

post-6936-0-58187100-1415621175_thumb.jp

post-6936-0-71388400-1415621215_thumb.jp

post-6936-0-49796700-1415621242_thumb.jp

post-6936-0-10775000-1415621266_thumb.jp

Share this post


Link to post
Share on other sites

Posted · Report post

Love the apprentice

Given the condition of the rear bush you should notice a significant improvement

The front bushes just need a decent drift, I used a large socket (over 22mm) and full arm swings with a plastic hammer or dead blow hammer

Share this post


Link to post
Share on other sites

Posted · Report post

Yeah, that probably would've worked nicely. I didn't want to drain the diff and wasn't sure if there was an issue with just plugging the breather.

 

The difference is definitely noticeable. Acceleration and deceleration are a touch smoother but you can really feel it in the shifts.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0