TherapistGuy

Just bought a Z and loving the car thus far, except for a couple small issues. One is when starting from a stop, shifting, or on/off throttle, I get a rear end clunk/pop. After searching it doesn't sound like it's the common problem with the axles. I have a guess what it is, but wanted to post up here and see if anyone had thoughts. I took some videos with the rear end in the air. One of the videos is just me using a crowbar (gently-ish considering it's on the sway bar), and the other three are with my girlfriend clutching in/out. The parking brake was slightly on if it makes a difference. The squeaks in the videos where the wheels are turning are from the clutch pedal so ignore that.

As far as I know the diff is stock, however it does have the Nismo vented cover and the SPL solid rear bushing. All the rest of the bushings are stock. I can't see any fluid coming out of either of the front diff mounts - not sure which is the fluid filled one.

So I'm not sure if this will be helpful or diagnosable, but figured I give it a shot. Thoughts?

Squeak seems to come from the solid bushing




Thanks!

AdvanZ33

iTrader: (105)

Good lord. In for the answer.

TherapistGuy

Lol, always a good first reply ^_^

labelworkshop75

iTrader: (13)

To me in the Diff pop 3 video your drive shaft appear to wobble at .05 seconds in. Maybe loose nut/nuts? I would check that out?

TherapistGuy

It seemed to me that any movement of the driveshaft was concurrent with the diff moving, but I can definitely check. That'd be a nice easy fix

guitman32

iTrader: (15)

What year Z is it (just curious becuase it looks like the bottom of the pumpkin itself has fins not just the cover, which I havent noticed on any Z before)?

As you said it looks like whoever did the diff work on your car did the solid diff bushing, but not the diff ears, as you can clearly see a ton of movement there and on the whole diff assembly. That already leads me to believe some backyard work has been done.

The driveshaft, diff, and axles are all moving when you clutch in with the car in the air...this is BAD.

You need to open up that rear end and verify everything is still intact.

eZg

iTrader: (5)

Are you close enough to Nashville that you could take it to Crawford Z?

Or are you a DIY kinda guy?

TherapistGuy

I'm more of a DIY guy and have a lot of car friends (couple with lifts). I'm about 45 minutes from Nashville. Hopefully this will be something I can tackle, but I didn't know about Crawford Z's so thanks for the info. I'll definitely keep it in mind.

2003 track edition. My guess is that the car was drifted so who knows what's going on back there. It was a single owner car so he may have put in the solid diff bushing when there wasn't an aftermarket option for the front ones, but who knows.

I was going to open up the rear end when I changed the fluid just to see what's in there (aftermarket diff maybe), but this gives me another reason to. Good info, thanks.

If it matters, I believe it has a lightweight flywheel and aftermarket clutch. It revs very quickly in neutral and there is a slight clutch shudder that feels like my RX7 did with a 6 puck clutch.

Could all of that stuff move that much with just bad front diff mounts?

mkiv20vt

Yikes!

Sounds simple, but worth a check. Is the diff mount nut tight (110 ft/lb)? Diff ears (100 ft/lb)?

guitman32

iTrader: (15)

Yes, maybe the diff ear bushings are so shot the misalignment is creating the noises and movement.

Though it sounds and looks worse than that to me...actually your videos illustrate quite nicely how the forces from the driveshaft act on the differential. You can even see how the diff pivots around the stud because of the play in the ear bushings. Once can visualize how a hard launch with a lot of power might just snap the stud.

This issue is probably unrelated to your clutch/flywheel, the movement I see looks like it originates are the diff, not like there is something going on with the driveshaft/transmission.


Maybe the diff was welded and it has since broken?

guitman32

iTrader: (15)

Oh and Ive NEVER seen a diff housing like that on a 2003.

TherapistGuy

Well that's interesting. Is it from a later model?

I will definitely check that. I did a hand tight test on most of the bolts under there and got a ratchet on a few and everything was good, but I'll double check and make sure.

Glad my messed up car can be used an example lol

That's possible, especially if it were a drift car. The previous owner did seem to spend some money on the car so I would expect it to be a decent setup (fuel, intake, harness bar, exhaust, sway bars, stereo system all upgraded), but who knows where someone may have cheaped out. I guess we'll find out when I'm able to open the pumpkin.

Thankfully it seems that doing the rear subframe/diff bushings is pretty easy on a Z...

guitman32

iTrader: (15)

Not sure maybe the housing is a compatible R200 off another Nissan...im honestly not sure lol like I said Ive never seen one on a Z before like that.

Italianjoe1

iTrader: (6)

I kinda like the welded and now broken suggestion, does the diff have proper LSD action? If you turn one wheel by hand does the other match it's direction or go opposite?

Some of what you are hearing is drivetrain lash because it's airborne, but that's excessive noise and you are also hearing it when driving so it's definitely not right.

Also, agreed on that not being a 350Z diff, possibly from a 300ZX or something similar, it has a completely different housing.

TherapistGuy

All the bolts are tight, including the driveshaft. When I turn one wheel the other one goes the same way so it seems to have LSD action.

If it's the diff bushings, does anyone know if buying the 350z ones should work, in light of not knowing exactly what diff this is?

superlim9

Have you checked the oil in the diff? I would first check that to see its condition or if there is metal chunks. I also agree with guitman, the next thing I would do would be to put some Solid ear bushings in and go from there. And then pull the bracing off and check the sub-frame bushings and bolts to see if they are secure.

you mentioned that when you rotate the wheels forward they go the same direction... what to the do when you rotate the reverse way?

There should be a number on the pumpkin to be able to look it up to see what/where it came from but outside of a G I'm not sure what else would fit and bolt up correctly

TherapistGuy

I haven't checked the oil. For minimizing cost I was going to replace the fluid when I dropped the diff to replace the bushings (or sooner if I don't replace the bushings).

The car is going to be a weekend fun/HPDE car. Would you guys suggest solid bushings or the Whiteline bushings for the diff?

When I rotate the tires backwards they both go in the same direction.

From what I've read, it could be a 370z pumpkin. Apparently they're mostly interchangeable and I found a description of a 370z pumpkin that matches what I have. Unfortunately the picture on the370z.com is for members only and my new account has been pending for a few days.

You can see the thumbnail (or full image if you're a member) here at post 35: http://www.the370z.com/engine-drivet...failing-3.html

I looked on the diff and couldn't find any markings, although I may have just missed them. The diff cover says N1 00186218 100428A, but Google can't find what it goes to. I'm not familiar with Nissan's parts system.

superlim9

The numbers will be on the top of the diff on the cover side like seen in the picture. Second picture is off a 370z first is off my 350





The only diffs i know of from Nissan with a finned pumpkin come off the trucks/suv's.

I may be mistaken but if the wheels turn the same direction in reverse then its either a 2 way diff or its been welded. My stock vLsd spun opposite in reverse, together in Fwd. I'm overseas now or I would check my NISMO diff to confirm but I'm pretty sure they spin together both ways.

As far as the bushings go, I went straight to solid, if you don't mind the higher NVH then get solid. If you want it to stay relatively quiet get a Whiteline set and change all 3.

If it were me, I would check the sub frame bushings, change the ear bushings to solid, and open the diff for an inspection ASAP. You wont know what kind of oil you need till you know what diff you have... LSD vs vLSD = different oil type. 2 quarts of rear end grease and a tube of RTV is nothing but peace of mind if you can confirm the diff is ok

guitman32

iTrader: (15)

A welded diff with broken welds would still spin the wheels in the same direction...all that metal is still in there just loose.

TherapistGuy

Update!

Dropped the rear subframe to check out what's going on back there. All of the bushings were intact and had the appropriate amount of movement. We decided to swap in the urethane subframe and solid front diff bushings while it was down. Post swap, 97% of the clunk is gone (my guess is the 3% is sway bar). I'll call that a success.

I'm still a bit perplexed as to what the clunking was with all good bushings. I've read about the diff springboarding with a solid rear and stock fronts, but that'd have to be a lot of movement to make the clunking I heard.

Below are some pics of the diff. Google pulls up a lot of foreign links for that part number so it appears to be from another region. If someone is able to run a part number through Nissan that might help.