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p7x

280z - Hunt for the "CLUNK" with VIDEOS

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Posted (edited)

Hey Everyone,

 

So I replaced my front diff mount with a solid unit and now the clunk in the car is louder more pronounced than before. Worn diff mount might have contributed but now with the solid mount its exacerbated the clunk. I'm new to the S30s so with all the experience on this forum I was hoping you all could help me in determining if there is too much play in the drive line and what might be the source of the "Clunk". Assuming the old rubber diff mount absorbed some of teh slack and now with a solid unit the play in the driveshaft is now more pronouced.

 

Videos below showing some play in the driveshaft U-Joints at the tranny and very little play in the U-Joints at the diff. Based on the last video I think the driveshaft -Joint at the tranny is potentially the source of the clunk.

 

***REPLACED:

1) transmission mount (oem replacement)

2) front differential mount (solid unit)

3) Half shafts checked and U Joints are in good shape

 

transmission to driveshaft play

 

Driveshaft to Diff play

 

Driveshaft twist and clunk

 

 

I'd appreciate your thoughts / advice

 

Edited by p7x

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 I agree with you. U-joints sound like the source of the clunk. There should be absolutely NO perceptible movement in the u-joints in ANY direction. They will clunk when reversing or going forward and vibrate at high speed. Don't replace them with cheap ones. Nissan and Spicer are both good quality. I believe Nissan sells u-joint c-clips in different thicknesses to tighten up the slack I see in the 1st video. 

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9 hours ago, bunkhouse said:

 I agree with you. U-joints sound like the source of the clunk. There should be absolutely NO perceptible movement in the u-joints in ANY direction. They will clunk when reversing or going forward and vibrate at high speed. Don't replace them with cheap ones. Nissan and Spicer are both good quality. I believe Nissan sells u-joint c-clips in different thicknesses to tighten up the slack I see in the 1st video. 

 

Research tells me that you can't replace the U-joints or not easily anyways. Nissan changed them in 75 and it looks like if I were going down the route to fix it i'd have to replace the whole driveshaft...

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This is interesting. I pulled the R200 and half shafts from a 78 280Z, replaced the U joints and installed the R200 and half shafts in my 240Z.

 

Are you perhaps thinking of the driveshaft?

 

Take the half shafts to a drive line shop.

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7 hours ago, Miles said:

This is interesting. I pulled the R200 and half shafts from a 78 280Z, replaced the U joints and installed the R200 and half shafts in my 240Z.

 

Are you perhaps thinking of the driveshaft?

 

Take the half shafts to a drive line shop.

 

Ya just to be clear I’m talking driveshaft(prop shaft) between the tranny and diff, not half shafts. From what I can find from multiple sources is after 75 you can’t replace the u-joints on the driveshaft easily. 

 

In my hunt I’ll probably take the half shafts off as well to inspect them. 

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10 hours ago, bunkhouse said:

I forgot we working a 280. I was going back in my memory to my 240 days. I'd look into getting a repair quote from a drive shaft shop.

 

Ya there’s a good shop near by that I’m gonna call this week talk to them and see what they’ll charge. I feel I could do a driveshaft (prop) swap just no clue about the balancing of the driveshaft (prop)

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If you're going to pay somebody to repair it, you should consider having one made that has U-joints that you can replace.  I can't imagine that it would be that much more than having it repaired.  Places like Hoke Performance are offering custom CD009 to LN diff for $400.  A shop is probably going to charge you 4 hours + parts. 

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New drive shaft (prop) is ordered and last night went through the whole back end and tightened everything to spec. Something I should of done from the beginning ... lesson learned. Pretty much everything was spec except the inner and outer lower control arm bolts those were pretty loose. gonna take the car out today to see if tightening things helped at all.  

 

Once the new driveshaft is in I’ll update the thread.

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If the new Ujoints don't solve the problem, the next place to look is the mustache bar bushing and insulating rubber washers.  When they wear out they allow the mustache bar to slam up into the subframe, unfortunately the original rubber bushings are NLA so you are stuck with using Poly bushings which come with there own problems but they will fix the clunk.

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So moving the car around  in the garage and

 

1) when  backing the car out of the garage and a full second of grinding coming from the rear end while in reverse. This metal grind and moaning noise happens at very slow starts in first as well but this was the loudest i've ever heard it.

2) forcing the clunk to happen in 1st gear and then shifted into reverse and the clunk happen with no power going through the driveline. WTF
 

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23 hours ago, grannyknot said:

If the new Ujoints don't solve the problem, the next place to look is the mustache bar bushing and insulating rubber washers.  When they wear out they allow the mustache bar to slam up into the subframe, unfortunately the original rubber bushings are NLA so you are stuck with using Poly bushings which come with there own problems but they will fix the clunk.

 

I've check the bushing, mustache bar, bolts etc and things seem to be in good shape.

 

Honestly starting to worry that my tranny or diff are actually the issue.

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I would agree with you and the others that the "clunk" appears to be the u-joints (or possibly even the diff itself....they are notorious for having a lot of slop in the backlash settings).

 

A grinding noise is completely different.  Put the car on jacks, run it in different gears (i.e. neutral, reverse, first, etc) and check the components individually with a stethoscope.  If you don't have ready access to a scope, a long metal rod does a good job transmitting internal noises (I often use a long screwdriver or ratchet extension)....just put one end on the component and the other end in your ear.  If you're hearing this noise while the car's in neutral, doesn't seem likely that it would be your differential.  Possibly tranny or clutch, as you suspect.

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Posted (edited)

^^^^ Jebus!

 

Mine might not be that bad but maybe not far off. From the video below what to you guys think? I just installed the new driveshaft but haven't driven it yet. Regardless there's still a good amount of play in the diff but is it too much. The play is shown is the movement before the diff starts spinning the wheels.

 

I've been beating around the bush based on what ive read in the community but the bush (Diff) might 100% be the problem.

 

 

 

 

Edited by p7x

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32 minutes ago, bunkhouse said:

 Take it out and drive it. Some (hopefully all) of the clunk should have gone away with the new u-joints.

 

Need to swap the dust cover / sleeve from the old to the new shaft to cover the exposed gap then I'll be driving it to see if there is any change in the clunk.

 

 

new driveshaft installed.png

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Posted (edited)

I have the same slop in my R200. Very loud clunking when driving. My issue is when swapping from the R180 I had to switch to poly bushings including the RT front mount. It is awful to drive is the poly is the issue.  I will be digging my R180 out to test for the same slip that is in your video. If that’s the case I guess it’s just the hard mount and bushings. I’ve swapped the carrier in the r200 to an obx and there was no change in slop (proper backlash).

Edited by HuD 91gt

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Posted (edited)
20 minutes ago, HuD 91gt said:

I have the same slop in my R200. Very loud clunking when driving. My issue is when swapping from the R180 I had to switch to poly bushings including the RT front mount. It is awful to drive is the poly is the issue.  I will be digging my R180 out to test for the same slip that is in your video. If that’s the case I guess it’s just the hard mount and bushings. I’ve swapped the carrier in the r200 to an obx and there was no change in slop (proper backlash).

 

Really?

 

I had clunking with the stock diff mount that was worn (thought that was the problem because the diff moved up and down) so I went to the solid mount and it actually made the clunking worse. which is starting to make a little more sense if the diff is the issue, bolting it down with a solid mount  would exacerbate the issue...more and more thinking its the diff itself. 

 

 

Edited by p7x

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Posted (edited)

Driveshaft installed!! There's good news and bad

 

Good:

Acceleration clunk reduced by 30% to put a number to it

Clunk seemingly no longer happens on deceleration 

Shifting into each gear is smoother (unexpected)

Taking up on the clutch better aka the clunk doesn't happen when releasing clutch mid speed

Acceleration seems somewhat smoother

 

Bad:

Still have a noticeable clunk in the rear end under quick acceleration or quick release of the clutch.

 

Overall:

The driveshaft (prop) u joint was definitely part of the problem but not the full solution. Also noticed that when I was reversing quickly as part of my testing that there a rumbling noise coming from the rear.

 

Next Steps:

Remove the half shaft to check those u joints

Play with the differential some more.

 

 

Edited by p7x

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Posted (edited)

Took the half shafts off today and found very little to no play in them. Took them to a driveline shop and they also confirmed the same. Played the shop the videos below and the general consensus was the Diff is in bad shape. thoughts from this community?

 

 

 

 

Edited by p7x

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On 8/23/2019 at 5:49 PM, Miles said:

Drain the differential and check for metal particles.

 

Another possible source of a clunk:

 

 



This is your problem. The cross pin has wallowed out the hole in the carrier. Carrier is fucked. Get a new one, or get a whole new diff.
 

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From my big diff FAQ post:

SPIDER GEAR FAILURES EXPLAINED:

 

What we tend to see most often is that the cross pin which holds the spider gears comes loose by breaking it's retaining pin. When this happens the shaft can then move back and forth and will eventually wallow out the hole in the cast iron carrier. This causes misalignment of the spider gears which makes the gears grind on each other and puts a lot of metal shavings in the oil. As the gears wear on each other and get looser the pin gets looser. Once that happens the pin works its way out of the carrier and starts beating the inside of the case. Sometimes the pin breaks in half, sometimes it just bends, but that's the end of the differential. This problem is pretty well known in drag raced, open, 2 pinion carriers. Welding the diff or switching to an LSD generally alleviates this problem.

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Time to pull the differential and remove the cover to see what is going on.

 

If the differential is toast then replace it with another used R200 with the same gear ratio.

 

Gear ratio: rotate the ring gear until you see two numbers separated by a slash ( / ) or colon ( : ). and divide the larger number by the smaller number to give the  ratio.

 

Most likely you have a  differential with a 3.54 ratio.  Verify.

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