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Rear end noise


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#1 Datz350

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Posted 22 August 2012 - 10:11 PM

Just finished swapping a r180 with 4.11 in my 71 240z. Took it out for a test drive. It was running smooth until I took my foot off the throttle and let it coast. As soon as I let my foot off I hear this strange noise that sounds like it's coming from the right rear wheel. This sound only happens when I let off the throttle and let it coast. Everything looks ok. I'm not sure what the problem could be... Any ideas?

#2 BluDestiny

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Posted 23 August 2012 - 07:46 AM

Is it like a metal rattling sound? or like the bearings are going out?

Also how many mile were on the dif? Did you open it up before you put it in? What fluid are you using?

I have the same dif in my 280zx and it had about 100k miles on it ( front diff probably a lot less) I opneed it and there was some sparkle to the old oil but nothing major. Filled it up with some redline and it was fine when I started driving, but after about 10k miles its making a rattling noise WHEN WARM. When it's cold it perfectly fine.
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#3 78zstyle

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Posted 23 August 2012 - 10:11 AM

Same thing happened to me, was my driveshaft bolts. I bet you it is in your case too.

#4 Leon

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Posted 23 August 2012 - 12:17 PM

Same thing happened to me, was my driveshaft bolts. I bet you it is in your case too.

Agreed, driveshaft and half-shaft fasteners would be the first thing to check.

#5 Datz350

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Posted 23 August 2012 - 02:43 PM

It's a metal sound. Sounds like it comes from the passenger rear wheel side. The diff "looked" good when I got it. I used 75-90 oil. Not sure how many miles.

The half-shafts have no play to them. I give them a good tug and they feel solid. I went to "tug" the driveshaft and noticed a bit of play. Is that normal?

I was thinking that it may be a wheel bearing as well, seeing that the grinding noise only happens when I have let go of the throttle and am coasting. Any ideas?

#6 SUNNY Z

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Posted 23 August 2012 - 03:00 PM

I bet you dollars to donuts its just whiny. Mine does this too. whisper quiet under load, then when you take the load off it, it whines.

the solution: KEEP YOUR FOOT IN IT :lol:

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#7 Datz350

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Posted 23 August 2012 - 03:30 PM

Lol! Trust me, I've been thinking of just biting the proverbial bullet, but it isn't whiny, it's more like grindy..

#8 Datz350

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Posted 27 August 2012 - 04:14 PM

Alright, took the driveshaft off. Some oil came out from where the driveshaft and differential connect, not sure if this is normal... Then I noticed the "gear" where the driveshaft connects to the transmission has a bit of play. Also sounds like something is broken inside the "tailshaft" of the transmission. It's a th350. I'm thinking I need a rebuild or swap, right? That loose "gear" in the tailshaft of the transmission seems to be causing the grinding noise. Any one experienced this before?

#9 Datz350

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Posted 27 August 2012 - 05:47 PM

Well, figured out one of the u-joints on the driveshaft has some trouble spinning freely. Could this cause the grinding noise??

#10 Scarab73

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Posted 13 September 2012 - 05:34 AM

Well, figured out one of the u-joints on the driveshaft has some trouble spinning freely. Could this cause the grinding noise??


Hi,
By now, you would have replaced both universals on the drive shaft. So, still have the noise?
Scarab73
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#11 Datz350

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Posted 18 September 2012 - 01:31 AM

Yeah. Figured out it was the front pinion bearing in the differential. Have yet to get it fixed. Any idea at how much I'm looking at?

#12 Scarab73

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Posted 18 September 2012 - 03:08 AM

Yeah. Figured out it was the front pinion bearing in the differential. Have yet to get it fixed. Any idea at how much I'm looking at?


Hi,
Sorry, can't offer any advice labor costs, as I usually do my own wrenching. I have a noise back there as well. So, I'll be visiting the area too.
Good Luck!
Scarab73
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