Need some help with differential whinning

[chiefmd]

First let me clarify a few things:

 

1. I’m 70 years old and don’t push my cars hard. Just love the sound of a V8
2. I have a 73 240Z with 350SBC 340hp T56 trans, R200 with Brute Force CLSD. MMS Flanges with 280Z stub axles. Z31 300ZXT CV Half Shafts with bearing cages flipped and 1/8” ground of the axle.
3. The Brute Force CLSD was constantly chattering no matter how much friction modifier was

added so I decided to just go back to an open R200.

 

I picked a 1986 300ZX Non turbo R200 with 60k miles. Made the change out and took it for a test ride this morning. Diff is loud, whinning.

Not sure if it’s the pinion lash or a bearing. The reason I’m not sure is I had to change out the pinion flange. I forgot to mark the pinion nut so when I installed it on the newer R200 I torqued the nut to 125- 150 fibs.

The reason I was thinking bearing is that the passenger side cv axle was tight getting it in even with the modifications to the half shafts. I was thinking that the axle is putting a lot of pressure on the bearing.

 

I read about having to replace the axles with shorter ones. Is the reason for doing this because the  turbo  cv half shafts put too much stress on the bearings?

 

If it is the pinion is there any information on how to set the lash?

 

Really appreciate any and all input you can give. Thanks

[NewZed]

Never mind.  I  linked you to your own thread.

 

You should just follow JMortensen's advice.  He has dug deep in to this subject.

Edited October 16, 2016 by NewZed

[JMortensen]

The pinion bearing preload is set with a solid spacer, so the torque is not really relevant unless the pinion nut comes loose. You should be fine.

 

Seems to be that Z31 diffs tend to lose the front pinion bearing, the ball bearing right inside the pinion seal. If you have one apart to the point where the carrier is out, spinning the pinion will feel gritty. Seen it several times, makes an obnoxious whine.

 

Here are some tips on diagnosing diff noises from my former employer:

https://www.ringpinion.com/TechnicalHelp/contentframe.aspx?filepath=%7e%2fcontent%2fhowto%2fgeneralinfo%2f%2fdiagnosing_noise_(part_1).inc

 

https://www.ringpinion.com/TechnicalHelp/contentframe.aspx?filepath=%7e%2fcontent%2fhowto%2fgeneralinfo%2f%2fdiagnosing_noise_(part_2).inc

[heavy85]

When my R200 started whining it was the tapered roller bearing on the pinion shaft. You can get all the bearings from Courtesy Nissan if you need to rebuild it. Not hard if you have a press.

[chiefmd]

Put the car up on the lift this morning. Lower the rear onto jack stands to take the droop out of the axles. Ran the car and the rear is nice a quiet. Used a

stethoscope and listened to the pinion and axle bearing thru the case nothing abnormal. Could the noises I heard be the gear noise being transmitted thru the frame.

When I had the previous rear (clsd) in just had the chatter/grabbing sounds. Could the spider gears make the differential that much noise?

[JMortensen]

Spider gears only move when you turn.

[seattlejester]

Interesting, when I put my pinion flange back, the guide I looked up had a preload setting in in/lbs, I think I had to get up to a pretty high torque rating to hit the right level. 

 

Very interested to see what the problem will be. 

[NewZed]

Don't overlook the diff mounts.  Urethane will transmit more nose than rubber.  The Z car diffs are inherently whiny.  A perfectly fine diff can sound terrible if you everything that's going on in there.

[mtnickel]

Since it's quiet at droop, could problem be due to the pressure exerted when the shaft is shorter and somewhat 'compressed'. I know on some other Diff's the CV or stub axle grease seal could rub on the diff itself. Is it possible that your CV is physically rubbing on the side of the diff anywhere? Could be something to check.

 

Good luck. I too was trying to find mystery diff noises. Thought I had double and triple checked everything trying to locate a clunk. Turns out the 3 coats of paint I put on my mustache bar were not 100% hardened and/or solid, and as a result even though they were torqued tight at one point, they wore a little loose and were making a nasty clunk. It was even mentioned many times on here, but failed to check them again until months later when I was getting fed up.

 

Mark

[chiefmd]

I am posting a video I made hopefully you will be able to hear the whine over the exhaust. I ran it thru all 6 gears getting up to 80mph. The noise on the video is more predominate in the higher gears.

But I can hear thru all the gears sitting in the car. It gets louder in the upper gears and higher RPM. Here's a link to Youtube with the video, its titled " 240z whining differential".

 

Edited October 18, 2016 by chiefmd

[NewZed]

Here's an odd thought - disconnect the CV's at the diff and let the engine spin it while it's on the stands.  The load will be considerably reduced but it will remove any CV-caused noise from the situation.  Or remove one CV at a time and do the same to see if one side is tight.  If you get both CV's removed and it's still whining, it's probably the pinion bearing.

 

The whine seems too high frequency and too "shallow" to be the typical gear whine.

[chiefmd]

Newzed - Took your advise and removed the half shafts and ran the car, the noise is still there. So looks like I'll be dropping the diff again to replace the pinion bearing. Are there any instructions on how to do

this as I've never done this before. And where can I purchase the bearings.

[JMortensen]

Factory Service Manual tells you how to get it apart. Basically pull the carrier again, remove pinion nut, press the pinion shaft out, then pop the pinion seal and there is a long spacer and the outer bearing. I'm thinking that outer bearing is the issue. As to replacing the bearing, check and see if it's available from Nissan. I seem to recall it's not an off the shelf part. I think the tapered bearings are, but the ball bearing is a weird one. That's old memory talking, so you'll have to double check me.

 

You can download the FSM here: http://www.xenonzcar.com/z31/fsm.html

[JMortensen]

If that all sounds like too much hassle, might be easier just to get another used diff.

[NewZed]

Did you mean Power Brute, not Brute Force?  Don't know much about the aftermarket products.  Seems kind of inexpensive.  They might have gone overseas with their manufacturing.  If Amazon can hold inventory for them, they can't be expensive, wholesale.  "Ships from and sold by Amazon.com."

 

 https://www.amazon.com/Precision-Gear-LOM83-Limited-Differential/dp/B005HJQRQK

 

 

Here are some CLSD's if you do go used again.  Should bolt right in with no flange swap.  You could still have the CV shaft problem though.

 

 https://whiteheadperformance.com/product-category/240z-260z-280z-70-78/240z-280z-diff-differential-axles-lsd/

Edited October 18, 2016 by NewZed

[JMortensen]

Wha wha wha??? The Power Brute is back on the market?!? It was unavailable forever. Same manufacturer that made the Z31 LSD, but has more aggressive ramps and more clutches. That's a SMOKING deal!!!

[NewZed]

I dug a little deeper around the web and it looks like only the Mitsubishi version is available.  Amazon only has three types.  One page has answers from Precision saying Mitsu only, the other two have MITZ in the part number.  Odd.

 

Is there a Brute Force brand diff?  Can't find one described anywhere.

[JMortensen]

Looks like it is not back in production. Part number LOM59 comes up no match on Amazon.

[chiefmd]

My mistake yes it was a "Power Brute" not Brute power. Just dyslectic in my old age. Contacted CourtesyParts and they had "1" in stock along with the seal.

Really appreciate all the input and assistance. Hopefully this with fix all.

Edited October 19, 2016 by chiefmd

[heavy85]

There I one ball bearing - that's the one that's sometimes really hard to find. There is also two tapered roller bearings on the pinion shaft. Three total bearings. For me it was obvious as there were chunks missing from one of the roller bearings.