Diff oil to redice whine.

Engine, Transmission and related drivetrain.
Chickenman
Posts: 477
Joined: 06 Sep 2010 15:10
Location: Coquitlam

Diff oil to redice whine.

Postby Chickenman » 24 Sep 2016 11:15

Have a slight, but annoying, diff gear whine on my 280Z R200. Only on very slight load and only between 80 to 90 KPH. No problem on Coast, decel or mild/heavy acceleration. Common problem with these diffs apparently. Nissan had a dealer fix that involves bolting 20 lbs or so of Steel plates to the diff as a Mass Damper. Don't feel like doing that if a thicker oil would solve the issue.

I'm using Amsoil 75w-90 Synthetic right now. Thinking of switching to Redline Shockproof gear oil ( The thinner grade ). Mustang crowd swears by it for eliminating diff whine in 8.8 diffs. But I've heard some conflicting stories about it breaking down in high temps. (I'm taking that with a big grain of salt ).

My other choice is Amsoil Severe gear oil 75w-140.

What are you guys running for a noisy diff? . And what are your conclusions? Car is not run in Winter.

datzenmike
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Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: Diff oil to redice whine.

Postby datzenmike » 24 Sep 2016 13:30

Do you have poly bushing holding the crossmember and mustache bar? Try rubber.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

Chickenman
Posts: 477
Joined: 06 Sep 2010 15:10
Location: Coquitlam

Re: Diff oil to redice whine.

Postby Chickenman » 24 Sep 2016 15:00

Nope. All rubber.

The diff whine is a common problem on Z's. Hatch back design makes any resonance even worse. More noticeable than on 510's. Dynamat in the whole rear hatch area helps... but that is down the road. Right now I'm interested in Diff oil solutions. I think Norm is using the RL Shock proof???

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funwithmonkeys
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Joined: 05 Sep 2013 09:34
Location: Vancouver, BC

Re: Diff oil to redice whine.

Postby funwithmonkeys » 24 Sep 2016 17:24

I was using the heavy stuff 75w250 I think it is. I couldn't find it up here after I got my diff checked out so I put in the Royal Purple 75w140 and it is hard to tell if there is a difference. I'm going to change back to the shockproof this week so I can do a back to back test and see. The royal purple has friction modifier in it but it is not enough. I'm getting a bit of chatter still on corners. My diff was cooler with the shockproof though. 20 or so degrees C
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?


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