Help me diagnose a high pitch whine (audio link to listen to)

Tech tips and how to's

Moderators: notoptoy, garth, S Allen

User avatar
Davbret
Roadster Newby
Posts: 6
Joined: Sat Jun 09, 2018 2:08 pm
Location: Portland, OR

Help me diagnose a high pitch whine (audio link to listen to)

Post by Davbret » Thu Jul 11, 2019 7:43 pm

Hello and thank you in advance. My 68 2000 has a high pitch whine seemingly coming from the rear end. Only at higher speeds (end of 3rd, mostly 4th and 5th due to speed), only on throttle. Immediately goes away off throttle. Going to be taking to the mechanic next week, but having a clue what it could be would be fantastic. Please take a listen, included is audio from the rear and from the engine bay. Thanks!

Ryan
Portland, OR
SRL31105451 1968 2000

User avatar
Gregs672000
Roadster Fanatic-Site Supporter
Posts: 6686
Joined: Fri Aug 07, 2009 11:47 pm
Location: Tacoma, WA

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by Gregs672000 » Thu Jul 11, 2019 8:14 pm

Have you checked it for oil?
Greg Burrows
'67 2000 #588
Tacoma, WA

JT68
Talented Enthusiast
Posts: 1916
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by JT68 » Thu Jul 11, 2019 8:29 pm

That is pretty much classic worn-out differential behavior- described perfectly.
JT/LT
Datsunrestorationproducts.com
The very finest parts for your 311!

User avatar
redroadster
Roadsteraholic
Posts: 1063
Joined: Tue Mar 12, 2013 10:58 am
Location: KCMO

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by redroadster » Thu Jul 11, 2019 9:31 pm

Mostly I hear the exhaust
A bit of wine. Sure it rear not trans
A. Electric steathascope is used to determine point of noises if it set for long periods the ring may have rusted out of the oil

greydog
Roadster Fanatic-Site Supporter
Posts: 1661
Joined: Sat Nov 21, 2009 11:37 pm
Location: Vancouver, Washington

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by greydog » Thu Jul 11, 2019 9:58 pm

Sure sounds like the cuff is worn.
Dan
.68 SRL311 aka "Skortch". On the road again.
'69 SPL311 aka "Scooter" terrorizing the streets
1990 Nissan 300ZX
2008 VW GTI
2017 VW Passat

greydog
Roadster Fanatic-Site Supporter
Posts: 1661
Joined: Sat Nov 21, 2009 11:37 pm
Location: Vancouver, Washington

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by greydog » Thu Jul 11, 2019 9:59 pm

Damn auto correct.
Diff not cuff.
Dan
.68 SRL311 aka "Skortch". On the road again.
'69 SPL311 aka "Scooter" terrorizing the streets
1990 Nissan 300ZX
2008 VW GTI
2017 VW Passat

User avatar
Davbret
Roadster Newby
Posts: 6
Joined: Sat Jun 09, 2018 2:08 pm
Location: Portland, OR

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by Davbret » Thu Jul 11, 2019 10:00 pm

JT68 wrote:
Thu Jul 11, 2019 8:29 pm
That is pretty much classic worn-out differential behavior- described perfectly.
Like needs a rebuild kit, or the gears are worn and need replaced?
Ryan
Portland, OR
SRL31105451 1968 2000

david premo
Roadster Nut-Site Supporter
Posts: 189
Joined: Wed Jan 24, 2007 8:23 am

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by david premo » Thu Jul 11, 2019 10:12 pm

Sounds link a bad differential from your video clip. The on acceleration only noise or on deceleration only is classic of a bad differential. What’s happening is the ring and pinion are no longer meshing properly. If it were a wheel bearing problem the noise would be constant. When a ring and pinion are not properly aligned it will ride high or low on either the ring gear or the pinion which will create the noise.

greydog
Roadster Fanatic-Site Supporter
Posts: 1661
Joined: Sat Nov 21, 2009 11:37 pm
Location: Vancouver, Washington

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by greydog » Thu Jul 11, 2019 11:14 pm

Chances are it's a total rebuild of center section. Ring and pinon gears plus assorted bearings.
You will have the axles out so makes sense to replace axle bearings and seals too.
You may get off cheaper by buying a known good diff from someone doing a ka or sr swap.
Dan
.68 SRL311 aka "Skortch". On the road again.
'69 SPL311 aka "Scooter" terrorizing the streets
1990 Nissan 300ZX
2008 VW GTI
2017 VW Passat

JT68
Talented Enthusiast
Posts: 1916
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by JT68 » Fri Jul 12, 2019 6:59 am

These guys (last two posts) are spot on. A good used diff is the least inexpensive route. (Either 3.89 1600 or 3.7 2L) j
JT/LT
Datsunrestorationproducts.com
The very finest parts for your 311!

User avatar
Gregs672000
Roadster Fanatic-Site Supporter
Posts: 6686
Joined: Fri Aug 07, 2009 11:47 pm
Location: Tacoma, WA

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by Gregs672000 » Fri Jul 12, 2019 10:29 am

You have a couple choices... rebuild and "while you're in there" doing the wheel bearings and collars (will require a shop to redo the collars); replace with a good used complete set up (options there are staying with the 3.7 or switching to the 1600s 3.9 for better off the line response with a small change to your speedo readings, likely swapping over your brakes etc. Can likely be sourced from someone on the list, but one has to consider shipping vs local); see if you can find anyone doing the RX7 3.9, disc brake limited slip conversion like I did many years ago, but I haven't heard from the guy who did mine (John in Oregon?) in a long time and they became harder to find.
We're here to help!
Greg Burrows
'67 2000 #588
Tacoma, WA

User avatar
Davbret
Roadster Newby
Posts: 6
Joined: Sat Jun 09, 2018 2:08 pm
Location: Portland, OR

Re: Help me diagnose a high pitch whine (audio link to listen to)

Post by Davbret » Fri Jul 19, 2019 8:16 pm

thanks for the replies everyone
Ryan
Portland, OR
SRL31105451 1968 2000