Noisy rear diff

[Mike Van Veghten]

I've used the same oil in posi rear ends with no problem for many years. I switched to full synthetic a few years back with similar quiet results.
Not sure what would cause your noise.

Mike

[karterfred88]

What oil would you recommend? Is any GL-5 for limited slip ok?

I would think in todays world, since they are all formulated to a specification, brands would not matter much. I'd add the additional modifier, see what happens, a little too much, shouldn't hurt it any. I wouldn't drain it, just add some first, to see if that cures it. When these things were built, the "modifier" was whale oil, long outlawed, so todays "modifiers" may give a different result from the those in 1959, on a one to one basis. Also todays "limited slip" units have somewhat different designs than our old TT units, with spring packs, different clutch materials etc., so some experimenting make be in order. GL5 is simply a hypoid lube spec-nothing to do with limited slip differentials, has to do with the ring and pinion loads only.

[swvalcon]

I've never had a problem if I used oil that said for limited slip. I think today I would use a something like Amsoil or Mobil one type. Maybe add some additive to it if I wanted to be sure. How long has it been that the cover has been off and a good cleaning and inspection done on it. The gasket is not much money and not hard to do plus piece of mind knowing what everything in there looks like.

[evilhawk]

What oil would you recommend? Is any GL-5 for limited slip ok?

[swvalcon]

A noise when turning and sometimes where you can feel the clutches slip is a problem with the oil most times. If it where me I would be sure I have the right oil and drain what you have and just start over.The least that would happen is everything would be a little cleaner.

[evilhawk]

I think its the right oil. It said on the bottle "where an API-GL5 or MT-1 fluid is specified". Ill try adding friction modifier. The rear end doesnt make any other sounds besides the clunking noise.

[StudeRich]

IF you used the Proper GL Spec GL-5 for Limited Slip Differentials, it is NOT enough Friction modifier for a complete Fill, it still takes the 4 OZ Bottle of Friction modifier to get the Clutches working properly and quietly.

It still MAY be possible that if you run it very long Low on Oil, that there is damage to the Pinion Bearings, which will make a Wah, Wah, Wah sound, but the limited slip issues are usually, but not ALWAYS the wrong Lube.

[evilhawk]

I changed the differential oil in my 59 Hawk and since then its been making some noise. Its a dana 44 with twin traction and makes a pretty good banging noise at take off and sometimes around corners. The oil I put in is Valvoline High Performance gear oil 75-90w (it has friction modifier). From what I understand, the wrong oil can cause a lot of noise. I am thinking it could be an issue with the spider gears or yoke, but am not sure how to check. Has anyone here experienced anything like this?

Also when I drained the old oil it seemed low, but it never made any sounds until after I drained and refilled.