40 replies to this topic

[MFM]

I've whinged about this before but there's got to be something that can be done about a diff whine. My car came with three LSD's as well as one in the car, so 4 in total. 3:55, 2 x 3:36 and 3.08. I had three of these fully reconditioned and they all whined at the same RPM (55-65mph) nothing before and nothing after. I'm currently running the Penrite 140 which is good when the diff is cold (no whine) but as it warms up it gets worse. Its worse under acceleration and quietens up a little bit when cruising and nothing on de-acceleration and its only at that specific rev range. I even took the three diffs to three separate diff specialists to recondition them thinking I might snag one that would get rid of it. A forum member sold me some gears saying they didn't whine in his wifes car and these are what are in it now as they are the best of the bad bunch. I'm getting pretty good at swapping centre's. I took two of the repairers for a drive and they says its definitely diff and not gearbox.

 

Is there a straight 140 or higher viscosity oil that can be used? something that will remain high when hot because I think the Penrite stuff is 90w140.

 

Someone said the housing could be bent or that the suspension bush rubbers are so hard from age its causing the diff harmonics to transfer/echo noise. I'd pay anything to make it go away. Any suggestions?

[LXCHEV]

I’m certain that Penrite also sell a straight 140 - pretty sure that’s what I run in mine from memory. Definitely worth a shot.

[claysummers]

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[LCK186]

Hi its possible it could be axle bearings, if u have had 3 lsd centres recoed, I bought an xu1 moons ago, when I drove it home on the highway  at 100km the diff was whining badly, so took it to my mechanic told me it was axle bearings, we replaced them and the noise was gone, have u replaced your bearing axles   I hope this helps

[MFM]

I haven't replaced the axle bearings but they are nice and tight and smooth to turn by hand. Also I can make the whine come and go by playing with the accelerator, so I figured if it was bearings wouldn't the noise be constant  and not come in at 55mph and go away at 65mph? 

[S pack]

Hi Mark, the fact that you have had 3 differentials (of differing ratios?) reconditioned and they all make the same whine between 55 - 65mph indicates to me there may be some other common denominator causing the noise.

LCK186 may be on the right track with the wheel bearings.

[jpxu1]

Mark,

 

I'm tending to agree with others here.

 

Different diff ratios would have the crown wheel/pinion spinning at different revolutions to give the same road speed, so it would be an absolute fluke for them all to be whining at the same mph. (This is assuming the whine is originating from the crown wheel/pinion. The carrier bearings will be doing the same speed in each diff at the same mph, but presumably these will all be new after the reco's).

 

The axles on the other hand are doing the same speed to achieve 55-65mph, no matter what the diff ratio.

Axle bearings are cheap and easy to replace, so I would be doing it, if nothing else than to eliminate them as a source.

 

Good luck,

 

JPXU1

[jpxu1]

Another thought.

 

Can you intensify the whine by slaloming the car?

 

If so, this would also suggest a wheel bearing culprit. Slaloming left increases load, and therefore noise on the right hand wheel bearing (and lessens the left), and the opposite applies when slaloming to the right.

[MFM]

Another thought.

 

Can you intensify the whine by slaloming the car?

 

If so, this would also suggest a wheel bearing culprit. Slaloming left increases load, and therefore noise on the right hand wheel bearing (and lessens the left), and the opposite applies when slaloming to the right.

jpxu1 I did exactly that at the beginning and no change in sound intensity. I think the suggestion to replace wheel bearings just to eliminate that side of things might be a good idea. I need a straight 140 oil not multigrade. It needs to remain at 140 viscosity when hot. Its driving me crazy. Remember I took two of the three diff repairers for an actual drive and they both said definitely it was the diff. Everything keeps pointing towards the diff. One of the repairers (Diff Lapping Brisbane) had me take his out and he said he would try a different tooth setting but still made no difference. His crown wheel and pinion was lapped whereas the others were not. I've had the diff centre out at least 6 times. Is there a way to check for a bent housing? What I need to try is a whole centre from another car that definitely doesn't whine. Then I know its something else.

Edited by MFM, 01 February 2022 - 06:25 AM.

[S pack]

Mark, replace the rear axle bearings, then you can be sure one way or the other.

[RallyRed]

In the last few years, I have used these products with great results. Cheap and easy...whine simply goes away.
Obviously it is just masking a real issue, but good to stop the racket until your diff guy is ready to sort it properly.
p.s. not suggesting it is not a bearing issue, just offering a quick fix.

Attached Files

•  Screenshot_20220201-074645_Google.jpg   78K   7 downloads

Edited by RallyRed, 01 February 2022 - 06:49 AM.

[MFM]

I'll try anything. 

[LXCHEV]

Hey Mark,

 

You mentioned in your first post that when cold, it's quiet - and then develops the whine as it warms up. You're running multi-grade gear oil yeah? Sounds like the Penrite 85W/140.

 

I checked mine in the garage - and as I thought, it's the single grade / straight Penrite 140. This is what my diff guy highly recommends and says it offers a bit more protection.

 

However in your case, switching over to the single grade may not offer what you seek as a potential solution. If I'm not mistaken - the 'W' rating of a multi-grade oil is the viscosity when cold (Winter mode if you like) - so you have 85 weight oil when cold, and then 140 weight oil when hot. Your issue might be more related to the simple expansion of the metal - who knows if the oil is having any influence on the whine or not (if indeed it is coming from the diff). You could try the straight oil, but it likely won't make any difference.

 

For what it's worth - I actually have a minor diff whine myself - however I put mine down to my gear-set which is quite old and has been in a few different cars. My solution was to retain exhaust dumpers at the diff - it's so loud I never hear the minor diff whine. Only if I put the tailpipes back on do I hear it! I've replaced wheel bearings in mine, and had the centre re-co'd - so in my case, it's definitely gear-set. Too minor to worry about for me, but I totally get your frustration.

 

If I were you - I'd do the axle bearings (can't hurt and nice piece of mind anyway). And the perhaps one of those additives mentioned above could be worth a shot (if that has worked for others, then sounds like a proven solution).

 

FYI - the straight 140:

 

 Penrite 140.JPG   28.99K   2 downloads

[MFM]

Brett I see what you mean. I was told that the Penrite 140 in the above photo was in fact 85-140 not straight 140? This is the oil provided by Diff Lapping Brisbane with an additive when they recondition your diffs. I'll look into it a bit more

[LXCHEV]

Penrite definitely sell both - here's the multi-grade one:

 

 Penrite 2.JPG   50.74K   2 downloads

[MFM]

Oh ok, well if that's the case I reckon that's whats in it now (straight 140)

[grumpy xu1]

Viscosity = the ability of a liquid to flow, I probably heard that at least 200 times, when i studied mechanics years ago. Now seems this is a street car, personally i believe that you should stick with a multi grade oil. If I'm mistaken penrites additive is called limslip additive. There's about 100ml in a bottle & it stinks. I would do the wheel bearings first & add it to the 85/140 limited slip oil. When you drain the oil looking for foaming or metal fragments ect. You may even want to try a different brand of oil, like the nulon. If you do a bandaid repair, it's going to bite you on the bum sometime ! As for checking the housing straightness yourself, that is not a basic job. It requires special tools to be made tbh.

[MFM]

Gary I personally think its a meshing issue rather than worn out crown wheel & pinion. I was told all the centres I gave them were serviceable and they were all happy how the gears meshed (using that coloured (yellow) stuff diff joints use. All had new bearings fitted and were tight to turn by hand. Most said we have no choice these days with regards new crown wheel and pinions for Banjo's, so you have to make do with whats available. I'll just buy a couple of non LSD ones to try till I strike it lucky. Anyone local Gold Coast/Brisbane want to lend me a 3.36 to try ha ha ha

[grumpy xu1]

Places like strange in the USA offer a coating on their gear sets. You can buy spray on coatings specifically for differentials, transmissions ect. I have Richmond gears in the SS & at 80kph they wine, but nowhere else. Obviously i don't like 80 K zones. Try the "axle bearings" first i think mate.

[MFM]

Whining diffs seem to haunt me. I had a whine in my 73 GTR in the 80's. Spent $1200 back then replaced all the suspension bushes and sent Diff lapping Brisbane the whole housing and they apparently checked for out of alignment, and not a peep after that (it was glorious) but they used new gears. Then I had a 75 LTD (Landau) with 9" which I bought new Gleeson 3.25 gears for. They whined loud and couldn't be quietened down after lapping so bought 2nd hand 3.25 gears genuine Ford, got them lapped and they were perfect. Seems to be my affliction in life.

[Heath]

You can also send your gears to a vibratory finishing place like:

http://www.hpsf.com.au/

 

Ultimately, the setup has to be right, and the gears have to be in the right condition.

But if I only had one set of gears to choose from and I was trying to give myself the best chance, I'd be getting them polished like that. Helps reduce the oil temperature a bit and stuff. I did that to the gearset in my car.

[MFM]

Thanks Heath. I guess I am of the opinion that they didn't all come out with whiney diffs so don't want to spend more $ when clearly there's no guarantee that it will eliminate my whine. surely there's one out there that is quiet . Just need to find it

[S pack]

Replace the wheel bearings then look at your options if the noise has not been resolved.

[MFM]

Replace the wheel bearings then look at your options if the noise has not been resolved.

Thanks Gary 

Edited by MFM, 02 February 2022 - 11:54 AM.

[LCK186]

mfm  hi in all the cars u have owned with whiney diffs,  gtr, Ltd  etc  have u ever replaced axle bearings, lol