Driving in tight circles at low speed, rear noise. Normal?

[Stranger in the Black Sedan]

Hi guys, I just noticed something the other day, that occurs under conditions I very rarely see driving around. If I turn around in a cul de sac, requiring me to make a tight circle at a very low speed, I get a noticeable whine from the diff. I have had this rear apart several times and the bearings, gears, etc are all new and quiet, except for this low speed tight turning scenario. My axles, wheel bearings, etc are also all brand new. Is this normal noise w/ a clutch type posi, just because the spiders have to turn so fast, and they ride on a solid shaft w/ no bearings? Above a few mph you can't hear it, but at really low speeds it's pretty noticeable.

If anyone has a stock exhaust and stock posi, and wants to humour me, next time you are out driving, do a few mph circle with the wheel locked or nearly locked, and see if you get some spider gear whine.

Probably normal but every little noise gets me thinking!

[Zack]

Did you put the diff friction modifier in?

[Stranger in the Black Sedan]

Yes, although I used CRC lube, which did not eliminate the chatter that I get each time I enter/exit a sharper corner. I bought redline fluid w/ real Ford racing additive, which I am going to add when I refill in a couple days. I know the real Ford additive will get rid of the chatter, but I didn't know it would reduce the spider gear noise?

[BigCars4Ever]

IT's just your limited slip slipping. Try keeping both tires spinning in the really tight corners. That''ll make the diff happy!

[airborne_mp84]

Hi guys, I just noticed something the other day, that occurs under conditions I very rarely see driving around. If I turn around in a cul de sac, requiring me to make a tight circle at a very low speed, I get a noticeable whine from the diff. I have had this rear apart several times and the bearings, gears, etc are all new and quiet, except for this low speed tight turning scenario. My axles, wheel bearings, etc are also all brand new. Is this normal noise w/ a clutch type posi, just because the spiders have to turn so fast, and they ride on a solid shaft w/ no bearings? Above a few mph you can't hear it, but at really low speeds it's pretty noticeable.

If anyone has a stock exhaust and stock posi, and wants to humour me, next time you are out driving, do a few mph circle with the wheel locked or nearly locked, and see if you get some spider gear whine.

Probably normal but every little noise gets me thinking!i had a black 2002 p71 and had the same problem..it might be the rear diff

[Stranger in the Black Sedan]

Um okay. I have had this rear diff apart several times for gear swaps. I know that is where the sound is coming from. Everything in the rear looks fine and the limited slip works fine. The only parts that are moving when you are turning that don't move when going straight are the spiders and clutches, that's it. They look good and the cross shaft they ride on is like new. So there isn't anything visibly wrong. I do have posi chatter after changing the diff fluid and not having any Ford limited slip on hand. The CRC/TransX lube auto parts stores carry SUCKs. I might as well have pee'd in the diff, it probably would have worked as well. I am going to re-change the fluid this week w/ the Ford additive that I purchased and see what happens.

[fastblackmerc]

You don't have to use the friction modifier if your refilling with Redline fluid. I think mine was the 75w140 weight.

[Stranger in the Black Sedan]

Yeah Redline says you "may" have to put additive in it. I'll leave it out and if it chatters still, I'll add it. Mobil 1 75-140w/ CRC/Transx additive has chattered, and so has Lucas conventional 85-140 w/ CRC/Transx additive

[Stranger in the Black Sedan]

Update, I drained and refilled w/ Redline 75w-140. When the rear is hot (20-30 minutes of driving HOT), it chatters really, really bad cornering in a parking lot, or leaving a driveway turning, w/ just Redline w/ no additive. There is no way I can run this fluid w/ no adiditional modifier. I definitely need at least one bottle of the FMS additive, I hope that helps.

Every fluid I have put in here since the OEM fill has chattered. The least chattery combo I have run is Mobil 1 75-140 synth w/ FMS friction modifier, one bottle's worth. Hopefully the redline w/ the FMS modifier is as un-chattery as I need.

[RCSignals]

Put in the Ford friction modifier

Then look into this (http://www.dynamat.com/technical_specs_dynamat_xtreme .html)

[JMan]

The CRC/TransX lube auto parts stores carry SUCKs. I might as well have pee'd in the diff, it probably would have worked as well.

Need I say more? Okay, maybe it would have worked better!

J

[Stranger in the Black Sedan]

No dynamat necessary. The car did not make this noise/chatter w/ the original fluid fill from the factory. I have 2 bottles of the Ford racing additive, I'll add one, then 2 if necessary.

[Raudermaster]

Mine does it too, wasn't sure if it was my wheel bearings or if my axles were finally going south.

[magindat]

No driving in circles at low speed is not normal.... :D


You don't have to use the friction modifier if your refilling with Redline fluid. I think mine was the 75w140 weight.

I used Redline and the diff got QUIETER. I never had chatter to start with only a slight gear whine. My diff 'lock-up' point is far more predictable. I never knew before how long the left would take to break after the right. Now it's VERY predictable and a lot shorter time. I swear by Redline. If you're still chattering with Redline, something is wrong.

You will NOT have INSTANT results when changing diff fluid. It takes a while for the fluid to work in between the clutches. It shouldn't take too long, though.

[Stranger in the Black Sedan]

I have minor gear whine, have replaced the gears several times, used the $1500 rotunda tool, etc, and have learned to live with it. It is very minor and you can't hear it over the radio but it's always been there since the car was newer and apparently it's normal for this chassis w/ the extremely long large dia. alum. shaft.

Redline fluid did not quite the drivetrain noise at all, and I notice no difference in how the limited slip behaves. I have had Ford 75-140, Lucas 85-140 conventional, Mobil 1 75-140, and now this redline fluid. They all drove the same. Some chattered less than others but that was the only difference I noticed.

Still gotta get to putting the additive in. There can't be anything wrong w/ the clutches, nothing has changed since I had the Ford fluid in and they were not chattering at all. I should have never changed it. The chatter is a function of temp. so it is definitely the friction characteristics of the fluid. I'll go back to the dealer and buy whatever fluid I got from them the first time I refilled and it was not chattering, if this doesn't do it.

[Stranger in the Black Sedan]

Update, w/ one bottle of ford posi lube the chatter at low speeds turning is improved but not eliminated. It only does it when the fluid is really hot so fluid is the only explanation. My posi clutches must have been set up on the tight side from the factory (not a bad thing since a lot of people by 40k miles have shot slipping stock clutches). The only fluid I have had in this car that did not chatter turning was the 80w-90 factory fill. Ever since the dealer put 75-140 in it, and I have refilled with all kinds of different brands of 75-140 plus different brand additives, it still chatters turning only when I've driven a lot of miles to get the fluid hot.

I'm going to put regular cheap 80w-90 back in the diff w/ additive and see if I can get it to stop chattering. Since the 75-140 only chatters when it is really hot, it would make sense that the thinner oil should help it out if my clutches are on the tight side. Will report back.

[crimzon]

Just wondering if the chattering is bad, or just annoying? Ever since I rebuilt my rear end the second time, it chatters away through turns. Added a bottle of the ford fric modifier and it is barely noticable, but still easily heard if you are listening for it.

Is it something I should follow up on, or just ignore it?

[Stranger in the Black Sedan]

This is exactly what I have. It's probably not going to hurt anything and it's not that noticeable, but it annoys me. I have had other cars do this w/ rebuilt posi's that were set up tight but those were old POS cars and I didn't care. I have a 2nd bottle of friction modifier that I'm going to add before I drain and refill w/ 80w90