'01's wife here.

If you had ever driven a vehicle that had a true locker, you would understand what is happening.

When a clutch type limited slip is new, it is tight. It has to be tight, otherwise, when it would break in, it would almost be worn out (meaning it would be too loose to be effective). If there was no friction modifier in it............. or too little, the clutches will bind and lock (when this should only happen if one wheel spins and heats the clutches). This will cause the rear to react like a hard locker............ including all of its bad characteristics (excessive lash, chirping, slipping of one tire on a turn, clunking, and so-on). This situation will be exaggerated when cold due to the thickness of the gear lube. Once the lube thins out with heat, it will lubricate better (it can then get between the clutches to do it's job).

These noises do not cause any adverse, chronic problems with the rear.......... however, they can cause premature clutch wear in the limited slip. However, most drivers would never notice this shortening of life............ as the limited slip on a street driven vehicle has a pretty easy life. Trucks that are raced alot, or driven off-road alot will already shorten the life of the clutches due to them being used much more.

There are rebuild kits for these types of limited slips also.

My suggestion would be, if your rear axle is doing this........... drain the gear oil. Check the specs for friction modifier, and refill, using the proper amount. If you still have some binding, add more modifier. As in any manufactered thing, some will be tighter than others, and may require more modifier (friction modifier makes the gear lube more slippery to help reduce clutch binding). Also understand that this will just naturally lessen with wear and use.

As a person who has off-roaded alot (with a heavily modified Explorer that is hard locked both front and rear), I would be happy to know that I got a good tight limited slip. This lets you know that even as it loosens with age, it will still be good and effective.

If you are curious as to what the extreme of this annoyance is like, just go out with a 4wd club. On the street, you will see what a real hard locker is like. If this little noise bothers you, a hard locker would drive you absolutally insane.

 

I noticed this problem two days after I took delivery of my truck. I have not taken it into the dealer yet because I thought it was in my head. I have not noticed this in any other vehicle. I suppose I should take this in?

 

My '04's doing it as well. You should not have to replace the diff. fluid on a truck thats days old.
Its not binding as '01ArrestMeRed suggested. Its as if the driveline has too much play or slack in it.
I was thinking that it may be the just a quirk of the LSD, since Ive never driven w/ one.
Jeep TJ, was a daily driver, w/ 4.88s & Detroits........lets talk about some quirks

 

FWIW my 3.73 is not a LS diff, and yet I am having the little jerkiness upon takeoff from a stop.

However, it appears to be lessening. Truck now has almost 6k miles on it. Probably a break-in thing. In all other ways the driveline is perfect, apart from a small howl from the rear end at 50 mph under neutral throttle, but I doubt these are related. My 03 XLT with the 3.73 Standard rear end also had a howl, tho at 42 mph instead. Must be something about Fords, as I've not had a howl like this in any other vehicle I've ever owned.

 

I had a howl in the back of my '04..............so I told her to shut up.

 

not to sound too dumb, but what exactly does the LSD do for you? Is it good for offroad driving, which I won't do much of, or does it help you in snow? I got the 3:73 LSD, pretty much because the salesman told me too.

 

Hey '01's Wife.

That was a very good explanation .

Have you worked as a tech.

Mike

 

Not nearly as technical as '01's Wife. ie....laymens terms.

Open diff. (nothing at all) both wheels turn independantly....You go through a corner, the outside wheel turns faster due to having to travel farther than the inside wheel. You get stuck in snow & only one wheel will spin, that being the one with least resistance. So 4 wheel drive, isnt 4 wheel when you get stuck.

LSD From my understanding, acts like an open diff. under normal circumstances. It allows for a certain amout of independant movement, which would be a normal amount, such as while cornering. When theres too much, the diff. SHOULD exert some power to both wheels....hence..."limiting the slip of the diff." You get stuck in snow, the wheel w/ least resistance begins to spin, but the LSD should come into play and exert some power to that wheel. Ok for regular use & off-road use; but not for hardcore off road.

Locker...doesnt limit anything . Both wheels will have 100% power all the time.....results in.....some adverse reactions on road, if the driver's not use to it. Great for offroad.

 

'01's wife.

I have done a great deal of off-roading, and have built my own vehicles for years. This is where this knowledge came from. My current husband also had an auto repair and towing business (we have since closed it due to 9/11), which I would work at.

As for what a limited slip does for you............ the name tells all. It limits the slip between the two driven wheels. While they are almost necessary for off-roading, they also have important uses on a street driven vehicle. A truck has a light rear end. If you try to take off quickly, without a limited slip, you would almost always spin a tire (the tire with the least traction will spin as force will take the path of least resistance). With the LS, as soon as one tire starts to spin, it builds up heat in the differential. This build up of heat causes friction in the clutches of the LS, which then start to turn together. This causes the power to be distributed to both rear tires, and you move forward. This will also help you when towing because more power is needed to move the load from a stop.

One tire spinning is not a very efficient way to get anywhere.

Limited slips can have the same characteristics of a hard locker (where both tires turn the same all the time), but to a lesser degree. This includes more driveline lash. Driveline lash is the "slop" that you feel in the driveline before the vehicle moves forward. There is always more lash built in to a vehicle with a LS or locker to cushion the shock to the rear axle, to help prevent breakage under extreme stress. Driveline lash is when the driveshaft turns a little bit before the differential transmits the power to the tires. No lash would mean that as soon as the driveshaft turns, the tires turn.

The extreme degree of this is the Detroit Locker. There is a large amount of lash built in to it because it is a hard locker. This means that there is NO slip. When going around corners you will hear the tires chirping and a loud ratcheting from the rear (this is the release to let you turn corners). Sometimes the Detroit will not ratchet on a turn from the beginning, then it will disengage with an extremely loud CLUNK. It sounds like your rear axle is broken. I paid alot of money to have my rockcrawling Explorer sound like that.

 

Schlag, sorry to step on your toes.

I was typing, with interruptions, while you posted (we have a 21-month old).

Anyone is welcome to come to Payson, AZ to see just what those "bad characteristics" are, with a hard locker. Luckily, due to the long wheelbase in the Explorer, they are not as annoying. If you want to be scared to death, drive on the street in a CJ5 with a Detroit in the rear. I know it scared the sh*t out of me more than once. It takes quite a bit to scare me.

 

Yup......TJ w/ 4.88s & Detroit. Its funny to watch others at the gas station when the front tire would lift a few feet off of the ground....never mind the noises it made. God I miss it

 

The Beast (the Explorer), has 4.56's a Detroit in the rear, and a Lock-Right in the front (when this one blows it is Air Locker time). So I can relate.

When I was in the Mesa Fourwheelers club, one of my friends had a TJ with a Lock-Right (cheaper, weaker type of locker). I had to drive it up to Scottsdale for him. It scared the crap out of me on the freeway.



She's sitting right outside the window here. Just needs a transmission.

 

Sweeeeet. Believe me....its not a mall crawler I just dont have any action pics on line since I had to sell

 

I,ve had an 04 f150 since september, and I too have noticed a "weird" feeling in the rear end when taking off from a dead stop. I always thought it was something with the tires gripping. I sure hope this is nothing major

 

I am older than most of you.

In the 1950's there were no LSD or Lockers.
To make both wheels turn at the same time
we welded the spider gears solid.

Try to change lanes with that setup.

Mike