one more try
"Chatter" is a condition that Limited Slip Differentials (LSD) exhibit when the clutch pack creates a friction that takes more force to overcome than what falls within the design limits. The LSD limits slip between the two wheels by friction created by two sets of clutch packs (each axle shaft/wheel gets one pack). The clutch packs have a specified value of friction, or force that they should create for proper operation. That friction value is something that can/is tested fairly easily with the right tools. Too little friction, and the wheels will easily spin independently almost as if the differential is open (a one wheel wonder). Too much friction, and the wheels will resist turning independently which isn't a bad thing.. until you try to turn... This is where your "chatter" comes in. As the wheels try to spin at different speeds the clutches hooooooold then break free, then hoooooooold then break free, then hoooooooold then break free, and over and over and over. This all happens in seconds as you make your turn. The vibration it makes resonates up thru the chassis and into the cabin giving you the chatter noise and if you have a sensitive enough ass, you can feel the shock load thru the seat bottom.
Enter the friction modifier. The friction modifier, chemically modifies the resistance the clutch pack provides so that it holds just enough but still allows the wheels to turn independently during a turn without the hooooooold and break. For hard core off roading or drag racing, this style of differential pretty much sucks, but for your every day mom and pop driving, it suffices.
The amount of friction modifier you need depends; How worn are the clutches, how many frictions and steels make up a pack, how strong is the preload spring forcing these packs together, what kinda vehicle is this differential in and how is it used? I had three mustangs in my 20's and everyone of them had a LSD at one time that chattered. I did that on purpose. They never saw modifier, even when I rebuilt the LSD. Those clutches were going to hold tight, even under the smokiest horse whip'd burnouts. For customer vehicles that chattered it was different. I opted to rebuild most. Considering clutch material, clutch/steel quantity, spring strength and pre assembly secrets usually delivered a chatter free diff without bottle after bottle of modifier.
So, what does clutches and chatter and friction modifiers and mom and pop driving and one wheel wonders have to do with Raptors??? Nothing.. There is no LSD in the Raptor. The nearest clutch pack is in your transmission. Your rear differential is a mechanical locker. It uses tooth and groove to lock the wheels. That handy dandy pull out locker 4x4 switch sends voltage to a magnetic actuator which forces the tooth and groove hubs together, locking your axle shafts as one solid unit. No amount of friction modifier is going to help the voltage flow, the actuator to actuate or the tooth to groove.. Adding modifier is attempting to modify an element that doesn't exist.
I understand people seek the most concrete of concrete answers for what seems like such a confusing and conflicting question, but take it from someone that broke a LSD or two, rebuilt a LSD or two, built a mechanical diff or two, made a living doing this a time or two, went to school for a diff or two, messed with friction modifier a time or two, chased a nvh concern a time or two.. The answer isnt that complicated, the dead horse died back in practical land. This thread and the never ending quest for friction modifier reads about like this to me,
Are red zip ties required to help my friction blender fly faster to school bus island? Can we get some confirmation on that? I've heard a half salty owners manual with cracker crum bump stop thread additive will make so much black dragon chatter 3.0 horse power, my non lsd needing lsd fluid prerunner rear end will explode my thimble nimble spindles while sitting still at trr. This is serious shit, that needs serious answers, by serious people, people!!
