Just changed the fluid in my rear axle and left out the friction modifier. Isn't this supposed to help with making the limited slip clutches grab better? Well after changing the oil, I installed a SCT custom tune(street/economy) and now the right rear tire is spinning a lot more. I have a lot more power than when I was running a Predator in the performance/economy mode. I only have 17K mi on the truck. Do I need an aftermarket locker/limited slip?
Thanks

 

The modifier lets the clutches slip more. If you leave it out completely, when you make a U-turn, you will hear the rear gears locked.

Why you have to symptoms of a open differential is puzzling.

 

incorrect sir

It actualls helps the clutches engage better...you need the FM in there!

http://www.torcousa.com/technology/L...p_Additive.pdf

 

Not incorrect. Agreed the modifier help is some reguard to locking up the plates. Its number one function is to reduce chatter


Clutch Chatter
Traction-increasing devices, such as limited-slip "positraction" or locking differentials, are alternatives to the "open" differential configuration and are designed to increase traction to both wheels in any situation. Typically, these differentials contain clutch packs that lock and slip according to the situation. For example, when the vehicle turns, the clutches are designed to slip to accommodate for the different rotational speeds experienced by each wheel.

Stick-slip is essentially the buildup and release of energy between the differential clutch packs during operation. This phenomenon often occurs when torque is transferred between the clutches or when rotational speeds change. During the stick-slip phase, energy is built up to a point where contact between the clutch plates change between static friction (stick) and dynamic friction (slip), resulting in noticeable vibrations. It is this vibration that causes an audible chatter or ratcheting to be heard within the differential. While certainly an annoying characteristic, there is typically no mechanical damage occurring to the differential.

Friction Modifiers
In an effort to control this chatter, friction modifiers are often used. These additives result in a smoother transition between the two states of friction: static and dynamic. Static friction occurs when the clutches physically lock together, while dynamic friction occurs as the clutches are slipping.

We have a chart which illustrates the effectiveness of friction modifiers on the clutch packs, as represented by the curved, horizontal line in the middle. If you would like to see this tech bulletin and chart along with complete AMSOIL product and technical information please leave me your mailing address at dave@performanceoiltechnology.com

This lines on the chart represents the effect a friction modifier has on maintaining the dynamic friction characteristics while in the slip phase and not allowing the resistance to build back up to the stick phase until the unit stops turning. At the same time, it helps to insure maximum power transfer to the wheels. The friction modifier additive can be thought of as a friction "controller," insuring maximum clutch pack engagement while allowing the conversion from lock to slip to occur gradually.

 

[QUOTE=

The friction modifier additive can be thought of as a friction "controller," insuring maximum clutch pack engagement while allowing the conversion from lock to slip to occur gradually.[/QUOTE]

This line from YOUR post proves my point!!


you are incorrect in saying that the modifier helps the clutches slip more...that is just the opposite...modifier helps the clutches engage and do so smoothly...not slip!

Keep in mind the point of this thread...the guy said he didnt put in any FM and now he has slippage...he needs the FM in there to fix his problem...his problem is not chatter!!

 

Whoa!!!!!!

 

The modifier causes less friction between the plates to limit chatter. Without the modifier you should get chatter and increased wear to the plates. When you go around a corner most people like a smooth transaction not grabbing and catching, thus chattering.

Dick

 

What part of his clutches are slipping and not powering both wheels dont you get??

We are not talking about chatter here..we are talking about FM and its ability to improve clutch engagement inorder to put power to both wheels!

The FM does two things...it does limited chatter when turning yes...but that is not the issue here...it ALSO increases the engagement of the clutches and allows the clutches to lock-up better when traction is needed to power both wheels!

The issue with this guys truck is that his clutches are slipping all the time...the FM is needed to increase the engagement of the clutches....READ THE ABOVE POST WHERE TWO OF US QOUTED THAT FM DOES INCREASE CLUTCH ENGAGEMENT!!!


I qoute once again...

We have a chart which illustrates the effectiveness of friction modifiers on the clutch packs, as represented by the curved, horizontal line in the middle. If you would like to see this tech bulletin and chart along with complete AMSOIL product and technical information please leave me your mailing address at dave@performanceoiltechnology.com

This lines on the chart represents the effect a friction modifier has on maintaining the dynamic friction characteristics while in the slip phase and not allowing the resistance to build back up to the stick phase until the unit stops turning. At the same time, it helps to insure maximum power transfer to the wheels. The friction modifier additive can be thought of as a friction "controller," insuring maximum clutch pack engagement while allowing the conversion from lock to slip to occur gradually.
__________________

 

All I know after 30 years of LS"S if you don't put the modifier in the clutches grab real well. Super posi But they are noisey and wear fast..You can read what you want.
Most ford LS's are worn so bad that they don't work with or without modifier


Dick

 

So your saying that putting just straight gear oil in a LS will make a "super-posi"....lol that's too funny!!

I have been drag racing at a pro level for years....just think..if I had only thought of this sooner...maybe I could have saved some money...Silly me!

I bow to your obvious superior knowledge of high performance technology!!

you are the man!!

 

Whatever you say! Maybe you are right I'm only giving my observations..


Dick

 

I did that when i just stuck in straight 80-90W and i got my posi i wanted...and it didnt cost me a dime.

 

OK guys, I only have 17k mi. The clutches should not be worn out yet. Ford recommends adding 8 oz of friction modifier. I have heard 2-4 oz from you guys.
Can you put in too much modifier?
Thanks

 

The reccommended amount (8oz I think) is too much IMO. I start at 2 oz and try it. I keep adding an oz at a time until the chatter is gone. It usually ends up being around 2 oz.

 

What are you people smoking? For the tenth time...read this guys post...he IS NOT having trouble with his rear chattering...his LS is not working!!

BTW...You are still under warranty and I would service it and put in exactly what Ford says to...if you ever have a problem with the rear..ford may test the lube and see if it had FM in it..if it doesn't, well I wouldn't want to give them a reason to deny the claim!