What Is Friction Modifier , Anyone have Info on It ?

[Idrinkmotoroil]

Daimler Chrysler recommends I use Friction modifier with their ATF+4 tranny fluid. I cant figure out the purpose of the Friction Modifier. The limited slip differential I have is a Quaife Auto torque biasing lsd, it does not use clutches and Quaife America says it does not need any particular fluid to operate, they did recommend synthetic fluid if I was going to driving it hard or racing. It seems that Friction modifier goes into diffs with clutch style limited slips from all the info I've seen. I know some Ford Mustangs use a very similar product in their diffs but I was told those are a clutch like diffs which can chatter without FM. It seems to be a noise reducer from what I can tell.

So anyone know what FM is really made of ?, is it a synthetic fluid , how does it work ?. I have a 4 oz bottle of the Mopar one and it says that it is a severely hydrotreated fluid designed to reduce noise in limited slip differentials. Do you think it is intended to thicken up the thin ATF fluid ?, if it does that for gear protection them I am all for it, if it only quiets noise then it doesnt seem like I need it.

So far I've run a couple of Redline fluids in my tranny without the FM and have not heard any noise under all driving condition. The times I have used the FM it seems to mess up with the shift quality of the synchros from what I can tell. The diff and tranny are one compartment on my fwd vehicle, not two like on some rwd vehicles. The guys with rwd diffs dont have to worry about FM messing with their shift quality but I do with my setup.

any info or opinions would be cool. thanks

Joey

[ December 22, 2003, 11:43 AM: Message edited by: Idrinkmotoroil ]

 

[MolaKule]

The friction modifiers are synthesized oganic chemistries in a base oil of dino mineral oil or synthetic fluid.

Friction modifiers in LSD's modify the friction so that the LS portion doesn't go into "Stick/Slip" which cause chatter.

In other words, friction modifiers modify the "Dynamic" friction characteristics of the mechanism.

 

[Idrinkmotoroil]

thanks for the replies guys, so let me see if I am correct on this:

1. The Friction Modifier has no bearing on the performance of the tranny and its dedicated fluid. 2. On a clutchless limited slip such as a Quaife it would not have any use either. Am I correct on this ?. From what I can tell chatter refers to clutch style lsd's.

3. If the FM is such a slippery fluid it could likely mess up synchros when used in a single tranny diff. compartment such my fwd vehicle.

[ December 22, 2003, 01:46 PM: Message edited by: Idrinkmotoroil ]

 

[VaderSS]

For Torsens, FM reduces the torque bias by .2, which is the same reduction that will take place from running thicker oil(90 vs 140).

 

[MolaKule]

"1. The Friction Modifier has no bearing on the performance of the tranny and its dedicated fluid. "

It may have an effect on shift quality.

"2. On a clutchless limited slip such as a Quaife it would not have any use either. Am I correct on this ?. From what I can tell chatter refers to clutch style lsd's."

No, chatter can occur in metallic cone clutch-style lsd's as well.

"3. If the FM is such a slippery fluid it could likely mess up synchros when used in a single tranny diff. compartment." such my fwd vehicle."

First of all, slipperiness does not necessarily equate to friction modification, when we discuss differentials, manual transmissions, and automatic transmissions. Many of the organic friction modifiers do not feel slippery. Some feel thin and non-slipping (as for some ATF FM's, as for rubbing fluid between fingers), while others (such as the thick lsd FM's) fell thick and tacky.

I find that synchros are very finnicky and change with age. This is why I suggest that one try different fluids in a manual transmission, such as various ratios of MTL/MT90, Amosil Marine Gear Lube, Pennzoil Synchromesh, etc.

As for the ATF+4, if there are no noises or chatter, don't add the FM, you don't need it. If it chatters, then put alittle in at a time until it dissappears.

In this arena of Friction Modifiers for transmissions, more is not better.

See also:

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=16;t=000131#000011

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=16;t=000619

[ December 22, 2003, 04:47 PM: Message edited by: MolaKule ]

 

[VaderSS]

The Quaife diff is similar to the Torsen, which does not require FM and, in fact, does not work as well with FM.

I don't know if the Quaife can suffer from "rusty screw syndrome," which is the Torsen version of chatter, but FM is used to quiet the few cases of rss that have popped up. Torsen has stated that the rss is just a nuisance though, and has no effect on reliability or longevity.

 

[Idrinkmotoroil]

thanks very much , exactly the info I needed to make my decisions on this perplexing question I've been dealing with. Everyone has been extremely helpful with the replies. That is what this board is all about, best info bar none.

Here is my final decision on tranny fluid approach - I am going to run GM Synchromesh tranny fluid without Friction Modifier in it, if noise develops (which I dont expect) then add FM or use friction modified GM Synchromesh which has been reported as being available. I know for sure that my transmission shifts worse with FM added to it, I think the synchros dont care for it in my tranny.

thanks a million guys.

Joey

 

[MolaKule]

From the website:

quote:

---

The Quaife also controls loss of traction when the front wheels are on slippery surfaces such as ice and snow or mud, providing the appropriate biased traction needed to overcome these adverse conditions. The Quaife Differential provides constant and infinitely variable drive. Power is transferred automatically without the use of normal friction pads or plates seen in other limited-slip designs.

---

Definately no need for FM's in a Quaite. Thanks Vaderss.

 

[MRC01]

The friction modifier used in the Ford 8.8" traction lok differentials, is a very slippery fluid designed to soak into the clutch plates, reducing friction to eliminate differential clutch chatter on tight parking lot style turns (where one rear wheel is spinning faster than the other).