Would you add friction modifier?
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Would you add friction modifier?
I have a 1987 Ford F-150 with an 8.8 rear end. The 8.8 was recently rebuilt with 3.55 gears and a Ford limited slip diff. The 4x4 shop that did the work said they don't use friction modifier with their limited slips. By not using the modifier the limited slip "grabs" more and acts more like a locker. He said the modifier is used so the normal person doesn't feel the limited slip during normal street driving. Soccer moms and grandmas don't want to feel the limited slip or their inside tires locking up (such as a spool or locker would) The shop explained that if I wanted the friction modifier they would add it. I opted to leave the modifier out. The truck drives fantastic. The truck drives different (in a good way) now with the limited slip (before I had a stock open diff and 3.08 gears). Finally my question. Will leaving out the friction modifier result in a severly shortenfed life span for the limited slip? Has anyone else left out the modifier for improved performance?
Last edited by mcne; Sep 17, 2005 at 07:19 AM.
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Heres info from Ford
"M-19546-A12 Case of 12. (Single Bottles CM-19546-A1 soild in cases of 12 only)
Specially formulated additive to provide smooth operation of clutch-type limited-slip differentials."
To me it doesn't sound like leaving it it will cause premature wear. What do you think?
"M-19546-A12 Case of 12. (Single Bottles CM-19546-A1 soild in cases of 12 only)
Specially formulated additive to provide smooth operation of clutch-type limited-slip differentials."
To me it doesn't sound like leaving it it will cause premature wear. What do you think?
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During assembly the plates are soaked in gear oil. The modifier is added after assembly. Many gear oils now have friction modifiers in them. Adding the modifier is sometimes not required depending on the oil used and how much modifier it has. My truck drives very nice just like it has had the friction modifier added. I just want opinions on adding friction modifier if I already have a smooth running rear end with good gear oil.
Fleet Owner
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From: Brentwood,CA
well the modifier protects the clutches. you need 4 oz of it in there or you will chew them up. it is a very bad idea to run one with out hte modifier. why would that hsop tell you that?? also you need to use synthetic hypoid gear oil gl-5 rated.
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From: Louisiana
I agree the modifier is a good thing to have, because it helps keep the heat down from the clutches activating and deactivating constantally, and the heat brakes down the gear oil, and could cause you to wear out you set up if you don't replace it often.
It is said to change gear oil after about 500 miles so you take out all the little metal shaving from the gears.
So if you change the oil soon, add the modifier, or put a synthetic gear oil with a modifier in the gear oil.
It is said to change gear oil after about 500 miles so you take out all the little metal shaving from the gears.
So if you change the oil soon, add the modifier, or put a synthetic gear oil with a modifier in the gear oil.
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I asked the shop for specific info on the gear oil they used. Depending on their answer I might have to add the modifier. Thanks guys.
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I found out the oil used in my rear end is gl-7 rated. The standard for vehicles is gl-5. It is regular "dino" oil. The oil has friction modifiers in it and the company does not recommend adding friction modifier to it. The oil is designed for heavy duty applications. The shop that rebuilt my rear end uses the oil in all of their vehicles. Mainly extreme 4x4 jeeps. Aparently the oil has been working very well for them. I requested a spec sheet from the oil company and should pick it up today. I will post the numbers in the oil forum and see how it holds up.
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Post Fiend
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From: Louisiana
You still might think about changing your oil after 500 miles or so, to get rid of all those metal shavings from the gears.
You can either put the oil that was in there(prolly the best way), or put a reagular gear oil and add the friction moddifer.
You can either put the oil that was in there(prolly the best way), or put a reagular gear oil and add the friction moddifer.
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