ive got an 01 ranger with what appears to be a limited slip rear end. I had it jacked up the other day and noticed that when i spun one of the wheels forwards, the other wheel spun the same direction. This leads me to believe its a limited slip because wouldn't they spin in opposite directions otherwise? This being said, i put a chrome diff cover on about 1500-2000 miles ago and since i wasnt aware that it had a limited slip at the time, i just used the 80w-90 gear oil it called for. (i think thats the weight it was) so im concerned that i need to add an additive since i have a limited slip. is it possible that i ruined anything in the rear end? its not the daily driver and doesnt see any offroad action so hopefully i didnt screw anything up. i was gonna stop by the ford dealer after work and see if there was a special type of Ford gear oil i need to use for the limited slip. I dont mind taking it apart again, but im concerned that i might have damaged the rear end. im not sure how id even be able to check for that type of damage. any advice/comments/thoughts? Thanks guys.

 

FYI before anyone asks, the truck is just an XLT with the offroad package and not an FX4. I'm assuming there are clutch packs in the diff....im hoping i didnt burn them up by not running the additive. is there any way to check and see if i did burn them up?

 

2,000 miles shouldnt do much if any damage. just go to ur local parts house and pick up a tube of friction modifier and put it in the fill plug.

what brand gear erl did u use? some already have the friction modifier in the oil...

 

oooo yer pop-quizzin me now lol. i dont know off the top of my head. id have to look when i got back to the house. i dont think it was coastal, but i dont think it had the modifier in it. i hope i didnt damage it any. ill see what the dealer has to say too. is there any goofy type of friction modifier i need? probably the $10 stuff from Ford lol. i guess id sleep better if i got it from the dealer.

 

all friction modifier is the same IIRC. advance auto has it for around $5. i doubt u did and damage, because there would still be some in from the old gear lube since u cant get every drop.

 

i hope you're right! thanks for the insight. i dont feel so bad now lol

 

dont feel bad, i ran a few thousand miles w/ minimal gear oil because i had a leaky seal and the diff cover lip was bent and it didnt do any damage.

 

well, ill let you know what i find out. im gonna give them a call at lunch and see what they say.

 

The dealer will ALWAYS recommend the factory friction modifier..... Adding the aftermarket friction modifier which can be purchased at almost any autoparts store and Off Road shop.... has the same friction properties as the factory product. The only difference might be that some aftermarket items are composed of proprietary enhancers....

OR 4x4

 

ok, heres what the dealer told me. i told the guy that i probably drove less then 1000 miles without the modifier and he told me he didnt think that would be a big issue but to add the modifier asap. got transferred to parts, they have the modifier for $5. he shot me back over to service cause i had one more question. "Do i need to just add the modifier to the oil thats in there now or do i have to take off the cover and fill it back up again? i was told i could just add the modifier to the 80w-90 but this guy told me that he has seen them run without the modifier for about 400 miles and need rebuilt. said it was $700-800 to rebuild. i think he's trying to get me to come in a get it rebuilt lol. so im gonna go pick up the modifier, drop it in and see what happens. i dont think ill have any problems. i just wanted to get your opinions on the whole thing. i appreciate all the help.

 

sounds like a plan.

 

The function of the friction modifier is to prevent possible chatter from the LS when turning corners on pavement. Don't worry about your diff. Just add the modifier.

 

ok, thats good to hear....but i have one more question....then we can kill this thread lol. im running 80w-90 in the diff now. i went to the dealer and they had two different types of friction modifiers. one was synthetic and one was not. so i got the one that wasnt synthetic. simply because i know that in the manual for the 03's (which the salesman gave me when i bought the 01 cause mine didnt have a manual) it says that the rear diff takes 80w-90 for all applications EXCEPT the FX4. the FX4 takes 75w-145 synthetic so im assuming thats what the synthetic modifier was for. the guy at ford was no help lol. so i figured, if i went to autozone and had them pull it up on the computer, i was curious to see what it would say. it called for the 75w-145 synthetic..? ok, so im lost. ive got the ford anti friction modifier that is not synthetic, the truck currently has 80w-90 gear oil in it. should i just add the modifier and be done with it? or should i dump the 80w-90 and put in the synthetic stuff like the all mighty autozone computer says? i trust you guys over just about everyone, so im looking for a little more feedback. the guy at ford did tell me that if he could read the tag on the diff, he could tell me what it got.......yea about that tag. remember i put a chrome diff cover on?......yea well the tag is.....somewhere in the garage.....hard to say exactly where. its dark and i cant see to be able to do a proper "scavenger hunt" for the tag. i know i kept it.....i think. anyways, this is the last post guys. sorry for the length. go get a beer before you answer, you've earned it

 

All ford diffs that require the 75-140 have a second tag on the diff cover saying "75w-140 only" just run with the 80 90 and regular FM.... I only run about a half of a tube of the FM in my diff for less slippage....

 

The 2001 Owners Manual only lists one axle lubricant for your truck - 80W-90 for both the front and rear axles. Add 4 oz. friction modifier to the rear axle for the clutch type Traction-Lok LS like you have. No Rangers specified 75W-140 in 2001.

The 31-spline/Torsen LS rear axle in the 2002 FX4 Off-Road and the 2003+ FX4 Level II get the 75W-140 synthetic (w/o friction modifier). Other than the Torsen exception, all other 2002+ Ranger axles use the 80W-90 as used in the 2001 Rangers.

 

you guys have no idea how much i appreciate the reasearch. so dump the FM in the diff and im done. god bless america LMAO thanks so much. you guys kick a**