Help, I changed the axle lube and put in new 75-140 and 8 oz. of friction additive on my 05 F250 SD to try and take the vibration away when taking off from a corner, turning right or left. I was told $820 to change clutch pacs on my limited slip. I tried the option of changing the fluid first to see if I could save money. Can anyone tell me if it is hard to change clutch pacs or should I take it to a mechanic? Should I try adding just more of the friction additive?
Any help or suggestions would be greatly appreciated. Thanks

 

Are you certian it's the LS? I have a very short vibe on take-off due to the driveshaft, not enough for me to worry about. Maybe try some Royal Purple diff fluid to see if that helps...$15 in fluid is cheaper than the repair work.

 

I've been thru this, my 2000 F350 diff did that, I went to get the clutch pack serviced & the diff shop changed the fluid back to standard Dino fluid- I think its 80/90w,( not quite sure on the weight) & also used the ford additive.but it worked . no more problems like a new diff !

 

I second the Royal Purple. The 04 F150's had a simular problem, and lot of people changed the fluid to Royal Purple, including me, and it stopped the clutch pack chatter. I wouldn't use regular dino oil, factory spec is for synthetic.

 

Sometimes with the bigger diffs and synthetic fluid, you need more than one tube of additive. On my chebby car with LS and I forget... 10inch differntial, I needed almost 2 tubes of additive when I used Valvoline synthetic fluid.

On my 94 F250 with Sterling axle, I usually get away with 1 tube but seems it needs more maybe 20,000 miles later.

try another tube, it'll will cost a lot less than dropping the differential, and if it doesn't work no harm done.

Your truck is new enough that I would be surprised you have the miles to wear out a clutch pack.

Also there was a TSB awhile back about lubricating the slip joints on the drive shafts due to improper lube on the pinion. This causes vibration on starting from a stop. Might be worth looking it up.

Good Luck,

Jim Henderson

 

Thanks for the reply's. I did happen to use the royal purple lube but I might have screwed up by the friction additive I used. I bought what was available at the time of purchase. That was an 8 oz. bottle of friction additive by Kendall. Did I mess up. Now it sounds like I won't hurt anything by adding a tube of additive? Can anyone give me a name or part number for the additive so I can get it right this time? Thanks everyone again for your help.

 

I tried 2 tubes, it did not work with my 2000 , but you may have better luck, I looked at the TSB, & shimmed the steady bearing as well, no difference. My issue was in cornering as well. So, if that 2nd tube does not work, Try what my diff shop did. I was doubtful, but they
were bang on. No more chatter.

 

you need at least 2 tubes of friction modifier, possibly 4. i had this problem when i used to work at the dealer. the important thing though is to drive the truck in figure "8"s, over and over to get lube to the tight clutch packs. when they are that tight, they dont like to absorb the oil. leave what you have in there and drive in 10 or more figure "8"s and try it again. that should help. if not, the clutch packs need to be re-shimmed

 

The procedure is to start with at least one tube, then add more until you are happy with the way the LS acts. Throw in another tube and see how it acts, or drain it and add a synthetic lube (like Royal Purple or Redline) that does not require an additive.

 

Correct. The figure 8's help to heat up and move the clutch pack allowing the lubricant to free up the clutch pack. Also at least 2 tubes of the friction modifier. 1 is not enough. I rebuilt my corvette and had chatter like the driveshaft was falling out. The figure 8's solved it with more of the additive.

 

I'm not sure how much is in a "tube", but if you use more than 2-4 oz, you might as well pull out the LS rear end and put in a one wheel squeal rear end because you won't have your posi anymore. The 4 oz Ford recommends is way too much. I just changed the fluid and put the 08 diff cover on my 05. Motorcraft 75W-140 synthetic and 2 oz of friction modifier. I even think the 2 oz might have been too much.

 

Pulling the axles, you can remove the differential unit yourself, and bring it to a machine shop to put new clutch packs in. Much cheaper than having someone else do it. Just don't use too much BFH (Big freakin' hammer) putting it back in

I have to concur with sgthawkusmc - 8 oz. of friction modifier in the Sterling is more than enough to get rid of any chatter. If it's still doing it, there's probably something wrong.

 

Time for a truetrac. I wouldn't put that much $$$ in the stock LS.

I used Amsoil in my rear diff, has the modifier in it already. I don't have any chatter. Going to drain some out and add straight oil to try and get more diff action. I agree you shure shouldn't be getting chatter with 8oz. of FM in there.

 

I.W.E. Rear Ends Only Ltd.
Guys,
these are the guys that rebuilt my diff with my 4:30 gears, they swear by dino oil & the friction modier. I had changed the fluid back to syn & had nothing but trouble. All I can tell you is , it worked for me. I have a L.S diff that hooks on & does not chatter. Its been great & I tow a 35' 5th.

 

Rebuilt isn't stock. I'm sure using the clutch packs and materials they used to rebuild yours the dino oil is better. Factory recommends synthetic only for a Sterling so that's the only thing that goes in mine.