Rearend Grease?
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Joined: Dec 2007
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Rearend Grease?
I am going to change the rearend grease in my 01 Supercrew 5.4l and want to know whitch to use. The gears have been changed to 410s with a spool or limited slip, I am running 20'' wheels with 35'' tires. I dont know if I should use what the manual recomends or change the weight to something thicker because of the added stress? I have no idea what is in it now?
Tim
Tim
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Joined: Oct 2007
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You changed out the gears, was the rear end changed also? If you have changed the stock carrier out you need to use what the company that made it calls for. If it's a stock ford LS you need to use that 70/140 WITH friction modifier in it. If you put 80-90 in a ford LS you will crack it in a couple hundred miles. Trust me fords already tried it once on my truck. If you use what ford recommends it will keep the clutches lubricated. I would think all the stress should only be on the mechanical parts of the drive train. Maybe one of those finned rearend covers to help cool it from trickflow if you are worried about heat.
Fleet Mechanic
Joined: Nov 2000
Posts: 1,713
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From: In my House
You will not crack a Ford LS rear end from using 90w. Ford Recomends usings the 75/140W because it will last longer than the conventional 90W oil.
Rich
Rich
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Joined: Jul 2005
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i have used 80-w90 FULL synthetic also. the book calls for the 75w140 since the extra thickness might cut down on some noisy gear mesh. either is fine as long as it is full synthetic.--- and dont forget the friction modifier.-- if RP says its already in the oil, dont believe it.
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Junior User
Joined: Oct 2007
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90w will crack a LS carrier in a 8.8 rearend, I've been their and seen it. 154 miles is all it took.
Senior User
Joined: Sep 2006
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I use mobil 1 full syn 80w90 and it runs great with my 150k mi LS 3.55 rearend. No cracks and no additional modifier. Im careful not to gun it while turning to save the clutch pack. If I start getting chatter while turning I konw to back off the throttle. My understanding is that the friction modifier is friction reducer so that hard turns with throttle will save the clutch pack. Smart driving and light throttle will do the same...
Senior User
Joined: Sep 2006
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Nope, clutch packs still chatter, both wheels spin in wet and jacked up both wheels spin same way. I dont hotrod around corners on dry pavement.
Hotshot
Joined: Jun 2003
Posts: 12,359
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From: SW VA
Yes, your's was a fluke. 89-90 WILL NOT crack the clutch discs. In fact, that's exactly what these trucks came with off the assembly line. Mine's got nearly 110K miles on it, and the clutch packs still look, and work like new.