Truck Shudders
http://www.ebay.com/itm/FORD-XL3-FRICTION-MODIFIER-ADDITIVE-FOR-REAR-ENDS-/310303114133?pt=Motors_Car_Truck_Parts_Accessories&hash=item483f81c395&vxp=mtr
Was back to the beginning of this thread and don't see description of vehicle.
I was doing some checking on my 01 but figure I need to dig deeper for verification.
Supposedly, ford started using a permanent lube in rear differential that does not need additive added. A number of the aftermarket full synthetic have made that claim probably back to the early 90's.
So if you changed rear grease, what did you use?
On the other hand they did not do that for the front on 4X4 at that time. They hopefully have made that change as well.
Also I had a Bonneville with limited slip. It had over 100K when acquired and shortly I discovered the chattering when cornering. I suspect previous owners never had it serviced and by time I got into it there were lots of metal flakes in grease. I managed to salvage with new clutch pack and shims. I recall that when dumping all the fluid that one required a double dose of GM friction modifier, not just the maintenance dose.
I was doing some checking on my 01 but figure I need to dig deeper for verification.
Supposedly, ford started using a permanent lube in rear differential that does not need additive added. A number of the aftermarket full synthetic have made that claim probably back to the early 90's.
So if you changed rear grease, what did you use?
On the other hand they did not do that for the front on 4X4 at that time. They hopefully have made that change as well.
Also I had a Bonneville with limited slip. It had over 100K when acquired and shortly I discovered the chattering when cornering. I suspect previous owners never had it serviced and by time I got into it there were lots of metal flakes in grease. I managed to salvage with new clutch pack and shims. I recall that when dumping all the fluid that one required a double dose of GM friction modifier, not just the maintenance dose.
175K miles.
I changed all the driveline fluids to Royal Purple @ 153K. I bought the truck used with 144K, with no records indicating that any service had been done prior. The diff looked pretty normal when I changed it. No chunks or shavings.
https://www.f150online.com/forums/ot...driveline.html
I'm still a little confused as to what condition would cause a LS axle to not operate smoothly while driving straight ahead, like Bluegrass said...
Senior Member
Joined: Dec 2006
Posts: 43,542
Likes: 819
From: Joplin MO
Yes, the XL-3 is what you need.
Ford uses the modifier at the factory. Although not specified, it's a very good idea to change the gear lube every 100k. The rear uses 75w140 full synthetic, with modifier if it's LS, the front specifies conventional 80w90 but 75w90 synthetic is fine.
SOMETIMES the 9.75" LS needs a second bottle of modifier to smooth it out.
Ford uses the modifier at the factory. Although not specified, it's a very good idea to change the gear lube every 100k. The rear uses 75w140 full synthetic, with modifier if it's LS, the front specifies conventional 80w90 but 75w90 synthetic is fine.
SOMETIMES the 9.75" LS needs a second bottle of modifier to smooth it out.
Thanks everyone who posted! I added the one bottle of modifier today and drove in circles a few times and then drove about 40 miles... about 15 miles in the city at the 40-45 mph range.
So far everything's smooth. This my first time dealing with LS problems... never would've guessed it was causing that shaking.
I'm going to repeat the same loop tomorrow, and see if the shudder resurfaces.
So far everything's smooth. This my first time dealing with LS problems... never would've guessed it was causing that shaking.
I'm going to repeat the same loop tomorrow, and see if the shudder resurfaces.
