04_Lariat_SCrew

I've searched and know the issue is in the rear diff. I recently changed the fluid this past summer due to a shudder at low speeds while turning under power. I used royal purple and friction modifier. Now over the last month or so, the shudder has come back. My question is, is it possible I didn't use enough modifier? Should I try and add a touch more or is it a pretty sure thing my lsd is on its last leg. When i inspected everything over the summer, everything looked fine with pretty much no wear. Id hate to have to rebuild the rearend if I don't need to. Thanks in advance guys.

Summers22

iTrader: (2)

Cheapest route is to add friction modifier, then re-evaluate.

04_Lariat_SCrew

I was thinking this but was curious if adding another bottle would be too much or should I start with a half bottle? Plus I have no idea what happens if I put in too much. I can only assume it's not good for the lsd?

Summers22

iTrader: (2)

Put in half a bottle. What brand did you use last time?

04_Lariat_SCrew

In all honesty I can't remember. It was something I picked up at Oreillys. I know the royal purple said it had modifier in it also so I was a little careless in making sure I got every last drop of the friction modifier in since it was also in the gear oil.

Summers22

iTrader: (2)

I used a full bottle of friction modifier from my local Ford dealer, its the Xl-3. Also used 3 quarts of Mobile1 75W140 Synthetic Gear oil. Zero issues.

PerryB

I have a similar issue but instead of a shudder its a "whoop-whoop" sound while turning tight at low speed with a little power applied. Right or left doesn't matter. I was convinced it was the LSD clutches squawking so I changed the fluid and friction juice, to no avail. I've had this truck for about 2 years and 40,000 mi. and its always done it, with no noticeable change. I have axle code B6.