Took my 07 FX4 to the dealership to have the rear diff checked out today, its shuddering when I make any kind of turn. Anyway, the service manager wasnt too bright so I called Ford customer service about my issue and the dealership. Long story short, the customer service rep told me that if enough people call in about the rear diff issue, they will issue a recall. So if any of you have that same issue, just call Ford customer service and hopefully they can start up a recall.

 

It's your clutch packs in the posi unit. I must have replaced over 100 of them over the last few years. If it's an 07, should still be under warranty. 5 yr/60k drivetrain warranty after 06 I think it was.

 

It is, I only called because the service manager didnt know it was still under warranty and wasnt sure the rear end was part of the power train. Amazing.

 

How hard is it to replace the clutch packs?

 

Might just need the friction modifier.. But make them do the clutch packs if it is covered! Usually an issue on limited slips.. Do a search on rear shudder friction modifier on this board.. a common ailment

 

All depends. The 8.8 isn't bad at all. The 9.75 requires special tools. Both clutch packs need to be "set up" with shims. I use the 0.030" shim on the 8.8 and the 0.080" on the 9.75. Everytime I set up the shim packs for either rear end, these are the shims that I needed, so I don't bother anymore. I can give more detail if you need it.

Robbie

 

Honestly, I would try replacing the fluid and making sure it has the proper friction modifier. My 04 had the shudder, and before they condemned the clutch pack they tried the fluid and modifier change. That was at about 20k. I traded it at 70k with no problems after the fluid change.

 

It is under warranty! Get the dealer to replace the clutch packs.

 

Replaced it already, twice, first time was Royal Purple second was Mobil 1. Both had the additive in it, I added more additive to the Mobil 1 but that did no good.

 

I would just let the dealer take care of it. Do it before your local dealer goes out of business...LIKE MINE DID! I now have a 45 min trip to the closest one.

 

Yea its goin there Monday, the service manager told me itd take 2 or 3 days to fix with ordering parts and all. I didnt want to give it up over New Years weekend. Im really tempted to just buy a better diff carrier though, only because Im sure they will replace this one with the same weak kind they put in there to begin with.

 

The main problem is the diffs are built dry. The service procedure to replace the clutch packs tells you to soak each clutch in friction modifier for at least 15 min prior to assembly. If they did that to start with, there wouldn't be so many problems. But I'm only a technician, not an engineer, so what do I know. Should have gone to college. That wouldn't help, I have too much common sense to be an engineer. Oh yeah, we have the parts in stock at the dealer where I work, and I can do it while you wait. Only takes about an hour to hour and a half to replace. I think they're giving you the run around.

 

Well she's at the dealer waiting to get fixed. I actually got them to let the service tech to ride with me to see what I was talking about. Luckily it did as it usually does and shuddered, and the tech said he agreed with me, it was the clutches. Even luckier for me I have 2,000 miles left on the warranty. Hopefully this fixes it for good.

 

Update, they fixed it for free, replaced the clutch packs and a couple of bearings. The sheet said the clutches were burned, not sure how that happens, but either way its fixed and hopefully stays that way.

 

Anybody know roughly how much it would cost to have the clutch packs replaced? I have the same problem on my '04.