When starting from a dead stop I get a small tremor from the rear end at about 5 mph. It only shakes for about 2 sec. Does anyone know what causes this. I have a 2004 F-150 SuperCrew w/4wd.

 

Hey! My 2001 F-150 Supercrew does the same thing. I had it down at the shop. They said it was the posi rear end and was normal. I think they're full of it. If you get any tips, please post.

 

My 1999 F150 4X4 does exactly the same thing, and I got the same answer from Ford. They claim it is the Limited Slip Differential (posi) releasing, and is normal in very cold temperatures. Odd thing is, it only does it from a stop, and only when turning a corner, not when going straight ahead from a stop.

Go figure!

 

Mine did the same thing...got the same answer from ford....but I didn't belive them......So I changed the rear end fluid myself....and it stopped......every year and a half or two years it starts up and I change it again....you just got to make sure you add the additive for posi trac and limited slip rear ends with the lubricant.......

I suppose it wont hurt anything to let it go.....but I didnt' like it.....My owners manual said the rear end is considered "lubricated for life" but if you ask me....NOTHING is lubricated for life......

 

Of course the tremor would only occur when turning because the clutch pads or the friction device/material only slips when the wheels are moving at different speeds. In a straight line, the pads move together in unison with no slipping.

 

I have an 04 f-150 with a similar problem. when i start from a stop, i feel a slippage or hesitation just in the first seconds of acceleration. it doesn't happen all the time, but i'm very aware of it. i took it into the dealer, thinking it was a trans problem. they downloaded some software and claimed it was fixed. as soon as i drove it out of the lot i knew otherwise. went back a couple days later and had their trans tech drive it with me and it happened again. he said it felt like something in the drivetrain but probably wasn't anything to worry about. apparently they have a similar problem with an older model explorer, but much worse. they told me they'd hound ford for more info and get back to me about a potential fix. i'm not waiting by the phone. glad to hear i'm not imagining things though.

 

A while back some reported the same thing with their 04 f150. Do you have a limited slip differential? If so, tell FORD about it and they should replace the friction pads or clutches in the differential.

 

Yes, that's correct. My dealer said the rear diff "clutch pack" needs to be replaced. Mine does the exact same thing...slight shutter/vibration from take off while the front wheels turned. I have an 04 Lariat SC w/3:55LS Diff.

 

why not try some friction modifier first?

my '02 LS did that when new...the stealership added a bottle of the friction stuff and now it is only RARELY noticeable...

 

My 1999 f150 started doing the same thing. Took it to a repair shop (who used to work at a local Ford Dealer for a lot of years). He added the Limited Slip Friction Modifier (approx 4 oz bottle), and problem gone. It came back later, and I purchased the bottle and dumped it in myself. Again, problem alleviated (atleast for now).

Seems like it cost under $10, but might of been $12-14. My memory doesn't hold onto numbers real well.

 

Ford Dealer called today and said they have a "special" rear end grease that will fix the problem. Will update when they install it.

 

I've posted this problem with my 1997 a while back. I changed the differential fluid added friction modifier and it still did it. I then went and bought "FORD" friction modifier and added it. It is better, but it still does it. Doesn't do it as much.

I've learned to live with it though, and have decided that my next truck will be a JAP truck. I'm happy with my truck but I'm paranoid with it. I'm afraid a COP will go bad, wondering when the CEL will come on again, afraid I'm going to blow a spark plug out of the Head of my 5.4L (they have this problem). I've owned alot of vehicles and never was paranoid like Iam with this truck. I want a truck that I can change the spark plugs & not have to worry about spending $350.00 to have this done. I have 81000 miles on it and I'm actually thinking about selling it. Anyone interested?

1997 5.4L 4X4 Short Bed extended cab. Remote Control for the Alpine Stereo. $8000.00 & it's yours. Nice Truck

 

Same problem--99 4x4 f150 Dealer said they are now putting 75w 90 synthetic in instead of 75w 140 syn.-which my my rear end tag calls for, plus 1 bottle of friction modefier. He knew exactly what to do for my problem so FORD is keeping mum on this situation! If problem persist after changing to new fluids then need to get a posi clutch kit.

 

There is a TSB out on this subject. My 2000 F150 with traction lock rear chatters when I turn. The fix is to take out some of the shims in the clutch pack. Of course the complete fix recommended by Ford is to replace the clutch pack. But, like I said the real fix appears to be reducing the load on the clutch pack by reducing the shims. I got a copy of the TSB from the dealer Thursday. If anyone is interested, I will find it and post the number and exactly what it says. I assume this will be done under warranty if your truck is still under warranty.

 

I was suprised with my recent purchase of a 2001 Supercrew Lariat ot have the "tremors". What suprised me even more was that a dealership (not where I bought it) was so willing to tell me that it was normal. My question is: Does the axle come w/ synthetic fluid in it? I had an oil change, and the guy in the pit added fluid to the axle, and it never crossed my mind. Now I have a fluid leak, and wonder if the mixing of products could have caused the condition. Anyone have any ideas???
By the way, I am new to the Ford product line, (a die hard Toyota fan, they just dont make one big enough yet) so be gentle on me.
Thanks in advance.
Kurt