Rear end vibration on take off and turning

[Green04]

on slow speed take offs not all the time and when i turn i feel this vibration, from the rear end, could it be my Ujoint? do these things have carrier bearings? could it be something suspension related? ball joint, tie rod, sway bar end link? hoping something simple and cheap that i can do.

 

[tower]

If you have a LS rear end then it is a good chance you need the fluid changed, don't forget the additive.

 

[Green04]

Limited Slip? not sure if i do, its pretty much a XLS with all the basic options, and if i do change the fluid what kind of gear oil should i use? and whats additive?

 

[tower]

Limited slip additive. To see what you have look on the drives door tag, if it says D4 you have 3.73 LS if it says 45 then you have a a 3.55 open diff. To be honest you should change it no mater what it says use a good 95-140w gear lube I recommend Mobile 1.

 

[roush9799]

Friction Modifier is the additive. You can get it at the dealer for about $6. Put it in after the first bottle of oil so you get it all in, then top it off with the 2nd bottle. It won't take quite 2 quarts to fill it back up. I used Mobile 1 in mine, i changed it last week. Also, I recommend getting a foot or two of hose to put on the bottle that you can route from the fill plug out through the fender well so you can hold the bottle up beside the vehicle to put it in. I had noise in the parking lot while turning at slow speed like you mentioned. Haven't had it back in one yet to see, seemed like it was worse after the fluid was good and warmed up, we went on a 70 mile trip to get gifts for my daughters B day a couple weeks ago and that's the first I heard the noise. When I make the 8 mile trek to town I haven't noticed it. I also have limited slip. I'll know more if my problem is fixed on Thursday when I take it the 50 miles to Thanksgiving.

 

[Green04]

well haven't been on in a while, ill see if i have a LS tomorrow, and was wondering roush9799, did yours feel like more in the left rear, mine does seem to get worse as the diff warms up, it kind of growls too now, it keeps getting worse, and how did it do on the 50 mile trip? i may have to try this, any good way to get the old fluid out? does it just drain out like oil?

 

[roush9799]

Mine's worse as it gets warm. Wife rode in the back seat the other day and she could hear it more thru the floor back there than in the front. Sounds like it's coming right from the rear center to me from in the cab. Cold, trips 20 miles or less, no noise or binding at all. After about 30-50 miles it gets bad. I just drained it and put in new oil. They say that it takes time for the new oil and modifier to work it's way into the clutches. I only got to drive one long trip since then, seems a bit quieter. Make sure you can get the fill plug out before you take out the drain plug. drain plug takes a 3/4" ratchet/breaker bar, or a 1/2" to 3/4" adapter. I had to jack the back up and rest the ratchet against the ground and let the jack down the break the drain plug loose. Didn't have any trouble with the fill plug. Best way I found to refill it is with about a 18"-24" piece of hose and route it up from the fill plug out thru the wheel well. That way you can hold the bottles up beside the vehicle instead of having to try to do it underneath. I put one bottle of the oil in, then the bottle of modifier, then another almost full bottle, although some run out before I knew it was full. I put the plug in before it stopped running out, they say to add a pint into the speed sensor hole after it's full to the bottom of the fill hole, but I just put the plug in as it was still coming out a bit. I think the extra is for when the oil works it's way in to the gears/clutches, it isn't low.

I haven't had time to do this, but after you change it, I've read that it's good to do about 15 or so figure 8's in a parking lot to work the clutches good and get the modifier and fluid worked up into them.

I had an '02 F-150 that did this, noise wasn't as noticeable, but the rear axle is a lot farther from the cab on that. I just added the modifier to it and it stopped after a while.

 

[Green04]

good to know, i may do this when the weather warms some thanks for the info guys
Edit: ok i looked i have the D4 axle so is that the higher geared rear end then?

 

[Exproblems]

Edit: ok i looked i have the D4 axle so is that the higher geared rear end then?

No, you have the mid-range size set of gears, the (46 or D4)3.73 Limited Slip. There are a set of gears bigger than yours, 42 or D2 - 4.10's. The door codes that have just numbers for the code like mine (45= 3.55) are open diff's and the door codes with a letter then a number like yours(D4) are Limited Slip diff's. Don't forget to add the "Friction Modifier", it comes in a 7 ounce squeeze tube and you can buy it in parts stores as well as the Ford dealerships. Around $6-$7 for a tube of it. The Mobil 1 gear oil is pricey, around $18.95 per quart(but good stuff) and you need to buy 2 quarts of it and you'll use approx 1.60-1.75 qts of it to re-fill the diff.

 

[roush9799]

I put the mobil 1 in mine.

 

[Green04]

gotcha, i dont know much about rear ends, just about everything else i know some stuff, i may just take it to the garage i took my Oldsmobile to to get a motor swap done see what they say, and see how much they'd charge to change the fluid thanks for the input guys

 

[Green04]

Haven't been on months, hopefully gonna do this soon, is there any type of gear oil for a limited slip diff? And is there a drain plug for this or do I have to take off the inspection plate?