Vibration & shuddering from back wheels when turning from a stop.

[Laurie Jones]

My 2002 Sports Trac 2x2 just hit 100,000 miles. It's been a good car. The tires are new and front end was recently aligned. I have no leaks and no warning lights are on. I feel vibration & shuddering from the back wheels when turning from a stop. Feel it sometimes when taking off from a stop. The vibrations/shuddering do not always occur. I have been trying to pay attention to a pattern. It seems to occur more when I've been driving for 30 min. or so. It feels like it's coming from the left rear. Almost feels like the left rear tire is shuddering. Once the problem starts, it does not stop until the vehicle has been parked for several hours. It almost feels like the back tire or tires are going to fall off, but they are not. I read somewhere that this MIGHT be related to the transmission???? Hope not! Also, read in this forum that adding differential fluid might fix. I would appreciate any suggestions that might help. I just do not have the money to take the car to the stealership. If the fluid is the answer, would an oil change shop be able to do it? Would it be a bad idea for me to add fluid on top of what's there? And finally, where would I add the fluid? (Sorry for all the ?'s. I am a female and a novice when it comes to cars.) THANK YOU IN ADVANCE!!! :banghead:

 

[Vic Sorlie]

This issue could be caused by a number of things, but I recommend you start with the simplest first. 1) Check that all wheel lug nuts are tight (fronts too). 2) Check your transmission fluid level. The dipstick is on the passenger side of the engine, and it's checked with engine running, transmission in Park. If fluid is low or you've never had it serviced that may be it. 3) You don't add differential fluid; when it's time for service (you're overdue) the old fluid is either evacuated or drained by removing the cover, then refilling. I think you could have both services done for approx $150 at a decent quick lube shop. 4) Your rear brakes may be worn; have they been looked at? Let us know what you find.

 

[Yardsale]

Sometimes, it is less expensive to take it to a shop than to experiment with parts replacement.



Have the tires been inspected for defect (belt slippage) or damage? Have they been rotated since this began?



Seems that it is heat related. Could be bearings, either axle or differential, or u-joints.



Does it have a limited slip differential?



If the fluid is low, then adding fluid might fix it (this is where having the problem correctly diagnosed can be efficient). There is a fluid fill hole in the front right (driver) side of the differential that can be used to check fluid level and fill (fill until level with the bottom of the hole - ensure truck is on level ground). If it is low, where did the fluid go? There may be a leak and that needs to be fixed and there may be damage that occurred.



As a side note, while the maintenance schedule does not mention differential fluid change, many would agree that it should be changed every 50,000 miles as a maintenance item, transmission fluid, too (some argue about the frequency, but all agree about the maintenance). Transmission fluid level should be checked every 15,000 miles.



Might want to change the fluid if it hasn't been. If it is a limited slip, a "friction modifier" must be added to the fluid. I would not trust a "quickie lube" to perform this service.



P.S. When checking the transmission fluid, the transmission must be warm (operating temperature).

 

[RedRanger 7]

Or try a differential transmission shop for a test drive, they will probably easily diagnose the problem without taking anything apart on a test drive. :driving:

 

[Richard L]

The first thing I would do is a visual inspection. Check for loose lug nuts and if there are any visable wheel or tire defects..inside and outside. Then have someone drive behind me and check to see if they see any wobbling or anything that looks suspicious.



You may even want to check the exhaust pipes and muffler to insure that all the hangers are in good shape. I had a similar problem years ago with my new 1965 GTO while accelerating. turned out the oval muffler was turn a bit and vibrating against the floor board. Loosened the clamps and twisted the muffler a bit and that cured the problem.



If nothing is obvious, then you may need to have a shop see if they can find the problem like a bent axle, broken suspension, bad differential or drive shaft?



...Rich



...Rich

 

[Jeffksf B]

Most likely your rear diff fluid if you have a LS axle. Also of note, you have to add a friction modifier to the fluid if you have a LS differential. I've only had good luck with the motorcraft brand from the dealer.

 

[Dan B]

My brother-in-law had this issued with his '04 Sport Trac, his turned out to be bad bearings but as stated, it could be a variety of things.