I am new to posting on a Thread so please bare with me. I just wanted to say that I own a 1998 Ford F-150 with 60,000 miles on it.

My problem involves vibration upon stopping. It only last for a few seconds, when I begin to brake. So, my first thought was to check the brakes even though I just replaced them about 6 months ago. But, since they are the cheap kind and sometimes the rotors get warped, I thought it was worth checking out.

Upon inspection, both the brakes and rotors were ok. So I pulled off the rear tires and checked the drums and brakes for potential problems. That is when I think I have found the problem. I tried to turn the rear axle by hand, (out of park with the brake off of coarse, and both wheels off the ground) it turned but with very high resistance, much more than it should have!! With both wheels off the ground, we turned the left wheel and in normal cases the opposite (right) wheel should turn in the opposite direction however in this case, mine are turning in the same direction. I suspect that the Limited Slip Clutch in the rear end has some serious issues.

Ironically, I believe since there is such high resistance, I think it is also causing my transmission to delay seriously from 2nd to 3rd gear. Like it would if it was pulling a trailer uphill.

Is this easy to rebuild and if so then where can I get a diagram on how to do so? Is there one online or should I get the service manual? Any other comments and/or suggestions are welcome.

 

Is it hard to turn forward and backward, because it is normal for it to be hard to turn backward, it should turn fairly easy to turn forward, if it is not, then you probably have a trans problem, also have you checked the adjsutment on the rear brakes, or checked the drums for out of round?

 

Well, I agree it should turn fairly easy. The issue lies I think in the axel because when you have both back wheels off the ground with the tires and drums removed (to assure that there is no resistance being applied by the brakes) and the Transmission in neutral the axel is very hard to turn, you have to really put some force into it to get it to turn.

In my experience in non-limited slip rear ends. When you have the axel in this same situation with no brakes, off the ground etc, it should turn fairly easy. Like if you turn one side the other should turn in the opposite direction pretty easy, unlike here where when you turn one side the other side turns with it (like it is a posotrac rear end or something.

However, I agree with what you said about the different in resistance depending on which way you turn it, but it is more than I would expect. What really bothers me is the simulated posotrac, its almost like the limited slip is locked in or something.

 

Posi traction is a LS that is just what chevy calls a LS. Just thought you might want to know that. It does however sound like warped rotors to me and you will not be able to know that just by looking at the rotors in order to see if theya re warped you need to hook up a runout gauge to them. Your LS could be locked though but it should not cause a vibration when stopping which leads me to believ you have warped Rotors.


Richard D.

 

Mark the driveshaft and then disconnect it. This will help you to see if the drag is in the transmisison or the rear end. If you have LS it will be tougher to turn with the driveshaft as you are also turning the trasnmissions output shaft and some internals. Whereas, an open diff just has the opposite tire spin loosely in the opposite direction. If it is still tight after removing the driveshaft, you may have a bearing going out in the rear end. The vibration though, sounds like warped rotors.
Brian

 

Good job wamsleyb you said what i was trying to figure out I knew with the driveshaft still connected he was getting the resistence of the tranny but was trying to figure aaway for him to do it otherwise. Thanks for figureing it out for me.

Richard D.

 

Thanks to all of you that have posted a reply. I will try your suggestions. I hope to do this tomorrow. Depending on if it's a nice day or not. I will be sure to post my results so you can see how it goes. Thanks Again!!