Hello, I am posting this in this forum (newbie).

96 Explorer Sport 6cyl 4WD

To make a long story short, I had my tranny rebuilt at a dealer. It shifts fine but thumps intermittently. I took it back and even drove with the service manager and we could not recreate it.

I have now figured out that it only thumps on an incline, but will go away shortly after letting off the gas and then hitting the gas again. I will take the truck back in, but I was wondering if anyone has any insight to what could be loose or bad.

This has been a nightmare repair-they originally changed my speedo head when the tranny was jumping, and then claimed the mechanic who diagnosed it was quitting!

Thank You,

Lync

 

Always check or replace both u-joints when you have an intermittent thump problem. Moving the joint by hand is not enough - you must disassemble it and inspect or replace it completely. I had a ford dealership troubleshoot the same problem under warranty and they could not find it. I found one of the u-joints had no bearings inside and every once in a while when in the right position and I started to go forward it would thump. Try this first then go from there...

 

Thanks. The odd thing about this was that I never had the problem until the transmission was rebuilt. $1200 later, one problem is fixed but another has developed. The worst thing is that I am unable to always "create" the thump. It does seem to happen after an incline and not while the truck is cold.


Lync

 

I have realized that if you switch the Explorer into 4wd auto, the thump goes away and will not occur. In 2wd is where it happens.

Ideas?

 

bump

 

U joints.

 

Thanks to wick246 and Talyn for their help. I do indeed think it is the U-joints also. Hopefully I can change them myself.

 

I had a problem when I bought mine used. It had only a pint of nasty fluid in the transfer case when it was supposed to have 1 3/4 quarts. The clutches would grab once in a while because they weren't in a fluid bath.

 

You can also get a thump from a bad pinion bearing, mine thumps when i put it in Rev. facing downhill (weird)im in the process of changing mine and its a nightmare

 

Are your pinion bearings so bad they are loose or just ratchety / not smooth turning? Just curious...


@ Lync - let us know what you find to add to the knowledge base.

 

They are really bad, leaking around the pinion seal loud and really loose. Im not sure how to change them, Im worried about the crush sleeve and getting the yoke to tight but i cant find any procedures for my truck.

 

What is your truck and which differential is it - front or rear? Maybe I can find some info that would help...

 

A friend of mine works for Infinity, and I can bring my truck there to lift it and take a look.

Would it be possible for the U joints to not be tight? Are they ever loosened for any procedures?

It just seems odd to me that they were fine, but since I had my tires rotated and my tranny rebuilt they thump.

They stop thumping if I put it in 4wd though.

Thanks.

 

Can U-joints be loose? As in, are they something that can be tightened? The thump only happens on acceleration like that flop back into place.

Lync (annoying newbie)

I still am waiting to get to the garage on a weekend, but this forum is very informative and I just am hoping that this is the case.

 

Do a search on "clunk" I think you will find the real problem. Chances are it's not the u-joints but the "yoke".