periodic thumping in drivetrain?

[roadventure]

I have a 1999 4x4 Explorer Sport with about 108,000 miles on it currently. Today it was a little snowy again and I was reminded of something that seems to happen when the roads are a little slippery.

I am driving along at a constant speed and will feel a pretty firm THUMP somewhere in the drivetrain. It feels like if could be in the rear, but I am really not sure. It almost seems like there is some build up of tension when there is not perfect traction that will suddenly release and make a thumping sound. The transmission switch is set to "AUTO".

Have any of ever experienced anything like this?

I'd appreciate any ideas about what this might be and also if it is something common in the Explorer.

 

[corkey]

all the tires the same size ?

 

[roadventure]

tires

Yes, all the tires are the same brand, model and size. Also, the tire pressure is within 2 psi on all four tires.

I think I see where you are going with your question though as different O.D. tires could cause the driveline to bind, right?

But, in my case the tires are all the same.

 

[mr2fix2it]

possibly dirty speed sensor in transfer case to fix remove speed sensors clean and drain and refill fluid to check if this is it put into 4x4 high when problem happens and see if it goes away if tires are not all matched disregard all this info. Tires MUST match!

 

[mr2fix2it]

Also there may be a computer update for this problem not sure if it was only on the 98

 

[roadventure]

speed sensor

A dirty/faulty speed sensor sounds like a good suggestion as this thump only seems to occur when the road traction is not good (i.e.: some snow on roads, heavy rain, and very wet roads).

Thanks for the info!

 

[shakin]

A dirty/faulty speed sensor sounds like a good suggestion as this thump only seems to occur when the road traction is not good (i.e.: some snow on roads, heavy rain, and very wet roads).

Thanks for the info!

I have an issue a lot like this. Have you cleaned the sensor yet?

 

[wjz]

Would anyone have a picture of where the speed sensor is in the transfer case?