Jolt at 80+ mph

[gdgiordano]

I have had a rear end moan for years now. At 80+ mph something causes the vehicle to rapidly decelerate at 80+ mph. It is accompanied by a good clunk. When I get off the highway and move from a stop all the power isn't getting to wheels, but after I complete the turn it 'clicks' back in and moves normally. All of the fluids in the DT components look good though.

What could be causing this?
Specs:
4l SOHC
1997 XLT
Control trac

 

[Robman]

Well, a bearing gone in the rear end is usually the moan..

 

[gdgiordano]

Well, a bearing gone in the rear end is usually the moan..

Could that be causing a bind that leads to the other stuff?

 

[koda2000]

Abnormal noises in the drivetrain are never a good sign. You say you've had a groaning noise in your rear diff for years. Something is definitely worn out (most likely a bearing) and has gotten worse. It will eventually lead to a complete failure. At high speed this could be really ugly. If I were you I'd fix the problem, which by now would be most easily/inexpensively done (as all the other parts are probably trash by now) by replacing the complete differential assembly with a good used one. In the meantime, keep you speed well under 80+ MPH. Personally, I won't even drive it on the highway.

 

[gdgiordano]

Will this work?

http://www.##################.com/s...n/Differential_Rebuild_Kit/1997/TMDRK335.html

OR

http://www.##################.com/s...n/Differential_Rebuild_Kit/1997/TMDRK311.html

 

[gdgiordano]

koda I sent you a message,

 

[gdgiordano]

Koda I just sent you a message it isn't letting me post the links here.

 

[XLTrunner]

Rear end moan is very common on these trucks as the rear diff pinion gears and brgs wear. Just did mine this past summer w/150K miles on it and couldn't believe how quiet it ran. Not sure about the clunk, though...unless things are really starting to bind up from excessive wear. For what it's worth, I personally don't like pushing my older vehicles to that high of speed on the highways. Just don't think it's good for an older engine/drivetrain considering the wear after so many miles. But, that's just me...and, have no evidence to support my way of thinking.

 

[gdgiordano]

I'm pretty sure it's causing a bind. The rpms only drop 100-200 when it happens. It's pretty violent. I don't think it's the motor cutting out.