Thumping From 4x4 Drive Line

[lmarkie74]

With moderate to heavy acceleration between 40 and 50 mph, I get a thumping noise and feeling from my 4x4. Either front axle or transfer case. It goes away when I let off the throttle.

I disconnected the 4x4 control module behind the glove box, the noise and feeling go away. Transmission shifts perfect.. So problem lies in the 4x4 system.

 

[Perana]

check rolling diameter/pressure(less pressure in a tyre = less rolling diameter) of the tyres.....does not take too much of a difference to make the transfer case pitch a fit.....if no joy with that....check abs senders....

 

[lmarkie74]

check rolling diameter/pressure(less pressure in a tyre = less rolling diameter) of the tyres.....does not take too much of a difference to make the transfer case pitch a fit.....if no joy with that....check abs senders....

How do you check ABS senders? Maybe wheel bearing?

 

[Tech By Trade]

Have a real close look at the front u joint

 

[IIGood]

check rolling diameter/pressure(less pressure in a tyre = less rolling diameter) of the tyres.....does not take too much of a difference to make the transfer case pitch a fit.....if no joy with that....check abs senders....

The tires are certainly a good place to start. When I first bought my current '03 XLT, the front tires were one brand and the rears were another. While they were the same size all around, the fronts were more worn than the rears. So I would also get a "bucking" feeling under hard acceleration. I bought 4 new tires and that took care of it.

 

[lmarkie74]

Have a real close look at the front u joint

Changed the front U-Joint tonight. Brand new. Didn't get rid of the "bucking" problem. Thinking about putting a switch to the 4 wheel drive module. Don't need 4x4 Automatic all the time.

 

[IIGood]

Changed the front U-Joint tonight. Brand new. Didn't get rid of the "bucking" problem. Thinking about putting a switch to the 4 wheel drive module. Don't need 4x4 Automatic all the time.

When the vehicle is in 4X4 AUTO, 4-wheel-drive only kicks in when it's needed...basically if the system detects enough slippage to warrant 4WD, it will engage 4WD. When you're just driving around, it's in 2WD mode.

What do the tires/treads look like?

 

[Tech By Trade]

Yep, next up is tires, all 4, same age, size and brand or they may cause issues. After that things get expensive.

 

[lmarkie74]

When the vehicle is in 4X4 AUTO, 4-wheel-drive only kicks in when it's needed...basically if the system detects enough slippage to warrant 4WD, it will engage 4WD. When you're just driving around, it's in 2WD mode.

What do the tires/treads look like?

All same size tires. 230/70R16. Front 2 are Toyo and the back 2 are Michelin. Might have around 3/16" of tread left on each tire. You can see the top of Lincoln's head. Maybe a couple thousand miles left. I bought this car about 4 months ago. Not the tires I put on. It does need a set of new tires. Just seems ridiculous that the 4WD system is that picky.

 

[IIGood]

All same size tires. 230/70R16. Front 2 are Toyo and the back 2 are Michelin. Might have around 3/16" of tread left on each tire. You can see the top of Lincoln's head. Maybe a couple thousand miles left. I bought this car about 4 months ago. Not the tires I put on. It does need a set of new tires. Just seems ridiculous that the 4WD system is that picky.

Yep...I'd bet that's it. See my prior post about the tire difference I had...had Firestones up front, BFGoodrich on the back. The BFGs were newer and the Firestones were practically bald. About a good 3/4" difference in overall diameter between the two. Once I got 4 new BFGs on there, the thumping/bucking stopped.

Sometimes the bucking would get real bad, so I'd check the tire pressures up front...the passenger front tire would usually be pretty low by about 10 PSI. The driver side wasn't as bad...maybe 5 PSI low.

I kept reading and hearing that if the tires read the same size, it shouldn't make a difference. But with the tread levels the way they were, there was a difference. Also the low pressures made it worse.

 

[IPcamper]

The 4WD system is fairly "picky". Mismatched tire are a sure way to get the bucking behavior. Question, when was the transfer case fluid changed last? When my 03 XLT was around 150,000 miles, the tires would buck on tight turns ( parking garages ) and the 4WD would engage. The tires were matched. So I changed the fluid in the transfer case and the 4WD started to behave itself. Changing the rear limited slip differential fluid helped as well.

 

[Tech By Trade]

Its the tires, get a match set.

 

[lmarkie74]

Well..........it turned out to be the tires on my explorer. I had previously stated that the front tires and the rear tires were a different brand. Turns out also the the right rear was a 235/65/R16 tire and the rest of them were what they were suppose to be. 235/70/R16.
4 same brand and size did the trick. Thanks everyone.

Now on to my rebuilt transmission problem.

 

[IIGood]

Well..........it turned out to be the tires on my explorer. I had previously stated that the front tires and the rear tires were a different brand. Turns out also the the right rear was a 235/65/R16 tire and the rest of them were what they were suppose to be. 235/70/R16.
4 same brand and size did the trick. Thanks everyone.

Oh wow, I'll bet that lone 235/65 tire was the main culprit. Glad you got it easily squared away.

Good luck with the transmission!

 

[doug625]

Well..........it turned out to be the tires on my explorer. I had previously stated that the front tires and the rear tires were a different brand. Turns out also the the right rear was a 235/65/R16 tire and the rest of them were what they were suppose to be. 235/70/R16.
4 same brand and size did the trick. Thanks everyone.

Now on to my rebuilt transmission problem.

Yep, that 65 series has a smaller diameter so it would have been turning faster than the other 3, just like if it was spinning on ice according to the module.