Torque Bind?
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From: Newport, RI
Torque Bind?
I recently purchased a used 2001 F250 Super Crew 4x4. I did not notice at first but soon heard and felt a bump coming from the front end whenever I make a tight turn, left or right. It bumps when I back up in a tight turn also. When I bought the truck I replaced all four tires with new Michelin LTX M/S 75R16 which I was told was the standard size tire that originally came on the truck. At first I thought the bumping sensation was the new tires gripping the road in a tight turn because I only feel the bump when I turn on hard, dry pavement.
I young mechanic from my local Ford dealer test drove the truck and told me the bumping was not uncommon to 4x4s. He said it was Torque Bind and that many of the newer 250s and 350s do the same thing.
Is this true or do I have a problem that needs further attention?
I young mechanic from my local Ford dealer test drove the truck and told me the bumping was not uncommon to 4x4s. He said it was Torque Bind and that many of the newer 250s and 350s do the same thing.
Is this true or do I have a problem that needs further attention?
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From: Washington State
Yeah...you'd get "torque bind" if the hubs were locked. Are you sure they're BOTH unlocked? Reach behind the wheel and try and turn the axle shaft. Both sides should spin freely when unlocked. 
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From: Stephensville WI
If you're hubs are unlocked but you still feel this binding, chances are high that your hubs are not unlocking. They probably need to be replaced, but you'll have to tear things down to check.
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From: Wake Forest, NC
There is also the possibility of a bad ball joint shifting in the turns. Torque bind as mentioned would only be an issue with the axles locked and the transfer case in gear. Otherwise, the shaft will spin and the front will differentiate. As long as the u joints are good, you shouldn't have a problem.
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From: Stephensville WI
Originally Posted by aldridgec
Torque bind as mentioned would only be an issue with the axles locked and the transfer case in gear..
No, you get the bind when the hubs are locked, you are turning at or near as sharp as the truck will turn and moving forward. The transfer case does not have to be locked for the binding (almost a slow hopping motion) to happen.
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From: Newport, RI
Thanks for the feedback. "Torque bind" may have been overstated by the mechanic. I checked both front axle shafts behind the wheels and they turn freely. Hubs are unlocked and 4X4 HI/Lo funtion works normally.
I guess I'll have the ball joints and U joints checked next. Hard to believe that's gonna be a problem because the guy who owned the truck before me took extremely good care of the vehicle and kept very detailed records of everything. He mentioned nothing to me about a "bump" in the front end which is very slight - almost unnoticeable if the driver is not waiting for it to happen. I'm not an experienced 4x4 driver so maybe this is really nothing to worry about.
I guess I'll have the ball joints and U joints checked next. Hard to believe that's gonna be a problem because the guy who owned the truck before me took extremely good care of the vehicle and kept very detailed records of everything. He mentioned nothing to me about a "bump" in the front end which is very slight - almost unnoticeable if the driver is not waiting for it to happen. I'm not an experienced 4x4 driver so maybe this is really nothing to worry about.
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Originally Posted by redford
No, you get the bind when the hubs are locked, you are turning at or near as sharp as the truck will turn and moving forward. The transfer case does not have to be locked for the binding (almost a slow hopping motion) to happen.
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From: Peoria, IL
The wheel is still locked to the axle if the hubs are locked. So when you turn the front wheels hard one way the U joint is put at an extreme angle. When a U joint is at an exteme angle it will have peaks and valleys of high and low stress.
Go try it with your tools. Put a socket on a U joint, and then use an extension from the U joint to the ratchet. Vary the angle of the extension in relationship to the bolt you are loosening/tightening. As you approach a more extreme angle between the two you will begin to notice a difference in the amount of force it takes to turn the ratchet. Eventually when the angle is great enough you won't be able to tun the ratchet at all, unless you let the angle change. The same thing is happening with your axle/hubs.
Go try it with your tools. Put a socket on a U joint, and then use an extension from the U joint to the ratchet. Vary the angle of the extension in relationship to the bolt you are loosening/tightening. As you approach a more extreme angle between the two you will begin to notice a difference in the amount of force it takes to turn the ratchet. Eventually when the angle is great enough you won't be able to tun the ratchet at all, unless you let the angle change. The same thing is happening with your axle/hubs.
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Originally Posted by Beerstalker
The wheel is still locked to the axle if the hubs are locked. So when you turn the front wheels hard one way the U joint is put at an extreme angle. When a U joint is at an exteme angle it will have peaks and valleys of high and low stress.
But if the transfer case is unlocked, the u-joints are essentially driving zero load, in the form of the open differential of the front end. So it's hard to see how you'd notice any effect, unless the TC was locked also.
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From: Long Island USA
Does the "bump" happen over and over again with the wheel turned to one side, or just once?
If it's "bump bump bump" - it's the hubs are still locked - or even worse, the needle bearing (inner spindle bearing) where the axle stub rides is so bad that the axle is locked up to the wheel bearing.
If it's a single bump, I'd start looking for loose components.
I know the track bar is known to come loose and needs a re-torque, at least on the early SD's.
If it's "bump bump bump" - it's the hubs are still locked - or even worse, the needle bearing (inner spindle bearing) where the axle stub rides is so bad that the axle is locked up to the wheel bearing.
If it's a single bump, I'd start looking for loose components.
I know the track bar is known to come loose and needs a re-torque, at least on the early SD's.
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From: redmond WA usa
Originally Posted by KelVarnson
True, if you drive one side (the wheel) with a constant velocity, you will get a sinusoidal variation in speed on the output side of the joint (the differential), and the amplitude of that variation wil increase as the angle does.
But if the transfer case is unlocked, the u-joints are essentially driving zero load, in the form of the open differential of the front end. So it's hard to see how you'd notice any effect, unless the TC was locked also.
But if the transfer case is unlocked, the u-joints are essentially driving zero load, in the form of the open differential of the front end. So it's hard to see how you'd notice any effect, unless the TC was locked also.
U-joints DO NOT provide anything close to a linear rotational function except when the driveline is "straight", not operating at an angle. CV joints are somewhat, quite a bit, better, but will still exhibit this trait, especially at high angles of operation.
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From: Stephensville WI
To experience this for yourself, lock your hubs without engaging the transfer case, crank your steering wheel to full lock left or right and drive forward slowly.
You'll feel the binding of the U-joints on the drive axle.
You'll feel the binding of the U-joints on the drive axle.
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From: Newport, RI
It's a bump, bump, bump all the time, in all tight turns (I'd say 90 degrees or more) left or right. In a non-accelerating turn, like at idle speed, I can't feel it, but at a slightly accelerated tight turn the bump, bump, bump is there and is worse the faster the turn.
Sounds like the hubs are still locked for some reason. I'll have that checked. thanks
Sounds like the hubs are still locked for some reason. I'll have that checked. thanks