Front wheel drive binding

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kmac5130

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I had my rear driveshaft out yesterday while painting it and replacing its u-joints. I went for a drive in 4HI, so the jeep was really just operating in front wheel drive. As expected, there were some handling differences, such as the front wanting to dart around a bit while driving on bumpy roads. There was also less traction while accelerating on wet roads because the weight of the jeep shifts off the front tires while speeding up.

Anyway, I also noticed that the front wheels were binding up significantly while making tighter turns. I avoided very tight turns so that I wouldn't stress the front axles, but even a right hand turn at a 4 way stop was enough to feel some binding and tire slippage/skidding. It felt exactly identical and as extreme as if both driveshafts were in and I had 4HI engaged like normal 4WD. I was always under the impression that the binding while steering in 4 wheel drive was exclusively because the front and rear tires under power were rotating different distances around turns. I guess I am just curious for an explanation as to what was going on. I have a rubicon, so was a limited slip differential causing this to happen? I have no related mechanical issues otherwise, so it was not faulty front axle u-joints binding up.
 
Are you the original owner?

Have you ever had the front diff cover off?

Do you know if your front locker is working?

My wild theory is the front locker failed and was replaced with a spool.

Let's see what everyone else thinks.

I'd jack up both front wheels and spin a tire. If they both go in the same direction you've got a locker engaged.

-Mac
 
The front rubi locker doesn't have a limited slip. What does it do when you jack up the front axle and spin a tire?

What about with the tcase in 4x4?

Turn the wheel all the way and repeat?

Tires should rotate in opposite directions when in 4x4.

Excessive binding for any of those actions?
 
I am not the original owner.

I have had the front diff cover off and it is all stock as far as I'm aware of. I had the carrier out to replace the inner seals recently and everything was identical to pictures of oem carriers.

The air lockers are original and still work. They were not engaged when I was experiencing the binding, and they couldn't have been engaged since I was in 4HI.

It is not a spool and drives completely normally without any binding whatsoever, except when in 4HI. Some binding is expected when both driveshafts are in, but I was surprised that it happened with only the front shaft in.

When in 2HI, I know that when either the front or rear axle is jacked up, spinning a tire on one side spins the opposing tire in the opposite direction. I'll see what happens when I do that in 4HI. I can't think of why that would change the outcome but I will definitely test it out. And I'll try that with the wheels turned, then I'll report back.
 
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kmac5130 said:
I am not the original owner.

I have had the front diff cover off and it is all stock as far as I'm aware of. I had the carrier out to replace the inner seals recently and everything was identical to pictures of oem carriers.

The air lockers are original and still work. They were not engaged when I was experiencing the binding, and they couldn't have been engaged since I was in 4HI.

It is not a spool and drives completely normally without any binding whatsoever, except when in 4HI. Some binding is expected when both driveshafts are in, but I was surprised that it happened with only the front shaft in.

When in 2HI, I know that when either the front or rear axle is jacked up, spinning a tire on one side spins the opposing tire in the opposite direction. I'll see what happens when I do that in 4HI. I can't think of why that would change the outcome but I will definitely test it out. And I'll try that with the wheels turned, then I'll report back.
Click to expand...

I mentioned 4hi because my front rubi spiders are kinda tight and will sometimes rotate both tires the same direction. Figured I'd try to eliminate that tendency.
 
I jacked up the front axle and spun a tire while in 2HI, resulting in the other tire wanting to spin in the opposite direction. It didn't really spin much though because the front driveshaft was not engaged in the transfer case, so the driveshaft spun instead. However, like I said, the other tire wanted to spin the opposite direction, so that was normal.

I repeated while in 4HI, and then the opposite tire was actively spinning in the opposite direction. I also repeated this with the steering turned fully to the right and then to the left. Both resulted in the opposite tire spinning in the opposite direction with no binding.

After jacking up the rear axle, the tires also wanted to spin in opposite directions, both while in 2HI and 4HI.

So basically, everything was behaving as you would expect a normal stock rubicon to behave. There was never any problem to solve, I was just curious as to what caused the binding. With the rear driveshaft back in everything is normal again for driving around. I think the binding in front wheel drive might be a combination of the short wheelbase of the TJ allowing very tight turns, and my 35" tires. I don't really know but it is interesting. Thanks for the replies.
 
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kmac5130 said:
I jacked up the front axle and spun a tire while in 2HI, resulting in the other tire wanting to spin in the opposite direction. It didn't really spin much though because the front driveshaft was not engaged in the transfer case, so the driveshaft spun instead. However, like I said, the other tire wanted to spin the opposite direction, so that was normal.

I repeated while in 4HI, and then the opposite tire was actively spinning in the opposite direction. I also repeated this with the steering turned fully to the right and then to the left. Both resulted in the opposite tire spinning in the opposite direction with no binding.

After jacking up the rear axle, the tires also wanted to spin in opposite directions, both while in 2HI and 4HI.

So basically, everything was behaving as you would expect a normal stock rubicon to behave. There was never any problem to solve, I was just curious as to what caused the binding. With the rear driveshaft back in everything is normal again for driving around. I think the binding in front wheel drive might be a combination of the short wheelbase of the TJ allowing very tight turns, and my 35" tires. I don't really know but it is interesting. Thanks for the replies.
Click to expand...

Did you do any honda style burnouts while you had the chance?
 
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I think you're just feeling fwd with u joints instead of cv joints.

U joints, when at an angle, don't have a constant speed output, it speeds up and slows down through a single rotation. They'll still produce a lurching, binding feeling in sharp turns even with an open diff.
 
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When turning sharp, the inside tire runs a smaller circle than the outside tire. Not only do you need differential action, but also the inside tire should steer sharper. Some steering geometries do that, but I don't think our TJs do. I could be wrong.
 
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OldBuzzard said:
When turning sharp, the inside tire runs a smaller circle than the outside tire. Not only do you need differential action, but also the inside tire should steer sharper. Some steering geometries do that, but I don't think our TJs do. I could be wrong.
Click to expand...

You're talking about Ackermann but I'm under the impression the TJ does.

I really do think it's just the variation in output vs input speed of the u joints. Same reason we line our pinion up with the driveshaft to avoid vibrations.
 
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freedom_in_4low said:
You're talking about Ackermann but I'm under the impression the TJ does.

I really do think it's just the variation in output vs input speed of the u joints. Same reason we line our pinion up with the driveshaft to avoid vibrations.
Click to expand...

I didn't know about ackermann steering but that does make total sense that you would need that. And yeah it does seem like the TJ accounts for that after some quick searching. Also I think you are probably right about the u-joints causing the binding. I guess it would make sense that they would only behave that way while being powered. It also felt exactly like a rhythmic skidding/binding, since the outer axle shaft would be speeding up/slowing (repeatedly) very quickly as the tire turns while the Jeep is making a turn.

And that also answers my confusion about why other cars with front wheel drive do not have the binding. They are all using CV axles up front. Interesting. Thanks guys
 
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kmac5130 said:
I guess it would make sense that they would only behave that way while being powered.
Click to expand...

Right. You basically have 3 "variables" (the speed of each of the axle shafts and the front driveshaft). You can choose what two of them are but the third one will be a function of the other two.

In 2wd the wheels are the two inputs and the driveshaft does what it will, and is free to, so any oddities in the axle shaft speeds resulting from u joints will go unnoticed.

In 4wd you're dictating the driveshaft speed and the axle shaft on the side of wheel with the most grip, and then the wheel with the least grip does what it will, and that may involve some tire slip. Whether or not you can feel that slip as it manifests in the chassis and steering depends on how much resistance there is to slipping on the surface you happen to be on. On pavement you'll feel it.
 
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freedom_in_4low said:
Right. You basically have 3 "variables" (the speed of each of the axle shafts and the front driveshaft). You can choose what two of them are but the third one will be a function of the other two.

In 2wd the wheels are the two inputs and the driveshaft does what it will, and is free to, so any oddities in the axle shaft speeds resulting from u joints will go unnoticed.

In 4wd you're dictating the driveshaft speed and the axle shaft on the side of wheel with the most grip, and then the wheel with the least grip does what it will, and that may involve some tire slip. Whether or not you can feel that slip as it manifests in the chassis and steering depends on how much resistance there is to slipping on the surface you happen to be on. On pavement you'll feel it.
Click to expand...

100%. Makes sense and a good explanation.
 
freedom_in_4low said:
I think you're just feeling fwd with u joints instead of cv joints.

U joints, when at an angle, don't have a constant speed output, it speeds up and slows down through a single rotation. They'll still produce a lurching, binding feeling in sharp turns even with an open diff.
Click to expand...

^^^ THIS ^^^^^ ;)
 
I recently had my rear drive shaft out because of a failing U-joint and drove the jeep for a couple hundred of miles in 4HI, front wheel drive only. It did exactly as you describe. It felt like it was binding in turns but I guess that is just due to the non-constant speed of universal joints. It also behaved very badly in loose gravel or sand. When one wheel lost traction it would spin and hop violently. It almost seemed like something was broken, a shock, a ball joint, or something. But everything checks out. I have never experienced this in 4WD.
 
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