Weird bumping at full lock with 4wd

[Ewhitaker0020]

Does anybody know what would be causing this weird thing my truck does at full steering lock when I'm in 4wd? It's like I'm driving over something every time the wheel makes a full revolution. The truck doesn't do this when in 2wd so I know it's because I'm in 4wd.

I'm assuming 4wd is just weird when making that tight of a turn. But it's pretty extreme so I was wondering if this was a classic symptom of something being broken. It happens in the front right when when making a hard right turn

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[hirschdalechevy]

I was thinking maybe a front axle joint could be warn out.

Or a hub problem

 

[Keith Seymore]

On dry pavement? That would be expected. (We always called it "crabbing").

Or are you saying it's doing it on snow/dirt or some other deformable surface?

K

 

[Ewhitaker0020]

On dry pavement? That would be expected. (We always called it "crabbing").

Or are you saying it's doing it on snow/dirt or some other deformable surface?

K

I wouldn't say dry pavement, but it was on the edge of a partially snowy parking lot. Either way it would have been wet. And crabbing is a very good description

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[Ewhitaker0020]

I was thinking maybe a front axle joint could be warn out.

Or a hub problem

It could be. Wouldn't surprise me a bit if it's the u joint in the front axle. It was pretty rough looking the last time I looked at it

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[gmbellew]

get in some grass and try it again. I could see the tires grabbing on partially covered pavement.

 

[Ewhitaker0020]

get in some grass and try it again. I could see the tires grabbing on partially covered pavement.

I just tried it in the snow, it still happens

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[Blue Ox]

At full lock they have a tendency to hop from the extreme angle of the U-joints at the knuckles. If it's not accompanied by a noise it's probably normal. Sometimes a little throttle helps, but it will still do it to some extent.

 

[shiftpro]

A U joint in the axle is seizing.

I try to never turn to full lock when my 4x is locked in. When those knuckles are turned the joint opens up and is at it's weakest position.

Now is the time for you to get the front end rebuilt. Both U joints should be done and while it's apart wheel bearings and you might even want to rebuild your locking hubs.
If you don't get those U joint fixed there will be breakage and most likely with destroy the knuckle and cost ^^^ not good.

 

[Bextreme04]

Here is a pretty good video on how universal joints work.

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The driveshaft utilizes two universal joints to act as a constant velocity drive. The front driveshaft don't have two joints and therefore have a fluctuating velocity on the output shafts. The harder the wheel is turned, the greater the velocity cycling will be. You also can end up in some situations where the joint can bind at too much of an angle and can cause it to break. As a general rule I try to avoid going anywhere near full lock in 4wd.

 

[Ewhitaker0020]

A U joint in the axle is seizing.

I try to never turn to full lock when my 4x is locked in. When those knuckles are turned the joint opens up and is at it's weakest position.

Now is the time for you to get the front end rebuilt. Both U joints should be done and while it's apart wheel bearings and you might even want to rebuild your locking hubs.
If you don't get those U joint fixed there will be breakage and most likely with destroy the knuckle and cost ^^^ not good.

I still have my factory automatic hubs. So I'll have to do some research on how to rebuild them as they still work really well.

Thanks for the input. This truck could definitely use a rebuild of the front end.

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[Ewhitaker0020]

Here is a pretty good video on how universal joints work.

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.

The driveshaft utilizes two universal joints to act as a constant velocity drive. The front driveshaft don't have two joints and therefore have a fluctuating velocity on the output shafts. The harder the wheel is turned, the greater the velocity cycling will be. You also can end up in some situations where the joint can bind at too much of an angle and can cause it to break. As a general rule I try to avoid going anywhere near full lock in 4wd.

But the turning radius is so awful in 4wd. You're correct though. I should probably be more careful

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[shiftpro]

But the turning radius is so awful in 4wd. You're correct though. I should probably be more careful

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When I'm on tight logging roads or skid trails my hand is almost always on the TC lever. I'm in and out of 4x all the time. Those switchbacks on logging
roads for example.
But I use 4x on these roads all the time, even if it seems I don't need the traction. There's so much washboard and chiggers, it's easier on the truck,
tires AND the road.

 

[WebMonkey]

When I'm on tight logging roads or skid trails my hand is almost always on the TC lever. I'm in and out of 4x all the time. Those switchbacks on logging
roads for example.
But I use 4x on these roads all the time, even if it seems I don't need the traction. There's so much washboard and chiggers, it's easier on the truck,
tires AND the road.

sorry for straying off topic

i know what washboard roads are.
what are chiggers?

here in missouri, chiggers are biting insects that make your legs itch like the dickens.

 

[shiftpro]

sorry for straying off topic

i know what washboard roads are.
what are chiggers?

here in missouri, chiggers are biting insects that make your legs itch like the dickens.

Yes we have the little bastard bugs called chiggers. But on logging roads old loggers call protruding rocks 'chiggers'. A lesson in political correctness here.. By the late 80's the logging industry was effected by PC. They used to call protruding rocks '****** heads'. Even BC Forestry's road prescription called them NH's... when building a logging road it had to conform to the standards listed on the prescription, which was 'how you do it' part of the contract. There was limited count of protruding rocks allowed... and the techs would count them to verify compliance. Well the loggers then started calling them.... protruding NG's haha! Eventually the slang term became 'chiggers'.
Gotta love them loggers! Even though we wear women's undies under our bucking pants.

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