Wheel hop

[James Morse]

If you use 4x4 on dry pavement you get wheel hop in front. Shouldn't use on dry pavement, etc.
Dana 35 is an open differential, right? So why the wheel hop, it should just act like a regular open diff.

Front and rear driveshafts are turning identical, but, rear has LSD, it's not locked, and seems like the front/rear diff's should operate independently.

So what causes the wheel hop? It's like saying the fronts have a locked diff but they don't. I'm missing something.

 

[Ranger850]

Tires can also cause wheel hop. Sidewall rotates before the tread moves, then the tread jumps forward to catch up to the sidewall.

 

[James Morse]

Well, ok, but if you're not in 4x4 you don't get that, at least not to the noticeable degree you do in 4x4.

I guess they sell LSD for the Dana 35 but even if I had that, which I'm pretty sure I do not, it still shouldn't cause wheel hop, that's what diff's are for.

 

[Blmpkn]

Wheel hop is a different animal than the binding that happens with 4x4 on pavement.

The binding comes from the front and rear wheels wanting to spin different speeds but not allowed to because they're locked via the trade.

Wheel hop happens because the front/rear axle is twisting back and forth on the same axis that the tires are spinning. The leaf springs get sort of load up and get 'twisted' when there's traction.. and then when there isn't traction they'll unload real quick and cause a hop. It's not exactly great for the leafs, shafts.. anything. Traction bars are a cheap solution, going to a linked suspension setup and ditching the leafs is a more extreme solution.

 

[Blmpkn]

THIS is wheel hop lol.

 

[James Morse]

Wheel hop from axle wrap then. Nice!

OK, binding then it is. I get that the f/r driveshafts are turning the same rate so the ring/pinions are turning the same rate. What I don't get is why the differences aren't taken up in the respective differentials.
Are you saying the way the diff's operate is they are essentially locked together and one must operate the same as the other? In other words, it's not the left/right that are locked it's front/rear per side?

I guess what I don't get is why they are bound together, it seems like the two diff's ought to take up the differences, that's their job.
The rears are still free to slip (i.e., act like mostly like an open diff) if required so why can't they adjust for whatever is going on up front?

In a thought experiment, if you disconnected the rear drive shaft and had only front wheel drive, would it still happen?

 

[97RangerXLT]

you definitely do not want to use 4x4 on dry pavement for any extended length of time. the binding will also occurs in the transfer case itself, and if that grenades, it is expensive to rebuild/ replace lol

AJ

 

[Blmpkn]

Wheel hop from axle wrap then. Nice!

OK, binding then it is. I get that the f/r driveshafts are turning the same rate so the ring/pinions are turning the same rate. What I don't get is why the differences aren't taken up in the respective differentials.
Are you saying the way the diff's operate is they are essentially locked together and one must operate the same as the other? In other words, it's not the left/right that are locked it's front/rear per side?

I guess what I don't get is why they are bound together, it seems like the two diff's ought to take up the differences, that's their job.
The rears are still free to slip (i.e., act like mostly like an open diff) if required so why can't they adjust for whatever is going on up front?

In a thought experiment, if you disconnected the rear drive shaft and had only front wheel drive, would it still happen?

It's not just the right and left wheels that see different speeds in a turn.. if your making a turn ALL the wheels are turning at different rates.. so the front and rear shafts are wanting to be spinning at different rates as well. This is why an awd system with a center diff doesnt bind.

 

[scotts90ranger]

To not have binding on a hard surface in 4x4 you would have to have it steer like a center articulated tractor or loader, then both inside tires are turning the same speed and both outside tires are going the same speed (or close enough at loader speeds...), instead of all 4 tires going different speeds (all tires have a different radius in the turn so they are going different speeds)

 

[97RangerXLT]

It's not just the right and left wheels that see different speeds in a turn.. if your making a turn ALL the wheels are turning at different rates.. so the front and rear shafts are wanting to be spinning at different rates as well. This is why an awd system with a center diff doesnt bind.

and to expand on this, basically your 4 wheels are all turning at the same speed, which is what causes the binding/ hop, as Blmpkn mentioned above, all 4 wheels will need to turn at different speeds during the turn, and if they cant they will bind/ hop. an AWD has a "viscous couple" in the transfer case (or another clutch system) that allows the drive shafts to slip or turn at different speeds so the transfer case does not go Boom and rain metal confetti all over the road.

AJ

 

[00t444e]

Wheel hop from axle wrap then. Nice!

OK, binding then it is. I get that the f/r driveshafts are turning the same rate so the ring/pinions are turning the same rate. What I don't get is why the differences aren't taken up in the respective differentials.
Are you saying the way the diff's operate is they are essentially locked together and one must operate the same as the other? In other words, it's not the left/right that are locked it's front/rear per side?

I guess what I don't get is why they are bound together, it seems like the two diff's ought to take up the differences, that's their job.
The rears are still free to slip (i.e., act like mostly like an open diff) if required so why can't they adjust for whatever is going on up front?

In a thought experiment, if you disconnected the rear drive shaft and had only front wheel drive, would it still happen?

It is because there is no differential in the transfer case, when making a turn the front axle travels a further distance than the rear but since the front and rear driveshafts are locked together by the transfer case that can't happen so you get binding, the differentials in the axles only account for the speed difference between the two wheels on that axle but not between the two axles. Full time 4x4 or AWD transfer cases do have a differential in them so you don't get binding when turning. Yes you can remove the rear driveshaft and drive with just the front axle in 4x4 and not have any binding, it would be the same as a FWD car at that point.

 

[don4331]

Picture is worth 1k words

As you can see the front wheels turn a larger radius than their rear counter parts. So, you either need a center differential or loose material on road or things bind.

Actually, even driving straight ahead there is slight difference in tire size due to the difference in weigh on the wheels/air pressure in tires/manufacturing differences to cause binding.​

 

[pjtoledo]

 

[Josh B]

Picture is worth 1k words

View attachment 86583
As you can see the front wheels turn a larger radius than their rear counter parts. So, you either need a center differential or loose material on road or things bind.

Actually, even driving straight ahead there is slight difference in tire size due to the difference in weigh on the wheels/air pressure in tires/manufacturing differences to cause binding.​

This is what I was speaking of on the other thread.
Also if 4WD is engaged how can the differentials be independent while they are locked together via the TC

 

[pjtoledo]

amateur crop circles?