Rear wheel lug issue

[The Last Cowboy]

I'm surprised that you didn't hear clunks, or feel vibrations long before they broke.

You better check the torque on all of your others wheels lug nuts. And since you have aftermarket wheels, make sure you have the correct lug nuts. Most aftermarket wheels aren't designed to use the OEM lug nuts, even when torqued to spec, they will come loose, and/or break the lug nuts.

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[Old Dogger]

Whoever installed your new tires, either over torqued the lug nuts, or they left them loose. But most likely over torqued them

 

[GATORB8]

Ok, but if both receive the same amount of torque they should both have the same rotational force pushing both of them down no ?

Not down, torque "pushes" rearward against friction. When it exceeds available friction, you loose traction. First tire to lose traction spins.

Super simplified, but in real life one side or the other will have more available traction, even if just slightly.

 

[Pape]

Not down, torque "pushes" rearward against friction. When it exceeds available friction, you loose traction. First tire to lose traction spins.

Super simplified, but in real life one side or the other will have more available traction, even if just slightly.

So you are telling me the wheel that will do the burnout is dependent of where the kid sit in the back ?

 

[Vinman]

Ok, but if both receive the same amount of torque they should both have the same rotational force pushing both of them down no ?

No, due to the rotational force of the driveshaft the axle will attempt to lift one side and push down on the other resulting in the tire on the lifting side losing traction first and spinning.
If you attempted a hard launch in reverse the opposite would happen, the rotational force will attempt to lift the drivers tire and push down on the passenger tire resulting in the drivers tire losing traction first and spinning.

 

[Vinman]

So you are telling me the wheel that will do the burnout is dependent of where the kid sit in the back ?

In a sense, yes.
If you load up enough weight on the right rear corner the left tire will lose traction first and spin.

 

[The Last Cowboy]

In an open differential, the wheel with the least amount of traction will get the most power transferred to it. Doesn’t matter which side it is. However, given equal traction and a dry, level road, it will usually be the right rear that has the power applied to it.

A limited slip will begin to transfer power to both rear wheels, once the one with traction begins to slip. Some differentials are far better at it than others.

A locker, when locked, or a spool will transfer power equally to both rear wheels.

When a locker, like in Rubicons, is unlocked, it is simply an open axle.

A JL uses a BLD (Brake Lock Differential) system that uses traction control sensors to modulate the brakes in order to keep any one wheel from losing traction. The system works surprisingly well.

 

[Deen]

I'm surprised that you didn't hear clunks, or feel vibrations long before they broke.

You better check the torque on all of your others wheels lug nuts. And since you have aftermarket wheels, make sure you have the correct lug nuts. Most aftermarket wheels aren't designed to use the OEM lug nuts, even when torqued to spec, they will come loose, and/or break the lug nuts.

Every aftermarket wheel I've ever had except for my 1962 Buick has used taper seat lug nuts as does my present '21 JLUR diesel.

 

[PT's19Rubi]

Every aftermarket wheel I've ever had except for my 1962 Buick has used taper seat lug nuts as does my present '21 JLUR diesel.

If memory serves: The diameter of the lug nut's tapered portion can vary, and the taper itself can be straight sided (acorn) or arched slightly (ball). The angle of the taper can also differ. Most are 60 deg., but some are 45 deg. Makes choosing lug nuts not as straight forward as one would think.

And, I agree with others - whoever changed the tires screwed up (and I would hold their hands to the fire about it). Sometime in the mid 2010's, most automakers (including Jeep) changed from 12mm diameter lugs (90 -100 lb./ft. torque) to 14mm lugs (130 - 150 lb./ft. torque). This makes it a little harder for the guerrilla tech to over torque the lug nuts, but it can still be done. If I have a tech Not use a torque wrench in a star pattern, I go home and re-torque all lug nuts - and I Never go back to that shop.

 

[Terrymo]

I'm surprised that you didn't hear clunks, or feel vibrations long before they broke.

You better check the torque on all of your others wheels lug nuts. And since you have aftermarket wheels, make sure you have the correct lug nuts. Most aftermarket wheels aren't designed to use the OEM lug nuts, even when torqued to spec, they will come loose, and/or break the lug nuts.

Good catch, I totally missed the aftermarket wheels

 

[txj2go]

No, due to the rotational force of the driveshaft the axle will attempt to lift one side and push down on the other resulting in the tire on the lifting side losing traction first and spinning.

This is the general concept, I've seen people do it in old POS vehicles that you wouldn't think have the power to do it.
There are other factors that might have an affect- different traction in different locations, uneven roads that could unload one of the wheels.

 

[JT23JL]

In an open differential, the wheel with the least amount of traction will get the most power transferred to it. Doesn’t matter which side it is. However, given equal traction and a dry, level road, it will usually be the right rear that has the power applied to it.

This is my understanding of an open differential. In an open differential, both of the wheels are applying the same amount of torque/power. The spinning wheel is spinning because it has less traction/resistance than the non-spinning wheel.

The torque available to each wheel is limited by the wheel with the least amount of traction/resistance. If it takes 100 foot-pounds of torque to spin the wheel with the least amount of traction, then the non-spinning wheel is also going to be applying 100 foot-pounds of torque. If it only takes 5 foot-pounds of torque to spin the wheel with the least amount of traction, then the non-spinning wheel is only going to be able to apply 5 foot-pounds of torque.

 

[txj2go]

This is my understanding of an open differential. In an open differential, both of the wheels are applying the same amount of torque/power. The spinning wheel is spinning because it has less traction/resistance than the non-spinning wheel.

The torque available to each wheel is limited by the wheel with the least amount of traction/resistance. If it takes 100 foot-pounds of torque to spin the wheel with the least amount of traction, then the non-spinning wheel is also going to be applying 100 foot-pounds of torque. If it only takes 5 foot-pounds of torque to spin the wheel with the least amount of traction, then the non-spinning wheel is only going to be able to apply 5 foot-pounds of torque.

This is what happens with a true open differential. It can't be any other ways because that's the way the gears work. If there are limited slip clutches in there they will offer some torque transfer from the faster side back to the slower side. If there is a Torsen differential it can offer enough friction in some situations to work like a locker. If there is a locker or a spool it can transfer all of the torque to the side that is getting good traction, but one of the wheels wouldn't be spinning in that situation. The cheap jeeps have their brake lock system which applies additional torque to the spinning tire just as if it was having more traction, allowing more torque to go to the non-spinning tire. Any system that uses brakes will limit the torque going to the tire with traction to 50% of the total torque, the gears won't allow anything other than that. Some of the torque is acting against the brakes. With a locker you can get 100% of the torque to the non-spinning side.

 

[The Last Cowboy]

This is my understanding of an open differential. In an open differential, both of the wheels are applying the same amount of torque/power. The spinning wheel is spinning because it has less traction/resistance than the non-spinning wheel.

The torque available to each wheel is limited by the wheel with the least amount of traction/resistance. If it takes 100 foot-pounds of torque to spin the wheel with the least amount of traction, then the non-spinning wheel is also going to be applying 100 foot-pounds of torque. If it only takes 5 foot-pounds of torque to spin the wheel with the least amount of traction, then the non-spinning wheel is only going to be able to apply 5 foot-pounds of torque.

Years ago I had an old half ton Chevy pickup with a PosiTraction in it. One day on a boat ramp, I could not get the truck to pull the boat out. The right rear wheel would spin, slow down, then the left would spin. The rear of the truck was hopping up and down.

After that, I had a '69 Buick Gran Sport, without a PosiTrac. That thing would roast the right rear tire, unless I was tuning. On a wet road it would predictably slide the right rear to the side when giving it some throttle. But if I made a right turn, the the left rear wheel would lose traction, when the speed between the two rear wheels would change.

When I sold that, I got a '75 Scout II that had a Detroit Locker in it, IH called it the No Spin. The slightest loss of traction would be followed by a clunk, and the rear was locked. And you better hang on, because that thing would do a quick 360 on a wet road. And it always left 2 strips of rubber if you gave it full throttle from a dead stop.

I get what you're saying, but maybe you're thing of a limited slip/PosiTrac type rear axle. Get stuck in the sand, or mud, with an open rear differential, and you will see that the tire that's not spinning is getting very little power applied, and certainly not equal power, or it would be able to push the vehicle, at least to some degree.

 

[txj2go]

I get what you're saying, but maybe you're thing of a limited slip/PosiTrac type rear axle. Get stuck in the sand, or mud, with an open rear differential, and you will see that the tire that's not spinning is getting very little power applied, and certainly not equal power, or it would be able to push the vehicle, at least to some degree.

A limited slip or positrac is supposed to help transfer torque to the wheel that has traction, i.e. is not spinning. However I've seen a lot of them that I didn't think could do that. With limited slip you should be able to raise the car so both rear tires are off the ground, put the transmission in park or in gear, and shouldn't be able to turn a rear tire by hand. I've seen a lot of cars where you could turn the rear tires and there didn't seem to be much resistance. I never knew why, maybe the clutches wear out or the springs holding them together lose their tension.

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