2020 Jeep Gladiator pickup

[zzvyb6]

Bingo ! We have a winner for identifying the root cause. Keeping the drag link level decouples a front wheel vertical input from an axle lateral input. So, you raise the drag link on the axle or drop the pitman arm ball from the steering gear to make the link level. Check out the videos on Youtube because there you can see how the motor plays a part in this, too. I suspect that the large forces involves in this form of shimmy can break a motor mount as well as failing the splined shaft on the pitman arm at the steering gear. Yes, the caster inducing forces, weak steering gear structure and worn out ball joints on the linkage parts make this problem worse. Dealers recommend new high friction parts and stronger steering dampers, but the root cause will only make the new parts wear out all over again.

 

[ovrszd]

Never had it in the GPW or CJ5. Had it in a Ford F250 with minor lift and 35's. Steering stabilizer and alignment fixed that.

Yep. As Raspy explained above it's usually caused by worn parts. But it can also be caused by misaligned front end.

 

[ovrszd]

Bingo ! We have a winner for identifying the root cause. Keeping the drag link level decouples a front wheel vertical input from an axle lateral input. So, you raise the drag link on the axle or drop the pitman arm ball from the steering gear to make the link level. Check out the videos on Youtube because there you can see how the motor plays a part in this, too. I suspect that the large forces involves in this form of shimmy can break a motor mount as well as failing the splined shaft on the pitman arm at the steering gear. Yes, the caster inducing forces, weak steering gear structure and worn out ball joints on the linkage parts make this problem worse. Dealers recommend new high friction parts and stronger steering dampers, but the root cause will only make the new parts wear out all over again.

In my experiences the angle of the drag link doesn't cause DW by itself. There are literally tens of thousands of Jeeps on the road everyday that do not have a level drag link. I don't know of any solid tierod, drag link setup that sits level.

 

[Raspy]

I break the Death Wobble problem down into two categories. There are things that initiate it, or set it off. Then there are other things that allow it, or facilitate it. These facilitators don't actively start it, but they don't prevent it either, even though they could prevent it if better designed or less worn out.

Large, out of balance front tires are likely the biggest "initiator". Remember that the wobble is a violent shimmy of left and right shaking at the natural oscillation frequency of the wheels. Now imagine a wide tire that is out of balance. The heavy spot on the tire is offset toward the outside of the tire, not in the center of the tire. As that tire rolls along the heavy spot moves from the rear to the front and back to the rear. It is actually going around, but the important movement is front to back. As the heavy spot moves to the front, it tries to make the tire turn to the right, when it is at the rear it tries to turn the tire to the left. Right left right left. I call this tricycling. If you roll a tricycle along you'll notice that the handlebar wants to turn left right left right. The pedals act as out of balance weights. When the speed of an out of balance truck tire is matched to the natural oscillation frequency of the mass, it takes on a life of it's own and becomes a wobble. This is a pendulum where very little input sustains a big movement. This natural frequency is reached at about 45 MPH, or so, depending on the diameter and mass of the wheel/tire combo.

Then we have the "facilitators". These allow a lot of shaking by being loose or weak. A flexible track bar, or worn track bar bushings, for instance, will allow the wobble to move back and forth, right left, right, left with little resistance. These things don't "cause" the problem, but they allow it to happen once started. Play in the steering gear, flexible steering gear mounts, worm ball joints or tie rod ends, weak steering stabilizers can all play a part in this. Anywhere there is play or flexibility.

It can also happen with normal sized tires, that are correctly balanced by hitting a bump or hole at the right speed where the wheel is pushed off to one side and then released such that it springs back and starts the wobble.

All tires, especially larger or wider tires, should be spun balanced carefully and accurately. Static balancing does not correct for off-center imbalance where the heavy or light spot is near the outer edge of the tire. Therefore it cannot prevent the tire from tricycling or initiating a wobble.

A low caster angle is a facilitator and means that the wheel has little resistance to turning back and forth as described, because it is pivoting on a spot near the center of it's contact patch. Instead being resisted by having to skid as it wobbles, or move the whole front of the vehicle as it wobbles, by having it's contact spot offset from a point inline with it's axis. More caster angle means more damping against the ground and more stability. Or, at least more massive machinery has to move in response, which damps it out. More caster means the tricycling or wobbling tire has worse leverage against the "facilitating" parts, than it would have with less caster. And remember, caster is reduced by lifting a control arm suspension Jeep.

TJ Wranglers have short front control arms that, when lifted, cause the caster to be reduced. They also have weaker parts than the JKs do and seem to be very susceptible to wobble with oversized tires. JK Wranglers do to, but not quite as much. Any coil sprung wrangler that is lifted should also get adjustable lower control arms to correct for low caster. Ram trucks from 2003 through 2012 have weak front end steering systems They were improved some in 2008, but not much. Then in 2013 they were re-designed to be very stiff and the problem of wobble went away, as far as I know. The newer ones also steer much more precisely, stop straighter and tolerate oversized tires much better than the earlier ones that were prone to wobble. My parents had a 1963 VW bug when I was a kid and it would death wobble every once in a while even though it was completely stock and had a steering damper. That one was set off by ruts or pot holes. My Dad was an ambulance driver in WW2 and drove military Power Wagon ambulances. They would do it too, and the fix was to run them in 4WD on the highway.

 

[MinnesotaEric]

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Bruce

Compared to the big three (Ford, Dodge, GMC--cause you get a GMC when you want a Chevy), I wouldn't touch an off-brand full size truck for the quality, comfort, refinement, and E-Class ammenities--not to meantion the 10,000 pound plus tow rating nearly every half ton now has.

 

[Raspy]

The Gladiator seems to just be a Wrangler Unlimited, but with a tiny box on the back. The only one that remotely interests me is the standard cab model, but I already have a Wrangler. I don't see anything about it that makes it some kind of fantastic breakthrough that we all have been waiting for. It's a slightly altered Wrangler and it is only 44" inches between the wheel wells. Good for bringing a can of paint or some groceries home, or taking a bicycle to the trail on Saturday morning. For four wheeling the departure angle look bad. Another thing is funny: the towing capacity of a JK Wrangler Unlimited is 3500 lbs and this Gladiator is rated at, I think, 7,650 lbs. Hmmm. Where did twice the capacity come from? And towing that kind of weight with a Pentastar would not be very much fun.

 

[BLSXJ]

the rear suspension is pulled from a Ram 1500, and 19" more wheel base

 

[dalola]

Any body who would regularly try to tow 7000#'s with that needs their head examined. Same thing with all the mid-size trucks, completely ridiculous for realistic tow ratings. I also wouldn't tow 12000#'s with a half-ton, with the exception of perhaps the 3.5EB Ford. Makes for good marketing tho.

 

[MinnesotaEric]

Any body who would regularly try to tow 7000#'s with that needs their head examined. Same thing with all the mid-size trucks, completely ridiculous for realistic tow ratings. I also wouldn't tow 12000#'s with a half-ton, with the exception of perhaps the 3.5EB Ford. Makes for good marketing tho.

In every way my 2011 F150 blows my 1980 F250 out of the water. The F150 has bigger brakes, doesn't have holes cut into the frame like the F20 (done to reduce weight, and likely to buckle), the 400 CID engine in my F250 is rated at 153hp, 300ftpt while the F150's engine is rated at 365hp and 420ftpt. The F250 does have a full floating Dana60 rear end, which is superior to my semi-floating 9" F150, but still the weights of the trucks are similiar. Meanwhile I regularly see 16-18mpg and 8-10mpg when towing 8-10,000 pounds and around 13mpg towing boats. My F250 gets at best 12mpg empty on the highway and much less when pulling a load of any kind. The F250 does benefit from load range E tires which theoretically should wear longer than the light truck tires on the F150, but don't because the F250 cups the front tires no matter how it is aligned increasing tire wear due to the 4WD design of the independent front suspension.

I think people are thinking is that light trucks are still light trucks, but by weight, newer light trucks have been creeping up and are well into the specs of 80s and 90s three-quarter and one-ton pickup trucks. Meanwhile our new three-quarter and one-ton trucks ratings have also gone through the roof.

 

[ovrszd]

In every way my 2011 F150 blows my 1980 F250 out of the water. The F150 has bigger brakes, doesn't have holes cut into the frame like the F20 (done to reduce weight, and likely to buckle), the 400 CID engine in my F250 is rated at 153hp, 300ftpt while the F150's engine is rated at 365hp and 420ftpt. The F250 does have a full floating Dana60 rear end, which is superior to my semi-floating 9" F150, but still the weights of the trucks are similiar. Meanwhile I regularly see 16-18mpg and 8-10mpg when towing 8-10,000 pounds and around 13mpg towing boats. My F250 gets at best 12mpg empty on the highway and much less when pulling a load of any kind. The F250 does benefit from load range E tires which theoretically should wear longer than the light truck tires on the F150, but don't because the F250 cups the front tires no matter how it is aligned increasing tire wear due to the 4WD design of the independent front suspension.

I think people are thinking is that light trucks are still light trucks, but by weight, newer light trucks have been creeping up and are well into the specs of 80s and 90s three-quarter and one-ton pickup trucks. Meanwhile our new three-quarter and one-ton trucks ratings have also gone through the roof.

You do realize you are comparing two trucks that are 31 years apart??