Americas Death wobble at 90-100km/h

[INEOS OG]

Is the Carraro Axle designed for the Grenadier or something from the stock?

AWo

I don't want to be a buzzkill, but the axle in your vehicle doesn't know that it wasn't designed to be in your vehicle.

The laws of physics are finite and absolute. See Newton's first three laws for a primer.

I've been replacing shit axles with 3/4 and 1 ton Dana units in everything from Suzuki Samari's to F series trucks for decades and most do not use a steering stabilizer.

 

[AWo]

It is not about the axle knowing where it is fitted to (By the way, I strongly believe axles have brains and know exactly in which car they are!!!)

It is about the caster, which is an important stabilizing parameter. If the axle is normally used with larger tires (as Cararro makes axles for tractors) the caster would be greater due to the larger diameter of the tire. If smaller tires are mounted then, the caster gets smaller (wasn't the small caster discused here somewhere, was it, as well as weak self-centering forces?), as the kingpin ground intersection is different then

AWo

 

[Dokatd]

I don't want to be a buzzkill, but the axle in your vehicle doesn't know that it wasn't designed to be in your vehicle.

The laws of physics are finite and absolute. See Newton's first three laws for a primer.

I've been replacing shit axles with 3/4 and 1 ton Dana units in everything from Suzuki Samari's to F series trucks for decades and most do not use a steering stabilizer.View attachment 7924172

That pic shows a radius arm style suspension. That's why it resists DW. Throw on a short arm 4-link and you MIGHT be in trouble. Longer arm 4-links are a bit less troublesome seemingly.

Your experience is seemingly with more aggressive trucks as is mine. I agree that stabilizers shouldn't be needed. But some trucks just need them straight from the factory. The Grenadier is one of those trucks.

 

[255/85]

It is not about the axle knowing where it is fitted to (By the way, I strongly believe axles have brains and know exactly in which car they are!!!)

It is about the caster, which is an important stabilizing parameter. If the axle is normally used with larger tires (as Cararro makes axles for tractors) the caster would be greater due to the larger diameter of the tire. If smaller tires are mounted then, the caster gets smaller (wasn't the small caster discused here somewhere, was it, as well as weak self-centering forces?), as the kingpin ground intersection is different then

AWo

I don't think that is correct. The caster angle doesn't change with tire size but larger tires do extend the distance from the point where the axle center line crosses the kingpin axis down to where the tire touches the ground. Since the rear tires on a 4x4 would generally match the front there would be no change in the caster. Conversely, if you increase the front tire size only then, yes, that would increase positive caster or reduce negative caster with a smaller tire.

As to Carraro's axle offerings...

They do have several front/rear axles listed in their catalogues that offer varyied weight-carrying capacity. It would be interesting to know how much input Ineos had into the assembly specifics beyond the basic width. Example: The left side lower control arm attachment point is cast in place so I doubt Ineos would be considerd a large enough purchaser to convince Carraro to re-design the front differential casting.

 

[AWo]

I don't think that is correct. The caster angle doesn't change with tire size but larger tires do extend the distance from the point where the axle center line crosses the kingpin axis down to where the tire touches the ground.

That's what I meant. Did I wrote angle? That would be wrong, in deed.

I thought the distance on the ground is called caster (without the term "angle").

AWo

 

[255/85]

That's what I meant. Did I wrote angle? That would be wrong, in deed.

I thought the distance on the ground is called caster (without the term "angle").

AWo

No, you didn't write "angle". I just assumed you were referring to such.

I don't know what effect changing tire size has on steering if pressures, rolling resistance, and material specs are equall across sizes. Maybe you know of Ackerman angle or turn radius changes that would occur? Does a larger tire move the ground contact point to any great degree thus changing effective caster though the kingpin angle remains constant? How much would be felt by the driver if the tire diameter was changed (for example) 10% as when changing from 30" to 33" tires?

 

[AWo]

Yes, I know about Ackermann, you may want to read my article about thst stuff: https://matsch--und--piste-de.trans..._sl=de&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp

In the cornering section in the part about the track the translation wrote toe-in instead of toe- out...that is wrong, toe-out would be correct.

A larger tire increases the length of the caster on the ground (point of intersection and tire contact point).

AWo

 

[Dokatd]

Tire size does not change the effects of caster. Increasing tire size increases trail. Increasing trail gives a similar sensation to increasing caster.

 

[skinny_tom]

That's what I meant. Did I wrote angle? That would be wrong, in deed.

I thought the distance on the ground is called caster (without the term "angle").

AWo

I think the word is "trail." At least it is for motorcycles.

@Dokatd beat me to it.

 

[AWo]

Ok, then trail is the right term. Thanks.
AWo

 

[matthewaddison]

I have a 2024 Grenadier with a post-market Fox stabilizer bar, odometer 8300km.

Yesterday, while driving on a highway at around 90-100km/h, I hit a moderately-sized pothole and the car went into a prolonged wobble, I had to use all my force and nerves to keep it straight and brake. Luckily I was on the right lane. I returned home driving at less than 90km/h, nothing happened afterwards.

Is it a case of death wobble? Solutions? I bought the car new last autumn and haven't even drove it offroad yet...

Thank you all for any infos,

Constantin

I had the same issue. Scary as hell! I brought the vehicle to the dealer and had them check all the bolts on the axle/steering components. The mechanics reported multiple bolts were loose. This could only have been sent out from the factory in that condition.
When I first got the vehicle, I noticed a slight rattling from the front end and upon inspection noticed that the radiator bolts were all loose! So there was obviously an issue at the factory when they were churning out the 2024 model year vehicles.