Steering and Poor Stability

[pmatusov]

Going from 35 to 40 psi in 6000 pound truck on an E rated sidewall wouldn't be noticeable. It would be like playing the Pepsi challenge with 4 cups of Pepsi. If I had a truck that went from dangerous high speed handling to calm by changing a few PSI, I's sell it, because something is waaaaaaay out of wack.

When you air down in the Grenadier from 43 to 28 psi you definitely see the sidewall flex. Would I see it between 40 and 35? Probably.
On the subject of front/rear tire pressure differential - I always suspected that on the D1/RRC it was means to introduce understeer, and I think Ineos is doing the same. I like the truck's handling at even 45/45 better than at 43/49 psi.

 

[Zimm]

When you air down in the Grenadier from 43 to 28 psi you definitely see the sidewall flex. Would I see it between 40 and 35? Probably.
On the subject of front/rear tire pressure differential - I always suspected that on the D1/RRC it was means to introduce understeer, and I think Ineos is doing the same. I like the truck's handling at even 45/45 better than at 43/49 psi.

Introducing a slight bit of under-steer isn't quite the same as people describing their truck as dangerous at high speed with tires in the 40's, and people suggesting to add a few pounds as a solution. These trucks have skidpad numbers in the .5's Between the low 30's and up to 50, all I've ever noticed on 4 different LC models, a defender, a trooper and a G, is ride quality.

The steering IS unusually odd in this truck, but if its got the 2* of caster, and there isn't anything loose in the linkage or steering-box, I'm thinking some people aren't used to the sailboat effect on a box truck in cross winds at high speed combined with sloooooooow turning and a swartzeneggar strength dampner.

I bet the rig would feel much more normal without the dampner altogether.

 

[Lord Ripon USA]

I bet the rig would feel much more normal without the dampner altogether.

Catastrophic shimmy.
That's a hard no.

 

[grenadierguy]

As do I - otherwise flipping people off is too difficult. As is eating rames, playing Candy Crush, and shaving.

Was that you waving at me today Krabby?

 

[bigleonski]

Coming from Nitto Ridge Grapplers to BFG AT’s, the sidewalls on the BFG’s bag out considerably more.

 

[grnamin]

The bracket is just a little narrow for what you are shoving in there, particularly because there are two fat washers, so you need to line up the holes in all three at the same time. This was the only tricky part of the install, and why I put it on my lift after starting on the garage floor. But what I eventually worked out would probably have worked on the floor.

Without the damper, I partially threaded the bolt back into place in the bracket. Then I used a bearing puller to shove the bolt in all the way. The nut is welded onto the bracket, so this pushed the two plates apart. I let it sit like that for a few minutes. It was just enough to get everything in there. I think once you see it this will make sense, but I'm going to make use of my incredible Paint skills here. The goal is to just spread apart the C bracket a little bit. Also, I don't know how to draw a bearing puller.

View attachment 7853535

Is the bearing puller the same one used to remove bicycle headsets?

 

[Korg]

When I picked up my Grenadier Trialmaster a few weeks back the steering was sloppy with around 10 degrees of "play" in the steering wheel. It was very hard to keep the car straight at 100km with a lot of steering input required. I have checked and adjusted the tyre pressure, caster, camber and wheel alignment to spec (all were out). This improved the steering but did not fully address the wandering due to the slop. 3,500km later on a trip to the South Coast the steering wheel rotated from the 12'o clock position to about 1pm. Alarms for the ESC, uphill assist, downhill assist etc. etc. all bing bonged and have stayed on since. On the way back from the South Coast the steering moved now to 2:30 pm for dead centre wheels but .... the steering is actually much better in respects to the slop has now almost gone. Car goes into service Tuesday.

Update 1st May: Car picked up after dealer service. Steering issue found to be lose nuts on steering arm. I will blame the third party who did the post delivery wheel alignment, however the torque required for these nuts is a whopping 180Nm! The dealer fixed this at no charge. Steering wheel now centered correctly, rear door sensors adjusted, replacement door knobs on order as they need to be coded to the key for the front, vibration was fixed by adjusting a heat shield, bings and bongs all gone for now. Great work by the dealer - Purnell Motors Blakehurst.

Other notes: next software update (due soon) allegedly addresses the size of the reversing image and also wireless Android Auto plus fixes for Apple Car Play plus others. 2024 models have a different steering damper (Bilstein) that appears to improve the steering. I have enquired about a retrofit of this even as a chargeable fix.

 

[OGrid]

‘Wandering due to slop’ - I think you’ve summarised the steering experience of others (myself included) quite well

 

[ZemTyrion]

Is the bearing puller the same one used to remove bicycle headsets?

I have no idea. Anything that can grip on a flange and push in the middle should do the trick.

 

[grnamin]

@ZemTyrion, did you have to heat up the nuts in order to break up/dissolve any thread lock before you could remove the OEM steering stabilizer?

 

[Commodore]

Catastrophic shimmy.
That's a hard no.

Why would you think it is going to shimmy?

 

[Lord Ripon USA]

Why would you think it is going to shimmy?

Because I worked in steering systems at GM when I got out of school. I saw it a lot.

Conversely, "Why do MANUFACTURERS put stabilizers on track bars?"

Answer: Because if you hit a bump at the right speed and shimmy sends you to your death, we had to pay for that.

 

[pmatusov]

The steering IS unusually odd in this truck, but if its got the 2* of caster, and there isn't anything loose in the linkage or steering-box, I'm thinking some people aren't used to the sailboat effect on a box truck in cross winds at high speed combined with sloooooooow turning and a swartzeneggar strength dampner.

I bet the rig would feel much more normal without the dampner altogether.

If your thoughts are based on the experience with the closed-knuckle trucks, you're wrong. The dry friction in ball joints in steering knuckles is nowhere enough to dampen shimmy or prevent it from happening.

 

[ZemTyrion]

@ZemTyrion, did you have to heat up the nuts in order to break up/dissolve any thread lock before you could remove the OEM steering stabilizer?

Nope. I don't think I even used a breaker bar. Just a normal 3/8in socket.

 

[Lord Ripon USA]

There is a lot going on in the steering system of any vehicle. Lots of surfaces, clearances, movements, and gradual wear.
Please don't start deleting parts from the system. Whatever anyone might believe or have been told.

I would opt for a good bi-directional steering dampener to reduce side to side looseness, and then increase the assist in the box.
But I didn't design it. They must have felt it was gtg when they released it.

Ideally, lots of electronic assist at low speed for parking, and then no assist at speed and let the geometry and stiff stabilizer control high speed tracking.
It's mature technology. Very easy to hit the marks once the parameters are determined. But you have to tell the engineers what you want first.

 

[wolftimj]

Just got aligned, upped caster to about 2.5 degrees. Tracks much nicer. Nothing else was changed.

 

[Commodore]

Because I worked in steering systems at GM when I got out of school. I saw it a lot.

Conversely, "Why do MANUFACTURERS put stabilizers on track bars?"

Answer: Because if you hit a bump at the right speed and shimmy sends you to your death, we had to pay for that.

The damper has been off my 1967 bronco for years and I have experienced a shimmy. My understanding is that shimmy happens when bushings are worn out. Just my experience.

 

[FlyersFan76]

Hopefully I cross paths with an owner of an unstable Grenadier. Right now I just scratch my head. Mine is tight, dare I say sporty, and I often drive with one hand.

Thinking the same. I had a loaner Nissan Pathfinder and as soon as I drove away I felt that the steering was very loose and needed to use 2 hands. Granted the steering returned to center but it felt spongy.

 

[Tazzieman]

The damper has been off my 1967 bronco for years and I have experienced a shimmy. My understanding is that shimmy happens when bushings are worn out. Just my experience.

I replaced all the bushings on my '73 Land Rover. It was a bastard of a job, one which my independent LR guy refused to do . "Young man's work" he told me.
I aligned the wheels myself. Not hard , as toe is the only adjustment. I installed new shock absorbers, bearings, brakes etc.
All was well until one day I put an extra 5psi in the tyres.
Copped a very scary death wobble going downhill on a curve on a 2 lane hwy with concrete barriers on either side. My 13 yo son in the front seat lived to tell the tale of his dad wrestling to keep us both from certain demise.

 

[Tom109]

I replaced all the bushings on my '73 Land Rover. It was a bastard of a job, one which my independent LR guy refused to do . "Young man's work" he told me.
I aligned the wheels myself. Not hard , as toe is the only adjustment. I installed new shock absorbers, bearings, brakes etc.
All was well until one day I put an extra 5psi in the tyres.
Copped a very scary death wobble going downhill on a curve on a 2 lane hwy with concrete barriers on either side. My 13 yo son in the front seat lived to tell the tale of his dad wrestling to keep us both from certain demise.

Swivel ball preload?