Death Wobble with original suspension

[Honger]

The issue:
Death Wobble in my steering. The severity is somewhat road/pavement condition dependent. Between 50-60 mph, sometimes 55-65 mph, I get a rhythmic oscillation in my steering that goes all the way up into my steering wheel. It occasionally gets severe enough to go into out-of-control wobble that can only be countered by slowing down to around 35-40 mph. If it doesn't get out of control, once I hit 65 mph and above, the truck drives wonderfully smooth. No lift on this truck. Tires are 32.5-ish.

The background:
I had my power steering gearbox rebuilt by Red Head some time ago... and before the 1-year was up it started leaking. They took care of me with no questions asked. When it started leaking again I felt like I needed to dive into some occasional vibration I'd been having in the steering wheel (wasn't death wobble yet). That condition had seemed to be worsening, so it made sense to tackle that as a root cause of the gearbox leaking. It's leaking at the output shaft seal above the pitman arm.

Going down the rabbit hole I decided to put 2-degree castor shims in. @orangefj45 gave me some input on this before I pulled the trigger and he was able to supply the shims and extended pins no problem. He encouraged me to explore the idea of this possible being a worn rear driveshaft, but I've ruled that out based on the behaviors I'm seeing.

After installing the 2-degree shims (fat side forward) I took it for a test drive before getting an alignment. Horrible death wobble at anything over 45 mph. Had never experienced it before and understood how bad a feeling it is then. So I went and got the alignment I needed obviously. They said all tires were balanced. Here's the results. Definitely increased my caster.

The alignment obviously fixed the automatic death wobble, but now I was getting the behavior in the 50-60 mph zone very consistently. It seemed to be getting worse as well now. So I went for another alignment to see if things were getting out of whack... and if I had a tire balance issue. They made a very minor balance chance to one of the tires. Second alignment result.

I was amazed to see the caster had reduced like that in a month. This didn't help. Still had very consistent problems in the 50-60 mph zone. Drove it like this for a bit and then gave up and removed the shims... it seems like they are what precipitated the worsening. Alignment after shim removal. Back to flat. For reference, when I'd last had an alignment several years back I was at 0.6 and 0.8 degrees of caster.

The problem didn't get fixed with shim removal. It may have improved just a little. I noticed the front left shackle bushings were bad from the old power steering residue so I replaced those. No improvement.

What should I attack next?
Maybe more caster; say 4-degree shims?
Replace the steering damper? Shocks?

Maintenance history, FYI:
Tie Rod Ends in 2022 (40000 kms ago)
Spring Bushings in 2019 (70000 kms ago)
Spring Bushing on front left (one month ago; balance of front will get done soon)
Rebuilt Power Steering Box in 2024 (15000 kms ago)

 

[nuclearbeef]

I got death wobble on my Troopy after replacing springs and bushings. I didn't replace the pins, but cleaned the corrosion off of them.
I guess the corrosion was keeping them tight in the old bushings, but after cleaning them there was just enough play to cause death wobble.

I installed new greasable shakle pins and that fixed the death wobble.

 

[Felde]

Hi
Death Wobble usually is not caused by caster, in particular not on a stock suspension (where the caster usually is about 0. Spec says about +- 1°, if I recall correctly. Your 2° should be just fine).
Usually Death Wobble is usually caused by play in the steering components. Can be any bushing, including suspension and swaybars, tierod ends, pitman arm or even knuckle bearings or hub bearings.
Tackle it systematically:
Check wheel play and play in knuckles (well, your alignment shop should have found any issues there, but who knows). Then tierod and connection rod ends (Note: The factory setting of the adjustable ones is too weak and needs proper tightening, but often those are mounted as is).
Grab a breakerbar and try to find parts moving in suspicious directions. (Best done with wheels on the ground). Swaybar first.
However, giving the history the steering box bearing would be my first suspect.
Good Luck Ralf

 

[orangefj45]

Caster typically doesn’t cause or affect death wobble, but will help with handling and “return to center” steering.

This is a list of items that can/will cause death wobble:

1) loose/worn steering shaft splines or joints.
2) play in the sterring box
3) loose steering box to frame bolts
4) loose pitman arm ( nut & lock washer )
5) worn or mud-adjusted TREs
6) loose wheel bearings
7) loose/failed reunion bearings
8) bad suspension bushings
9) loose u-bolts
10) bad/worn steering stabilizer
11) worn/cupped tires
12) tires out of balance
13) damaged/bent wheel
14) bad/damaged wheel studs
15) bad/damaged wheel mounting surface

Work your way thru the list. You’ll find the culprit.

FWIW, as discussed, your caster should be at 2-3.5 degrees.

Hope that helps.

Georg @ Valley Hybrids & Terrain Tamer

 

[Hdj75]

The list of Orangefj45 is really good.

One more thing to add are the spacers. Steel rims with too small diameter spacers cause death wobble. I just had case with oem 8x16 steel rims and cheap 165mm diameter alloy spacers with multiple holes and with too big inner hole diameter. The steel rim mounting surface is not flat as in alloy wheels, so steel rims need 182mm outer diameter spacers without any excessive holes. So spacer should have same surface measures as the brake disc.

Funny thing is that the cheap alloy spacers worked few hundred kilometers without any problem and for some reason one of the front spacers moved and started to cause death wobble st speed of 70kmh.

 

[HZJ75 FARMER]

What model is it?

Have you replaced the kingpin/trunion bearings in the steering swivel at the ends of the diff housing?

Also, does it have free-wheeling hubs? If so, does it make a difference if they are disengaged? The brass bush that the CV joint runs in can cause shake problems. Or needle roller bearing if it's a later model.

 

[Honger]

The list of Orangefj45 is really good.

One more thing to add are the spacers. Steel rims with too small diameter spacers cause death wobble. I just had case with oem 8x16 steel rims and cheap 165mm diameter alloy spacers with multiple holes and with too big inner hole diameter. The steel rim mounting surface is not flat as in alloy wheels, so steel rims need 182mm outer diameter spacers without any excessive holes. So spacer should have same surface measures as the brake disc.

Funny thing is that the cheap alloy spacers worked few hundred kilometers without any problem and for some reason one of the front spacers moved and started to cause death wobble st speed of 70kmh.

No spacers on this truck.

What model is it?

Have you replaced the kingpin/trunion bearings in the steering swivel at the ends of the diff housing?

Also, does it have free-wheeling hubs? If so, does it make a difference if they are disengaged? The brass bush that the CV joint runs in can cause shake problems. Or needle roller bearing if it's a later model.

Trunion bearings and wheel bearings were changed out in 2019 (70000 kms).

It does have the Aisin selectable hubs. They have been disengaged throughout this issue. I'll engage them to see if it's different. I have the brass bushings in my truck.

Caster typically doesn’t cause or affect death wobble, but will help with handling and “return to center” steering.

This is a list of items that can/will cause death wobble:

1) loose/worn steering shaft splines or joints.
2) play in the sterring box
3) loose steering box to frame bolts
4) loose pitman arm ( nut & lock washer )
5) worn or mud-adjusted TREs
6) loose wheel bearings
7) loose/failed reunion bearings
8) bad suspension bushings
9) loose u-bolts
10) bad/worn steering stabilizer
11) worn/cupped tires
12) tires out of balance
13) damaged/bent wheel
14) bad/damaged wheel studs
15) bad/damaged wheel mounting surface

Work your way thru the list. You’ll find the culprit.

FWIW, as discussed, your caster should be at 2-3.5 degrees.

Hope that helps.

Georg @ Valley Hybrids & Terrain Tamer

Thank you Georg! This is supper helpful. I can work through a list.

2) I'm assuming that Redhead checks this as they are working on the steering box. I'll communicate with them to confirm. I should stress here how helpful they've been with me.
9) When tightening u-bolts I do it in a pattern to keep the amount of exposed threads roughly the same on each end... and do that to spec torque. Any other tricks I'm missing here?
10) Working with your team now on a replacement stabilizer and shocks actually.
11), 12), 13) I'm assuming the tire shop I use for alignment and tires would have caught any/all of these when balancing and aligning, correct?

Will get cracking at the rest of the list. One at a time as best I can.

 

[orangefj45]

No spacers on this truck.


Trunion bearings and wheel bearings were changed out in 2019 (70000 kms).

It does have the Aisin selectable hubs. They have been disengaged throughout this issue. I'll engage them to see if it's different. I have the brass bushings in my truck.



Thank you Georg! This is supper helpful. I can work through a list.

2) I'm assuming that Redhead checks this as they are working on the steering box. I'll communicate with them to confirm. I should stress here how helpful they've been with me.
9) When tightening u-bolts I do it in a pattern to keep the amount of exposed threads roughly the same on each end... and do that to spec torque. Any other tricks I'm missing here?
10) Working with your team now on a replacement stabilizer and shocks actually.
11), 12), 13) I'm assuming the tire shop I use for alignment and tires would have caught any/all of these when balancing and aligning, correct?

Will get cracking at the rest of the list. One at a time as best I can.

Always happy to help!

First thing:
Put the front axle of your cruiser on jack stands.
Grab the top and bottom of each tire and see if there’s any play. Then do the same horizontally. That will tell you if you have loose tire rod ends, wheel bearings, or trunion bearings.

Keep us updated.

Georg @ Valley Hybrids

 

[Eurasiaoverland]

70,000 kms is a lot between servicing (not necessarily replacing) the front wheel bearings. Bearings typically need repacking with grease and the pre-load resetting. If not done, they often start to wear the spindles, compounding the problems. Withe the vehicle on its wheels, grab the top of the front tyre and firmly rock it in and out. Any clunking means things are loose.

How wound in is the adjuster on the steering box?

 

[orangefj45]

70,000 kms is a lot between servicing (not necessarily replacing) the front wheel bearings. Bearings typically need repacking with grease and the pre-load resetting. If not done, they often start to wear the spindles, compounding the problems. Withe the vehicle on its wheels, grab the top of the front tyre and firmly rock it in and out. Any clunking means things are loose.

How wound in is the adjuster on the steering box?

Agreed 100%

This is a golden rule we try to teach every single one of our customers:

When it comes to Landcruiser, you should change your engine oil every 3500 miles. At that point, you should also check your front wheel bearings and grease both driveshafts.

THIS IS IMPORTANT!!!!!!

Georg @ Valley Hybrids

 

[Honger]

70,000 kms is a lot between servicing (not necessarily replacing) the front wheel bearings. Bearings typically need repacking with grease and the pre-load resetting. If not done, they often start to wear the spindles, compounding the problems. Withe the vehicle on its wheels, grab the top of the front tyre and firmly rock it in and out. Any clunking means things are loose.

How wound in is the adjuster on the steering box?

Agreed 100%

This is a golden rule we try to teach every single one of our customers:

When it comes to Landcruiser, you should change your engine oil every 3500 miles. At that point, you should also check your front wheel bearings and grease both driveshafts.

THIS IS IMPORTANT!!!!!!

Georg @ Valley Hybrids

I have not neglected checking pre-load during those 70,000 kms. I've tied it to rotating the tires instead of oil changes... so not nearly as frequently as Georg indicated. On at least one of those occasions I removed the hub and loosened and reset the pre-load proactively.

I just changed out the front diff fluid and it showed definite signs that knuckle grease and gear oil are mixing... so due for re-sealing now as it is.

Will be diving in over this weekend on a number of items and will report back.

 

[Rigster]

When you replaced the TRE's 40,000km ago, have you adjusted them since? Assuming of course, they are the stock style. Pull the cotter pin, tighten the end screw, replace cotter pin.