78 series death wobble (1 Viewer)

[Mobby]

G'day,

New to the forum but ive joined hoping someone can help me out on an issue i have with my troopy.
Troopy is 2023, 13,000kms.
Had the full 4.2t GVM upgrade 4" lift coil conversion with 35" tyres.
Car drove like a dream for the first 9000kms.
Its since developed a pretty wild wobble when braking.
While driving it doesnt happen, as soon as you start braking from around 80kms it wobbles, gaining momentum until you cannot hold the steering wheel anymore.
Ive had multiple wheel balances and alignments with no improvement.
Workshop that fitted the gear said it must be either spring loaded control arm that bolts onto the dampener or the brakes as apparently the stock brakes are no good on the 70 series.
Had the bar replaced along with another alignment and balance to now improvmement.
Most recently just replaced the rotors with no improvement.
My front diff looks to be slightly leant over forward, not sure if this is meant to be plumb?
Any help would be amazing, ive contacted Jmacx directly just waiting for a reponse.

 

[coldtaco]

Doesn’t look like the new arms are built with a castor (or whatever it’s called) built in

 

[Mobby]

Doesn’t look like the new arms are built with a castor (or whatever it’s called) built in

Nah i dont think it needs any other gear,
They fit thousands of these kits every year and dont seem to have any dramas with them

 

[Mobby]

Further,
It will sometimes wobble just driving around the 80km mark, that seems to be the sweet spot.
Something is causing the wheels to wobble around the 80km mark, then when I begin to brake it must exacerbate the issue.
There's almost nothing left to replace, I'm thinking its either the wheels are faulty from factory, like out of shape or something,
But wouldn't that mean i would of had the issue since new? the first 9000kms it drove perfectly so that tells me something has worn over time?
Or that the bushes in the radius arms are not offset far enough to level the front diff causing the tyres to wear unevenly,
But again, I would of thought after a wheel balance+alignment that they would come good.
Im all out of ideas but keen to get it fixed if anyone has any ideas?

 

[Squash]

Front wheel bearings for the win.

 

[AirheadNut]

Really curious to know what the castor angle would read on an alignment rack. 4” is a lot of lift if there isn’t castor correction built in to the radius arms.

 

[Houser]

If you haven't already done so I would take it to a different shop to have the alignment and castor checked. The original installers might be covering there butts or just trying to sell you more parts.

 

[rick_d]

Check torque on all suspension parts especially the pan hard. It must be tight! My pan hard was under torqued and had same issue about same speed.

 

[Houser]

Also, defective tires will cause a death wobble. My wife had the same troubles with her 3/4 ton Ram a couple months after installing new Cooper tires. Tried all the same steps as you and ended up getting another brand of tires. Problem solved.

 

[coldtaco]

Nah i dont think it needs any other gear,
They fit thousands of these kits every year and dont seem to have any dramas with them

I came to this conclusion due to the one picture/concern you posted about how it looks like the axle is angled forward instead of upright. Usually the last thing left after doing/checking everything are the kingpin bearings but I don't think that would be doing what you are describing.

 

[Squash]

Have you personally checked the wheel bearing?
Lift both tires or one at a time and feel for any play in the hubs.
I just did my Hdj80 last week, bearings were slightly loose.
Tightened inner nut to 20ft lbs( not factory spec) and she is nice and smooth.
This takes mere minutes to complete.

 

[jblueridge]

Maybe warped brake rotors plus another problem.

 

[rick_d]

Folks this is a 2023 with 13,000 klms. Why would factory set and no messed with knuckle and or wheel bearings be an issue? Tires might be off but a spin balance will reveal immediately. He added a new suspension system. The issue is there.

 

[JuanJ]

Hello,

A suspension modification needs a camber and caster check, as well as a toe-in check.

If the values are outside spec it is necessary to correct them as it is detailed in the FSM.





Juan

 

[Mark W]

Long list of possibilities.
Since it has been modified, make sure that caster is within acceptable limits.
Make sure that the adjustable panhard bar is locked down tight.
Make sure that all the bushings are in good shape (the sure look to be in your pictures).
Carefully check for any cracking in the panhard bar mount (frame end).
Check wheel bearings for any slack.
Check knuckle bearings for any slack.
Check TREs for any slack/slop.
Check the frame around the steering box for cracks.

I don't care how new any or all of it is. Check it anyway. New stuff can break, wear and otherwise be not right. Something obviously is not rigjht.

"Death wobble" is usually not associated with the brakes being applied. But new things are encountered every day, so...

Not sure what sort of"spring loaded control arm that bolts onto the dampener" you have going on, but if that is suspect... remover the damper and see what happens.

Not sure what this means either: "apparently the stock brakes are no good on the 70 series." But OEM brakes in OEM condition are not gonna cause death wobble. Not really sure how brakes could cause DW anyway...

Death wobble needs something to start the wobble. Might be a tiny input that would normally be easily controlled by the system and you would not even be aware of it. Pretty nominal stuff. It also needs looseness/slack/slop in order for the wobble to grown and hit a harmonic resonance. That looseness is the real problem.


Mark...

 

[coldtaco]

Have you contacted the lift kit company?

 

[Indestructible 47]

I'm having a similar issue in my 79. Jmacx aren't mugs with these things - they have done thousands and maje gear that works.

Swap the rear and front tires and check for any difference.

Check the wheel bearings. Take the hub off and get in there properly, I have seen these things feel tight with the wheels on and then taken apart they're loose. Toyota doesn't do them up enormously tight from factory and they can get loose or settle in and create problems like your experiencing.

Check all nuts and bolts, but my money is on the wheel bearings. Post up the alignment charts, if you don't have them the alignment shops should keep a copy, just call them up.

 

[Rigster]

G'day,

New to the forum but ive joined hoping someone can help me out on an issue i have with my troopy.
Troopy is 2023, 13,000kms.
Had the full 4.2t GVM upgrade 4" lift coil conversion with 35" tyres.
Car drove like a dream for the first 9000kms.
Its since developed a pretty wild wobble when braking.
While driving it doesnt happen, as soon as you start braking from around 80kms it wobbles, gaining momentum until you cannot hold the steering wheel anymore.
Ive had multiple wheel balances and alignments with no improvement.
Workshop that fitted the gear said it must be either spring loaded control arm that bolts onto the dampener or the brakes as apparently the stock brakes are no good on the 70 series.
Had the bar replaced along with another alignment and balance to now improvmement.
Most recently just replaced the rotors with no improvement.
My front diff looks to be slightly leant over forward, not sure if this is meant to be plumb?
Any help would be amazing, ive contacted Jmacx directly just waiting for a reponse.

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Since this "started" after 9000km of beautiful driving, I would check your bearing preload as these can require adjustment. It has been mentioned by others as well.

Also, the radius arms you have in your picture... are they castor correcting? (IE: keep the front axle at the right tilt or castor) At a 4" lift, they need to be.

Not sure why they would suspect brakes. I have never had an issue with brake performance on my 76. The reason braking will exacerbate the issue is simple physics - braking puts more weight onto the front axle. When anything is out of spec on the steering axle, it is exacerbated with the additional forces applied.

 

[Fishbulb]

Castor, like many many people said.

Mine drove like crap after its lift until I put castor shims on the front axle.

 

[Squash]

Folks this is a 2023 with 13,000 klms. Why would factory set and no messed with knuckle and or wheel bearings be an issue? Tires might be off but a spin balance will reveal immediately. He added a new suspension system. The issue is there.

35"tires will always loosen bearings!
Hence a check and tightening pre-load over the factory specs....
Do this easy thing first and then move along to any other issues.
Own a few cruisers, so I've seen and done it.