Death wobble, fully rebuilt front end

[Sensei]

So I've got this jeep that I've had for about two years now, did pretty much everything frame down fresh, new axles, new steering, new trackbar, the whole 9 yards. Its probably easier for me to list what I haven't changed. Basically the only parts that arent fresh are the axle side lower control arm bushings, frame side control arm bushings, and the PSC steering box itself. What started as a shimmy has now turned into pretty consistent death wobble that I cant quite seem to pinpoint. It seems to consistently happen when only the drivers side tire hits a bump. On really massive bumps, it feels like the whole jeep jumps sideways to the right, and then the deathwobble starts. Passenger tire seems to handle bumps well, I do not get the same type of jumping out of the front end, nor does death wobble seem to occur. When I was running my tires around 22 psi, there was a shimmy before, but now I filled them up to 30 psi and its full on death wobble, much more pronounced. Recent alignment shows Im running around 9 degrees of caster. Im attaching some videos of some dry steering tests I did. I think im noticing the slightest bit of play in the trackbar, frame side, but that trackbar is relatively fresh. The weirdest thing Im noticing on this jeep is excessive play in the steering wheel with the vehicle off, but that seems to be going into the box itself. There also seems to be a clunk that comes back into the steering wheel, no clue where thats coming from. When I disconnected the drag link from the pitman arm, I can actually move the pitman arm maybe a mm in either rotational direction and there is a slight thud, the shaft DOES rotate with the pitman arm, pitman arm is also brand new. On decent roads my jeep doesn't really wander, unless theres like a 35 mph wind outside but I'd consider that normal. Idk to me everything is pointing to the steering box itself. It's a PSC box and I know the PO was running 37's on this thing before, but I literally bought the jeep without axles so everything else is fresh. Ive done prybar test, dry steering test, and cannot find any sort of play. Maybe you guys see something I dont?


View: https://streamable.com/ge8zfl


View: https://streamable.com/r0aq0o


View: https://streamable.com/yryq4o

 

[Sensei]

Ignore the "current measurement" specs for the rear above, rear wasnt adjusted and the result shown is from when they took the sensors off the jeep already

 

[jjvw]

Balance the tires

 

[Sensei]

Balance the tires

They have less than 5k miles on them and the weights are literally clean enough to eat off, if the balance was off, wouldnt I experience issues more akin to vibes or constant wandering symptoms?

 

[macleanflood]

Is that me or is there a ton of castor? Those Cs look leaned way back.

-Mac

 

[Sensei]

Is that me or is there a ton of castor? Those Cs look leaned way back.

-Mac

Yeah a bit high at 9 degrees according to the alignment printout

 

[Rickyd]

So I've got this jeep that I've had for about two years now, did pretty much everything frame down fresh, new axles, new steering, new trackbar, the whole 9 yards. Its probably easier for me to list what I haven't changed. Basically the only parts that arent fresh are the axle side lower control arm bushings, frame side control arm bushings, and the PSC steering box itself. What started as a shimmy has now turned into pretty consistent death wobble that I cant quite seem to pinpoint. It seems to consistently happen when only the drivers side tire hits a bump. On really massive bumps, it feels like the whole jeep jumps sideways to the right, and then the deathwobble starts. Passenger tire seems to handle bumps well, I do not get the same type of jumping out of the front end, nor does death wobble seem to occur. When I was running my tires around 22 psi, there was a shimmy before, but now I filled them up to 30 psi and its full on death wobble, much more pronounced. Recent alignment shows Im running around 9 degrees of caster. Im attaching some videos of some dry steering tests I did. I think im noticing the slightest bit of play in the trackbar, frame side, but that trackbar is relatively fresh. The weirdest thing Im noticing on this jeep is excessive play in the steering wheel with the vehicle off, but that seems to be going into the box itself. There also seems to be a clunk that comes back into the steering wheel, no clue where thats coming from. When I disconnected the drag link from the pitman arm, I can actually move the pitman arm maybe a mm in either rotational direction and there is a slight thud, the shaft DOES rotate with the pitman arm, pitman arm is also brand new. On decent roads my jeep doesn't really wander, unless theres like a 35 mph wind outside but I'd consider that normal. Idk to me everything is pointing to the steering box itself. It's a PSC box and I know the PO was running 37's on this thing before, but I literally bought the jeep without axles so everything else is fresh. Ive done prybar test, dry steering test, and cannot find any sort of play. Maybe you guys see something I dont?


View: %5BURL%5Dhttps://streamable.com/ge8zfl[/URL]


View: %5BURL%5Dhttps://streamable.com/r0aq0o[/URL]


View: %5BURL%5Dhttps://streamable.com/yryq4o[/URL]

View attachment 682541

I see a few things to address.

Like you said, there is quite a bit of play in the frame side track bar joint. I only had 1/8" or so in my track bar to give it full blown crap myself death wobble when combined with wheels that were out of round.
You notice i didn't say balance. They balanced fine but wobbled when you spun the tire by hand.

That steering box definitely seems trashed.check all the joints on the way to the box,but it does look like a lot of play on the input. Will psc rebuild it? Probably unrelated to the wobble.

Lastly, i would cut off that axle side trackbar mount and find a way to put a stock length bar back where it belongs at the factory pivot point. The double sheer at the frame is ok, but i would want its pivot point to be where the balljoint on the factory setup is. All kinds of weird things can happen with your current setup

 

[KennethS]

wheels that were out of round.
You notice i didn't say balance. They balanced fine but wobbled when you spun the tire by hand.

I recently got new tires and the shop said they balanced the wheels, but they were bent. At 40 MPH and 55 MPH it vibrates like hell, but at all other speeds it’s fine.

 

[Rickyd]

I recently got new tires and the shop said they balanced the wheels, but they were bent. At 40 MPH and 55 MPH it vibrates like hell, but at all other speeds it’s fine.

I was standing in the bay opening watching the tire jockey balance them again and saw the tire tread jumping side to side as it spun. That was my ah hah! moment to get new wheels. Crappy thing was those wheels were less than 6 months old with no abuse whatsoever.

 

[OilSpot74]

Yeah a bit high at 9 degrees according to the alignment printout

We do 100 alignments a month and I never see 9 on the castor. Might not be a terrible spot to check out.

Yeah a bit high at 9 degrees according to the alignment printout

 

[OilSpot74]

Something has the upper and lower ball joints out of whack.

 

[KennethS]

I was standing in the bay opening watching the tire jockey balance them again and saw the tire tread jumping side to side as it spun. That was my ah hah! moment to get new wheels. Crappy thing was those wheels were less than 6 months old with no abuse whatsoever.

Yeah, new wheels would be nice but as the TJ is the 4th vehicle in the fleet I can’t see spending a large sum for 5 wheels.

 

[Skylark]

Obviously not the same vehicle or situation but my wife's 06 GTO would do what could be described as death wobble under braking at freeway speed. Typically the front rotors are warped for that. I found zero run out on all 4 corners. I inspected the front end which was completely rebuilt about 20k before, nothing wrong. The car had an aftermarket rack that felt fine but the headers had cooked the boots. I found a factory rack and I was pleased that the "death wobble" under braking was gone.

 

[06TJ35's]

I have found out that no one in my area knows how to balance a larger tire. Not even a dedicated off-road shop.

I'm having a wobble at some speeds only. I really suspect they are my wheels.

I'll be chaning them out soon and Ill report back.

Currently looking for a shop that has a road force balancer.

 

[06TJ35's]

I recently got new tires and the shop said they balanced the wheels, but they were bent. At 40 MPH and 55 MPH it vibrates like hell, but at all other speeds it’s fine.

Same I think mine are bent to.

I told the tire guy which wheels balanced out better. He said two were ok to balance and the other two gave him a hard time.

Glad I talked to him to.

 

[Intimnasc]

So when mine was wobbling it took new tie rods, track bars, and adjustable control arms. After all the geometry was finally set it drives like a dream now. Each thing I fixed relieved a small amount of wobble until in the end the Savvy double adjustable arms corrected the last of it. I did the Crown automotive tie rods and I forgot who suggested it way cheaper than the currectlynk. rods. Prolly not as good but did the job for me.

 

[MikeE024]

I recently got new tires and the shop said they balanced the wheels, but they were bent. At 40 MPH and 55 MPH it vibrates like hell, but at all other speeds it’s fine.

Yeah, new wheels would be nice but as the TJ is the 4th vehicle in the fleet I can’t see spending a large sum for 5 wheels.

You don't have to spend a large sum. Vibrations aren't good for your tires

Edit: I can forward PHX FB marketplace finds if you are interested (lmk if you have a specific style or model you prefer)

 

[Skylark]

I was standing in the bay opening watching the tire jockey balance them again and saw the tire tread jumping side to side as it spun. That was my ah hah! moment to get new wheels. Crappy thing was those wheels were less than 6 months old with no abuse whatsoever.

I used to manage a tire and auto shop. You'd be amazed at how many steel wheels wobble on the balancer when they're brand new. I'd always try to talk someone into an aluminum wheel just to avoid that.

 

[John Cooper]

I used to manage a tire and auto shop. You'd be amazed at how many steel wheels wobble on the balancer when they're brand new. I'd always try to talk someone into an aluminum wheel just to avoid that.

Yep that's why the majority of big trucks run aluminum on steers and drives, they save the steel for trailers.

 

[Rickyd]

Yeah, new wheels would be nice but as the TJ is the 4th vehicle in the fleet I can’t see spending a large sum for 5 wheels.

I bet we could help you out for under 500$?

I used to manage a tire and auto shop. You'd be amazed at how many steel wheels wobble on the balancer when they're brand new. I'd always try to talk someone into an aluminum wheel just to avoid that.

Yep, cheap steel wheels from bart wheels