Front end help needed !

[toojayzee]

Please read my story and help see if you have any advice on the problems im having (related to the vehicle)
Some of you have have read my build thread for the v8 swap. That was just the begining of a long road.
Since the swap runs as oem as can be, im doing my best to sort out problems. Power window motors, lockers, leaks etc.

When I got the rig it started off with - 315/75/16 MTR's that were about 50% tread but cupped and worn wrong. It had a 2.5" OME lift with the OME caster bushings and some type of home brew welded washer on the lower front control arm to increase the caster further.

The rig seemed to drive ok, but as time went on I wanted to start getting it to drive more like a maintained vehicle than a jalopy.

The front hub nuts were loose and the spindles were damaged from that. So I replaced the spindles, hubs, bearings/races, calipers, pads and rotors since the majority of that stuff was trashed.
I also did rotors, pads and calipers in the rear at the same time.

The beast drove much better but there was still a slight shimmy and as the months ran by, the tires became more chewed up.
At this point I was holding off on a tire purchase because I didnt want to throw money out the door if I couldnt narrow down the problem.

I decided that the oem bushings may have been shot so I ordered up the full set of bushes from ebay austrailia. What a pita it was to do that job. Took a full day for the entire rig setup.
That fixed a little more of the shimmy but as time went on I still wasnt fully satisfied.

Goodyear was having an $80 rebate if you bought 4 315/75/16 MTR Kevlars so I shoped the priced and pulled the trigger. Got them mounted up two weekends ago in hopes that it would fix the remaining problems I was having. Big negative on that. WTF Over.

At this point im pissed off and worried that im going to destrooy $1,400 worth of tires... and the only thing I hadnt done was rear wheel bearings. So I did those. The old ones were worn quite a bit and I got a little more of the vibration out. Now im passed being pissed and just frustrated

Now before you think drivelines, its not a driveline vibration im feeling. Its in the tires for certain. And it was causing cupping and shredding of the tires which im fairly certain wouldnt be caused by drivelines.

I had been bothered with the fact that the axles werent dead center so I decided I would get the slee panhard adjusters.
I figured WTF, since im throwing money at the fawker cause I daily drive it and want it to run totally sweet, lets throw some trunion bearings, front kuckle rebuild kit and tie rod ends at it.
Then the rig will ostensibly be brand new under the frame.

I installed all that stuff on saturday and took it for a ride, boy was it smooth as silk. At 70mph on the freeway it felt like my wifes lexus, but darted around a bit. So im thinking fawk yea finally some major headway. Time for a lifetime alignment from firestone.

Get that biotch in for an alignment sunday morning first thing. Got it back, holy sh1t it darts around even more now. Called them up yesterday, explained the situation. Brought it back to them last night, worked with the tech to put a little more toe back into it, and road tested it three different times. Still darts around a bit. Thier lead tech is thinking worn steering box.
When we move the steering wheel, the pitman arm moves right away.

Where to go from here ? Make some small adjustments to the steering box maybe ?

Please advise (and no I wont be giving the beast away due to frustration. Ill just be keeping it longer once I get it figured out )

 

[toojayzee]

More details. I had the guy set it at .30 each side for toe last night.

Here is the settings as the rig went in for the first time sunday morning with lots of toe because I used a tape measure to adust the drag link and tierods. It did drove smooth and straight with that huge amount of toe.

 

[Pin_Head]

"Darting" implies sudden movement, right? The caster is correct, so the wheels should have plenty of self centering force and they should not be wandering without some input from the steering linkage. Since it is still darting, maybe there is some wear or slop in any component that locates the wheel, so it is changing the wheel location. This could include slop in things you think you have fixed, so it may be worth a second look. Jack up the wheels and check for play in the vertical and horizontal directions and look for slop in all the linkage from the steering box to the wheel.

Does the darting correspond to anything, like hitting a bump? If so, it may be bump steer. I'm just throwing that out there because you are getting to the bottom of the list of possibilities.

 

[toojayzee]

Yea I should include in the list, and also mention wandering. I chase the wandering with the wheel. The rig walks back and forth in the ruts on the freeway. It goes right so I chase it with a little left, just when the rig starts to go left, ill have to correct and give it a little right...
I've been reading a bit more this morning and it seems probable that it could be the steering box. Its just so weird why it drove so awesome with so much toe holding it in place.
The bump steer I had is gone now with the panhard extensions which is awesome.
Everything feels solid. I guess ill have to pull the draglink off and see if I can move the pitman by hand w/o affecting the steering wheel.

"Darting" implies sudden movement, right? The caster is correct, so the wheels should have plenty of self centering force and they should not be wandering without some input from the steering linkage. Since it is still darting, maybe there is some wear or slop in any component that locates the wheel, so it is changing the wheel location. This could include slop in things you think you have fixed, so it may be worth a second look. Jack up the wheels and check for play in the vertical and horizontal directions and look for slop in all the linkage from the steering box to the wheel.

Does the darting correspond to anything, like hitting a bump? If so, it may be bump steer. I'm just throwing that out there because you are getting to the bottom of the list of possibilities.

 

[Pin_Head]

The only explanation I can think of for why it drove well with excessive toe in is that the toe creates force that "loads" one side of a worn or lose component so that it can't easily flop back and forth. The steering box is adjustable for slop in the sector gear and worm gear follower. Don't over do it and make the box so tight that it won't self center.

If it wanders too, then I would wonder if the caster measurements are correct. Maybe they are negative caster?

Pan hard adjustment won't change bump steer. This is determined by the angle of the drag link.

 

[LINUS]

Is the "homebrew front caster correction" still on the rig?

I'm betting you already deduced the cupping is from the extra toe you currently need to achieve a smooth ride. -At least that would be my thought as I did the exact same to my MTR's (old version) when I was still running around on my bent front housing.

And that leads me to the following - have you double checked with a straight edge that you aren't running a bent front housing too? After I bought my new one I was talking about it to Christo (who else would know the breaking points better-right?) - he said it's semi-common to bend a front housing.

I bent my housing pretty hard, I had metal shards from the inner driveshaft where it meets the diff & the diff cuff that holds the shaft was beating metal shards off it too - when I straight edged mine I found I'd bent mine a good 3/8" from center to PS trunion bearing. The day I did it I wouldn't have said the hit the axle experienced was all that great either - and I'm really a conservative granny driver in my mind.

 

[toojayzee]

The homebrew caster correction is still in place, but looks like it may have moved the hole 1/8" max on the front of the two lower holes. And I am running the blue caster correction bushings from AUS as well. From past experience more caster has made drive straight with less effort.
Agreed about the cupping. I wonder how much toe it had before I screwed with the front end alignment ?

I havent checked it for a bent front end. Looking at these things I dont know what it would take to check that, let alone what kind of damage it would take to bend one.
I replaced my left birf and no shavings were present then.
Nor when I took both sides apart this weekend to replace the trunions.

Ill definatly check that tonight but, I would think that an alignment would reveal a bent housing no ?

Is the "homebrew front caster correction" still on the rig?

I'm betting you already deduced the cupping is from the extra toe you currently need to achieve a smooth ride. -At least that would be my thought as I did the exact same to my MTR's (old version) when I was still running around on my bent front housing.

And that leads me to the following - have you double checked with a straight edge that you aren't running a bent front housing too? After I bought my new one I was talking about it to Christo (who else would know the breaking points better-right?) - he said it's semi-common to bend a front housing.

I bent my housing pretty hard, I had metal shards from the inner driveshaft where it meets the diff & the diff cuff that holds the shaft was beating metal shards off it too - when I straight edged mine I found I'd bent mine a good 3/8" from center to PS trunion bearing. The day I did it I wouldn't have said the hit the axle experienced was all that great either - and I'm really a conservative granny driver in my mind.

 

[landtank]

check your tie rod ends for sure and the steering box is checked with the engine off.

 

[toojayzee]

check your tie rod ends for sure and the steering box is checked with the engine off.

Just put the new 555 TRE's in and they feel solid.
I am going to pull the TRE that at the pitman tonight and check the box with the rig off.

Im really wondering just how much play I should have.

 

[landtank]

why would you pull that TRE?

 

[landtank]

another thing you might want to check is the lower steering arm studs. They've been known to back out.

 

[toojayzee]

why would you pull that TRE?

another thing you might want to check is the lower steering arm studs. They've been known to back out.

I figured I would pull the TRE so I could grab the Pitman and move it to check play w/o having to turn the wheels.

I just torqued the arm studs when I did the knuckle rebuild on saturday but ill take a look again just to be sure.

 

[landtank]

you turn the key to the on position and then rock the steering wheel back and forth to feel the play in the steering box.

You need the box to be attached to the linkage.

 

[LINUS]

I was fortunate to have lift access & I have a decent eye, so just sighting acroos the housing I swore the housing looked bent so then it was just a matter of proving what I thought I saw, so while I was doing my 3rd member swaps to get lockers in, I was seeing shards in my diff fluid that had started showing up after the incident where I was pretty sure I'd done something - and I didn't have it in my diff fluid before that.
It was real helpfull that I was going to full teardown anyhow, and the wear spots I saw just confirmed what i thought I was seeing.
I also had "birf soup" that started right after the bozo move that bent the axle & I came to understand it was because the inner shaft wasn't riding like it should against the seal since the seal location was now shifted slightly.

I had my PS inner driveshaft splines chewed & the cuff for that side in the diff was chewed too, so what I did was to use 2 carpenter squares & measure the inbetween them front & rear - I came up 3/4" difference front to rear, so divide that by 2 = 3/8" bent. It bent right where the housing transitions from the diff bellhousing to the PS tapering box shape.

If you butt the squares' corner right to where the housing "balls" are attached, then measure you can if it's bent horizontally - the taper in the design of the housing makes using my method impossible for vertical checking of trueness though - but maybe Rick or one of the other resident smart fellas could give you a way to check this.

Chances may be slim, but if you have somehow checked near everything else, then it's possible. HTH

 

[Pin_Head]

If the axle housing was bent, you would expect the camber to be off and it is not.
Cupping is caused by bad balance and/or bad shocks. Bad toe in causes scuffing and feathering of the tread.
More caster provides more self centering force, but increases steering effort.

Check for slop in things you haven't checked yet, like the control arm bushings and brackets, cracked frame. Get the truck up on a lift with a big pry bar and check for movement in anything that shouldn't move.

 

[toojayzee]

I just adjusted the fine adjustment on the steering box. That made a difference in the wheel slop, but it doesnt feel like there is enough range of motion to take out the rest of the slop. I've used the max amount of adjustment the FSM allows for. I presume that means the gear is worn beyond specs ?

 

[Pin_Head]

I kind of doubt it is the gear box. A worn out box gives too much wheel free play before it turns, but it wouldn't make the truck wander and feel darty.

 

[toojayzee]

I kind of doubt it is the gear box. A worn out box gives too much wheel free play before it turns, but it wouldn't make the truck wander and feel darty.

I think I have two things going on here. I think the reason the truck darts around is because I have either too much or not enough toe at this point.
The steering wheel has alot more play than I originally gave it credit for. Everything else is new upfront.

 

[landtank]

as Pin head said check the frame around where the steering box bolts to. They have been known to crack there allowing the steering box to shift around.

 

[Pin_Head]

Some toe in is good for straight line stability, but you don't need much. Maybe the alignment machine is lying and you really have toe out or zero toe in? Toe out causes darty handline, especially if you have some play in the steering components. You can eyeball toe in to at least be sure it is not zero or toe out. You just put the wheels straight and sight along the inner edge of the tire to the rear tire. If you have wheel spacers, you may need a bit more toe in as the wheel gets out farther away from the knuckle turning axis.