Swapped to 4x4, now the truck dances all over the road

[purplestaff]

I recently 4x4 swapped my 1985 c20, I used a donor 4x4 half ton that had the back of the frame rusted out for the brackets. But now the truck dances all over the road, I measured from same spots on frame to the axle and it all seems even side to side. Nothing is loose in the front end. Anyone else 4x4 swapped their truck? Did you have something similar? I had an idea that the frame was flexing where the steering box is, seeing as how I'm test driving it without a bumper on, anyone heard of that?

 

[Shorty81]

I recently 4x4 swapped my 1985 c20, I used a donor 4x4 half ton that had the back of the frame rusted out for the brackets. But now the truck dances all over the road, I measured from same spots on frame to the axle and it all seems even side to side. Nothing is loose in the front end. Anyone else 4x4 swapped their truck? Did you have something similar? I had an idea that the frame was flexing where the steering box is, seeing as how I'm test driving it without a bumper on, anyone heard of that?

is it lifted? Make sure you have the correct steering arm. It needs to be close to horizontal.

 

[purplestaff]

is it lifted? Make sure you have the correct steering arm. It needs to be close to horizontal.

Not lifted, I just leveled the back to stock height 3/4 ton springs in the front. The steering is off a half ton though. Apparently I wasn't thinking, toe is 7/16 out, gonna get it under an 1/8 and see what changes, I'll check the steering arm though, maybe the half ton and 3/4 are different since springs are maybe taller? I don't know, new to these trucks, have a few gmt400s that I know good though.

 

[purplestaff]

Just went and looked, took a couple of pictures. Sorry if they aren't very good it's dark now. Seems like the arm is relatively straight. Maybe slightly angled down?

 

[Ricko1966]

Not lifted, I just leveled the back to stock height 3/4 ton springs in the front. The steering is off a half ton though. Apparently I wasn't thinking, toe is 7/16 out, gonna get it under an 1/8 and see what changes, I'll check the steering arm though, maybe the half ton and 3/4 are different since springs are maybe taller? I don't know, new to these trucks, have a few gmt400s that I know good though.

It's supposed to be toed in not toed out. Toe out will make most cars super twitchy,it will quick steer no matter which way you turn. It is a racer trick though to get the car to turn in quicker.. Also not enough caster will make them super squirlley get your alignment right then post back of it still acts funny.

 

[Originalthor]

How is your steering stabilizer shock? If those die it will affect handling alot. The best ones I've found are the Ranchos. I hate there shocks but like there steering stabilizers

 

[Grit dog]

How is your steering stabilizer shock? If those die it will affect handling alot. The best ones I've found are the Ranchos. I hate there shocks but like there steering stabilizers

Not in my experience.
If a steering stab helps much in daily driving, you have other steering issues to fix.

 

[Grit dog]

Assuming steering components aren’t worn out, toe and caster are the 2 things that will make it drive bad. (Unless what you’re feeling is a wore out steering box).
“Frame flex” is a non issue when driving straight ahead normal conditions. There’s very little stress on it driving straight.

Obviously get it set to toe in a smidge and see what happens.
Considering it’s custom fab work I wonder what your caster is and if you were able to maintain proper caster in the 4wd swap. Could be an issue too.

 

[Rickf]

Might be a SWAG but any cracks in the frame around the steering box?

 

[squaredeal91]

centering pin?

 

[purplestaff]

Might be a SWAG but any cracks in the frame around the steering box?

No cracks, I just had it all apart and made sure to look

 

[purplestaff]

I will set the toe in tomorrow and get back ti you guys, thanks for the input

 

[Strick]

Check to make sure that you don't have a brake caliper hanging up on you as well.

HS

 

[bucket]

I will set the toe in tomorrow and get back ti you guys, thanks for the input

Yes, without setting the tow, everything else is just a shot on the dark. It HAS to be set correctly for the truck to drive decent. Like Ricko said, it should be slightly tow-in. You are way off right now.

 

[Ricko1966]

You did your 4x swap. This question is not to insult you,but do you know what caster is,and what things can change it?. I ask because if you were unaware that the rotation of the front axle beam relative to the frame is critical. If the front axle beam is rotated it will affect caster. Things like are the spring mounts on the right location,right height,etc. If you look at the front wheels on a grocery cart the way they trail when you push the cart. That is caster. Without that trailing effect the wheels would go every which way..