Alignment Problems...any ideas?

[westofb]

I will start by telling you what I got. I have a 75 c 20 truck that I have converted to 1/2 ton suspension and lowered it. I used the following parts to make it a 1/2 ton: 1) 1/2 lower control arms and ball joints 2)3/4 ton upper control arms with 1/2 ton ball joints 3) 1/2 ton 1.25" thick rotors 2.5" lowering spindles 4) 1/2 ton springs with one coil cut off. My issue is with alignment, by lowering it in this fashion, the lower control arms are nearly level with the ground, thus my wheel track is about 2-3" inches wider over stock. Since the wheel track is wider, the upper control arms do not have enough adjustment on the studs through the cross shafts to get the alignment anywhere close to factory specs.

I figure the easiest cure would be to find a company that makes lower control arms that have the ball joint move inward about 1", but I have found no such animal. The second cure would be to find upper control arms that have the ball joint moved outward about an inch. The alignment shop, got it as close as possible, could not get both the camber and caster to spec, either one or the other. They said they aligned it so it would not wear out the tires (not sure which one the adjusted caster or camber, I know one is the lean of the tire from inside to out and the other is the lean forward to back, I am not an alignment guy so I don't know which is which).

The truck drives okay, but has bump steer issues, hitting small bumps wants to make it wander a little. I could live with it as is, but I would just as soon get if fixed to make it more enjoyable to drive. Any and all suggestions would be appreciated.

The best cure would be the lower control arms if someone makes them, surely someone makes a lower control arm with inward set ball joints.

Here is a pic of the truck as is sits now, I love the stance!

[lolife99]

Got any pics of your suspension?
Did the truck have any prior frame damage?

[westofb]

Originally Posted by lolife99

Got any pics of your suspension?
Did the truck have any prior frame damage?

No I don't have any pics of the suspension, I could get them, but looks like another suspension that I have seen. No there is no damage to the truck what so ever. I would not went to the trouble of doing the swap to 1/2 ton, except the truck was in awesome shape, CA truck, no rust, 65K actual miles, 454/ th400 silverado. The suspension is basically half ton now, the only difference is the upper control arms, the studs that go through the cross shaft are much larger than 1/2 ton ones, so I stayed with the 3/4 ton arms and changed ball joints to half ton, which bolted directly in place of the 3/4 ton ones. Just trying to figure out how to make it drive a bit better, it is okay as is, but could stand improvement.

[lolife99]

Originally Posted by westofb

No I don't have any pics of the suspension, I could get them, but looks like another suspension that I have seen. No there is no damage to the truck what so ever. I would not went to the trouble of doing the swap to 1/2 ton, except the truck was in awesome shape, CA truck, no rust, 65K actual miles, 454/ th400 silverado. The suspension is basically half ton now, the only difference is the upper control arms, the studs that go through the cross shaft are much larger than 1/2 ton ones, so I stayed with the 3/4 ton arms and changed ball joints to half ton, which bolted directly in place of the 3/4 ton ones. Just trying to figure out how to make it drive a bit better, it is okay as is, but could stand improvement.

I just wanted to see the upper a-arms and the tie rods.
There has been a rash of people installing the inner tie rods and center link incorrectly. I'm just trying to see what's causing the bumpsteer issues.

[westofb]

Originally Posted by lolife99

I just wanted to see the upper a-arms and the tie rods.
There has been a rash of people installing the inner tie rods and center link incorrectly. I'm just trying to see what's causing the bumpsteer issues.

All those parts are orginal to the truck, they were in excellent shape and they fit with the swapped in parts, so I left them installed. I am pretty sure the bump steer is coming from the alignment issues. I would guess the alignment shop set the camber as close as possible, but the caster is way off resulting in the driving issues. When rounding a corner, the steering wheel does not want to self center as it should, you actually have to turn it a bit to get it go back to center. I used the term "bump steer", actually the truck just tends to wander a bit over rough spots in the road. Or they set the caster and the camber is off, not sure which, they said they set it so it would not wear out the tires and they told me it probably wouldn't drive like it should...they were right! In it's current form, I could live with it, but I don't mind spending a little cash to get it driving better. Just from what I have read, I am guessing they set the camber and the caster is way off.

I think the alignment shop would have caught this if that was the case....well they should have!

[lolife99]

I had a buddy install the upper a-arms on the opposite sides of the truck.
He had them off changing upper balljoints, and thought he put them back on the correct sides. The caster was way off.
My blazer was static dropped 5.5" in the front and it drove really good with CPP tubular upper a-arms. (they supposedly add addition caster)

[68laydout]

Originally Posted by lolife99

I had a buddy install the upper a-arms on the opposite sides of the truck.
He had them off changing upper balljoints, and thought he put them back on the correct sides. The caster was way off.
My blazer was static dropped 5.5" in the front and it drove really good with CPP tubular upper a-arms. (they supposedly add addition caster)

Yeah it's not hard to do and it will throw the caster way off! Caster is front to back. The camber looks ok in the pics. The spindle is probably rocked back too far causing the issues you describe. Something as simple as the control arms being on opposite sides like lolife99 said could be the issue. Easy fix if so.

[875.3CHEVY]

what you need is an offset control arm shaft.i got mine from advance autoparts.its only offset about 1/2 ' though.but it fixed my problem.moog Part No. K6355

[LONGHAIR]

Originally Posted by westofb

. When rounding a corner, the steering wheel does not want to self center as it should, you actually have to turn it a bit to get it go back to center. I used the term "bump steer", actually the truck just tends to wander a bit over rough spots in the road.

These are 2 differnt things.
First, the steering wheel not re-centering is a caster issue. You are probably lacking "positive" caster. This not only straightens the wheels after a turn, it aids in high-speed stability.

"Bump-steer" is a "geometry" issue of the travel arcs of the supension itself and the ralationship of the steering parts (outer tie-rods). If these arcs of travel do not "work together" the wheels "toe out" (or in) during suspension movement. As the "toe" changes, the vehicle "wanders" trying to follow which-ever tire is "dominant". It is not really and alignement issue. The alignment could be "dead on" and still have bump-steer problems.

This could very-well be at leat part of your problem. You stated the the track width had changed, but those pivot points have not....But an inch of difference from the upper to lower arms sounds like a lot, for no more than a single coil cut from a stock spring? There must be some issue caused by the mixing of the 1/2 and 3/4 ton parts?

It would be really good to see a picture of the front suspension at ride height.

[westofb]

I will try to get some pics of the front end tomorrow. As far as wheel track width changing, that is from the lowering itself. At stock ride height, the lower control arms are sitting at an angle, not sure of exact amount but probably in the neighbor hood of 25+ degree. By cutting off the coil, the lc is now almost level with the ground, raising the ball joint socket in relation to the control shaft, thus increasing wheel track. When I get it raised up to take some pics, I get some measurements of the upper control arms, and a set of 1/2 ton control arms that I have sitting around.... As far as getting the uppers switched from side to side, not possible, never removed them from the truck...besides, they only have a hole on them on the front edge where the brake hose bolts on. I am not even sure you could get it bolted together that way, if you did the upper ball joints would be so far rearward attaching the spindle between the 2 would be very tough.

I spent yesterday on the phone with DJM suspension parts, and then call air bag it and spoke with them. The tech guy at DJM did not seem to have any idea what he was talking about. I told me chevy never made a 3/4 ton truck in 75, only 1/2 and one tons, and when asked about some of there products, he wasn't even swore they made no such part....after getting on the internet, I got him the part numbers for the parts he said did not exists, he got pissed and was no help what so ever. The airbagit tech guy actually sounded like he knew what he was talking about. He suggested upper control arms to cure my alignment woes, I think he said I would have to use 1/2 ton uppers and use the 3/4 ton control shaft. He said the upper control arms relocate the ball joint outward and forward over the stock arms. I have heard of people having trouble with airbagit, so for now I have not ordered anything yet.