Shim's
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Shim's
I'm not sure if any of you guys are familiar with this, but here goes. I have extreme negative caster since I installed the lift springs on my truck (in sig). Now, I'm getting terrible, no... HORRIBLE death wobble. I've heard getting an alignment helps, which I am going to do BUT I was wondering about something.
Can I correct the caster somewhat by adding some shims to the front? I'm well aware that a full-on block to lift the front is a big no-no, but a shim is not that big. Has anyone even considered this? This would also set my pinion pretty much to the way it was stock, eliminating any additional wear and tear on the drivetrain. I've read having a postive caster is the ideal thing, and my caster is extremely negative.
Any thoughts/suggestions are appreciated.
Joey
Can I correct the caster somewhat by adding some shims to the front? I'm well aware that a full-on block to lift the front is a big no-no, but a shim is not that big. Has anyone even considered this? This would also set my pinion pretty much to the way it was stock, eliminating any additional wear and tear on the drivetrain. I've read having a postive caster is the ideal thing, and my caster is extremely negative.
Any thoughts/suggestions are appreciated.
Joey
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You have me confused with the whole negative / positive thing. Too much caster means that the knuckle is rolled to far foward (positive), and that creates the shopping cart affect, or death wobble. The opposite should make the steering very slow, and actually drive very well at high speeds. Again the steering is slow, and the radius is compromised. How did you lift your truck to change the angle so much? Just changing the springs would not have that greaat an affect on the caster, unless you installed longer shackles, or a hanger kit incorrectly.
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okay, I read up again on what everything means, lol... and I definitely have a postive caster, since the top balljoint is behind the lower balljoint in relation to the vertical plane...
http://www.familycar.com/Alignment.htm
positive caster is what causes the "death wobble" apparently, not the other way around, unless I'm reading something incorrectly... and its so out of spec, its noticeable...
Joey
http://www.familycar.com/Alignment.htm
positive caster is what causes the "death wobble" apparently, not the other way around, unless I'm reading something incorrectly... and its so out of spec, its noticeable...
Joey
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We still have to figure out why this is the case. It should not be with only 2" springs. Did you install springs or shackles? The only way for the condition to exist the way you describe is to lower the rear of the spring too far.
This affect is bumpsteer, and is different from the wobble that occurs when the knuckle is too far foward, and the steering is too fast. We could talk about this all night, but to correct your problem, you could install some shims, or wedges, but the come in different angles, or degrees of pitch. Knowing howw far this thing is out is important. If you lifted the truck with shackles only, then the problem is there, and the band-aid shim is not the true solution to your problem.
This affect is bumpsteer, and is different from the wobble that occurs when the knuckle is too far foward, and the steering is too fast. We could talk about this all night, but to correct your problem, you could install some shims, or wedges, but the come in different angles, or degrees of pitch. Knowing howw far this thing is out is important. If you lifted the truck with shackles only, then the problem is there, and the band-aid shim is not the true solution to your problem.
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the springs are apparently the same length as the stock ones if you measure along the spring... however, the springs have more of an arch to them, meaning from eye-to-eye the lift springs measure less... before the lift, the shackles were really close to hitting the frame rail, but that would never happen because the springs were pretty much flat... now, the shackles at a good 45* angle, so I guess now I see where you coming from by asking me if I installed shackles alone... so, if you think about it, the shackle is the correct length if you extend the springs completely...
I hope you guys are understanding my logic on why using shims could work... let me try to get some pics right now, so you guys can see how far out of spec I think it is...
Joey
I hope you guys are understanding my logic on why using shims could work... let me try to get some pics right now, so you guys can see how far out of spec I think it is...
Joey
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your shim idea is an alright fix, it is done all of the time. It will also correct the angle of the front u-joint. If the caster is as far off as you say, then the pinion angle has got to be way off too. This should not happen with only two inches of lift, that is why I believe there is something we are missing here.
Pics would be helpfull.
Pics would be helpfull.
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here is an interesting observation...
this is the DR 4" Lift with springs in front for 2000-2004 SD's... the part of the kit that is highlighted in red are what looks to me like shims... I'm guessing DR realized what happened and they addressed it with those shims... any ideas?
Joey
this is the DR 4" Lift with springs in front for 2000-2004 SD's... the part of the kit that is highlighted in red are what looks to me like shims... I'm guessing DR realized what happened and they addressed it with those shims... any ideas?
Joey
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If the springs are installed correctly, and the springs are correct the pinion should never change angle. The real purpose for the shims, is to correct the pinion angle from the added heigth. The downside to too much lift and too much wedge is hat the axle has to be rolled too far foward, thus creating steering that is too fast, and the end result is the shopping cart affect. I have never seen a shim (wedge) used to change the pinion angle on such a smal lift. The reason your angle is so far off with such a short lift, has me baffled.
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just springs by itself in the front... just wanted to let you guys know that I already had this slight problem before the springs, but they were AMPLIFIED after the springs were installed... now, maybe my balljoints are on there way out but there is no play in them from what I can tell (used a crow-bar)... but, her are some pics... its dark outside, so this is the best I could do right now...
Old springs vs New springs:
Shackles after lift springs installed:
wow, I guess its more like a 60* angle on the shackle compared to the rough 20* it had before...
Joey
Old springs vs New springs:
Shackles after lift springs installed:
wow, I guess its more like a 60* angle on the shackle compared to the rough 20* it had before...
Joey
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One of my biggest concerns is that when the spring compresses, the shackle has to pivot towards the back of the truck as the spring gets longer. With that angle it may not have enough room to do so.
That is a totally different issue than the caster problem. The caster should stay the same, even if the spring was a 10 inch unit, the caster should remain the same.
Here is a thought, did the center pin engage the hole in the pad correctly on both sides? If one missed and is too far foward or towards the back it will put an incredible amount of torque on the tubes, and create different caster for the two front wheels, and could cause your problem. The same is true if one did not go into the hole all the way. Did you check the bottom of the spring where it meets the perch to see if there is any type of gap?
That is a totally different issue than the caster problem. The caster should stay the same, even if the spring was a 10 inch unit, the caster should remain the same.
Here is a thought, did the center pin engage the hole in the pad correctly on both sides? If one missed and is too far foward or towards the back it will put an incredible amount of torque on the tubes, and create different caster for the two front wheels, and could cause your problem. The same is true if one did not go into the hole all the way. Did you check the bottom of the spring where it meets the perch to see if there is any type of gap?
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no gap whatsoever, the center pins went all the way in, etc... not the first time I've changed out a set of leaf springs ... and I've already torqued everything after about 100 miles of driving... personally, I don't think there is going to be a problem with the shackle, because the lift springs when compressed will be the same length as the stocks ones (which were flat to begin with, refer to above pic)... if the springs were longer along the actual spring (not measured from eye-to-eye), then yeah, there wouldn't be enough room for the springs to fully compress with the stock shackle, which is not the case with these springs...
I guess I'm actually stumped... I wonder what does other people with 2" lift springs shackles' look like (not hangar/shackle lift or mini-pack)...
Joey
... and I've already torqued everything after about 100 miles of driving... personally, I don't think there is going to be a problem with the shackle, because the lift springs when compressed will be the same length as the stocks ones (which were flat to begin with, refer to above pic)... if the springs were longer along the actual spring (not measured from eye-to-eye), then yeah, there wouldn't be enough room for the springs to fully compress with the stock shackle, which is not the case with these springs...I guess I'm actually stumped... I wonder what does other people with 2" lift springs shackles' look like (not hangar/shackle lift or mini-pack)...
Joey