# how can I determine what degree of shim's I have?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by solowookie, Dec 25, 2001.

1. ### solowookie1/2 ton status

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how can I determine what degree of shim\'s I have?

ok guys; there is the scenario;

when I lowered JMT back to stock height the front went stock, but the rear had a combination of body lift, blocks, and springs. well I took out the blocks (will take out the rear body lift at some point), but left the springs.

had vibration so I raised the t-case which helped, but not enough. I took the shims off the front, and put them in the rear which also helped, but again not enough.

I am ordering a driveline angle finder, but in the mean time I'm wondering if I can determine what degree my shims are so I know what I should order; or do I have to take the shims out and then mearsure it?

<font color=blue> Jeff - may the force be with you</font color=blue>

2. ### solowookie1/2 ton status

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Re: how can I determine what degree of shim\'s I have?

jms, how in the WORLD do you know all these equations?

<font color=blue> Jeff - may the force be with you</font color=blue>

3. ### solowookie1/2 ton status

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Re: how can I determine what degree of shim\'s I have?

yea, I figured it had to be something like that - I don't think there would be many members capable of those equations...

<font color=blue> Jeff - may the force be with you</font color=blue>

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Re: how can I determine what degree of shim\'s I have?

Actually, I expect there are quite a few who know the basic rules. At least the fabricators and those who work in machine shops. Not to mention engineers of various sorts. I've worked a bit in all 3 areas and I have needed that information repeatedly.

For what it's worth, there are 3 simple Trig helpers to find angles based on simple measurements of the sides of right triangles (like your shim).

SOH CAH TOA
Memory aid: "Soak a Toe(a)" {pronounced toeah}

SOH =&gt; Sine = Opposite / Hypotenuse =&gt; angle = InvSine * (O / H)
CAH =&gt; Cosine = Adjacent / Hypotenuse =&gt; angle = InvCos * (A / H)
TOA =&gt; Tangent = Opposite / Adjacent =&gt; angle = InvTan * (O / A)

For practical purposes, the most useful is TOA. Take the length of the side "opposite" the angle of interest and divide it by the length of the side adjacent to the angle of interest.

So, the angle is equal to the inverse tangent (arctan) of the rise (height of the tall side of the shim minus the height at the short side of the shim) divided by the run (length of the shim). This is the formula that jms gave you expressed specifically for your problem. By knowing the general solutions/rules you can apply the same thing to other similar problems. You can apply any of the three helpers in the same way and find any angle on a right triangle given the length of any 2 sides.

The corollary is that given an angle and the length of any side, you can easily calculate the length of any other side by simply rearranging the equations.

Simple trig rules are absolutely invaluable for fabricating.

Russ

85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.

5. ### hammer1/2 ton status

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Re: how can I determine what degree of shim\'s I have?

strange thing is I understand what baddog said.

<font color=red>Let me at it I can break it</font color=red>

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