# Understanding Driveline Angles

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Stoopalini, Dec 9, 2002.

1. ### Stoopalini1/2 ton status

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I wanted to start this post discussing driveline angles so I can have a better understanding of them. I know you can measure the angles and determine if they are reasonable or not, but I would like to understand how changes to the driveline effect the angles themselves.

Right now, I'm running a 2 1/2" ORD shackle flip on stock '90 K5 springs and a 14B/FF. My T-case is dropped using the factory spacers (1" maybe?) and my angles are off by 1'. My research suggests that 1' off is as perfect as you can get.

So, If I raise the t-case back up, how much will this affect my angles? It would seem that because the t-case is being raised and lowered in parallel, that the angles wouldn't change much in respect to each other. In other words, if my angles right now are 6' and 7', it would seem that raising the t-case would make the angles steeper, but shouldn't they change the same amount with respect to each other?

Or, if my angles are good right now with the t-case dropped 1", can I raise the t-case back up, add 1" add-a-leafs, and expect the angles to stay exactly the same?

If not, how can I go about determining what degree shim to use? Will the degree shim needed change if I use a 1" add-a-leaf that is tapered?

Thanks for any input on this,
Thomas.

2. ### Shaggy3/4 ton status

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<font color="green"> Math is your freind... Measure out all the dimensions that you have now. I use the frame as the unchanging reference point, so measure everything that affects the u-joint angles in relation to it. Include -

the angles of the t-case output and pinion (in relation to the frame)
hieght of each end of the leaf springs in relation to the frame ( you need this so if you add a shackle flip or something, so you can figure out the change in angle it creates on the pinion)
distance from the pinion to the t-case,
height differences between the pinion and frame and the t-case output and frame.

Once you have all of this info you can use trig to figure out anything you want. Make a change to something and use trig to figure out what needs to be adjusted in order to make it work. </font color>

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4. ### Stoopalini1/2 ton status

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Hey, thanks for the link. It definitely helps me understand how the angles work.

Thomas.

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