making drive lines

i want to make new drive lines for my xj and i want to know wat the best way to do it is. i can machine and weld. the front i will probaly extend the main tube and put a slip joint in the tube with a hack and tap.how do i figure lengths? i will soon put a little more lift on with some pucks in the front and blocks in the rear for now. i will cnc the pucks and buy the blocks.

i really need help to figure lenths. i will probaly end up with 6 in of lift on my 4.5 lift.

You don't know math?

its not the math its how far do i make the slip part out so it can extend and contract. math im good at, took algebra 5 times!! haha

Well - think what it has to do - if you still have short arms: driveline is longest at full compression

If you have a long arm system you need to measure as some are at max comp. and some are longest at droop

Take out the springs and measure the extended length (yoke centerline to yoke centerline) at full compression and the do the same at max droop - - the differance is the slip travel needed - add ~.75" to each end and set it so at ride height your slip is mid travel... There you have it - chop up your existing - on the lathe turn the yoke welds off and press on some new tube!

Matt

PS - just be sure to phase to yokes when you weld them on the tubes - ujoint caps parallel to each other