need some measurement help

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Oct 7, 2004
My 1 ton build is moving along. I need some help. I need to know the compressed length of a rear j spring and of a 6" rear slee spring (preferably the heavy spring) as they sit on an unloaded 80 series. (please measure at neutral height from the top of the spring where it hits the upper spring seat to the bottom of the spring where it hits the axle side spring seat. don't measure bumpstop) These measurement will greatly help me properly weld up the axle spring perches in their proper clocked position. It will also help me position the suspension brackets. I will set up the axle spring perch so that it will be clocked in such a way to accept either a 4" or 6" spring.
If I dont get the brackets right I risk having the spring arched forward or back. If I position the bracket in a fairly neutral postion I can still rotate the axle a little to adjust for pinion angle if i have vibration broblems after the build. If the bracket is set maxed either way (rotated to far forward or back) I am limited on adjustability.

also i am extending the rear wheelbase slightly to accomidate the 42" tires within the wheelwell. There is no option here-it must be done or uptravel is not possible-the wheel will hit the front of the wheelwell on compression. So I'm moving the rear axle back a few inches. some of this driveshaft extension is made possible by using a dana 70 and the custom pinion flange I had made.

I had a custom pinion flange made by tom woods so that I could use factory 80 series driveshafts. (similar flange made for front). The 80 series driveshafts have proven themselves robust so we will see if they hold up to 42's. I would like to make sure the rear driveshaft slipyoke is in proper position and not over or underextended when I set the position of the rear axle. I need a pic of the rear drivshaft slip yoke so i know about what the slip yoke should look like. Perhaps a pic of a rear slip yoke as it sits under a 4 or 6' lift.

included is a pic of what the slip yoke looks like now as i have it mocked up. I would love to keep the axle where it is now but realize the yoke may be overextended and I may need to move the axle forward slightly which would be ok-there would still be room for rear tires to stuff

Thanks guys
D, I believe I still have an Excel file with some of the measurements you are requesting. I'm not at home, but will check once I get there tonight. Sam
D, all I was able to find were the 6" Spring measurements. Unloaded w/ no weigh I have them at 21 7/8" and compressed with the coils practically touching I have them at 10 1/8" hope that helps

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