driveshaft binding up

[bigblazer433]

I have a 87 jimmy with a 6in lift and 36's. And when I start from a stop my driveshaft binds up but after i get up to about 10-15 mph it stops. could this be because I have a block lift. I have already had new lengthened driveshafts put in and had the differential tilteld up level whith the driveshaft??? could a 4" shackle flip and a 2" block solve any of this. Or should I just go to a 6" spring. Oh and I have also dropped the t-case cross member about an 1" 1/2. /forums/images/graemlins/confused.gif

 

[namkrow]

Sounds like you have a case of spring wrap.

The leaf spring is being twisted into an "S" and the pinion is rising upwards, causing the binding. The torque of first gear is the cause.

A set of stiffer rear springs would help (like the 6" lift springs), but I would venture to say that a more effective solution would be to check you pinion angle. I'm guessing it's too high to begin with.

Assuming you have a double cardan shaft (double U-joints at one end), since you say the pinion is pointed at the t-case output...I'd say your pinion is probably already pointed too high.

I needs to be about 1 or two degrees downward from "directly" at the t-case due to the forces placed on the rear axle when the truck is in motion.

http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml
http://www.drivetrain.com/driveline_angle_problem.html
http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html

 

[85mudblazin]

I have superlift 5 1/2 blocks out back and I had to drop the transfer case 2 inches ow and you may want to make the pinion point down a little you only really need to point it right at the driveshaft if you have a double cardon. The yoke at the rear end should be within 2* of the output at the transfer case. Hope this helps. /forums/images/graemlins/thumb.gif