custom drive shaft?
More Turbo
Joined: Mar 2002
Posts: 508
Likes: 2
From: Easthampton, Ma.
About 20 yrs. ago I installed a Skyjacker 4" lift in an 82 F250 W/IFS front axle. 8 cyl.,manual trans., 35" tires.
Almost every time I tried to spin the tires from a standstill it would break the rear "U" joint, driveshaft and differential yoke.
I called Skyjacker and explained, they claimed they never heard of such a thing (yea right!)
Eventually I found out about "axle wrap"
Upon sudden acceleration with good traction, your drive tire turns forward, the counter-rotational force twists the axle backwards.
The normal arch of the spring actually takes the shape of a horizontal S momentarily until it unwinds and kicks the axle back down. This results in violent twisting of the axle, wheelhop and in some extreme cases, binding of the "U" joint and breakage!
If you look at performance cars with leaf springs, they install traction bars to eliminate wheel hop. Under hard acceleration the axle twists slightly to bring the rubber snubber up against the leaf spring to "lock out" spring twist.
In my case I had the factory block and the Skyjacker aluminum angle block sandwiched between the spring and the axle. This combination gave the axle additional leverage encouraging spring wrap.
I brought the truck to a 4wd specialists (he referred to the Skyjacker block stacking method as "Goofy Block")
He installed "add a leafs to both springs to firm up the springs and to increase the arch. Then he installed shorter angled (longer) steel blocks resulting in less axle wrap and no broken driveshafts.
He said the correct way to do the lift would be to install 4" lift springs and eliminate the blocks altogether.
In your case it sounds like your springs are weakened from age and could be in need of replacement! Or maybe you could get away with ad "add a leaf" if you dont mind an additional 1-2" of rear lift.
Good luck!
Steve G.
Almost every time I tried to spin the tires from a standstill it would break the rear "U" joint, driveshaft and differential yoke.
I called Skyjacker and explained, they claimed they never heard of such a thing (yea right!)
Eventually I found out about "axle wrap"
Upon sudden acceleration with good traction, your drive tire turns forward, the counter-rotational force twists the axle backwards.
The normal arch of the spring actually takes the shape of a horizontal S momentarily until it unwinds and kicks the axle back down. This results in violent twisting of the axle, wheelhop and in some extreme cases, binding of the "U" joint and breakage!
If you look at performance cars with leaf springs, they install traction bars to eliminate wheel hop. Under hard acceleration the axle twists slightly to bring the rubber snubber up against the leaf spring to "lock out" spring twist.
In my case I had the factory block and the Skyjacker aluminum angle block sandwiched between the spring and the axle. This combination gave the axle additional leverage encouraging spring wrap.
I brought the truck to a 4wd specialists (he referred to the Skyjacker block stacking method as "Goofy Block")
He installed "add a leafs to both springs to firm up the springs and to increase the arch. Then he installed shorter angled (longer) steel blocks resulting in less axle wrap and no broken driveshafts.
He said the correct way to do the lift would be to install 4" lift springs and eliminate the blocks altogether.
In your case it sounds like your springs are weakened from age and could be in need of replacement! Or maybe you could get away with ad "add a leaf" if you dont mind an additional 1-2" of rear lift.
Good luck!
Steve G.
