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3" blocks

BPB

NAXJA Forum User
my boss gave me a set of 3" tapered blocks, he said that with the daper that I won't get axle wrap. I believe him, he has like 6-7" of blocks on his truck, and rancho springs, that set up has worked for him for like 3-4 years, and he abuses the hell out of that truck. will they kill my jeep???? By the way, I know that this is a dumb question, but what exactly is axle wrap?
 
Ive ran 4" blocks for about 1 1/2yrs now ive done just about every hard trail in the Souteast w/no problems, I dont get axle rap but my packs are somewhat stuff, axle wrap is the torqueing or twisting movement of leaf spring some may be able to explain it beeter than me.
 
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Axle wrap is caused by torque from the driveline trying to twist the rear end, basically the pinion rotating upward. The springs warp, basically turning into the shape of an S, then the spring force resists and forces the spring back, then the torque pushes it up, the spring forces it back......on and on. This dramatically shortens the life of the springs, causes a loss of traction as the rear end usually hops, and if the pinion raises enough it will snap the pinion yoke.

Blocks increase the leverage that the axle puts on the springs, thereby increasing the tendancy to have spring wrap. Big trucks get away with tall blocks because they have stiff springs which are designed to carrry a load, and those stiff springs can successfully resist wrapping. If you have stiff enough springs to not have axle wrap on an XJ with 3-4" of blocks, you have one stiff riding, non-flexing rig......neither are a good thing. Even 2" blocks can be a proplem with a good set of springs, unless the springs are designed to resist wrap or you use a traction bar. Look at the other thread currently going on regarding axle wrap.

The taper has nothing to do with whether axle wrap will be caused. The taper merely points the pinion up slightly to improve the driveline angle. I would not recomend using 3" blocks.
 
so do I want tappered blocks or non tapered blocks, if non is better, then I will take mine to the grinder, which I will probably have to do to get them to work properly in my jeep.
 
You don't want blocks at all. They just plain aren't the greatest. Your ride will be very stiff and blocks have a tendancy to break. They also put added stress on the axle.
 
bigpimpinben said:
so do I want tappered blocks or non tapered blocks, if non is better, then I will take mine to the grinder, which I will probably have to do to get them to work properly in my jeep.

Please go back and read Goatman's post again, especially the last part. The taper doesn't matter. Blocks increase both the liklihood and the magnitude of spring wrap. IMHO all blocks are bad. While you might not notice too much effect from a set of 1" blocks used to level things out, 3" blocks are just a bad idea. The taper has nothing to do with it.
 
Goatman said:
The taper has nothing to do with whether axle wrap will be caused. The taper merely points the pinion up slightly to improve the driveline angle. I would not recomend using 3" blocks.
 
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