On to the next topic.. axle wrap, or anti-wrap bars. Its probably one of the largest heated topics when it comes to leaf springs that I have come across. I have ran without them and with them on trail trucks and it made night and day difference with power and stability.... the only problem is that I didn't care about the inverse effects of binding on leaf springs on a vehicle that was rarely driven on the road. But now with a daily driver.... binding is more of a concern from a wear-and-tear perspective.
Ill try and make quick explanation of the binding problems with a wrap bar. As a leaf spring compresses and droops, the axle pinion stays within a few degrees (normally), it just goes up and down.... but with an anti-wrap bar, the pinion degree will follow the bar in a circular motion. Either way, an anti-wrap bar is going to bind, it just depends on how much and to what degree....
THE REAR
I took a degree finder and placed it on the pinion of the rear axle. I then measured from the point of the truck where the end of the anti-wrap bar would connect. At static height the rear pinion was at 18.5*.. and after lifting the rear end (before the tires come off the ground) my new degree was 16*....NEGATIVE!.... meaning the pinion angle actually shot downwards instead of upwards like I originally had planned, which is really odd. Now taking my anti-wrap bar measurements (making the bar as long as possible) and created a new graph to find the degree angle at the same height measurements... It gave me a difference of 4* positive.
So at full droop, the leaf springs are producing a -2.5* and the anti-wrap bar would be producing a +4*... giving me a 6.5* change difference. In other words, they would be fighting each other......
(Now if the rear end did what I thought was going to happen and give a positive 2.5* which would have made more sense since the shackle is behind the axle, it would have only been a 1.5* difference which would be very reasonable bind and no issue)
THE FRONT
The front is a little bit more complicated. Since my axle is pushed 3/4 of the leaf spring, the degree angle changes more dramatically. Since I have rear shackles on the front leafs, the anti-wrap bar would have to go on the front of the axle to compliment the leaf spring produced degree changes.
At static height, the flat bottom gusset showed +4*, at full droop, the axle showed 0*. Now given the very small amount of room and making the bar as long as possible given my situation, I did the same thing I did with the rear and plotted out the degree difference with an anti-wrap bar given my possible variables. From static to full droop, the bar would have a difference of 9.1*.
So at full droop, the leaf springs are producing a +4* and the anti-wrap bar would be producing a +9.1*... giving me a 5.1* change difference. Surprisingly, the front would actually bind less than the rear (which probably has a lot to do with axle placement on the leaf springs)
(also, as you will notice, I did a mid droop measurement to see how true of a progression the degree of change was.... midway between measurements, the axle only changed by 1*, YET, at double the height it went up to 4*) Leaf springs are so unpredictable damnit)
BUT with that said, if my normal road suspension cycling stays within that mid droop or less area... I am only looking at around 3.8* difference. If it is true about the rear, than I would have 3.25* difference as well......
So, I guess at this point, the question is... what degree bind is too much......? Remember, this is at full droop and I didn't do compression numbers, so unless I am jumping the truck, I shouldn't ever really see these extreme numbers......
The only other issue is the anti-squat figure..... Both bars will be producing an anti-squat force on the truck (Front would only do it in 4 wheel drive). I am not a fan of anti-squat and would try and eliminate it as much as possible in link designs and have had great luck by doing so..... and I have NEVER had anti-squat in the front.... so I have no idea what would happen or how the truck would act! My thinking is that front AS will make torquing over obstacles more difficult because the axle is trying to come up over the obstacle and the torque of the engine is trying to force the axle down into the obstacle........ I guess I need to do more research on this and see if anyone has had any experience with front AS.
