I have searched but I can't really find an answer to my specific question. I have found the question asked but it is generally never answered because the answers generally lean towards "how" to relocate the upper perch, but not giving a reason for moving the top vs the bottom.
The stock TJ has the rear upper spring perch leaning slightly forward in the forward part of the frame arch. The stock coil spring does have a slight bend from the factory. Is there a reason that the original Jeep Engineers positioned the perch in this manner (applying the force in a slightly leaning forward manner)? If the same wheelbase is maintained (or very close to it), should the load being applied to the frame not stay in the same direction? Thus, if we change the pinion angle should we change the angle of the bottom perch to keep the frame loading the same vs relocating the upper perch?
I am just asking out of curiosity. I am not debating the fact that the upper spring perch relocation is proven and seems like it would be much easier (trim off the stock, trim off the U, align the hole in the frame at the center of the arch to bump stop hole, weld in place). My questions are specifically was there a reason that the original upper perch was tilted and does relocating it horizontal change the loads applied to the frame? If the loading is changed, does it matter? X lbs of force applied at yy degrees compared to straight up doesn't seem like it would make that much different on flat ground, but on a hill climb it does seem like it would affect the overall load distribution on the frame/springs.
I generally see the response that the only benefit to spring perch relocation is to realign bump stop, but does realigning the bump stop by changing the load direction into the frame have any adverse or unknown effects? Possibly the effects could have positive results as well? Again, it is simple and proven and most likely what I will do when I do it, just asking from a "loads applied" both static and dynamic perspective, not an ease to do or is it effective.
The stock TJ has the rear upper spring perch leaning slightly forward in the forward part of the frame arch. The stock coil spring does have a slight bend from the factory. Is there a reason that the original Jeep Engineers positioned the perch in this manner (applying the force in a slightly leaning forward manner)? If the same wheelbase is maintained (or very close to it), should the load being applied to the frame not stay in the same direction? Thus, if we change the pinion angle should we change the angle of the bottom perch to keep the frame loading the same vs relocating the upper perch?
I am just asking out of curiosity. I am not debating the fact that the upper spring perch relocation is proven and seems like it would be much easier (trim off the stock, trim off the U, align the hole in the frame at the center of the arch to bump stop hole, weld in place). My questions are specifically was there a reason that the original upper perch was tilted and does relocating it horizontal change the loads applied to the frame? If the loading is changed, does it matter? X lbs of force applied at yy degrees compared to straight up doesn't seem like it would make that much different on flat ground, but on a hill climb it does seem like it would affect the overall load distribution on the frame/springs.
I generally see the response that the only benefit to spring perch relocation is to realign bump stop, but does realigning the bump stop by changing the load direction into the frame have any adverse or unknown effects? Possibly the effects could have positive results as well? Again, it is simple and proven and most likely what I will do when I do it, just asking from a "loads applied" both static and dynamic perspective, not an ease to do or is it effective.
