blocks vs springs

I was looking at lift kits and noticed that rear spring kits cost almost twice as much as kits using blocks. Im looking at lift kits for a pre 93 dodge. Is there acually a difference in preformance or is all a matter of budget and personal prefernce. i going to be trying to build a all-purpose rig. Any info will thanks  

Blocks is a bad/cheap way to do a lift and it increases spring wrapup and chances of Ubolt failure. Basically as I see it, do it right or do not do it.  

Good topic! Here's my Q on the whole block idea. Why does some trucks come from the factory with a block in the rear? I've been using block lifts and full spring lifts for years and haven't had any trouble with either of them as far as U-bolt failure goes.Sometimes its kind of a pain to set up the angles for the driveline to yoke on both types of lifts also. I've had that problem before because of the angles the blocks have. It depends on the height too.  

i agree, i have had no problem with the blocks myself. any spring lift, or blocks will be a stiff ride, its not like your doing any extreme flexing.....go with the blocks and save yourself that extra money. you'll be fine  
in God we trust

Blocks have been used because they are cheaper not better. Simply physics here. Blocks increases leverage against springs and spring wrap up from axle torque. You can mitigate some of this effect with a thick spring stack and trucks that use them from factory tend to have thicker spring stacks. Generally older trucks (before 90 or so) had much thicker standard spring stacks and tolerated blocks better than new ones. Even still no blocks is the best way to go.  

in my oppinion as long as they are not over 4in and your not putting any huge power or tires to them you'll be ok. but it would be best to do the springs if you had the money.  

heavymetalk20:
in my oppinion as long as they are not over 4in and your not putting any huge power or tires to them you'll be ok. but it would be best to do the springs if you had the money.

I disagree. Limit in size is a function of spring stack and tire size and there is no universal "one does all" like some thing a 4.10 is great no matter what tire size is or tranny type is. I would say 2 to maybe 3 inches at most is a sane safe limit. Beyond that you need to lift in other ways.  

So I'm guessing the reason why I don't have much axle wrap at all is because the springs are thicker and are stacked with more leaves than the originals? I had a spring shop build them for my truck, obviously they knew what they were doing because they still ride like factory and can take some weight and still has good flexing capabilities and I've got a 6" block also.  

This is somewhat true but even still if you were to tow a heavy load a lot you would find that you would have short Ujoint life on pinion flange because axle would twist up a lot under heavy sustained torque loads. This is because center line of axle thrust is far removed for spring centerline and this amplifies the effect of axle wrap under torque. Stiffer springs helps and makes it more tolerable but should not be considered a cure or a true solution.  

The only time I have any wheel hop or axle wrap and it is not much to really talk about (I've seen stock trucks have worse), is when I'm in high range 4x4 in soft terrain such as sand or snow. I'm hardly ever in high range 4x4. The only time is when I'm on the highway when the roads have ice or snow on them. This is the only truck I've built that I don't have the rear spring issues such as wrap and wheel hop.  

Consider yourself "lucky". I am glad it worked for you but it is still not a good way to get that much lift.  

By and far I know better. This was only supposed to be a temporary lift for a week to see how it worked out and it worked so I left it. I have always been on the "blocks no bigger than 4 inches" bit for years but I started with one truck that I installed a lift on for a guy and thats what he gave me so I installed it and it worked for him and he still has them in his truck to this day. When I put the lift in my truck, I went a bit further and had some springs made for it and told the shop what I was going to do with the truck and they made me what I manted. I have had the shop make several springs for my project trucks over the years and they have been good to me and also gave good advice when I was younger and didn't know any better. I still have them build springs today.  

I am sorry but you are still lucky. I am a engineer by nature and I look at the physics involved with this stuff. If you can get it to work then count your blessings and run but it is still not anything I would ever sign off on. You build strength  by reduces high stress areas to a minimum and keeping high thrush loads close to spring and frame center line on attachments. You are not doing this here. While you have been lucky and your Ubolts have not yielded yet, they are seeing torque stress loads 50 to 70% higher than they would if axle was mounted directly to axle.  

I know what you're saying. It boggles my mind too. I really don't understand how it has worked for me. I probably won't be able to do it again, but I doubt I will build another truck like this one either. I have seen people do some crazy things in my days and one thing I won't do is stack blocks. Can I say its like installing a shear press in the rearend? I would see this from time to time a few years ago and it would get me a bit weary to see these trucks going down the road and hitting bumps and seeing daylight between the two blocks. One guy lost his axle because he thought it would be cool to smoke the tires. He didn't "smoke" anything but the rear axle out from under his truck. Quite funny.