k5ryder
1/2 ton status
I have a 85 K5 Blazer with 10 bolts front and rear. Stock height. I'm looking at lift kit springs and for the rear my options are 52" or 56". How do I know which ones I have and which ones I should order?
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
Rear spring help
- Thread starter k5ryder
- Start date
owenst7
1/2 ton status
This is true. A lot of guys running a shackle flip use 56"s as an upgrade though. 64"s off a GMT400+ are popular also, but probably more complicated than you're looking at though.
k5ryder
1/2 ton status
Thanks.
Glad to hear from you again AV8TER
k5ryder
1/2 ton status
with a shackle flip and 56''s that would gain a pretty good amount of lift correct? I'm just looking at a 4" lift and I want to replace all of the leafs.
k5ryder
1/2 ton status
OK. I'm just looking for 4" of lift and all new spring packs. So I will stick with getting a new 52" 4" lift spring pack. Tough Country seems to be the most popular spring packs from what I can tell.
yakmastermax
1/2 ton status
right now i've got a DIY4X flip and 56" 1/2 ton springs from a 1990 suburban.
the angle almost seems negative?
rear driveshaft angles down from the pinion? hard to describe. if zero degrees is when the driveshaft is parallel to the pinion, and positive degrees is when the driveshaft points at a spot under the truck further back than the spot the pinion points at, (zero they both point at the same spot), the angle is negative (driveshaft points at a spot, t case, further forward than where the pinion points.
i've got slight vibes i think around 50mph not positive, could be imagination of just driveline noise.
flexes real good and the lift seems right about 4"
the angle almost seems negative?
rear driveshaft angles down from the pinion? hard to describe. if zero degrees is when the driveshaft is parallel to the pinion, and positive degrees is when the driveshaft points at a spot under the truck further back than the spot the pinion points at, (zero they both point at the same spot), the angle is negative (driveshaft points at a spot, t case, further forward than where the pinion points.i've got slight vibes i think around 50mph not positive, could be imagination of just driveline noise.
flexes real good and the lift seems right about 4"
I think I understand what you're saying yakmastermax. Let's see if I can make all this make sense. There are two sets of angles we need to be correct to keep driveshafts alive. There is the angle relationship of transfercase output to pinion, and operating angle of the u-joint. Two different things and both need to be good for u-joint life. Forget about the driveline for now and lets look at the t-case to pinion first. This is the one where vibrations come from. The t-case and pinion need to be on the same plane with each other. In other words, they need to be parallel with each other. So, if the output of the t-case was level, the pinion would have to be level. If you use an angle finder and your t-case is pionting down 10 degrees, the pinion would need to point up 10 deg to match it. Both lines would be parallel to each other. This is for a normal driveshaft with one joint at each end like a stock rear in a K5. Front shaft is a different deal as it has a cv joint. The problem with a shackle flip (for 4 inch lift) is when you drop the rear of the spring the pinion rotates up 8.78 degrees. This is with a stock 52 inch spring. A 56 would change 8.17 deg. So, now you have different angles. Will it cause problems? Lots of folks say theirs works fine and that may be but the angles do change. You have vibration and more than likely thats why. The other angle is the u-joint working angle. Thats the angle the joint "bends" coming out of the t-case or going into the rear end. If the pinion and t-case are on the same plane, each u-joint "bends" the same amount and thats what we want. U-joints are only made to bend a certain amount and the more the angle they work at the faster they wear out. Moral of the story is, get the pinion and t-case on the same plane. Thats the most important part. With 4 inch lift the joints working angle is ok.
