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Issues after installing SKY rear shackle flip kit on F-350

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Old 07-20-2011, 11:08 PM
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Issues after installing SKY rear shackle flip kit on F-350

Ok guys now I need some expert opinions. I put on the SKY kit tonight along with some 1999 F250 superduty blocks. My stock F-350 block measures at 4.25" and the superduty block is 3.5", which is a little more than I wanted. The kit ended up WAY higher than SKY says.

I knew that the advertised 4.5" lift from sky would be way too much. I only wanted a 3" lift. I measured before and after on multiple spots and measured the pinion angle from where it sat on my sloped driveway. I used the jack previously to lift the truck and measure the amount of lift I was after. This is why I went with an F250 block, to lower the lift SKY kit does.

Here it is with 3" of lift over stock. (Stock from ground to fenderwell was 44.25, here is was at 47.25


Here it is STOCK F-350 rear.


After putting on the kit, WITH the smaller rear superduty blocks it measures in at 49" Thats a 5.5" lift over stock . With SKYs advertised 4.5" lift over stock and with the .75" smaller block my lift should have been 3.75" over 44" to equal 47.75...NOT 49"

Thats issue number 1, number 2 is my pinion angle is SKY high. I measured relative angle, meaning that even though I was on a driveway slope I measured the angle and mean to replicate that same angle after the kit was installed. SKY recommends a 4 degree shim. I havnt got the shims yet cuz I wanted to measure after the kit was on.

My pinion angle sitting in the driveway nose facing down the slope measured at -2.5 degrees pointing down. After the lift the pinion angle reads +5 degrees pointing up! That means the pinion angle moved 7.5 degrees up!

Here are some pics...After the install sitting on the ground WITH the smaller blocks.





 
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Old 07-20-2011, 11:19 PM
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I was just thinking, Maybe there is a left and right side to the F250 superduty blocks??? Maybe they are tapered and I have them on backwards??


 
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Old 07-21-2011, 02:20 PM
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Anyone? Does the rear shackle angle look right?
 
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Old 07-21-2011, 04:00 PM
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The blocks "may" be tapered. But i dont think so. By the pics your pinion angle looks fine. your pinion looks perfectly in line with your driveshaft.
 
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Old 07-21-2011, 04:24 PM
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I totally agree...Your pinion angle is right where it needs to be...
 
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Old 07-21-2011, 04:53 PM
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Really?? Everthing Ive ever read about pinion angles is it should be parralell with the tran output...But thats with cars not lifted trucks. What about the rear shackle angle?
 
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Old 07-21-2011, 05:03 PM
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try taking the block out altogether, thats what i did on mine after i installed the 4 inch rearched f250 springs in my f150
 
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Old 07-21-2011, 05:23 PM
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May try that tonight, although I'll need new ubolts, dont have enough thread to remove that block.
 
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Old 07-22-2011, 08:46 AM
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Originally Posted by mdula
Really?? Everthing Ive ever read about pinion angles is it should be parralell with the tran output...But thats with cars not lifted trucks. What about the rear shackle angle?
I ran a drive shaft place and your pinion angle is right on. The pinion should be angle up towards the T-case for the least amount of wear and tear.
 
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Old 07-22-2011, 09:13 AM
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Originally Posted by yjzonie
I ran a drive shaft place and your pinion angle is right on. The pinion should be angle up towards the T-case for the least amount of wear and tear.

Great! Sorry if I sounded like I didnt believe you the first time, I just always read (for cars like my Torino) to have the shaft parralell with the transmission output to keep the u joints "in sync", Thanks for letting me know. I've been worried about it. I wonder why SKY recommended a 4deg shim in reverse?

Today or tomorrow I'll be dropping it down 1.75" (with blocks) to try and level it out, will that change t he angle at all? I found a 2" block from an F150 4x4 at pick-n-pull that im getting during my lunch break, but I think it might have a 2.5" width, will I be OK with it?
 
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Old 07-22-2011, 09:45 AM
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Your shackles look to be to far forward, they should have a slight lean to the rear. Also are you using stock shackles? If so, make sure you weld in a brace between the to uprights or you will find they may crack and or break down the road. It's real good insurance. I had to do it to the Bronco conversion I did. Good looking truck...
 
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Old 07-22-2011, 12:09 PM
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Originally Posted by yjzonie
Your shackles look to be to far forward, they should have a slight lean to the rear. Also are you using stock shackles? If so, make sure you weld in a brace between the to uprights or you will find they may crack and or break down the road. It's real good insurance. I had to do it to the Bronco conversion I did. Good looking truck...
Thanks! Yeah the shackles are stock. I plan on reinforcing them when I get everything squared away. I dont like the angle of the shackles either. I was thinkin of moving it farward an inch, but redrilling holes is a PIA on that frame. I dont want to weld it, I want options of removing it later down the road. What do you think? Is it because my bed was lightened from removing the bumper, spare, etc??
 
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Old 07-22-2011, 12:26 PM
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That's a very good point, lack of weight to the rear of the truck will cause the bed to lift a bit. When I did the Bronco, I moved the front mount back about an inch...The worst part is drilling out the rivets.
 
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Old 07-22-2011, 02:50 PM
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Removing the rivits sucked lol. I finally used a cutoff wheel, made a cross cuts on the head and used and air hammer and they snapped right off.

So what should I do, move the front back, move the back sky bracket forward, or throw some weight in the bed .

BTW. I got my 2" blocks from a pick-n-pull finally!
 
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Old 07-22-2011, 03:02 PM
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I think your shackle angle is fine. Remember, under load and bumps & such, the rear spring eye will need to move rearward significantly...
 


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