Flip kit calculations.

[BADAZ chevy guy]

Just wondering how much drop I can expect by moving the rear axle to the top of the leaf springs, And still using stock shackles and rear hanger? 1977 C10, 12 bolt dif. It's a heavy half, but I'm taking out the helper spring.

[HAULIN IT]

6 1/2" is a pretty good figure. Measure the leaf pack for an accurate number. The axle tube is 3", the perch adds a 1/2"...plus adding the additional 1/2" to the bottom side when doing the flip, so that's 4" plus the spring thickness. Lorne 

[Irish_Alley]

if you remove springs you will raise the truck (after the flip)

[HAULIN IT]

if you remove springs you will raise the truck (after the flip)

Really? Want to re-think that?

[Irish_Alley]

if the springs are bolted from the bottom (after the flip) and you remove a top spring it will pull the bottom spring up(that bolts to the shackle). if its the helper springs they will not effect the height till you put a load on it. so its just acting like a spacer, not unless im not seeing the whole picture i stand by that statement till someone proves me wrong if you where to put a block in after the flip you will lower the truck, so if you take  the block out you will raise the truck. now granted you have to excuse my crude drawling and the fact that the one only has one leaf spring. but if its a spring with a Zero Rate its the same ideal.

[BADAZ chevy guy]

I'm thinkin' the only difference removing the helper spring would make is before I did the flop. It would lower the truck the thickness of that leaf is all. But once I move the axle to the top all removing it will do is give the truck a softer ride. Also. I'm not going to spend a lot of money on a commercial flip kit. I'm going to get a set of heavy spring purches from the local trailer supply shop, cut the stock perches off and weld new ones on the bottom of the axle tubes. I just need so set it up on stands so I can keep the same drive train angles.

[Irish_Alley]

if its a "helper spring" its only active when you are loaded. but if you removed it before the flop you wouldnt change anything since the main spring is sitting on the axle if you flip it the axle would be sitting on the helper spring. if you remove it then your axle would pull the springs up that thickness this would pull the rest of the truck up. it would be very small but when your asking about how much of a drop you would get i thought i would throw it out there.

[BADAZ chevy guy]

if its a "helper spring" its only active when you are loaded. but if you removed it before the flop you wouldnt change anything since the main spring is sitting on the axle if you flip it the axle would be sitting on the helper spring. if you remove it then your axle would pull the springs up that thickness this would pull the rest of the truck up. it would be very small but when your asking about how much of a drop you would get i thought i would throw it out there.

I thought the helper spring was on the BOTTOM of the spring pack. Just above the axle tube. No?

[HAULIN IT]

Irish, Follow along...I've never seen a leaf spring stacked upside down (main leaf on the bottom) like in your drawing...definitely NOT on a '73-'87 GM truck. Go look under your truck & report back
So the number of leaves or thickness under the main leaf doesn't have anything to do with the outcome once the flip is performed...if anything, removing say one or two out of the heavy half pack has to lower the truck farther due to the less springs to hold up the same amount of weight. Agree? Lorne


 

[Irish_Alley]

lmao yup, i see what your saying dont know what the heck i was thinking. now you see why i thought what i thought. the only thing i can think of that made me think of that is the helper spring bolts to the top of spring pack
and thinking this i was thinking the bolting the axle on top of that. but you cant and that wouldnt make any sense. thanks for pointing me in the right directions guys

[BADAZ chevy guy]

That's NOT the 'Helper' spring I was talking about anyway. I was talking about removing the lower heavy spring shown in the Yellow portion of that drawing

[Irish_Alley]

lol see this is where i was getting my confusion from. 

[dvdswan]

I hope you're going to correct your pinion angle.

[BADAZ chevy guy]

Yes on the Pinion angle.
My plan is to get 2 spring perch's from the local trailer supply shop for a 3" axle tube. Then bolt up the assembly with the axle's on top of the spring and the new perch's under it. Not tight, just enough to hold everything together and still able to turn the axle tube. Then (with weight on the truck) rotate the axle until the pinion angle is right and tack weld the perch's in a few spots. Then disassemble and finish weld the perch's in place, grind off the original perch's and paint.

[Captkaos]

Depending on the kit, lately some are more like 5" instead, but plan on 6" if you really want to know you need the dimensions on the flip bracket.