rear leaf springs... - Diesel Forum

**janssen_nicholas** · 07-20-2007, 02:47 PM

i'm doing a solid axle swap on my 96 2wd f-250. I'm thinking of using the SKY manufacturing shackle reverse kit. .. the five inch kit... if i use the 5 in. kit and use stock springs up front, what kind of springs do i need in the back to balance the ride? i'm thinking about using the spring to lift it rather than blocks. any ideas?

Garbage_Mechanic · 07-20-2007, 06:34 PM

A stock F350 4x4 has 4" blocks. Sky's kit should be 5" over that. But you shouldn't need 5 inch block since there is 1.5 inches of rake in a stock truck. But still that would be 7 or 8 inches of block....

For me the choices are:

SKY's reverse shackle kit for the rear. I dont know about the tapered blocks needed to re set the pinion angle though. Some have "folded" the shackles so that is a concern. That could be covered by heavier shackles.

Donahoe lift springs for a SD. 6" with a little block or 8 " with no block.

Build custom dropped front hangar brackets to run with the SKY rear shackle flip. Fabtech or similar makes them for SD's.

**janssen_nicholas** · 07-21-2007, 01:07 AM

i'm kinda confused tho... i wasn't looking to put the shackle reverse kit in the rear, just the front. i didn't think ther was any blocks in the front... or did u mean there are 4in. blocks in the rear? i was just trying to put the reverse kit in the front using stock springs for the front. my issue is what to do in the rear trying to avoid using blocks if possible

Nit · 07-21-2007, 02:43 AM

on a 250 there are 2" block, 350 use 4" blocks so all you need to do is stack teh blocks or jsut run teh 4" ones, it should sit level then

just2dune · 07-21-2007, 04:17 AM

I just did this to my truck with the 5" sky kit also. I used a 4" rear lift spring from procomp and I also used a 5.5" untapered lift block from tough country. When I did mine I used the superduty front springs and the the truck sits almost perfectly level with a little nose down stance. Hope this helps.

Garbage_Mechanic · 07-23-2007, 03:53 PM

[ QUOTE ]
thinking about using the spring to lift it rather than blocks. any ideas?

[/ QUOTE ]

Sorry for the confusion. I have been researching this same issue since I am working on a 3"SKY kit on mine and the question is HOW TO LIFT THE REAR W/O BLOCKS IF POSSIBLE correct? That is what I covered.

psu927 · 07-24-2007, 07:29 AM

lift springs is the only way. Or, RSK for the rear. Which I didn't even know they made.

Garbage_Mechanic · 07-24-2007, 10:00 PM

The REAR RSK intrests me. SKY actually calls it a shackle flip. I have some questions and reservations. I have seen one or two comments about the stock shackles folding sideways. Since they are built to be in tension, and doing the flip puts them in compression. I think this couyld be solved with heavier duty shackles. If SKY will sell the ones thay use in the RSK, that problem would proabably be solved. I also wonder about the torque of the longer shackle to frame brackets and the effect of "twisting" the frame rails and weather the stock crossmembers will handle it, especially towing / hauling. A tapered block is needed to correct the pinion angle since only the rear of the spring is dropped. Lastly, I think the dropped rear of the spring will hit the tailpipe. I personally would like this system better if both ends of the spring were dropped with brackets.

STurbo90 · 07-24-2007, 10:30 PM

There was a post about a member who installed the rear kit,

but since the search sucks and you can't make more then one an hour, I couldn't find the post,

on top of that the search function in the archives doesn't even work,

but I found his picture album,

http://rides.webshots.com/photo/1126...43191295uRYVRU

Garbage_Mechanic · 07-24-2007, 11:58 PM

OH YEA, that reminds me of the other downside, since it only drops one end of the spring, it moves the wheel base and sets the wheels out of center in the wheel wells.

Man that is one clean truck though. I really like how the bottom of the front axle is clean, no U bolts hanging down to snag a rock and get torn off. And much more.

**janssen_nicholas** · 08-02-2007, 04:31 PM

yea guys this is basically my issue. not to use any kind of kit on the rear axle because of the trouble it causes wit alignment, etc. i just need to know what kind of springs to buy for the rear...

Garbage_Mechanic · 08-02-2007, 06:17 PM

Several MFG make lift springs for the rear. Look at Brainshop album to see some. Th info I have is that SD rears fit as well. This opens up the possibilites more. Many people claim the Donahoe Racing springs made by Deaver are the best quality and ride. The downside is that lift springs need airbags to hold much load without major sagging.

STurbo90 · 08-02-2007, 06:28 PM

8" lift springs with no blocks would probably be close with a 5" front lift.

When you buy say 5" lift springs, that is using whatever stock block is in there,

so on my truck with factory 350 blocks, and front 3" lift, I plan to buy 5" lift rear springs and install without the block, so overall lift will be about 1", as my truck had a little sag to the rear now.

So 8" for an additional 2" front lift should be comparable.

But all truck weigh different, you list 250, but CC, extended cab, short or long bed all will make a difference.

cgraham · 03-09-2008, 11:25 PM

I ran a shackle flip and 4" lift springs on a '79 Chevy. I first tried the shackle flip and 4" blocks, but the rear end wandered around and it drove terrible. After installing the new lift springs it was like a new truck, much more stable and the ride was better. The shackle flip won't shorten your wheelbase by enough to matter, and if it does you can just redrill your springs center pins further back and move your axle back until it's in the right spot. You will probably have to shim the rear end to get the driveshaft angle right, but that's easy too. All pretty standard stuff when you lift a vehicle.