OBS suspension lift with RSK questions

Huggy · Oct 8, 2014

I've got a '97 F350 with a stock suspension. My goal is to only go as high as needed to clear 22"x14" wheels with 37x13.50 tires. From what I've read I can do that with roughly 7 inches of lift and have little to no clearance issues. At the same time I was going to do a RSK with the kit from PMF and run superduty springs.
So if I'm understanding everything correctly, I can get 4" front lift springs for a SD and the 3.5" PMF RSK and that will put my front end where I want it. Now how do I go about lifting the rear? I'm guessing I would only have to lift it 6 inches or so to match the front. Does the RSK do anything to the rear? If possible I'd like to lift the rear with springs instead of blocks. I just have no idea what I need to piece everything together. I've lifted a jeep before and all I had to buy was one kit and just slap it all on, nice and simple like! This has me all confused for some reason. Thanks for any help you can give!
Here's the rig!

JSchuricht · Oct 8, 2014

Your right on with height, 6-7" will look good without going to cutouts. You may have to shim or trim the bumper, your also going to need to be careful with backspacing so the wheels are out far enough to turn.

On the front, combining the RSK and springs is perfect, just make sure of the spring rating. If you buy 4" springs that are designed for a gasser, the extra weight of the diesel may make you sit a bit lower than your expecting.

For the rear, I would look into a shackle flip. PMF has one for the SD which could probably be used on the OBS too but I would talk to Trevor before going that route. That would get you around 4.5" then you could use B code SD springs and your factory 3.5" blocks or a shorter 250 block.

Huggy · Oct 9, 2014

Well now I'm seeing that if I go with SD springs, that just that alone will give me roughly 2" of lift right off the bat compared to having obs springs. So does that mean that buying a 4" SD lift spring will actually net me 6" of lift once put on the obs without even factoring in the lift from the RSK?

zilla68 · Oct 9, 2014

CALL TREVOR AT PMF!!!

FrankTheTank · Oct 10, 2014

Rear SD hangers will not bolt up to an OBS with out welding the old holes shut and drilling new ones. I would know!

I do not like rear shackle flips, they always throw off the center of the axle. Unless you have blocks with multiple holes to adjust it front to rear

Huggy · Oct 10, 2014

So I guess I gotta find OBS rear lift springs...
Thank you for your help!

FrankTheTank · Oct 10, 2014

I never said SD springs won't fit the obs hangers.... I said SD hangers will not bolt to an obs frame without modifications.

Get SD rear springs, and drill out the OBS shackle and front hanger to accept the larger bolt