99-03 Super Duty spring tech

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    99-03 Super Duty spring tech

    Leafs are old, not as good as coils but still deserve some attention.

    I bought my 2001 F350 and it came with a terrible 4" BDS lift. It rode horrible, had no flex and was too tall for what it was trying to accomplish (clear 315s). No pictures of it but it is a pretty familiar sight among Super Duties.

    Quickly decided the 6" had to go. I prefer; soft ride, high clearance, and lots of flex! On-road and off-road performance is very important. Preferably something I can swap my 285/75 towing tires for a set of 37 or 38" TSL boggers without looking like the truck has a dumb lift with small tires. The first thing I did was ditch the sway bars, front and rear. Dont drive fast enough to need them and they hurt off road performance.

    Decided to go with a light spring in the front instead of the standard X-code. I went light, U-code! 4080lb vs 5260lb X code (or 4800lb vs 6000lb depending where you look. To compensate for the soft U-code I added a 1" zero rate spring. It also moved the front axle forward 1" to provide fender clearance and improve approach angle.

    It worked good this way but the shackle angle was very steep. The steep angle caused the leaf spring to become U-shaped and bottomed out fairly easy. To combat this I decided to move the front spring mount forward. What I did was unbolt the front spring mount, shim the shackle to the desired angle ans weld the front mount in place. This moved total front axle placement to 1.5" forward.

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    Last edited by back woods; 06-16-2020, 05:37 PM.

    #2
    Shackle angle comparison.

    Stock 7.3 Excursion.

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    U-code 7.3 F350 front spring mount moved 1/2" forward.

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    Stock code springs (Excursion)
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    Modified U-codes (F350)
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    Last edited by back woods; 06-16-2020, 05:31 PM.

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      #3
      I'm interested in this. Currently on 255/85r16 on mine, looking to go 315 as well. I did a zone offroad leveling kit, and my front leafs have gone s shaped. Ride quality has been...pretty 1 ton-ish, but i expected that. I'd love to take a little downtime and do radius arms and coils, but realistically, I won't.

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        #4
        I have some form of SD leafs in my obs, they sit slightly negative like most of them. I didn't do a ass drop bracket shackle reversal with them, I kept it stock height, but now I'm thinking about leaving the truck out and going with 35-37s. I'd like to get some leafs with a little arch to actually gain some travel. Flat leafs are OK for stock and free, dropping the mounts down for lift is ghetto imo.

        Is there any company's that make ~2" lift springs that ride decent?

        Comment


          #5
          Originally posted by YotaAtieToo View Post
          I have some form of SD leafs in my obs, they sit slightly negative like most of them. I didn't do a ass drop bracket shackle reversal with them, I kept it stock height, but now I'm thinking about leaving the truck out and going with 35-37s. I'd like to get some leafs with a little arch to actually gain some travel. Flat leafs are OK for stock and free, dropping the mounts down for lift is ghetto imo.

          Is there any company's that make ~2" lift springs that ride decent?
          These springs are from SD Truck Springs. The standard lift/level/snow plow spring is an X code. Usually good for ~2" of lift. The next softer is the V-code.

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            #6
            Shock angle with lower mount moved forward.

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            Bump stop in relation to the lower shock mount.
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              #7
              Inner fender clearance with 285/75r16 tires. By the way the Cooper HT3 is a SUPERB sand tire. Far better loose sand performance than the Cooper STMaxx I have been running for years. A lot of loose yellow beach sand in Michigan.
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                #8
                Have spent a lot of time looking at and reading about bump stops. Bump stops play a bigger roll than one would think when it comes to smooth suspension travel. Some bump stops are softer than others; Polyurethane vs Foam, solid puck vs progressive rate. In this case I went with soft foam progressive stops. Turns out bump stops from a low rider website are what I was looking for, and those trucks spend a lot of time on them so they must be smooth. The truck is setup with 4" of up travel. These look to be 3" long or so, no dimensions were given. They will allow approx 1" of up-travel before making contact, may have to trim the down a little bit but will ride around with them for a while first. I think they will be soft enough that no changes will be needed.

                https://www.airbagit.com/Cushioned-S...mx-pstop-3.htm

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                  #9
                  Was unsure on what shocks to run in the front. Previously I have ran Bilstein 5100, KYB Monomax and Rancho. Never liked how stiff the Nitro charged 5100 and KYB were, like 200lb to compress them. Had the parts store bring out everything they had and tested their compression. The Monroe Gas-Magnum fit the need the best. Still Nitro-charged but not as still as say a Bilstein 5100. Has a mono-tube and large body, Made in USA as well.

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                  These are the bump stops that came off.

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                    #10
                    Originally posted by back woods View Post

                    These springs are from SD Truck Springs. The standard lift/level/snow plow spring is an X code. Usually good for ~2" of lift. The next softer is the V-code.
                    I'm thinking mine are V code, I believe they were from a low mile F350. I don't see 2" of lift just from x codes. People get that on an excursion, but they practically sit on the bump stops.

                    I want a nice multi leaf pack. Multiple thin leafs, not a pile of thick leafs like cheap lift springs.

                    Edit: I just found out that old man emu makes a 2.5" kit. They have a really good reputation for making good riding leaf spring kits and the few reviews on the super duty kit confirmed that.

                    I'm having a really hard time finding a vendor with that kit listed though.
                    Last edited by YotaAtieToo; 06-17-2020, 12:04 PM.

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                      #11
                      i had 2 leaf code x leafs under my 1st gen cummins but they were too soft (heavy huge 1/4" wall bumper 18k winch 3/16" lumber rack) so i replaced them with 3 leaf f550 leafs

                      https://www.sdtrucksprings.com/99-04...-leaves-x-code
                      https://www.sdtrucksprings.com/index...oducts_id=7661
                      Last edited by rockyota83; 06-17-2020, 05:02 PM.

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                        #12
                        Originally posted by YotaAtieToo View Post
                        I have some form of SD leafs in my obs, they sit slightly negative like most of them. I didn't do a ass drop bracket shackle reversal with them, I kept it stock height, but now I'm thinking about leaving the truck out and going with 35-37s. I'd like to get some leafs with a little arch to actually gain some travel. Flat leafs are OK for stock and free, dropping the mounts down for lift is ghetto imo.

                        Is there any company's that make ~2" lift springs that ride decent?
                        you could have them rearched.
                        - Buck

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                          #13
                          Got the new bump stops installed. They mounted up at a very slight angle but seems to be no problem, may go back and adjust them. Their texture is soft and very rubbery. NO JARRING what so ever! We tested them out on some decent bumps and holes on the fire roads. Ranging from 6-8" deep with the deepest wash outs around 10-12". Hitting some 6-8" dips and bumps at around 30mph. No doubt you can feel you are going over some terrain but the in cab transfer is very smooth.

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                            #14
                            If you take the 6,000 lb log cabin off the back it won’t bottom out all the time.

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