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99-03 Super Duty spring tech

back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
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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back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
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:

Squamch

Canadian
Joined
May 19, 2020
Member Number
93
Messages
1,011
Location
republic of Vancouver island
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.:laughing:
 

YotaAtieToo

Thick skull
Joined
May 19, 2020
Member Number
142
Messages
3,607
Location
MAGAlia, CA
I have some form of SD leafs in my obs, they sit slightly negative like most of them. I didn't do a :rainbow: 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?
 

back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
I have some form of SD leafs in my obs, they sit slightly negative like most of them. I didn't do a :rainbow: 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.
 

back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
Shock angle with lower mount moved forward.

20200604_204411_63dadc01cec972a05f9507867941e97006ee47c1.jpg


Bump stop in relation to the lower shock mount.
20200604_204401_75efd55ceccd9b1f6b4bf39d79876ecfc44ae77a.jpg
 

back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
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.
20200604_213215_97951243e6935b36040b29382740b0f91c387730.jpg


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back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
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

bumx_pstop_3_2_63b309ffe0209168c31873a6fc8b2f3fdf1680d5.jpg
 

back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
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.

20200610_181030_a7bd36503a88e0a90ee5038237e76a18624b42fd.jpg


These are the bump stops that came off.

20200610_181048_0a9e58a7df1285e01a0d78092449304d5048cabd.jpg
 

YotaAtieToo

Thick skull
Joined
May 19, 2020
Member Number
142
Messages
3,607
Location
MAGAlia, CA
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:

dnsfailure

WHAT GEAR ARE YOU IN?
Joined
May 19, 2020
Member Number
198
Messages
1,028
Location
Gilroy
I have some form of SD leafs in my obs, they sit slightly negative like most of them. I didn't do a :rainbow: 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.
 

back woods

Active member
Joined
May 21, 2020
Member Number
1010
Messages
39
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.

20200616_174209_c5df81b06cbf1f2c4d84c1654723cc678eb627d6.jpg


20200616_174158_ed09a64ecd0ff8ea1f4ac5ac2718cb68777dfe0a.jpg
 

Gatorgrizz27

Well-known member
Joined
May 20, 2020
Member Number
756
Messages
524
If you take the 6,000 lb log cabin off the back it won’t bottom out all the time. :flipoff2:
 
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