[5280_7.3]

I currently have a 2001 F-350 CCSB and decided to pull the trigger on upgrading the suspension and purchased a Full-Traction 4-Link conversion kit (6.0" lift). I initially purchased the kit with King shocks in the front and Bilstein 5100s in the rear with the FTS rear leaf springs, but after a considerable backorder from Bilstein, I upgraded to rear King piggyback shocks.

While the front portion of the kit was installed and no alignment, I really liked how the truck handled. It absorbed the annoying big bumps very well, while still providing some stiffness on the bridge expansion joints/cracks in the road that I think will go away once I get an alignment and play with tire pressures a bit more. Overall, I was excited to put the rear stuff on and hopefully get me a very smooth riding truck.

Fast forward to this past weekend, when the rear Kings showed up and I had time to install the leafs and shocks. After a 25 minute drive home from my shop, I felt terrible. The whole truck feels worse: very big bumps are good if not better, but rutty/pothole/expansion joint bumps are far worse. Coming from the race car side, it feels like the rebound in the shocks is far too high, or the spring rate of the FTS leafs are too high.

Now, I'm looking for thoughts on some ideas that crossed my mind on how to make the rear softer:
1. Keep setup, run weight in bed of truck
2. Revert to stock leafs, keep King shocks
3. Try a new rear leaf with less lift
4. Try the 08+ leaf conversion with shackle flip
5. Get shocks revalved
6. ??????

Thanks for your input!

 

[layson]

1st I would call them up and tell them how bad it rides. Expensive setup to be a rough riding SOB.

Then after calling them and seeing what they say I would start looking into rear options.

 

[Skyd Ram]

A couple of questions:

1) Who valved the shocks?
2) Is it a full rear leaf lift as in no blocks?
3) Did you torque the rear shackles with the truck on the lift or after you dropped it down on it's own weight?

 

[Fall Guy]

I'll be watching to see how this works for you.

I rode in a truck after the same setup was installed & noticed a rough ride from the rear. The only difference was this truck had the 2012 factory springs with traction bars.

Ive seen mixed results on this setup & wonder if it has to do with how the shocks are valved.

If you get it setup right & are happy with the end result be sure & post up the solution. Ive considered this for my 01 but wasn't happy with the way the rear handled.

Good luck! opcorn:

 

[5280_7.3]

A couple of questions:

1) Who valved the shocks?
2) Is it a full rear leaf lift as in no blocks?
3) Did you torque the rear shackles with the truck on the lift or after you dropped it down on it's own weight?

FYI, I talked to FTS before posting this topic and I am waiting to hear back from their Tech Rep. I really just made this thread for inputs on softening the rear on 7.3L trucks in general.

1. I ordered the shocks directly from FTS, who then placed an order with King. The shocks are valved per their specs, I really had no say in what the valving was going to be. I was told it was matched to their springs.

2. Full leaf kit. The instructions state that the new leafs will reuse the old stock lift block, which is what I did (3" I believe on an F-350).

3. I only got the rear shackle bolts on loosely, then tightened everything when on its own weight. I forgot to mention that we had a hell of a time getting the shackles off because the bolt had seized to the metal bushing insert and ruined the bushing. After some sawzall action and a new Prothane shackle bushing kit, it went in with no issues.

 

[ZMANN]

here is what i would likely do

first i would pull the kings and fab up a way to run the shocks i just pulled off to see if the shocks are the issue

if the shocks aren't the issue I would be pulling a rear leaf and adding bags so the truck
would ride on them ( you get what I am saying? ) as they brought the height back up from the missing leaf
say 20-30 psi


now this is what I would do if i had just cobbled some stuff together ( in other words no arguing with this procedure anyone since it's just what I would do :tard

but you paid good money so I would look for some answers from the suppliers

 

[5280_7.3]

Just a bit of an update. I drove the truck last night for a few miles on new tire pressures (40/40). While the truck does feel a bit better, I am leaning more towards either the springs are just too stiff, or the shackle needs to be flipped. I say this because when the bumps were getting bigger, the ride was getting better (no, really). It felt like the shocks were doing exactly what they were designed to do, it was the spring and it's geometry that was inhibiting the travel needed to dampen the bumps effectively.

While I don't tow anything and I rarely have anything heavy in the bed, I always noticed that the truck rode so much better with some decent weight in the bed. So, I am interested in a solution that does not require me to run a ton of weight in the bed. If my towing capacity is reduced, I don't care one bit. I want a very smooth ride no matter how much weight is in the bed.

One thing I also forgot to mention is my wheel/tire setup. 18" rims with 325/65/18 Hankook DynaPro ATMs. These tires are somewhat old and are a bit cupped in the front from having a bad alignment from the previous owner. I think they only have about 10-15k miles left, so these could be another culprit of poor ride quality. But since only the shocks and springs changed, I am ruling those out.

 

[sbluke55]

I'd pull the rear shocks and take it for a ride. If it rides better it's the shocks if not it's the springs. You will have some bouncing but you just have to look past it and focus on the softness of the ride.


Sent from AutoGuide.com Free App

 

[94slowbra]

im going through this right now with my icon set up. icon 7" lift 2.5 icon resi's with cdc valve up front and 2.5" smooth bodys in the rear with and icon 5" leaf and a 2" block. i expected the truck to be much smoother with the new shocks. front is a very noticeable improvement but the rear feels the same as with the crappy bilsteins. called icon and they are going to revalve the rears for free. if that doesnt work i guess ill upgrade to a resi and cdc valve in the rear. will let you know how it goes

 

[5280_7.3]

Thanks for your account of your situation. Full-Traction recommended the same thing as sbluke55: Remove the rear shocks altogether and see if it still feels stiff. If so, I can return the springs and try something else. If not, I can get the Kings revalved. Waiting until the weekend to do the removal.

 

[94slowbra]

i may remove the shocks and see what it feels like first too, never thought about that. then maybe i can give the icon boys a little better feedback. i understand its a 1 ton with dual rear wheels but there has to be something to help smooth this thing out. im not sending mine back to icon till next week some time so it will be a couple weeks before i have results of the shock revalve

 

[5280_7.3]

Can anybody confirm that 2014 rear leaf springs are the same as 2011 leafs? If so, I found a set of new 2014 F-250 rear leafs, Code L & M, locally that I might pick up and try out with a set of PMF relocation brackets. I'm just hoping they have the U-bolts and bottom spring bracket too.

 

[sbluke55]

The springs are the same from 08 tell present.

 

[ZMANN]

Sbluke5 are you sure ?
I thought the 6.7 was even longer than the 08's eight inch extension from the previous years ?? but i only read that no experience

 

[sbluke55]

I have no experience but SD truck springs list them as the same.

 

[ZMANN]

thanks
maybe it's the 2015 i was reading about ? i know they claim new rear spring?

 

[Skyd Ram]

Sbluke5 are you sure ?
I thought the 6.7 was even longer than the 08's eight inch extension from the previous years ?? but i only read that no experience

The length and mounting point on the 08-10 and the 11-15 spring is the same. The actual spring pack is different on the 11+ trucks as most use 2 think main leafs as opposed to 3-4 on the 08-10 trucks. There is also a difference in the ubolt designs.:thumb:

 

[5280_7.3]

The length and mounting point on the 08-10 and the 11-15 spring is the same. The actual spring pack is different on the 11+ trucks as most use 2 think main leafs as opposed to 3-4 on the 08-10 trucks. There is also a difference in the ubolt designs.:thumb:

I was able to later confirm this some deeper searching. Thanks for summing those differences up.

 

[5280_7.3]

I found a set of 2013 new take-offs and will be purchasing them this afternoon. One quick question though. The spring code listed is L or M, which states that it's for a SRW F-250 with aux leaf. Is this a good spring to get for my setup? I can't find any spec on this spring.

 

[5280_7.3]

Picked them up at lunch. Will post pics tonight. These have a dozen miles on them. A guy purchased a brand new truck and wanted the dealership to install a lift kit before delivery. Also purchased the PMF relo brackets, U-bolts, and 6" block with 2.5 degree taper.