This is a response to questions about converting the stock Ford Excursion leaf spring suspension system to the newer +2005 Super Duty coil suspension. I've had several inquiries over the years so it makes sense to have a thread. My donor truck was a 2006 F-350 4x4 with the small V8 gas motor. Excursion was previously a bone stock 7.3 PSD 4x4 with a Dana 50 and 10.25.

The ride and feel of coil springs is significantly different. It takes getting used to. It at first felt very vague, felt like the truck was floating and could float in any direction. But since I used all of the donor vehicle's axles, suspension, and steering it became quickly evident that the truck tracked much better and no longer wandered all over the road. This let me trust it more and I quickly grew to appreciate and adapt to the change.

The coils also gave a little more clearance between the bump stops and axles in front so the harsh jarring was gone. Only time the front suspension feels like a really hard hit is not from compression, just from hitting either one tire or both simultaneously against a change in the road of a couple inches or more in height at fast speed. This is because there is no longer a shackle to allow rearward travel and absorption.

Yes, the turning radius is significantly tighter, some say it turns like a Dodge, I think tighter. There are no longer leaf springs for the tires to rub so the knuckle is able to swing further in both directions of travel. You will likely need to swap the steering gear and linkage to take advantage of the increased travel. Do you need your truck to navigate tight trails while following highly modified Jeeps through dense forest trails and narrow Mountain passes? With some help from the throttle I can usually make the same turns in one pass and definitely turn tighter than my buddy's mid 80's Chevy pickup.

If you can acquire both axles, all of the suspension, and steering parts including installation for only $3,000 that is a very good deal and I would jump on it but seriously question it as well. Sounds too good to be true. In my experience that usually means don't do it!

Is it worth the ride difference? This is subjective as the cost is high and there should be a need to justify such radical change. Do you ever jump your truck so that all 4 tires come off the ground? Do you need increased wheel travel for maximum rock crawling articulation? These are all things I get out of my conversion. If you're just after a smoother ride, tuning a leaf spring suspension can be done much more simply and for far less money. Air bags would ride smoother. The only thing I'm unhappy with is the side to side harshness which can be controlled by increasing shock stiffness which sacrifices regular ride quality. Hellwig's replacement bar was way too wide to fit, would have severely rubbed my tires. Coil springs in general have more side to side give, often allowing more roll than leaf springs.

The original coils were weak, didn't care for the stock shocks either. My 3rd set of coils are finally working out but required going to Rancho's newest adjustable shocks for the F-550 for the front, rear probably needs the same. The brakes are greatly improved on the newer axles but will require larger wheels to fit over them.

Hope this answers most of your questions. My best suggestion is to test drive some new trucks with the suspension you're after and see if you really like it. Doesn't ride like a luxury car, still rides and handles like a truck. I think it performs best at stock height without any lift, maybe just a little tuning. Much more responsive than leaves in front. I now have a 2.5" lift in front and 1" additional blocks in the rear. Really have to get the Panhard Rod and Drag Link lined up right or you'll feel the entire front end shift from side to side and get bad bumpsteer.

 

A few questions..

How "Bolt on" is this? There are mentions of the mounting holes already being in the Excursion's frame. Is this true?

Did going to larger brakes require changing the master cylinder and proportioning valve? Is the disc larger or just larger caliper and pads?

Thanks.

Doug