Wondering on a 2017-18 How difficult it is to lower the truck 3 to 5" front and back.

Was debating upgrading my 06 for a 17 or 18, but I tow a 5th wheel and my 06 is over 5" lower than the new trucks. I have a max of 2" adjust on the hitch so my options are really solely lowering the truck.

 

I have the same problem with my 2017 F350 CCSB being to tall for my fiver. My 2016 F250 was a full 7 inches lower and the hitch was set on the lowest setting. Pretty common problem and there are a number of threads in various forums on lowering blocks. Doesn't take much. If I can swap my 3.5 inch rear blocks for 2.0 inch blocks, I should be OK. This amount will almost perfectly level my truck.

Here's a link to the best thread I found. I has a PN for the 2 inch blocks, but I don't think they ever sorted out a PN for the U bolts. I have the blocks on order and intend to reuse the stock bolt since the nuts will be in a new place on the threads. Probably use a little locktite, too.

 

Honestly it depends on your fifth wheel. I have a 2015 Grand Design Reflection 317rst, pin weight is around 2000lbs and UVW is 10,900lbs.

I worried myself to death over this same issue when I made the decision to go from my '08 F350 2wd to a 2018 F350 4x4 in early January. My '08 sitting next to the '18 made me think there's no way my fifth wheel will hook up to this thing, but I went ahead and pulled the trigger figuring I would have to lower the new truck.


My new truck came with the fifth wheel prep package, but I didn't want to purchase a new hitch right now so I ordered the Reese adapter to use my old hitch. I had a decent weekend not to long ago so I thought I'd get outside and install my hitch and start taking measurements. With the Reese hitch adapter installed and the fifth wheel hitch mounted, I measured the top of the hitch plate to the bed floor which came in at roughly 19". Since I had a 2wd the RV dealer raised my hitch one notch and lowered my pin box one notch previously at the highest setting.

Since my driveway slopes down, my fifth wheel parked isn't level (nose high). I started with measuring the front of the RV's distance to the ground and the rear of the RV's distance to the ground. The front sat 8" higher than the rear so I knew the front would have to come down 4" to sit level. I also measured my trucks front distance to the ground vs the rears distance to the ground. The front measured at 41 15/16" (we'll call it 42") and the rear mearsured 44 7/8" (we'll call it 45") so basically a 3" rake.





Before making any adjustments to the pin box or hitch I needed to know how much the truck was going to squat once the fifth wheel was hooked up. I also wanted to know how much clearance I was going to have between the bed rail and fifth wheel. To my surprise the front went down 1" to 40 15/16" and the back went down 3 3/4" to 41 1/8" with a clearance between the truck and fifth wheel at slightly over 8".


This tells me I can raise my pin box back to it's highest position. I unhitched the RV and proceeded to move the pin box and re-hitch. The fifth wheel was still nose high after new measurements by about 2 1/2" and I still had over 7" of clearance between the truck and fifth wheel.

My next step was to lower my fifth wheel hitch one notch which put the hitch plate around 18" from bed floor. I re-hitched and measured again. The fifth wheel ended up about 1/2" nose high with a truck/fifth wheel clearance of 6 1/2" and about 1/4" rake on the truck. The one thing I didnt' do was slide my hitch to the forward position shifting the pin weight above the rear axles, but I don't anticipate the measurements to change much.





What's kind of a pain is how high I have to raise the fifth wheel to park my truck in front of it.

 

 

There are several ways to skin this cat, the first is that you actually need to hitch the truck (I know you haven't actually bought it) up to your trailer like has been said. My suspicion is that the rear springs have a pretty soft rate designed into them for the first few inches of wheel travel then they begin to stiffen up, then you get into the overload on top of the pack and lastly the thick overload at the bottom of the back. YOu might be suprised to find that even though the unloaded height is 5" different the loaded height might only be a couple inches.

IF, you determine you need to lower the rear you can basically lower it up to 3" in 1" increments. The 2017 F-350 factory block is a 3" block, Ford has a 2" block with the bump stop ears or do like I did and use a ORD zero rate at 1" thick, you will need to get a 7/16" center pin (I used a grade 8 bolt with the head rounded) It doesn't have the ears so you will need to pay closer attention to loading and may need to just get some air bags installed. You can choose to not even run the rear block to, I'm not sure about driveshaft length issues doing that. Depending on the way you go you will need to U-bolts. Ford sells different lengths but it's really hard to understand the part number vs. length. Several aftermarket companies can get the correct length u-bolts.

For the front the only (easy) way to really go about lowering is to get a softer spring. Most (maybe all) 6.7L PS trucks have a 5600# spring in the front, Ford sells a 5200# and 4800# spring that in theory will lower the front. I've read that the 4800# spring lowers the front about 1.5" or so. The factory bumpstops will need to be modified in the front or removed and replaced with something else. The down side here is that the reduced spring rate is likely to cause issues with getting into the bumpstops much easier. A good shock, 2"+ Fox or King should help keep things slowed down. A harder way would be to source a 5600# spring that was simply a few inches shorter.

What I did is in this thread towards the end, I think I even found a part number of a Ford U-bolt that would be correct for the 1" zero rates but I used an off the shelf kit from ORD, however they aren't technically the right semi-rounded u-bolt and I need to change them.
Lowering rear end