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02-16-2022, 11:25 AM
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#1
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Senior Member
Join Date: Nov 2021
Location: B’Ville, NY
Posts: 134
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Hitch adjustment question.
Okay, finally got to put the truck and trailer together to take some measurements. Didn't take it out, or even move it due to weather, just coupled and measured. I'm likely over thinking this, but here we go.
Truck 2022 3500HD DRW, trailer Fuzion 419, hitch is a B&W 25k. Pin box set for highest clearance, hitch set at middle, can go up or down 1 inch.
** Disclaimer, I did not measure the slope of concrete floor in barn as I have no means to do so. I am sure it isn't perfectly level.... its a barn.**
Here's what I found.
Truck rear dropped 1 3/4" with trailer on it. As measured at wheel well.
Truck bed rail to bottom of trailer 7 3/4".
Rest of measurements taken from floor to trailer skirting.
F d/s 25 3/8
R d/s 26 3/8
Difference 1"
F p/s 23/3/8
R p/s 26 3/4
Difference 3 3/8"
Difference from ground to skirt on trailer front corner to rear 1" on d/s, 3 3/8" on p/s. (See disclaimer above reference floor)
Measurements when trailer is auto leveled on jacks.
F d/s 25 1/2
R d/s 29 3/4
Difference 4 1/4"
F p/s 23 1/2"
R p/s 29 3/4"
Difference 6 1/4"
Difference from ground to skirt on trailer front corner to rear 4 1/4" on d/s, 6 1/4" on p/s. (See disclaimer above reference floor)
Pretty happy with the truck "sag" as it seems just about level with trailer attached. I'm thinking of moving the hitch head up to highest point to get the extra inch of bed clearance and that should make the measurements pretty close to 0 difference when hitched.
What I don't understand is why the difference in measurements F to R on jacks is so much larger. Just about 3 1/4" on each side. It doesn't look like the skirting runs downhill to the front on the jacks, or downhill to the rear on the hitch.
What am I not seeing?
Thanks in advance,
Charlie
__________________
2021 Fuzion 419
2022 Chevrolet 3500HD DRW HC Duramax with all the bells and whistles.
Got tired of "fighting stupid" (LEO) after 27 years and retired.
Active MX rider/racer, parent, sponsor, mechanic, transporter, and race fan for my son.
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02-16-2022, 11:36 AM
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#2
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Senior Member
Join Date: Aug 2021
Location: Eugene
Posts: 314
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Did you put a bubble on your trailer to see if it was actually level after hitting auto-level?
The zero point can get out of sorts if there's been any interruption in 12V connectivity.
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02-16-2022, 11:44 AM
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#3
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Senior Member
Join Date: Nov 2021
Location: B’Ville, NY
Posts: 134
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Quote:
Originally Posted by Essvar
Did you put a bubble on your trailer to see if it was actually level after hitting auto-level?
The zero point can get out of sorts if there's been any interruption in 12V connectivity.
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It's actually pretty close to perfect inside door both hitched and unhitched.
__________________
2021 Fuzion 419
2022 Chevrolet 3500HD DRW HC Duramax with all the bells and whistles.
Got tired of "fighting stupid" (LEO) after 27 years and retired.
Active MX rider/racer, parent, sponsor, mechanic, transporter, and race fan for my son.
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02-16-2022, 11:47 AM
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#4
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Senior Member
Join Date: Aug 2021
Location: Eugene
Posts: 314
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Quote:
Originally Posted by Skillet173
It's actually pretty close to perfect inside door both hitched and unhitched.
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Then you've got too much time on your hands
Just make sure you have 6-8" of clearance between your bed-rails and front cowling then go camping
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02-16-2022, 12:26 PM
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#5
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Senior Member
Join Date: Nov 2021
Location: B’Ville, NY
Posts: 134
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Quote:
Originally Posted by Essvar
Then you've got too much time on your hands
Just make sure you have 6-8" of clearance between your bed-rails and front cowling then go camping
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You’re not the first one to tell me that!!!!
If by I raise hitch head up 1” To 8 3/4” clearance I’m still good right? There’s about 4” between tail gate and trailer when hitching. Now, if I raise it an inch and just have to drop the “pro grade” part of new tailgate…..
__________________
2021 Fuzion 419
2022 Chevrolet 3500HD DRW HC Duramax with all the bells and whistles.
Got tired of "fighting stupid" (LEO) after 27 years and retired.
Active MX rider/racer, parent, sponsor, mechanic, transporter, and race fan for my son.
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02-16-2022, 12:46 PM
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#6
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Senior Member
Join Date: Aug 2021
Location: Eugene
Posts: 314
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Quote:
Originally Posted by Skillet173
You’re not the first one to tell me that!!!!
If by I raise hitch head up 1” To 8 3/4” clearance I’m still good right? There’s about 4” between tail gate and trailer when hitching. Now, if I raise it an inch and just have to drop the “pro grade” part of new tailgate…..
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8 3/4 is fine...
If you want to get REALLY crazy.... you have In-Command. Just raise the hitch from your phone above the tailgate, drive under then lower it with your phone.
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02-16-2022, 02:15 PM
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#7
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Site Team
Join Date: Mar 2011
Location: Gaylord
Posts: 26,841
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What you're "probably not seeing" is the suspension lift on the trailer between when it's "sitting on the springs/hitched to the truck" and "lifted off the springs/sitting on the leveling system".....
You're comparing two "different support systems", one springs and the hitch head and the other "lifted off the springs"... They will not give you the same measurements, even though the trailer sits "level in both conditions".
__________________
John
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
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02-17-2022, 04:35 AM
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#8
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Senior Member
Join Date: Nov 2021
Location: B’Ville, NY
Posts: 134
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Quote:
Originally Posted by JRTJH
What you're "probably not seeing" is the suspension lift on the trailer between when it's "sitting on the springs/hitched to the truck" and "lifted off the springs/sitting on the leveling system".....
You're comparing two "different support systems", one springs and the hitch head and the other "lifted off the springs"... They will not give you the same measurements, even though the trailer sits "level in both conditions".
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Understood. But shouldn’t the “rake” of the trailer be the same? I mean an inch or so over 44’ is pretty minimal but….. 🤷*♂️
__________________
2021 Fuzion 419
2022 Chevrolet 3500HD DRW HC Duramax with all the bells and whistles.
Got tired of "fighting stupid" (LEO) after 27 years and retired.
Active MX rider/racer, parent, sponsor, mechanic, transporter, and race fan for my son.
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02-17-2022, 06:34 AM
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#9
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Site Team
Join Date: Mar 2011
Location: Gaylord
Posts: 26,841
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Quote:
Originally Posted by Skillet173
Understood. But shouldn’t the “rake” of the trailer be the same? I mean an inch or so over 44’ is pretty minimal but….. ��*♂️
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There's a reason the SpaceX and Shuttle rockets have steering nozzles as well as thrust nozzles.... Small, minor changes in direction are going to be required in those "rocket science projects" because you can't "point the tip in exactly the right direction every time"... Just like you can't measure the front "exactly" by using the other end, 44 feet away.... Heck, just the "flexibility of the frame rails over that distance can easily cause a 1" disparity....
Next time you see an 18 wheeler towing an empty 53' flatbed trailer, look at the arch in the frame between the trailer tires and the trailer pin... Then try to find a loaded flatbed with that same arch in the frame... That "flexibility" is well over the 1" your 15,000 pound "flatbed" incurs when hitched and supported at the pinbox vs at the front landing gear, but illustrates how your trailer frame, like the flatbed, bends, twists and flexes as it is loaded, hitched, towed on unevel roads and/or backed into a campsite, warping the trailer suspension.
It's not just the tires that are "out of alignment" in a sharp backing angle, the frame flexes side to side as well. Then, when straightened out, and the front landing gear goes down, the frame flexes "up/down" as weight comes off the pinbox. Then, when the rear stabilizers go down, the frame flexes even more. Then extend the slides and the frame "drops on the heavy side" from the extra weight. With the stabilizers/landing gear "pushing against the weight of the slide, the opposite side of the frame is pulled up and the heavy side is pulled down...
That results in frame flex, easily measured more than an inch in some trailers, and that's just over the 8' width of the trailer, much less than the 44' of length that can induce significantly more "disparity in measurements between the front and the rear of the trailer.....
__________________
John
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
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