TV and 5er Leveling

[Licreek]

How critical is the leveling of the TV and 5er. I just purchaced a 06 F350 King Ranch. It has a 4.5 in. lift. Will i have a problem towing a 5er and is there a brand of sliding hitch that mounts lower that most? Thanks

[IHnutz]

danrclem wrote:

Harley Doc wrote:


I've been lurking for a while, new to the group, so Hi to everyone. I've been reading these topics for a while (as I am currently not pulling level myself) and wanted to add a comment, or really, make a request. While a 6 inch gap between the trailer overhang and the bed rails seems reasonable, do we have a math whiz or Engineer who could give us a formula to determine exactly how much of a dip in the front wheels would create a 4, 5, 6, 7, 8 inch rise in the tailgate (or rearmost part of the bed rails)? It seems to me it would be a function of the wheelbase compared to the distance from the rear axle to the tailgate. If the front wheels dip X inches (or degrees), with the rear axle as the pivot point, the rear bumper (or top of the tail gate) should rise a corresponding Y inches (or degrees).

While this formula would not be perfect nor take into account compound curves (turning when the front wheel dips or goes over a hump), it would at least give us a baseline for our TV and trailer combination. It seems like longer wheelbase TV's would have an advantage in the discussion of "gap".

Thanks.

I'm going to take a stab at this but in no way guarantee how accurate my answer is. It's been a long time since I've had any geometry classes.

I'll use my truck as an example but these are just tape measure readings and are not exact. My wheelbase is about 141" and the rear axle would be the pivot point. I could look my specs up and get an exact reading but this will be close enough. The distance between my rear axle center and the back of my bed rail is about 46".

If I divide the distance between my rear axle center to the back of the bed rail (46") into the wheelbase (141") that would be 3.065. The wheelbase would 3.065 times as long as the distance from the rear axle center and the end of the bed rail. So if I lower the front axle down 1" I would take the 1" and divide it by 3.065 and it would give a rise of .326" (a smidgeon over 5/16") at the back of the bed rail.

Just take every 1" drop of the front axle (on my truck anyway) and multiply it by .326" and that should give you the answer. If the center of my front axle was 12" lower than the center of the rear axle the end of my bed rail would be 3.912" higher.

To really use this you would have to take into account at how high the trailer axles are in relation to the rear axle of the tow vehicle.

I have not seen a situation where traveling in a straight line if the front wheels hit a 12" dip the rear wheels didn't roll through the same dip. Given that the the tailgate rose about 4" with the front wheels dropping then the tailgate would subsequently drop a corresponding 4" when the rear wheels fell into the dip. Using this "data" a 6" space between the bottom of the 5th wheel frame and the top of the truck rails is more than adequate. HOWEVER, you have failed to mention the relationship/ratio of the distance between the trailer axle/s and the 5th wheel pin. Assuming the trailer wheels will more than likely fall into that same 12" dip that ratio is also critical. The shorter the distance, the more movement will be seen between the bed and the bottom of the trailer frame. Therefore, the relationship of the trailer wheelbase must also be considered when determining minimum bed rail to trailer frame distance.

JMHO but yours may vary.

[danrclem]

Harley Doc wrote:


I've been lurking for a while, new to the group, so Hi to everyone. I've been reading these topics for a while (as I am currently not pulling level myself) and wanted to add a comment, or really, make a request. While a 6 inch gap between the trailer overhang and the bed rails seems reasonable, do we have a math whiz or Engineer who could give us a formula to determine exactly how much of a dip in the front wheels would create a 4, 5, 6, 7, 8 inch rise in the tailgate (or rearmost part of the bed rails)? It seems to me it would be a function of the wheelbase compared to the distance from the rear axle to the tailgate. If the front wheels dip X inches (or degrees), with the rear axle as the pivot point, the rear bumper (or top of the tail gate) should rise a corresponding Y inches (or degrees).

While this formula would not be perfect nor take into account compound curves (turning when the front wheel dips or goes over a hump), it would at least give us a baseline for our TV and trailer combination. It seems like longer wheelbase TV's would have an advantage in the discussion of "gap".

Thanks.

I'm going to take a stab at this but in no way guarantee how accurate my answer is. It's been a long time since I've had any geometry classes.

I'll use my truck as an example but these are just tape measure readings and are not exact. My wheelbase is about 141" and the rear axle would be the pivot point. I could look my specs up and get an exact reading but this will be close enough. The distance between my rear axle center and the back of my bed rail is about 46".

If I divide the distance between my rear axle center to the back of the bed rail (46") into the wheelbase (141") that would be 3.065. The wheelbase would 3.065 times as long as the distance from the rear axle center and the end of the bed rail. So if I lower the front axle down 1" I would take the 1" and divide it by 3.065 and it would give a rise of .326" (a smidgeon over 5/16") at the back of the bed rail.

Just take every 1" drop of the front axle (on my truck anyway) and multiply it by .326" and that should give you the answer. If the center of my front axle was 12" lower than the center of the rear axle the end of my bed rail would be 3.912" higher.

To really use this you would have to take into account at how high the trailer axles are in relation to the rear axle of the tow vehicle.

[avvidclif1]

It's a simple ratio if the pin is directly over the axle. Measure the front axle to the rear and the the rear axle to the tailgate. For example 150" and 30" = 5-1 ratio. 5" of vertical on front = 1" at the tailgate.

[ChuckV1]

Licreek wrote:
How critical is the leveling of the TV and 5er. I just purchaced a 06 F350 King Ranch. It has a 4.5 in. lift. Will i have a problem towing a 5er and is there a brand of sliding hitch that mounts lower that most? Thanks

I wouldn't worry to much about the sliding hitch, You can adjust the pin box to compensate for that. Also 4.5 inches of lift is not much, what I would be interested in is once the 5th wheel is hooked to the truck how much did the rear of the truck drop from the weight of the trailer on the bed of the truck. The back of my truck drops 4 inches once I hook up to my 5th wheel, thus when unhooked it goes up 4 inches, this is without air bags just stock.

I have a 16k Curt 5th wheel hitch which sits below my bed rails quite a bit, I'd say more than 6 to 8 inches so I have to adjust me pin box angle a bit down to make up the difference to be level ....

All these like pin box, 5th wheel hitch all come into play, your dealer if they a good dealer should help you with your setup ... If your salesman states anything will work then I would exit stage left as fast as you can, they are not the ones you want to buy from 😞

safe travels 🙂

[Harley_Doc]

Yes, what you say is true, but a simple formula could not take into account every possibility (as you describe and/or turning in a corner, for example). What I'm talking about would merely be a formula based on a level surface and only a change in the position of the front wheel of the TV being considered. While it would not replicate the real-world, it would give us a consistent, baseline number to have in mind when adjusting the pin and hitch AND it would give greater credibility to the whole notion of using a 6 inch gap as a target number, as opposed to 5 inches or 7 inches. I suppose another formula to consider would be a worst-case scenario in which, on a level surface, the trailer axle (assume a single axle) dropped as much as, and at the same time as, the front axle of the TV , how much drop would be required to make contact at the tail gate with a 4, 5, 6, 7, 8 inch gap? I assume then that the distance from the hitch (or TV rear axle) to the trailer axle and also the hitch (or TV rear axle) to the tailgate would have to be factors in the equation. Now that I've said much more than I know 🙂 .....hope there is a great math mind in the group who can help!

HD

(BTW, both the academic and the skeptic in me comes out when "they" make some recommendation that could easily be quantified but has not been. "They" say to replace your mattress every 8 years. "They" say replace your MC helmet every 3 to 5 years. I have not seen any independent, scientific study to support either of those recommendations.)

Thanks again, Troubledwaters. Hope you are having a good day in your part of the world. Mid 80's for high here in Central Texas today, so we are enjoying the weather more than usual.

[troubledwaters]

You only described half the issue. The other half of the issue is the rise and fall of the wheels on the fifth wheel as the TV axles rise and fall, which is dependent on how far back from the pivot point they are, and the number of axles, and the spacing, what if one side goes down and the other side goes up, etc, etc, etc.

That's why they say you just go for 6 inches or more of clearance and call it a day.

[Harley_Doc]

danrclem wrote:
I don't know if all pin boxes and hitches have adjustments but on mine I lowered my hitch 1" and am going to raise the pin box 1". I could go more than that but it won't be necessary for mine. If you lower the front 1" it also raises the back a bit so with that adjustment you're actually making is more than a 1" difference from the front of the fifth wheel to the back.

If you make any adjustments just make sure you have enough clearance between the bed rails and 5th wheel.

I've been lurking for a while, new to the group, so Hi to everyone. I've been reading these topics for a while (as I am currently not pulling level myself) and wanted to add a comment, or really, make a request. While a 6 inch gap between the trailer overhang and the bed rails seems reasonable, do we have a math whiz or Engineer who could give us a formula to determine exactly how much of a dip in the front wheels would create a 4, 5, 6, 7, 8 inch rise in the tailgate (or rearmost part of the bed rails)? It seems to me it would be a function of the wheelbase compared to the distance from the rear axle to the tailgate. If the front wheels dip X inches (or degrees), with the rear axle as the pivot point, the rear bumper (or top of the tail gate) should rise a corresponding Y inches (or degrees).

While this formula would not be perfect nor take into account compound curves (turning when the front wheel dips or goes over a hump), it would at least give us a baseline for our TV and trailer combination. It seems like longer wheelbase TV's would have an advantage in the discussion of "gap".

Thanks.

[Wild_Card]

A lifted truck is not for 5th wheel towing...not with factory bed. Get a flat bed if needed

[danrclem]

I don't know if all pin boxes and hitches have adjustments but on mine I lowered my hitch 1" and am going to raise the pin box 1". I could go more than that but it won't be necessary for mine. If you lower the front 1" it also raises the back a bit so with that adjustment you're actually making is more than a 1" difference from the front of the fifth wheel to the back.

If you make any adjustments just make sure you have enough clearance between the bed rails and 5th wheel.

[Dayle1]

Licreek wrote:
is there a brand of sliding hitch that mounts lower that most? Thanks

A lower hitch is not a solution, you need at least 6" clearance between the top of the truck bed and the underside of the fiver.

[Halmfamily]

Licreek wrote:
Thanks for the info. How close does it have to be? were you ok with 2.5 in nose high?

I didn't have any issues. Only towed that way for a year before I started having too many costly issues with the 6.0 and sold it. Our GMC tows level.

[Old-Biscuit]

The more nose high the more weight shifts to rear axle/tires n 5vr and the lighter the pin weight

The lighter the pin weight the more 'chucking'

Is it advisable to set up level for towing .........YES

[Licreek]

Thanks for the info. How close does it have to be? were you ok with 2.5 in nose high?

[Halmfamily]

I was about 2" nose high on our stock 2006 F350 with 7" of clearance on tbe bed rails. With 4.5" lift you will probably need to flip the axles on the FW. Make sure you have at least 5-6" of clearance on your bed rails or you may hit the fifth wheel on the truck bed.