Measuring fifth wheel cap to truck cab clearance

[BradF1956]

Hello,

Using the standard measurement process posted on some sites; i.e. measure the total width of trailer/ divide by 2 and then measure from center of hitch jaws to cab leaves my clearance short by about 2".

Specifically, my trailer is 96" wide, dividing by 2 leaves 48". My current clearance is 46".

#1- question- does the Grand Design Max Turn Radius front cap change this calculation? Note that I did not purchase a slider hitch because I heard they can cause contact to the tailgate on standard bed trucks. I have towed the trailer just once and made somewhat tight turns with no issues.

#2- question- what is typically the max turning radius of a trailer without damaging the trailer suspension?

I have been a motorhome owner for decades, no experience with a 5th wheel. Any advice is much appreciated.

Thanks!

Brad

[jacknife]

Short bed l wouldn’t go more than 70 degrees . Jacking your trailer is very hard on the spring hangers and the wheels and tires do to the torque put on the suspension . If your trailer does not have it put on a heavy duty shackle kit . About $120 . X factor cross braces also help because they tie into the shackles and provide an opposing force . I have both on mine and have never busted a spring hanger . Trailer is 10 yrs old about 70k on it . You also need to watch your bed rail clearance minimum 6 “ preferably 7 to 8 . Watch steep entry and exit . Where your truck is going up and your trailer nose is down . Like a steep driveway entering a road that has a high crown . Have fun !!

[Skilletface]

Brad;

#1- question- does the Grand Design Max Turn Radius front cap change this calculation? Note that I did not purchase a slider hitch because I heard they can cause contact to the tailgate on standard bed trucks. I have towed the trailer just once and made somewhat tight turns with no issues.

A. If the Max Turn Radius is like the Max Point found on GD, then yes this calculation does not apply as the pivot point is now under the front cap instead of at the hitch.


#2- question- what is typically the max turning radius of a trailer without damaging the trailer suspension?



A. Beyond a 70% departure angle is a good number for suspension damage to begin, that does not mean it may not occur sooner but a pretty good bet its close, to many environmental variables to calculate. As suggested, upgrade with the cross braces and shackle kit.

Opinion Since you have owned a Motor Home you'll understand when I state this hitch and suspension question can be a rabbit hole. I believe the Turning Point is a great solution for cab to cap clearance, it has one bearing that does require annual maintenance. I use the Andersen Ultimate Hitch (Turning Point locked) as it is engineered with a "4 setback and little to no maintenance required. As for suspension upgrades, they are cheap insurance and yes we need them because the world of RVing is not perfect. MORide suspension systems are in the top tear bolt on aftermarket suspension upgrades.

[Camp CA]

1. Does the Grand Design Max Turn Radius front cap change this calculation? Curious where this calculation came from as I never heard of it while owning 4 fifth wheel trailers with short and long bed tow vehicles with non-slider hitches. You will be fine with a non-slider hitch as long as you plan your backing and do not rush it.

#2- question- what is typically the max turning radius of a trailer without damaging the trailer suspension? Never damaged or heard of a fifth wheel trailer damaged turning or jack knifing it yet.

You might find this thread helpful on how tight can you turn a 5th wheel?: https://www.irv2.com/forums/f44/how-...el-391814.html

[BradF1956]

Thanks for the responses and advice.

Just to clarify, the "Max Turn Radius front cap" I believe is just a description of the rounded / aerodynamic design of the front cap. The exact description in the brochure is "Aerodynamic Front Cap with Max Turn Radius". My trailer does not have a Turning Point hitch. Just a regular Lippert Pin Box.


The distance calculation comes from videos put out by hitch manufacturers.


I have towed the trailer and have not had a clearance issue, however, I did not try to determine what my truck can handle as to the actual % angle.


Regarding the suspension, it sounds like anything at or near 70% is the max anyway. Which makes sense to me as 70% seems pretty tight.


Thanks,

Brad

[hamm2018]

Originally Posted by Camp CA

#2- question- what is typically the max turning radius of a trailer without damaging the trailer suspension? Never damaged or heard of a fifth wheel trailer damaged turning or jack knifing it yet.

I busted the rear spring hangar on our triaxle backing into a spot at Elkhart County Fairgrounds in 2020. Backing up and I heard a loud pop sound. Looked at it the next day while repacking bearings and there it was, one side of the weld broke.
I was not backing from a 90deg. angle, because I always try to cut the angle down as much as possible when backing it.

[traveldawg]

Brad,
It sounds like you are going to buy that 5th wheel you are talking about. Just buy it and forget all these calculations and guessing and turning radiuses and angles and popping spring hangers and such.

Once you get it go to a big parking lot and practice backing and turning. Use a spotter. Learn what you can and can not do with your particular set up as most everyones (except someone with you exact set up) are a bit different.

If getting a slider (auto or manual) eases your anxiety, get one.

Always use a spotter (I know - I keep repeating that).

As for turning sharply - yes, it is pretty hard on your suspension, at least on hard top. But it can be unavoidable at time with a lot of campgrounds. Moving forward a foot or two help straighten the truck an trailer a bit helps a lot; and there is no shame in doing that to keep a smaller angle and reduce the stress on the tires (and suspension).

Safe travels.

oh - when I had short bed trucks I always used an auto slider - I didn't want to have cab clearance on my mind when backing or towing - one less thing to stress out about.

[Rhagfo]

There is a reason I have a long bed truck!!
This is a personal choice and sure you have a reason for wanting a short bed. My reason for having a long bed, is I don’t have to think about max turn radius stuff.

Something to think about the 46” you have, take a tape measure and with 46” marked and one end attached to the pin, start moving from center front to the side and see where 46” hits.

[jimcumminsw]

Buy an autoslider hitch and do not worry about the trailer to cab clearance.

I use a Demco Hijacker Autoslider hitch with my Dodge Mega Cab short bed.

Another item to remember is the truck and trailer will pitch up and down sometimes as you are backing in do to uneven surfaces. That's what will get you on cab clearance.

[BradF1956]

So, I have towed the trailer with no clearance issues so far. To be fair it was only about 4 miles to the tire shop and back though.

I currently have a new non-sliding BW Companion hitch so I likely won't buy the slider version. Note that I purchased the standard hitch due to information regarding sliding hitches possibly allowing the pin box to contact the tailgates on standard bed trucks. My truck has the GMC Multi Pro tailgate which I really would rather not crush.

BTW I currently have 7" of clearance above the rails.

Really appreciate the advice, I can comment on any motorhome out there; Class C, Super C or Class A but obviously a rookie when it comes to trailers.



Brad

[Garyp4951]

The B&W Companion has several distance and height settings, and yours being 46" from the cab to king pin should be ok, but always be cautious when backing in.

I have the same hitch set at 42" from the cab or 5" behind the axle center and have not had a problem, but I'm always aware it could happen.

[C.B.]

Originally Posted by jimcumminsw

Buy an autoslider hitch and do not worry about the trailer to cab clearance.

I use a Demco Hijacker Autoslider hitch with my Dodge Mega Cab short bed.

Another item to remember is the truck and trailer will pitch up and down sometimes as you are backing in do to uneven surfaces. That's what will get you on cab clearance.

I'm with you on the autoslide.


Pullrite 16K Superglide here.


C.B.

[jimcumminsw]

Originally Posted by BradF1956

So, I have towed the trailer with no clearance issues so far. To be fair it was only about 4 miles to the tire shop and back though.

I currently have a new non-sliding BW Companion hitch so I likely won't buy the slider version. Note that I purchased the standard hitch due to information regarding sliding hitches possibly allowing the pin box to contact the tailgates on standard bed trucks. My truck has the GMC Multi Pro tailgate which I really would rather not crush.

BTW I currently have 7" of clearance above the rails.

Really appreciate the advice, I can comment on any motorhome out there; Class C, Super C or Class A but obviously a rookie when it comes to trailers.


Brad

Towing the limited distance, you did will not tell you anything.

Wait till you get in a park with poorly maintained roads. And you start to back into a site the road is uneven, and the pad is not real level. So, the rear of the cab pitches down and the trailer pitches up as you near the maximum turning point of truck and trailer. There goes the rear window, and the C-pillar is dented, hope your insurance is good.

I have seen a lot of damaged trucks in state parks and other parks. Were the driver thought he was safe with his hitch and trailer combination. And the rear window covered in plastic with Duck tape all over the rear of the cab holding the plastic in place. Just saying.

Even making sharp turn into a parking lot or into your driveway, backing up if it is slopped you could break the window and dent the C-pilar.

Depending on where the auto slider is mounted (should be over the axle in the forward position) the rear of the hitch should not touch. But some installers do not install the hitch correctly.

Now if you have the tow package with the puck system the hitch in the tow position should be mounted correctly.

[tuffr2]

I thought those fancy 5th wheel caps allow almost a 90 degree turn with a short bed truck. I remember seeing 88 degree on some of those caps. The trouble is you don't know for sure. Agree, how do you test.

If I wanted a 5th wheel I think I would get a GM truck that has the pin a few inches behind the axle. Also I would look for 5th wheels with the sharper turning cap.