Doubled rear cross frame to increase hitch tongue weight. OEM frame is 1/8” thin!

[EveryDayBronco]

OEM tongue weight is 350 lbs and I want to carry my exc-f on the hitch and since the load would be farther I doubled the rear frame to beef up the hitch tongue capacity.

Super tedious work and had to modify the muffler location to make space for a second cross frame.

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[mmbretts]

I've not had any issues bith a bike carrier, but I respect the belt and suspenders approach. Hauled this bike 7hr without issue or any signs of structural issue.

Does your setup tie the new crossmsmber to the hitch at all or is it just tying the fram rails together?

 

[EveryDayBronco]

I've not had any issues bith a bike carrier, but I respect the belt and suspenders approach. Hauled this bike 7hr without issue or any signs of structural issue.

Does your setup tie the new crossmsmber to the hitch at all or is it just tying the fram rails together?

You're scaring me!

The cross member is thin box section, and tongue weight is rated for 350 lbs at the ball which is around 8" from the pin.

The carrier extends another 24" farther out which put approx. 3x the moment on the cross member.

IOW 300 lbs of bike + carrier that far back works out to around 900 lbs on a hitch that is rated for 350 lbs.

Now that you've tested it, how does it handle with the weight of the bike back there?

I would check the welds here, all around and both ends.

 

[BigMeatsBronco]

OEM tongue weight is 350 lbs and I want to carry my exc-f on the hitch and since the load would be farther I doubled the rear frame to beef up the hitch tongue capacity.

Super tedious work and had to modify the muffler location to make space for a second cross frame.

Nice work, can't tell from the pictures exactly what's going on.But I would definitely tie those two together directly.At the hitch.

 

[mmbretts]

You're scaring me!

The cross member is thin box section, and tongue weight is rated for 350 lbs at the ball which is around 8" from the pin.

The carrier extends another 24" farther out which put approx. 3x the moment on the cross member.

IOW 300 lbs of bike + carrier that far back works out to around 900 lbs on a hitch that is rated for 350 lbs.

Now that you've tested it, how does it handle with the weight of the bike back there?

I would check the welds here, all around and both ends.

No signs of deflection or fatigue. Minimal concern and I'd do it again without hesitation.

Handling is fine. Little more sway and the headlights were high terrorizing traffic, but I'm not expecting sportscar handling or one-ton dually carrying capacity.

I'm not sure since mine's removed, but the spare tire might give you grief. Not much room between bike and tailgate, at least on my carrier.

 

[EveryDayBronco]

Nice work, can't tell from the pictures exactly what's going on.But I would definitely tie those two together directly.At the hitch.

The new cross member is 2.5x2.5x.25" tube steel and is bolted to the back of the hitch with the four 1/2" bolts. Contact area is 9.75"x 2" with bolts torqued tight.

Welding the new tube steel to the hitch would be next level for strength but the end brackets, which you can see, are as strong as I could practically design, and out of the entire system, they are the weak points. So, welding my new tube steel to the hitch wouldn't make the whole thing any better.

I would not weld anything to the bronco frame. If it was old, I might but not now.

 

[EveryDayBronco]

No signs of deflection or fatigue. Minimal concern and I'd do it again without hesitation.

Handling is fine. Little more sway and the headlights were high terrorizing traffic, but I'm not expecting sportscar handling or one-ton dually carrying capacity.

I'm not sure since mine's removed, but the spare tire might give you grief. Not much room between bike and tailgate, at least on my carrier.

Not having the spare tire puts you about 8" closer which is not as bad but you're still overloading the hitch by 2x.

 

[swamp2]

The carrier extends another 24" farther out which put approx. 3x the moment on the cross member.

IOW 300 lbs of bike + carrier that far back works out to around 900 lbs on a hitch that is rated for 350 lbs.

Nice quick back of the envelope calculation. It shows Ford uses decently large factors of safety. That said the dynamic loads significantly amplify static losds, probably by around double (say 1 g dynamic load). Ford obviously uses dynamic trailer loads though as well (to determine the static rating number), so your 2.6 factor is more apples to apples.

Nicely executed solution as well! It relies on a very close fit and contact with the hitch itself?

 

[EveryDayBronco]

Nice quick back of the envelope calculation. It shows Ford uses decently large factors of safety. That said the dynamic loads significantly amplify static losds, probably by around double (say 1 g dynamic load). Ford obviously uses dynamic trailer loads though as well (to determine the static rating number), so your 2.6 factor is more apples to apples.

Nicely executed solution as well! It relies on a very close fit and contact with the hitch itself?

Yes, the new tube steel is bolted to the back of the hitch with the four 1/2" bolts that would normally just bolt the hitch to the cross frame. Contact area is approx. 20 square inches.

I crunched the numbers and the weakest points are the end brackets.

Welding gusset plates to the new cross member and hitch would make it stiffer/stronger but the friction fit with the four bolts already exceeds the strength of the end brackets.

It's as strong as I can practically make it and it satisfies my needs so I'm calling it, done!

I also built a motorcycle carrier that I might post after I test it out.

 

[Higgspeed]

After hauling my 350lb Honda XR650 I ended up installing the Bronco Raptor Hitch Support Braces (easy since I had already changed my exhaust and got rid of the huge factory muffler)

I also added a manual fill Air Bag system to the rear axle, which I still need to test it loaded down like this.

Disclaimer (this photo is before I did any of this )

 

[swamp2]

After hauling my 350lb Honda XR650 I ended up installing the Bronco Raptor Hitch Support Braces

As noted just above, it's more about the leverage than the load itself. The Raptor bracing only takes the static rating from 350 to 450 lb.

 

[‘21OBX]

I’ve started thinking about this when I installed our hitch last week. I’d like more contact with the rear crossmember but I like this easier approach. You basically built a hitch for behind the hitch keeping the approach angle where it was. I like it.

 

[Tonka Bronka]

From someone who pulls a max capacity off grid camper, I like this, but there is a drawback. I was rear ended by some crackhead. Due to the spare tire, I have to use a hitch extender and got into the habit of leaving the extender in when not towing. Bad habit. The extender took the brunt of the impact and twisted the crossmember. It was replaceable because the crossmember is designed to be sacrificial. I like the idea, and your execution. And now you have peace of mind.

 

[Motovita]

OEM tongue weight is 350 lbs and I want to carry my exc-f on the hitch and since the load would be farther I doubled the rear frame to beef up the hitch tongue capacity.

Super tedious work and had to modify the muffler location to make space for a second cross frame.

Nice work. Of course it will do you no good in any inspection or insurance claim. Your Bronco still has the same rating.

 

[EveryDayBronco]

Nice work. Of course it will do you no good in any inspection or insurance claim. Your Bronco still has the same rating.

That has no bearing on my reason for doing this.

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