Riser Hitch Concept (1 Viewer)

[Chris Wilcox]

Opinions:
Would you tow a 3400 lb gross weight military trailer with this riser hitch concept?
Rise is 9.0" higher than the OEM crossmember pintle holes. Trailer has surge brakes. FJ80 is otherwise stock.
Assume welding is not a concern.

 

[98 SNAKE EATER]

Interesting design

Honestly, I wouldn't hesitate with only 3400 lbs, but then again, I've been known to tow a lot more with just a pintle hitch

 

[BILT4ME]

I wouldn't, but I'm not you. That's a LOT of cantilever up that high from the pivot point. I would be concerned about having it bend forward during heavy braking. That would also put a lot of lift on the back of your truck during heavy braking since the connection is well above the center line of the rear axle.

Also looks like there would be a LOT of movement with the multiple connections and pins holding it together. I'm sure others have done worse, but not I.

 

[Chris Wilcox]

Appreciate the thoughts. I am concerned as well about the cantilever but with hydraulic braking on the trailer it should be less of a problem but not necessarily acceptable.
The M1101 tongue height is 29.5" which is really high.
I'm still thinking on what to do. Some have rewelded the trailer ring lower but I'm not a huge fan of that either.
I may do this to go get one empty at ~1500 lbs and see what happens from there once I experience the towing.

 

[Chris Wilcox]

This is another option I've seen but to be totally level would require quite an extension.

 

[mingles]

Does the hitch shown exist as a product or as a concept only? I like the design and would not be concerned with a 3400lb trailer that is already braked. If used regularly, the fact that your tailgate would probably hit the hitch when opened would be a pain.

I have an M1101 flat deck version and my solution was to replace the military run flat tires with civilian 31" tires. There was probably a 200lb weight savings, Dodge and GM 8 lug rims bolt right up, and this lowered my lunette height to a more manageable 24". I have done this on a M116A3 as well and both trailers tow and brake great (behind 1/2 ton pickups) with this setup. I am new to the 80 world and am currently setting up my LC with a B&W Tow and Stow pintle drop/rise setup to tow the above trailers.

A word of caution on rewelding the lunette height on the trailer side. In my work we occasionally make trailers that need to adapt to both military and civilian tow vehicles and changing the geometry of the surge brake mechanism on the trailer will render the surge brakes ineffective. By increasing the distance between the lunette ring and the slider brake actuator the braking force is changed from pushing the slider straight in (the way it was designed) to basically creating a lever arm that binds the slider actuator and prevents the surge brakes from applying.

Keeping the surge brake mechanism as it was designed and adjusting the hitch height on the vehicle side (with a proper hitch design) is the easiest way to safely mate the two.

My M1101 with civilian Dodge rims.

 

[inkpot]

Just don't forget to pull the vertical hitch extension from the rear bumper before opening the tailgate.

 

[astr]

I had the same situation as you. i just purchased one of these http://www.etrailer.com/dept-pg-Bal...tch-hs-Fits_2_Inch_Hitch-sz-8000_lbs_GTW.aspx and one of these http://www.etrailer.com/Ball-Mounts/Draw-Tite/63012.html bolted them togeter and have had no problems. I did drill another hole in the shank of the mounting plate to allow it to slide further into the receiver so that the standard safety chains would reach. I did go to a smaller tire but that was primarily to drop the trailer deck to make loading easier.

All the photos are of the trailer empty. Put a good load in it and it will drop.

 

[Chris Wilcox]

Thanks everyone I really appreciate the different experiences and knowledge. The first picture is just something I threw together in cad to see how it would look. It is not a production item. If I ever made one it would be only one. Lots of thinking but I'm crossing off modifying the trailer lunette.

 

[wearsabrowncoat]

Astr's solution looks the most sound.

 

[ZA80]

6" lift and 38" should solve the problem.
Seriously that is a very big adjustment with way to much leverage.

 

[Lionsgarage]

By the way.....either way you decide to go, make sure you understand the forces involved under emergency braking maneuvers. Oh, and cross those safety chains....it's the law in my state....for a very good reason.

 

[Chris Wilcox]

Yeah, I'm going to try and get a copy of SAE J684 and may apply loads in FEA to see how things behave.