2" receiver hitch on M37

[John Mc]

I'm looking to add a 2" receiver hitch on my 1951 M37. I want to keep the stock pintle hitch. I've seen a few pictures of people who fabricated a receiver set up. I'm thinking of mounting a stock aftermarket receiver hitch sold for modern trucks. It seems the frame rail spacing is the same as modern trucks. On another site, a member mounted a hitch he removed off his 2001 Dodge Ram onto his M37. All that was required was drilling the mounting holes in the frame. His hitch had a LOT of drop (necessary to clear the bumper on his modern truck). It caused him to lose more ground clearance than necessary.

I'm looking to find a manufactured hitch that will fit as close as possible under the frame without interfering with the pintle hitch. I'm open to other options, but I don't want to lose the pintle hitch (I dont currently own any pintle hitch trailers, but I like the look, and may own one in the future). I'm concerned about mounting something on the cross member, particularly because the large drop required to get the ball to the proper height (I have 11.00x16 tires) seems as though it would put quite a twisting moment on the cross member when towing. A frame mounted hitch avoids this concern.

Since none of the online trailer hitch places I've checked have any dimensional information online, I'll be making a visit to a local hitch sales/installation place to see what they may have. Since I doubt many places have a huge inventory of hitches waiting to install that we can just hold up for a test fit, I'm hoping someone here has already done this, and has a recommendation for an make/model of an aftermarket, frame mounted hitch that makes for a good fit on an M37. Appearance-wise, I'd prefer a "squared-off" look; I think that would make a better fit with the character of the truck, rather than a hitch made from round or bent tubing.

So has anyone done this? Any leads would certainly shorten my search process.

 

[zebedee]

I am just about done with a QD mount hitch for a M932 that utilises the inner pintle hitch large nut and the outer shackle brackets for a triangulated 2"reciever. Pics soon will give you my approach..
Cross reference for M932 QD Hitch:-

QD 2" Reciever hitch.

Allie in NJ contacted me about a dismountable hitch for his M932. I went down and made some measurements of height required and possible "structures" available on his tractor. Strict requirement that it be easily removable so as to retain originality for shows etc., with the minimum of...

www.steelsoldiers.com

 

[Explorer0863]

I do realize that this is an old thread, but I found this on eBay: https://www.ebay.com/itm/M37-MILITARY-TRUCK-HITCH-PINBALL-TM-2-RECEIVER-HITCH-TRUCK/153408234738

 

[thmpr]

Be careful with the flat-faced, eBay 2" receivers. M series have an outward structural bend in the rear crossmember below the pintle that would need to be shaved off for the new receiver. Thinking of doing it, but worried about the crossmember bending inward under heavy braking. Maybe add 2 gussets behind the crossmember to compensate?

 

[John Mc]

I do realize that this is an old thread, but I found this on eBay: https://www.ebay.com/itm/M37-MILITARY-TRUCK-HITCH-PINBALL-TM-2-RECEIVER-HITCH-TRUCK/153408234738

As mentioned in my original post: I have 11.00x16 tires, it's likely I'll need a substantial drop from the receiver to get the right height for my 2" ball hitch trailers. I'm not interested in putting that kind of twisting moment on my rear crossmember when towing. This means either reinforcing the rear cross-member, or installing a frame mounted hitch.

I'm still looking for a modern frame mounted hitch that will fit and not eat up a large amount of my ground clearance. None of th etrailer hitch places in my area would take on searching out a hitch that would fit. They go by entering a model and year and look up the part to order. The project took a back burner util I mentioned it to a local auto mechanic. He recently pulled a hitch off a Jeep that he thinks might fit. It's got about a 2" drop from the frame mount to the top of the receiver, which is just about ideal: just enough to clear the little bump on the bottom center of the rear cross member and the bottom of the pintle.

I'll let folks know how it goes - it's going in for a test fit next week.

 

[John Mc]

Well, I finally found a couple of option for this. I'll describe the first one here. The second option, which required modifying an off the shelf receiver, appears in my next post,

DRAW-TITE #75054
A local mechanic had a hitch from a 2000 Jeep Cherokee (not a Grand Cherokee) that had very little drop. He said it was rated for 5000#, so I asked him to install it using the rivet holes which attach the truck's rear cross-member to the frame as the mounting hole for the rear-most hole on the hitch. The only modiications to the truck were to drill holes in appropriate locations in the frame for the hitch's mounting bolts. On the hitch itself, the flanges that mount to the frame are wider than the frame, so about 1/4" needed to be ground off the outside edge of the hitch flange for about 3.5"-4" from the front end to clear where the rear springs attach.

Overall, the fit was decent. The hitch hung down about 1.5" lower than it really needed to to clear the bottom of the rear cross-member. So it lost a bit more ground clearance than absolutely necessary, but it was the least drop on a commercially-made hitch I could find.

I ended up pulling that hitch off, because it turned out, the 5000# rating was for a weight-distributing hitch (which none of my trailers are set up for). For a regular weight-carrying hitch, the rating is only 3500#. Since I want to use this truck in the woods, pulling around trailer loads of logs, that rating was not enough for me (my empty log forwarding trailer weighs almost 1500#). Unfortunately, I can't find my pictures of the photos I had taken with this hitch mounted on the truck.

If I had kept the hitch, I probably would have slid it forward on the frame a bit more and not used the truck's rear cross-member rivet holes as a mounting point. This would tuck the hitch in just a bit further under the rear cross-member.

The hitch had a RIGID label on it, but it appears to be the same thing a the Draw-Tite # 75054 (Rated for 3500# & 350# tongue weight or 5000#/500 with WD Hitch.)

CURT #13084
It appears Curt Makes a similar hitch rated for 5000# tow / 500# tongue (6000#/600# with WD hitch). See Curt #13084. If 5000# tow rating is enough for you, and you don't need the absolute minimum loss of ground clearance, using this receiver unmodified might just be one of the better "off the shelf" matches out there for an M37. It's hard to tell from the photos, but it appears that it may have only slightly more drop than the Draw-Tite model noted above. If i were mounting it, I think I would slide it forward enough to not use the truck's cross-member rivet holes. This would tuck the receiver cross-bar in nicely under the truck's rear cross member. Take a look at the fit yourself before making a final decision. The price is quite reasonable: currently $112 on eTrailer.

If you need the absolute minimum loss of ground clearance, you could always modify the hitch, similar to what I did to a different hitch as described in a later post.

 

[John Mc]

I ordered a Draw-Tite #41536 receiver hitch. It was the hitch with the least amount of drop I could find rated at 6000# towing weight / 600# tongue weight (10,000#/1000# with weight distribution hitch). It has noticeably beefier construction than the 3500# rated Draw-Tite/Rigid hitch noted in my previous post. Cost was $187 from eTrailer.com.

This post shows how the hitch fits unmodified, using the truck's cross-member rivet holes for the rear-most mounting hole in the receiver. As expected, the drop was more than I wanted, but it was not too bad. It might work fine for someone who did not need every bit of ground clearance.


I above picture, the top of the hitch cross bar sits roughly 2.5" below the lowest point of the truck's rear cross-member (the rounded part under where the pintle mounts).


Hard to see in the picture above, but the receiver cross bar is almost centered fore and aft under the lowest part of the pintle. This puts the front edge of the cross bar about 1/4" behind the rear edge of the truck's rear cross member.


There is about 2.5" between the lowest point of the pintle, and the top of the receiver's cross bar. (The top of the receiver tube itself sits about another 2.5" below that.

As you can see from the first picture, at least with the 11.00R16 ties on this truck, the ground clearance is still pretty good. Plenty for on-road use, and some off-road. The ball shown installed in the pictures is still slightly higher than standard for my other vehicles. I suspect it would be right where it should be with the receiver insert shown, and something close to stock tires on the truck.

If I were mounting this hitch unmodified, I would slide it forward several inches on the frame rails to tuck the receiver's cross bar in under the truck's rear cross member (this would also mean you would not need to drill out the rivets in the rear cross member).

 

[John Mc]

Here is what I ended up doing. I took the Draw-Tite 41536 hitch noted in the previous post and had it modified by a welder (who has far greater welding skills than I do). He moved the receiver cross bar forward about 2.5" and up about 2.5 - 3" (dimensions are approximate). When using the trucks cross-member rivet hole (which was already drilled out for my attempt with the Cherokee hitch), the fit came out right where I wanted it.

I will be substituting grade 8 fine thread bolts in the holes which go through the old rivet holes in the truck's rear cross member, as called for in the frame repair technical manual. The rest of the mounting bolts will stay with the grade 5 hardware that came with the hitch.







I'm happy with how it turned out. The only tricky part was getting the forward-most mounting bolts installed on each side. The gas tank sits too close to the frame rails to easily get the bolts in place. Fortunately, the included hardware is carriage bolts, and they ship with rectangular "washer" blocks with square holes in them to capture the square under the carriage bolt head. This locks the carriage bolt in place without the need for a wrench. It took a bit of creativity to get the bolts and rectangular blocks slid up the rail so the bolt would drop through the hole, but it ended up not taking long to figure that out.

Overall, I'm happy with the result. I'm sure Draw-Tite would have fits if they knew the hitch was being mounted on an "unapproved" truck, not to mention the fact that the hitch has been modified. However, I have confidence in the welds, and the only time the hitch will come anywhere close to it's rated capacity is in the woods, where it is moving less than 10 MPH.

If I could live with a bit more loss of ground clearance, I would probably go with the 5000# Curt unit mentioned previously. No modifications to the hitch required, and the odds of me doing serious towing over 5000# with a mostly stock M37 are pretty slim.

 

[Explorer0863]

Thanks for the information on those hitches. I will definitively explore that option when I'm closer to finishing my project.

By the way, those tires look good. What are those?

 

[John Mc]

Thanks for the information on those hitches. I will definitively explore that option when I'm closer to finishing my project.

By the way, those tires look good. What are those?

Those are Michelin 10.00 R 16 XL tires. Larger than standard. They were on the truck when I bought it. They are a little "over the top" for my taste appearance-wise, but I've gotten used to them. I used my truck in the woods, so the extra ground clearance has proven handy. I understand that they can be hard to find these days, and they are expensive (glad I've got a couple of spares).

If you want more info on how the hitch was modified, I had the fab shop make me a sketch of what he did (see below). Basically, he cut out the cross bar including a little bit of the sides around each end, then cut the sides of the hitch, moved it upward and welded it back in place. (He said the tough part was maintaining exactly the same spacing, especially since he did not want to mount the hitch and tack things up in place: welding near a 70 year-old gas tank was not something he was really looking forward to.)

As mentioned above, I used the rivet holes that attach the rear cross member as the holes for the rear-most mounting bolts on the hitch, since I had already drilled them out from my attempt with a lighter duty hitch. If I were doing this over again, I would probably leave the rivets intact, and just slide the hitch forward enough more to clear them. This would do a couple of things:

1. I could leave the original rivets alone (though frame repairs which replace them with a grade 8 fine thread bolt were an approved repair)
2. Keeping things perfectly aligned would be less critical when welding: the frame flanges are wide enough to allow some leeway in the positioning, so you could weld it back up and as long as you kept things square and reasonably close, you would be fine when custom drilling the new holes.

I believe there is enough room that a ball on a receiver insert should still have plenty of clearance, even if things were moved forward a bit. If anyone is interested, I can post a picture of my hitch with a receiver insert & ball in place.

 

[Explorer0863]

Those are Michelin 10.00 R 16 XL tires. Larger than standard. They were on the truck when I bought it. They are a little "over the top" for my taste appearance-wise, but I've gotten used to them. I used my truck in the woods, so the extra ground clearance has proven handy. I understand that they can be hard to find these days, and they are expensive (glad I've got a couple of spares).

If you want more info on how the hitch was modified, I had the fab shop make me a sketch of what he did (see below). Basically, he cut out the cross bar including a little bit of the sides around each end, then cut the sides of the hitch, moved it upward and welded it back in place. (He said the tough part was maintaining exactly the same spacing, especially since he did not want to mount the hitch and tack things up in place: welding near a 70 year-old gas tank was not something he was really looking forward to.)

As mentioned above, I used the rivet holes that attach the rear cross member as the holes for the rear-most mounting bolts on the hitch, since I had already drilled them out from my attempt with a lighter duty hitch. If I were doing this over again, I would probably leave the rivets intact, and just slide the hitch forward enough more to clear them. This would do a couple of things:

1. I could leave the original rivets alone (though frame repairs which replace them with a grade 8 fine thread bolt were an approved repair)
2. Keeping things perfectly aligned would be less critical when welding: the frame flanges are wide enough to allow some leeway in the positioning, so you could weld it back up and as long as you kept things square and reasonably close, you would be fine when custom drilling the new holes.

I believe there is enough room that a ball on a receiver insert would still have plenty of clearance, even if things were moved forward a bit. If things got too tight, you could not re-weld things quite as far forward as I had done (the hitch crossbar could easily have been moved 3.5" forward, rather than the 4" I did). If anyone is interested, I can post a picture of my hitch with a receiver insert & ball in place.

View attachment 808667

Hey John, thanks for the additional info. For sure I'll be using it later on this year.

 

[John Mc]

Another minor addition: I added a brake controller to my truck.

I chose a RedArc TowPro Elite. It will accept either 12 V or 24 V input while providing braking voltage appropriate for 12V trailer brakes. (Those of you with hybrid 12/24V systems, just make sure you are feeding it with the same voltage from the brake sense switch as you are for its main power.)

In addition to the wide input voltage, I also like that it has a choice of either proportional braking mode (best for on-road) and a user preset braking level mode (better for off-road, since rough terrain can confuse a proportional brake controller).

Added bonus: the main unit mounts remotely, with just a small knob on the dash. (That knob will need to get relocated, if I ever get around to converting back to the stock light switch.)

 

[firewhenreadym37]

I'm looking to add a 2" receiver hitch on my 1951 M37. I want to keep the stock pintle hitch. I've seen a few pictures of people who fabricated a receiver set up. I'm thinking of mounting a stock aftermarket receiver hitch sold for modern trucks. It seems the frame rail spacing is the same as modern trucks. On another site, a member mounted a hitch he removed off his 2001 Dodge Ram onto his M37. All that was required was drilling the mounting holes in the frame. His hitch had a LOT of drop (necessary to clear the bumper on his modern truck). It caused him to lose more ground clearance than necessary.

I'm looking to find a manufactured hitch that will fit as close as possible under the frame without interfering with the pintle hitch. I'm open to other options, but I don't want to lose the pintle hitch (I dont currently own any pintle hitch trailers, but I like the look, and may own one in the future). I'm concerned about mounting something on the cross member, particularly because the large drop required to get the ball to the proper height (I have 11.00x16 tires) seems as though it would put quite a twisting moment on the cross member when towing. A frame mounted hitch avoids this concern.

Since none of the online trailer hitch places I've checked have any dimensional information online, I'll be making a visit to a local hitch sales/installation place to see what they may have. Since I doubt many places have a huge inventory of hitches waiting to install that we can just hold up for a test fit, I'm hoping someone here has already done this, and has a recommendation for an make/model of an aftermarket, frame mounted hitch that makes for a good fit on an M37. Appearance-wise, I'd prefer a "squared-off" look; I think that would make a better fit with the character of the truck, rather than a hitch made from round or bent tubing.

So has anyone done this? Any leads would certainly shorten my search process.

You can buy the hitch off ebay for around 90.00 for a humvee. You have both worlds.

 

[thmpr]

You can buy the hitch off ebay for around 90.00 for a humvee. You have both worlds.

Agree with firewhenready. I purchased the humvee hitch off ebay:

M998 M1038 HMMWV MILITARY HUMVEE 2" RECEIVER HITCH TRAILER TRUCK MILITARY JEEP | eBay

Find many great new & used options and get the best deals for M998 M1038 HMMWV MILITARY HUMVEE 2" RECEIVER HITCH TRAILER TRUCK MILITARY JEEP at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Installed it a bit differently on my M152. Mounted it from behind to clear the M's "S" shaped rear cross member leading edge. Had to trim some of the hitch's gusset and shorten the pintle's castle nut to account for the thickness of the hitch's mounting plate. 4 new longer grade 8 bolts. Works perfect. Attached pictures .

 

[John Mc]

You can buy the hitch off ebay for around 90.00 for a humvee. You have both worlds.

Agree with firewhenready. I purchased the humvee hitch off ebay:

M998 M1038 HMMWV MILITARY HUMVEE 2" RECEIVER HITCH TRAILER TRUCK MILITARY JEEP | eBay

Find many great new & used options and get the best deals for M998 M1038 HMMWV MILITARY HUMVEE 2" RECEIVER HITCH TRAILER TRUCK MILITARY JEEP at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Installed it a bit differently on my M152. Mounted it from behind to clear the M's "S" shaped rear cross member leading edge. Had to trim some of the hitch's gusset and shorten the pintle's castle nut to account for the thickness of the hitch's mounting plate. 4 new longer grade 8 bolts. Works perfect. Attached pictures .

As mentioned in my initial post, the whole point of my search was that I did not want to use a receiver which just bolts on to the rear cross member. I need a large drop from the receiver to get my ball to a reasonable height. That makes for a long lever arm putting a twisting moment on the rear cross member. I would not be as concerned if I were just pulling lighter trailers on the road. However, I bought Brutus to use in the woods over rough terrain, pulling a forwarding trailer full of saw logs.

As noted in the advertisement for this hitch: https://www.ebay.com/itm/M37-MILITARY-TRUCK-HITCH-PINBALL-TM-2-RECEIVER-HITCH-TRUCK/153973942800 (similar to the one linked above) you are not supposed to use a drop hitch if the trailer weight exceeds 3000#. The trailers I pull with my M37 regularly far exceed that weight (or at least they will once I complete the brake upgrade), and require a 5" drop if I want the trailer to ride close to level. I'm not going to risk my rear crossmember to towing heavy trailers off road with that hitch. If all I was doing was over-the-road towing of my 800# log splitter, or our 2500# pop-up camper, sure, that would be fine, but I can do that sort of thing with our minivan or Subaru.

 

[Mullaney]

As mentioned in my initial post, the whole point of my search was that I did not want to use a receiver which just bolts on to the rear cross member. I need a large drop from the receiver to get my ball to a reasonable height. That makes for a long lever arm putting a twisting moment on the rear cross member. I would not be as concerned if I were just pulling lighter trailers on the road. However, I bought Brutus to use in the woods over rough terrain, pulling a forwarding trailer full of saw logs.

As noted in the advertisement for this hitch: https://www.ebay.com/itm/M37-MILITARY-TRUCK-HITCH-PINBALL-TM-2-RECEIVER-HITCH-TRUCK/153973942800 (similar to the one linked above) you are not supposed to use a drop hitch if the trailer weight exceeds 3000#. The trailers I pull with my M37 regularly far exceed that weight (or at least they will once I complete the brake upgrade), and require a 5" drop if I want the trailer to ride close to level. I'm not going to risk my rear crossmember to towing heavy trailers off road with that hitch. If all I was doing was over-the-road towing of my 800# log splitter, or our 2500# pop-up camper, sure, that would be fine, but I can do that sort of thing with our minivan or Subaru.

Just remember that the Large Drop puts a lot of strain on the metal it plugs in to. I have a foot of drop on the one on my truck (when I got it) and it is UNSAFE. The welds were done right. Plenty of strength in the metal used, but the trailer that was being towed was heavy. Look closely and you can see cracks in the metal on mine. Picture # 3 in particular shows the problem (symptom?) clearly.



I haven't done the calculations on (for example) a 5000 pound trailer that is pushing on a metal drop a foot long - but it has to be pretty substantial. And when you take off, the pull toward the back is another strain on the system.

If you notice, all the pintle connections are straight into the back of the truck frame. Less stress. Easier on the equipment...

 

[John Mc]

Just remember that the Large Drop puts a lot of strain on the metal it plugs in to. I have a foot of drop on the one on my truck (when I got it) and it is UNSAFE. The welds were done right. Plenty of strength in the metal used, but the trailer that was being towed was heavy. Look closely and you can see cracks in the metal on mine. Picture # 3 in particular shows the problem (symptom?) clearly.

View attachment 817559 View attachment 817560 View attachment 817561 View attachment 817562

I haven't done the calculations on (for example) a 5000 pound trailer that is pushing on a metal drop a foot long - but it has to be pretty substantial. And when you take off, the pull toward the back is another strain on the system.

If you notice, all the pintle connections are straight into the back of the truck frame. Less stress. Easier on the equipment...

Which is exactly why I wanted a frame mounted hitch, and chose one with longer surface which bears on the frame to distribute the load well across the frame (lighter rated hitches only bear on the frame for a little over a foot on each side). I did contact the manufacturer about whether is was safe to use their hitch with a 5" drop, or if I needed to derate the hitch. (The hitch is rated for 6000# GTW, 10,000# with a weight distributing hitch, and 600# / 1000# tongue weight depending on hitch type.) They said it was fine. Even so, I'm not planning on pushing the limits.

 

[Mullaney]

Which is exactly why I wanted a frame mounted hitch, and chose one with longer arms which distributes the load well across the frame. I did contact the manufacturer about whether is was safe to use their hitch with a 5" drop, or if I needed to derate the hitch. (The hitch is rated for 6000# GTW, 10,000# with a weight distributing hitch, and 600# / 1000# tongue weight depending on hitch type.) They said it was fine. Even so, I'll mostly running about 4500# on a typical load, give or take (straight hitch, no WD.)

I am not scared by much, but when I found that after towing a big heavy trailer for a friend - it made me take a couple of deep breaths!

FANTASTIC that you got some good words from the manufacturer! Even so, I would definitely give it the "evil eye" on a regular basis. Visual inspection is cheap.

This thing I have looks like it could tow a tank - just looking at it - but that isn't quite right based on what I see. I am in the process of gathering materials to remove and replace mine. Will build a better replacement with a lot more "beef" to it.

 

[Rolls Canardly]

In a previous life I had a 1969 1 ton Chevy 4 X 4 pickup with a 6"body lift. Installing a drop hitch was a challenge.
I ran two 1/4"X 3" Hot rolled steel straps, on a 45 degree angle, up from back of hitch to the top inside of frame rails.
Bent appropriately to be level, then incline, then level. Attached thru existing holes in top rails, and hitch.
Used Grade 8 hardware, and any twisting or pulling on mount points was relieved by these gussets, they were
stronger and thicker than the frame section they went to, pulled my trailer with 6,000 lb. skid-steer, no problem.
Any drop hitch relying only on a plate is looking for trouble, you need resistance to the twisting or lifting forces.
Even if you took tubing the same size as the hitch; welded it on back to go forward, and welded the same tubing
90 deg. across it, to cut to length, and bend appropriately to mount to frame - it would provide strength/support.

 

[Rolls Canardly]

Just had a minute to open attachments and look at picture #3 to see rust.

Rust is indicative of flexing that allowed water intrusion thru the paint.
If you were to add 1/4 X 1" angles vertically, on both outside edges behind this plate,
so the two legs are flat on plate, (so it looks like two tents,) and weld entire length, both legs, 4 places, not just tack,
...^.................^...
that type of gusseting is very resistant to flexing.