Max Coupler inverted (1 Viewer)

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D

Dell

Joined
Jan 12, 2011
Threads
25
Messages
252
My only concern would be that crossing a deep draw or V straight on... that the coupler, the way you have pictured, looks like it would hit and buckle the area where the swivel nut is.. It would have to be an extreme V, but I've had my rigs in some tight areas like I am describing.

I may be wrong, but I am looking at building an expedition trailer soon with the same coupler, I'm interested in the responses as well.

J
 
Dell said:
anyone else hitching up using this method ?
Concerns ? issues ?

My only concern thus far...
is that the primary nut isn't pinned or safety wired

Otherwise... it seems to be functioning as it does upright
Click to expand...

<Darn, didn't type quick enough....>

Why?

Bolt goes from being in shear to shear and stress, but probably not a big deal.

The mfg web site doesn't give the numbers for the movement in angles. ( Or i didn't see it. ) It looks like you will limit the upward travel of the trailer, where that limit use to be the downward movement of the trailer. If you cross a deep narrow washout, you might bottom out sooner in that configuration that the original, but that is where the question of the angles comes in.

Last year the forest burned again, so we have a bunch of deep narrow arroyo's to cross for a while, again. With a trailer, I bet I would be close to 90° than I would like when the trailer is going into the ditch and the vehicle is climbing up the other side. But you probably wouldn't drag a expedition trailer though that anyway.
 
Would you sell me the unused lunette ring assembly in the picture?
 
Tobiasinla said:
Hey Dell, so what benefit you getting by doing this? It looks like it is still at the same height.
Click to expand...
I know it might look that way...
but believe me... there is a difference.

I'm trying to keep the trailer's tongue level with the Rr bumper...
as well as keep the trailer sitting near level.
If I did the spring over mod... most all of my issues would be gone.
But I don't want to do that, as the COG brings deh suck.

The issue is... that the coupler's "U" bracket mnt. is about 2.5" tall at the coupling pin
So regardless of which way it is mounted, upright/inverted...
that 2.5" of rise or drop need be accounted/compensated for with the drop or rise of the "U" bracket's mounting surface. (ball mnt.)

Had I taken pictures of the set up with the 5.25" drop hitch...
It would be more explanatory, I'd think.
And I don't like how low that has to be to compensate for the 2.5" rise of the MC's "U" bracket. I basically becomes a tail dragger...
Except the bolt's nut would take a beating using that method and could likely loosen that as it gets hammered.

Inverting the coupler has many disadvantages...
Including allowing the coupler to be vulnerable to impact when dragging that thru rocky terrain.

Though I will likely weld up a tail dragger onto the lower part of the ball mount hitch... and hope that will take the harder hits...
and minimize the Max Couplers chance of serious damage.
 
You mentioned no safety for the nut since it's upside down. I haven't laid eyes on a max-coupler myself so Idon't know if you can install it down (head up) or not. However, if you can locate the appropriate sized castellated nut, torque to spec and drill the bolt through one of the castellations and cotter pin. Although I haven't seen it commonly used on much in the US, I see it on British stuff (Hawker aircraft for one) and it works well and is preferred because the torque is exactly where you want not one castle more or less although not critical for a hitch like on aircraft.
 
^ I'm familiar with a castellated nut
but could only utilize that if I locate a longer bolt
that meets the specs of the original

The nylock nut seems to work fairly well...
I just would like to have a few more threads of the bolt protruding thru the nut.

===========================

on a different subject...
I'm trying to figure out a way to minimize damages to the Max C
when on the trail or rock banging

Was wondering what you all might think of this idea...
I'll call it a "tail dragger" ...for lack of any other terminology I'm aware of.

It will be thicker plate stock then the paint model depicts...
and maybe even somewhat longer...
I just wanted to see if any other opinions of it might be supportive or nay

MaxCinverted6a.jpg
 
With the bolt that you have already drill thru both the nut and the bolt for a 3/32" or 1/8" roll pin. Buy one with a length equal to the wrench size for the nut. Roll pins can work their way out, so the safety solution is to run a piece of Safety Wire thru the center of the roll pin and wind it snug per usual Safety Wire practice. This results in a tidier and less likely to snag clothing or flesh securing of the bolt than does a cotter pin.

The bolt is large enough that the tongue weight of a trailer within the Max's weight range pulling down on it should be insignificant to the overall loading of the bolt. Should this still bother you I'd suggest moving to an F911 bolt as those are both stronger and more ductile than a Grade 8 bolt (performance numbers are roughly the same as the 1960 spec for Socket Head Cap Screws).

I'd sooner cap the 'U' bracket on it's front, angled edge and the now bottom flats. If you want to be tricky use Core-10 steel as it is both abrasion resistent and deals with impact OK. Not all AR steels deal well with impact, but since Core-10 is used to line dump truck and trailer beds I would assume that it does.
 
Not a bad idea with the addition of the skid. Maybe a little longer with a bend (kind of L shaped) so it will slide through the dirt or over rocks smoothly?

Looking at some pics I found online it appears as though the attach bolt is a large Grade 5 piece. You should be able to find a selection of Grade 5 and 8 bolts of adequate length at your local hardware store. If you were to go slightly longer and use a castellated nut you could orient the bolt with the head up so the cotter pin doesn't snag clothing or skin.
 
ntsqd said:
With the bolt that you have already drill thru both the nut and the bolt for a 3/32" or 1/8" roll pin. Buy one with a length equal to the wrench size for the nut. Roll pins can work their way out, so the safety solution is to run a piece of Safety Wire thru the center of the roll pin and wind it snug per usual Safety Wire practice. This results in a tidier and less likely to snag clothing or flesh securing of the bolt than does a cotter pin.

The bolt is large enough that the tongue weight of a trailer within the Max's weight range pulling down on it should be insignificant to the overall loading of the bolt. Should this still bother you I'd suggest moving to an F911 bolt as those are both stronger and more ductile than a Grade 8 bolt (performance numbers are roughly the same as the 1960 spec for Socket Head Cap Screws).

I'd sooner cap the 'U' bracket on it's front, angled edge and the now bottom flats. If you want to be tricky use Core-10 steel as it is both abrasion resistent and deals with impact OK. Not all AR steels deal well with impact, but since Core-10 is used to line dump truck and trailer beds I would assume that it does.
Click to expand...
I'm somewhat uncomfortable with drilling into the original bolt and nut... as the roll pin hole may not re-align... if removed and reinstalled.
Plus... because the coupler's "U" bracket is hanging shear load on the threads... I really don't think compromising the bolt with drilling a hole in it is a good thought.

I've thought about creating some sort of skid for the coupler...
But yer idea can't work...
reason being...
the "U" bracket is flared towards the forward side...
and ya can't push it thru the backside as the tolerances are too tight. In other words... to attach the bushing end into the "U" bracket...
I have to come up from the bottom and forward end...
and slide up and rearward in order to be able to make the connection.
So welding a bridge joining both vertical side plates would not work so well.

IBCRUSN said:
Not a bad idea with the addition of the skid. Maybe a little longer with a bend (kind of L shaped) so it will slide through the dirt or over rocks smoothly?

Looking at some pics I found online it appears as though the attach bolt is a large Grade 5 piece. You should be able to find a selection of Grade 5 and 8 bolts of adequate length at your local hardware store. If you were to go slightly longer and use a castellated nut you could orient the bolt with the head up so the cotter pin doesn't snag clothing or skin.
Click to expand...
Yeah... I was thinking about some type of bend to that...
but I have to be careful... as I'd think to expect some bending of that to occur... just from getting hammered into a rock or slammed into the earth.
Probably take alot to bend 7/8"... but the longer it is...
and with a bend in it... the weaker it would be I'd think ?
 
If you were to torque down a castle nut, and drill (like mentioned above) It would be the same difference as drilling the nut and bolt that came with the MaxC.

If you're not worried about a castle nut re-aligning I'm not sure why you would worry about these not aligning?

For your skid plate add some triangulation to it, Or a rib if you will, between the hitch and your new plate.

Best of Luck
Mark

Dell said:
I'm somewhat uncomfortable with drilling into the original bolt and nut... as the roll pin hole may not re-align... if removed and reinstalled.
Plus... because the coupler's "U" bracket is hanging shear load on the threads... I really don't think compromising the bolt with drilling a hole in it is a good thought.

I've thought about creating some sort of skid for the coupler...
But yer idea can't work...
reason being...
the "U" bracket is flared towards the forward side...
and ya can't push it thru the backside as the tolerances are too tight. In other words... to attach the bushing end into the "U" bracket...
I have to come up from the bottom and forward end...
and slide up and rearward in order to be able to make the connection.
So welding a bridge joining both vertical side plates would not work so well.


Yeah... I was thinking about some type of bend to that...
but I have to be careful... as I'd think to expect some bending of that to occur... just from getting hammered into a rock or slammed into the earth.
Probably take alot to bend 7/8"... but the longer it is...
and with a bend in it... the weaker it would be I'd think ?
Click to expand...
 
yzftaco said:
If you were to torque down a castle nut, and drill (like mentioned above) It would be the same difference as drilling the nut and bolt that came with the MaxC.

If you're not worried about a castle nut re-aligning I'm not sure why you would worry about these not aligning?

For your skid plate add some triangulation to it, Or a rib if you will, between the hitch and your new plate.

Best of Luck
Mark
Click to expand...
A castle nut has multiple notches to align a roll pin
and possibly still meet the required amount of torque needed.
Tho' a castle nut may still not allow for the fine tuning required.

The issue is... things wear down...
specifically the delrin washers...
as they wear... the nut would need to be re-adjusted (re-torqued)
These coupler require a certain amount of torque (pressure)...
there can be too little... and too much...
so it is a fine line that needs to be balanced in order
for it to function properly.

And that is the reason the mfg'r designed it to be used...
with a nyock type nut. (my guess)

If I can find a replacement bolt that has threads that
extend beyond the nylock nut...
I would then drill for a roll pin at the upper threads...
But I'm not going to drill a roll pin hole thru the meat
of the bolt/nut... as the nut is simply held in place by the thread shear...
and weakening the bolt's threads and shear in anyway...
isn't likely a good idea.

I think I get your triangular support comment...
I'm guessing you mean gusseting the lower plate at the sides
to the drop hitch plate. Yes ?

That would help reinforce things...
but I'm guessing a hard enough hit...
could still possibly bend the plate that extends beyond the gusseting support.

But I think your idea here is sound...
and I actually have already considered that.

Thanks for the input tho' :)
 
I was under the impression that there was a sleeve under the bolt head that the 'U' bracket rotated around. Are you saying that there is not and that the 'U' bracket bears directly against the the bolt shoulder or threads?

If so, that is exceptionally poor design practice. Only shoulder bolts should be used that way as they are designed for it. Tension bolts, like all SAE graded bolts and Socket Head Cap Screws are, are intended to only be in tension from installation torque. They can capture or hold a bearing surface in place, but they aren't intended to be the bearing surface.

I would have drilled the nut and bolt as a torqued-in-place unit, and nowhere near any shear zone. Would be no different than the hole in a Castle Bolt.

A Castle bolt is designed to have a cotter pin thru the hole drilled in it, I wouldn't bother with a roll pin in one of those.
 
ntsqd said:
I was under the impression that there was a sleeve under the bolt head that the 'U' bracket rotated around. Are you saying that there is not and that the 'U' bracket bears directly against the the bolt shoulder or threads?

If so, that is exceptionally poor design practice. Only shoulder bolts should be used that way as they are designed for it. Tension bolts, like all SAE graded bolts and Socket Head Cap Screws are, are intended to only be in tension from installation torque. They can capture or hold a bearing surface in place, but they aren't intended to be the bearing surface.

I would have drilled the nut and bolt as a torqued-in-place unit, and nowhere near any shear zone. Would be no different than the hole in a Castle Bolt.

A Castle bolt is designed to have a cotter pin thru the hole drilled in it, I wouldn't bother with a roll pin in one of those.
Click to expand...

There is a sleeve that extends thru the "U" bracket.
But does not go thru the drop mount, nor the whole length of the bolt.

When the sleeve is positioned... it rests flush to both the upper and lower surfaces of the "U" bracket.

I believe when the bolt is snugged down...
the sleeve is locked in position... as the bolt tightens that down.
Meaning... the sleeve does not rotate and nor does the bolt.
The "U" bracket turns on the sleeve. as well the metal washer(s) and the delrin washer(s) that exist both above and below the "U" bracket.
The sleeve is flush to both upper and lower sides...
with the washers in place. (two above, two below)
^ ( two are metal, two are delrin)

eh... I'm probably not doing a great job of explaining things...
But I'll hope you might understand what I'm saying.

In my thought... drilling a hole thru the bolt could weaken that.
And the bolt's structure/strength could be compromised.
And I would rather drill the pin hole above the nut, then at the threads that nut tightens down on.
The torque or tension on that bolt and nut... requires fine tuning... no flat ft/lbs torque rating that I'm aware of.
And it can be too tight... or too loose... so it requires fine adjustment to set it correctly.

A castle nut could work... sorta
but I don't think that it would be able to fine adjust...
if a roll pin and castle nut precludes what position the bolt must be at to insert the pin.

roll pin - cotter pin = pin in general

Maybe you can explain better why my thinking is off ?
 
Last edited:
The idea behind drilling the hole for the roll pin was to do it after everything was set. In a normally sized bolt nothing much is happening past about 1 bolt diameter away from the bearing surface. With this large of a bolt in this application you could likely place the hole near the top (bottom) of the nut though still something less than 1 diameter and not compromise the bolt. In some design circles the first three threads are considered to be the only threads actually working, the rest are just along for the ride.

With the sleeve in there it should be of the proper length to be able to torque the nut and bolt to something reasonable (probably NOT the max for that size bolt given the likely thin wall of the sleeve or you would buckle the sleeve). If you are having to adjust how tight the nut is to gain operational clearance then per std design practice the sleeve is the wrong length.

In some cases I have been known to drill a small hole thru the end of a bolt and run safety wire thru that hole after the nut has been installed and torqued. The object in those cases was to make sure that the nut could not be lost rather than trying to maintain a specific nut position on the bolt. This isn't a case where I personally would do that, but it's an option.
 
^ appreciate your input.

I'm thinking you may be right about the sleeve
and that it's maybe a fraction too short...

If I torque/tension the bolt too much...
The "U" bracket seems to have too much friction at the washer/gasket...
and if torqued/tightened excessively becomes difficult to turn at the "U" bracket.
But I didn't design it...
And I'm not sure that I remember the instructions stated...
if there was a specific torque/tension value when securing the bolt.

The only reason I was thinking of a roll, cotter type pin...
was to eliminate the nut from backing off and the bolt falling free.

I may just safety wire the dang thing... and see how that goes.

I'm not a dummy... so I'm not going to get anyone else hurt...
or hurt myself, nor my hauler/trailer.

I just wanted to be sure the nut would be secure enough...
that the nut couldn't back off of the bolt...
Nor could the bolt completely fall away.

I doubt I'm going to mess with the sleeve in attempt
to modify it's original design... right or wrong... I can't say.
But I have made two road trips from SoCal to Moab...
Wheeled it for a week there...
and tho' it was mounted in the upright position then...
It never showed signs of the nut backing off.

I checked the connections often during both trips...
and do that always when I roll the trailer on a public road.

This coupler/bolt is supposedly rated for 6K #'s...
I'm pulling a max of 1350 #'s
and the tongue weight is prolly only about 120 #'s

So with that in mind....
this coupler's bolt/nut should easily support my trailers weight.

the only time I would have any concern..
would be if the nut backed off... and the bolt became loose.

The play associated in that... wouldn't make matters better.

Thanks again for your comments...
And I will responsibly consider your input
 
Lock tight they make it in different strengths some industry use only this no lock washer or lock nut ie. Airplanes. Decide how easy you want to be able to remove it later and use the appropriate lock tite with a lock nut a top lock nut will give you a couple more threads than a nylock if you want to keep your bolt you have now.
 
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