Dual Cam Setup

I suspect the DC bend is related to the snap up bending it first. I will say that the DC seem to want to twist with the inside going down towards to road and there's no way for the pinch bolt to prevent it.

I guess it's possible that a turn got all this kicked off, but it would have had to have been a right hand turn to load the driver side right? I don't think we've had any tight right hand turns at all.

Having the snap up not flat on the top of the frame due to it being more than 90 degrees is not likely a contributing factor?

Is 1/8" typical for these frames?

AHHHHH more puzzle pieces...

Your tube frame has very little resistance agasint tube crush. WOW...

This is a tell tail pic. and the others are not great either.


Your plate idea is for sure in need now.

The bent DC chain keeper plate, odds are high, that was bent when the DC frame plate was bent in. I have seen that chain keeper bend in that area before from guys trying to snap up under full load rather than jacking up the truck and camper hitched. It really does not take much force to bend the chain plate where it is key hole attached to the DC arm

The new Reese gusseted snap up may work on a channel iron frame unbolted or on a heavier tube frame that will not crush so fast. In your case, I agree, fix the frame and then bolt on the snap ups with no play to allow the bracket to slide down. You will need to deal with the DC frame plate too. Once the fix is in, if you have access to a welder buddy, some stitch welds on the plates to the frame may not be a bad idea. I do not see needing a lot of them.

Good luck and hope all this typing helps.

John

Lets look at this older style failure


Came from here:

And now yours.


There are a number of similar things going on. The set screw bend is the same or at least ended up the same. I believe that bend happened as a by product of the snap up letting go. It did not bend that hard at first, but did later in the failure.

Now what is common, both snap up's where not bolted to the frame. Both can have 1,200# WD bars and heavy tongue weights. In a compound angle turn where the truck is on angled ground in relation to the TT axles the outside WD takes "all" the load, the inside turn bar is loose just laying there doing nothing. This bar action is normal but it creates one really large load on the outside snap up bracket.

On the older style bracket the top angle laying on the frame would start to spring open, (open up more than 90 degrees, starts heading to say 95 to 100 degrees) from the heavy vertical pulling down on the chain. The snap up is also sliding "down" the frame now too as there are no through bolts to stop it. Once the bracket was pulled hard enough and you get to maybe approx 110 degrees sprung open, the chain is now hanging way out beyond the toggle locking point and not straight up and down any more. If the heavy chain load continues the set screw is straining hard to resist and starts giving way. It is now the only thing left to hang on as the snap up keeps sliding down the side of the frame and pivoting outward.

Now on yours they helped the top spread open problem by adding the gussets, but still if the chain forces are heavy enough and if the WD had any contact with the cam arm like I show in the beyond 76 degrees pics, the next weak spot is the set screw and the thin wall tube frame. It is some speculation what gave way first, did the frame start to collapse 1st and then the set screw start to bend? Or a high WD force pulling outward from beyond the 76 degree area pull down and out agaisnt the set screw?

Again in your case you do not have the snap up's bolted on. So the bolts cannot prevent the slide down the frame problem or help prevent the down and outward force of a WD bar pulling on the snap up trying to pivot outward agasint the set screw. This is even more complicated by the thin tube A frame as the support which can crush.

In my case I have the old snap up's, 1,600# loaded TW, 1,700# bars and I'm lifting a level of truck bed weight with the WD aft of the rear axle. But mine are bolted on. The bracket cannot slide down and the bolts resits any outward pull. Trust me, I turn hard. I should of killed this setup by now if it was not for the bolted on snap up's. I also have 6" standard C Channel frame and that will not colapse in like the tube frames.

Summing this up, the thinner tube frame can bow in and that flex "might" start this chain reaction. In order for the set screw to bend like that there has to be a moment load (torque) on the snap up by the chain. The force vector in the chain is not straight down.

OR

The load on the chain is high enough what little moment distance the chain is away from the frame starts pivoting on the lower ears of the snap up and pulling hard on the set screw as the top is gusseted to not spring open. Once the set screw starts to bend, all bets are off and the thing collapses.

On heavy tongue loads and strong WD bars the only way I can see to stop this the snap up cannot slide down or bow out on the frame. Once either of those actions start, it's all over. Have you ever had a C clamp fail because you over tighten it and sprung it? this set screw snap up setup uses a simialr concept.

The DC bending in, I think this "might" be a by product of the snap up failure. The snap up died first. Towing continued with a bent bracket. The chain hang is no longer vertical as the snap up is all out of kilter. In a turn somewhere after the snap up let go, the angled chain pulled on the DC arm and bent the frame "in".

OK does any of this seem to fit what you are seeing?

Hope this helps

John

Dual Cam Mount:




Dual Cam Pinch Bolt




Bottom of snap up:



Snap up pinch:



Threaded area (I knew this was an issue and Reese was sending rivnuts - probably need something beefier than that now...)



One more possibly important piece of the puzzle:




Also I went out and hooked up everything to double check clearances with just the drive side bar attached and moved the hitch around. I didn't see anything obvious.

Also, no obvious gouges or missing (or new rubbed on) paint on the bar, ball or dual cam.

JBarca wrote:


I'm "assuming" you really did not know you had a problem until after the short trip you made, right? Meaning you did not hear a bang or anything, just you pulled out of your drive, went for a ride, got to the end of the trip got out and found this mess? Yes or no? Any bangs, snaps or noise of anything?

Correct. There were noises, but as far as I know these are the typical noises you get when turning. Nothing jumped out as different than any other day.

I do get some creaks and pops when turning - I thought that was par for the course - metal on metal, cam popping in and out, etc.

The thing that does not fit is the DC frame plate bowed "in", but I have a thought on this too.

I'm "assuming" you really did not know you had a problem until after the short trip you made, right? Meaning you did not hear a bang or anything, just you pulled out of your drive, went for a ride, got to the end of the trip got out and found this mess? Yes or no? Any bangs, snaps or noise of anything?

OK I'm typing, hang tight

JBarca wrote:

No. 3 2 small bends at the top of the DC frame plate. OK which way is the bend? If the A frame rail bowed in or bowed out? It could be either way and you did not state. This answer really helps tell a good part of the story.

Bowed in, and you can see the "scar" from the pinch bolt where it got dragged down.

JBarca wrote:

AND did you make a real hard left turn that could of approached the 76 degree or greater area?

My toughtest left turn was out (forward) and into my driveway. I really don't think it was 76 degrees as that would get me into the uncomfortable area. Sorry for the vague answer. It was way less than my sharp left earlier in this thread.

I looked at your 76 degree photo again. I don't think so. I don't think the bumper ever got parallel to the A frame. I have to get out and make sure nothing's going to hit way before I get that tight.

Your photos look right - raised ball, new head, 2 washers at front and one to rear, 6 links on chain.

I think the frame is 1/8" - that's from measuring on of the end caps though.

mrekim wrote:
I think part of the problem is that the snap up brackets are not square to the frame.

So when when you tighten the pinch bolt, the snap-up get pulled flush to the side of the frame, but then it's only touching the top of the frame at the outer edge.

My guess is, since the snap up is only touching the top of the frame at the outside, that the pinch bolt is taking on a lot of the force from the spring bar that is really supposed to be handled by the bracket itself.

If enough load is present, the the pinch bolt will start to bend the frame (or the bracket will bend - or both) and the snap-up will begin to tilt down even more as the frame gives way. Once that starts to happen the snap up starts applying a point load on the side of the frame at the bottom of the snap up. So the snap up only contacts the frame in 3 places once it starts to go 1) the pinch bolt, 2) the top outer edge, and 3) the center of the frame on bottom of the snap up.
#1 and 3 are basically point loads - the bottom of of the snap up has 2 points that contact the frame and the pinch bolt obviously has a small surface area.

If the snap up goes over far enough the keeper pin for the snap up takes all that load as well and begins to bend.


Is this speculation even in the ballpark?

You where typing as I was. Tell us about the DC bracket, was it pushed in or pulled out?

Yes you are in the ball park but need to know the DC bend to tell what base we are on...

AND did you make a real hard left turn that could of approached the 76 degree or greater area?

H'mmm.... the plot thickens..

Wish I was there in person to inspect better but here goes. You see if this fits with what you are seeing.

I did not see your final setup, so I'm going by these 2 pics which I "think" you came back to. Did you?





OK I'm going to break down each of your comments to see if I can add this all up. I added the blue numbers

mrekim wrote:


Simple round trip to the dealer and the snap up bracket bent.

1. There's a bend in frame where the pinch bolt for the snap up goes

2. as well as 2 smaller bends where the snap up ends on the outside

3. and 2 small bends at the top of the dual cam.

Everything was tight - and not too tight - before I left.

Here's the snap up:



What a mess.

Here goes..

No 1. The set screw frame bend, I "think" this bend happened 2nd, not 1st.

No 2. 2 smaller bends in the A frame wall at the ends of the snap up. This "might" have happened 1st.

No. 3 2 small bends at the top of the DC frame plate. OK which way is the bend? If the A frame rail bowed in or bowed out? It could be either way and you did not state. This answer really helps tell a good part of the story.

The snap up keeper clip bent last after the frame and snap-up caved.

OK see this turn, did you turn real hard left in the truck?

This is 74 degrees left, this is OK


This is beyond 74 degrees left. About 76 ish. This is not good.




Here is the same setup, (TT & TV) straight ahead


Now lets look at the snap up toggle concept.

Here the snap is over center and the keeper clip locked. The chain hang (vertical line the chain makes) is in line with the snap up pivot pin.


Now the snap up is not clipped in place and slightly open. The chain hang is now outside the snap up pivot pin.


OK how does this all connect? I really need to know on no. 3 if the DC bent into the frame or pull out as the forces of that event sort of tie all this together.

Before I speculate, let me know this.

Thanks

John

PS, your frame fix with the plates, yes this is a good thought. Make sure the 6" wide plate fully reaches the to top and bottom of the A frame rail so the compression is backed up by the top and bottom leg of the tube frame. You will have to fine tweak the anti crush tubes to get just the right squeeze.

Also any idea of the thickness of the A Frame tube? Ideally with a caliper but I'll take what you to can get. This tube crushed way too easy. They keep thinning these things up. I'll stick with my heavy 6" channel iron.

BTW, Rees may replace the snap up under warranty, they have a lifetime warranty.