Dual Cam Setup

mrekim wrote:

JBarca wrote:

In light of this new realization, if it holds water that is, you will have to retrace you total trip in your mind on where did the truck riding surface create any level of back flex and did it come with a compound angle turn at the same time?

There's a right turn with compound angle. Here's a video of the turn in the Excursion (no trailer).

Here's a link to a video:

http://youtu.be/Rq-PMx90R4I

Now that is cool!!! Sharp looking EX too. :C

That right turn:

Had a compound angle right turn
Had a level of back flex in the middle of it combined with the compound angle turn

And the left side of the camper had the frame damage.

Well, let's see if the trail of puzzle pieces fit...

Be back later

John

JBarca wrote:

In light of this new realization, if it holds water that is, you will have to retrace you total trip in your mind on where did the truck riding surface create any level of back flex and did it come with a compound angle turn at the same time?

There's a right turn with compound angle. Here's a video of the turn in the Excursion (no trailer).

Here's a link to a video:

http://youtu.be/Rq-PMx90R4I

JBarca wrote:

We know the damage occurred on the drivers side of the TT. You or I really need to know the amount of level or uneven ground and which turn direction was the kill shot that created the high WD forces. Or there where several turn events. Pending the amount uneven ground you drove on I can build a case for a left or right turn doing this.

The only other compound angle turn I can think of is in and out of the driveway. That's a left.


Here are some specs on my setup. I don't have the trailer or hitch here.


..............Front Axle...Rear Axle......Trailer Axle
WD............4020..........4940...........7260
No WD.........3800..........5440...........6800
Truck Only....4360..........3800


Tongue Weight.....1080
Avt Trailer wt....7970
Percent Tongue......13.55%


Truck wheel base : 137
Truck rear overhand, rear axle to tow ball
( I have rear axle to hitch pin: 53")

I don't have these (trailer and hitch are not here):
> Tow ball to TT axle distance
> TT axle distance on the tandems

The above measurements are before my last hitch adjustment. Which was to return the front axles to unhitched weight. This was done by going one notch on the hitch head after the above weights were taken.


Loaded TW: 1080
WD bar size: 1200 Lb.

Campin LI wrote:
I had binding issues with my old dual cam setup. Sometimes the detent on the inside bar would not unlock from the cam on a turn. This put a lot of outward pressure on the outside lip of the cam. When this happened, sometimes the cam would lift up leaving slack in the chain because the cam was lodged into the detent. It would eventually let go and make a real loud bang. When this happened, the bolts that hold the cam to the frame would become loose or tear out. Sometimes on not so tight turns, when the detent of the bar was jammed onto the cam, I got bent snap bracket from the outward pulling of the chain, maybe 25-30 degrees off vertical alignment (on edit - maybe less of an angle than this). I did eventually get tired of trying to stop the problem and I switched to Equal-i-zer brand hitch. The commonality was that the bar did not unlock from the cam and it was related to binding. I could never get rid of the binding. No matter what I did, the instance of binding was just moved to another location. I think a lot may have to do with the slop between the hitch and the receiver of the truck. I also think the angle the bar makes on the cam plays a role. There is a lot to analyze. I also think the stiffer bars are less forgiving.

Hi,

Did you have the HP DC or older standard DC with the U bolts holding it to the frame?

And what capacity WD bars?

The older standard DC in some cases had WD bar flare interference with the newer 1,200# WD bars. And the newer HP DC had flare issues too as I posted just above.

Thanks

John

TUCQUALA wrote:
Well, back from an unsuccessful trip to DC adjustment land!!!

After centering the detents, took 2 right turns in parking lot which produced 2 pronounced bangs and associated shakes in Ex. Straightened out to remove bars for trip back to stable, and found that either side would not release. Don't think it was totally the detents hanging up, 'cause the chain hangers would not rotate when the chains were loose. Took a few whacks with brass hammer to dislodge the bars and remove. Now I have a slight indentation in the right side frame from the snap up pinch bolt, but the snap up looks unhurt.

Parking lot is fairly flat other than drainage slope at the ends toward a flat center. The turns probably were close to a flat turn without much up or down to either of the TV or the TT during the turns. But I would bet that if I was in a compound angle turn, the head rotation may have made the binding even worse, only speculation.

FYI, I have not done any reinforcing on the frame, and maybe the new HD snap ups would not have dented the frame if used, don't know. Have to step back and think and decide what to do next. I am thinking of going back to the old welded round bar head and my 750# bars and recheck how the combo works. Maybe look for a couple of used 1K bars for the old head.

John, do you know if the cams have been changed, like maybe widened (??), since my purchase of the DC in '04??? Too late now to call Cequent out here on the left coast.

Hi,

I'll add some here to help the cause as this does come back to the DC and where all the forces are coming from. 1st the easier question. The DC and WD bar rub when sliding through. Yes, I use to have a little of this but I dusted off the WD bar when I found it get rid of it. My cam arms are from late 2003, (moved from camper to camper) so your 2004 vintage is just like mine. And mrekim's is different. From this post and helping work through it, I have found Reese helped fix the problem with our long ago vintages.

See here. I have a collection of Reese hitches and parts.... This is my 1,200# set of trunnion WD bars resting on the 2003 purchased DC. Note there is not much if any daylight between the WD bar and the cam area between the inside boss and the chain plate. The space is 1 3/8"


Now look at mrekim's one he bought in 2013. Same rating 1,200# trunion bar. He has approx 1/8" space extra as he reported his was 1 1/2". Reese fixed it.


In my pile of Reese parts...I'm a good customer, LOL here are the 800# WD bars compared to the 1,200# WD bars


You are right, your older lighter WD bars where thinner even in the round bar hitch

When I bought my 1,700# bars I saw the problem you are referring to slightly more pronounce. The V shaped end of the WD bars are forged, when they bend the end of the bar the metal flares out a little in the bend. That flare can bind when trying to slide through the DC area of the vintage DC we have. I corrected this by grinding off the little bit of flare interference. Early on with my 1,200# bars I would have real heavy scraped grooves in the chain plate and the on the DC inside boss are from that flare. Once I dusted off the flare, the issue went away.

If you cannot by hand slide the WD bar through the DC area with the chain plate tight to the side of the cam arm, I myself would dust off the WD bar flares and move on. That may help your instantaneous shutter bang coming around a turn.

To add to this, when there is a ~ 1,100# and up loaded TW I have noticed the bang too. It sounds like the entire hitch is going to fly apart. I never felt the shutter in the truck, in either my 2003 K2500 Suburban or the F350 though. It may have been I addressed the WD bar flare. The bang is the high friction lock of the DC breaking free from the WD bar. It is going to happen when the turn is quick and more degrees of turn.

To tame down the bang, I use a light coat of vas-o-line (not grease)on the cams with these higher TW's. The bang goes away almost to nothing. This is a Reese approve weak lube. You will loose a little friction grip holding power, however with your heavier truck and if your TT has good TW (13% and up) odds are you will not feel the loss of holding power. The vase-o-line will help slow down the cam wear too. In case you did not know, mark the WD bars left and right and always put them back on the same side. They will become matched wear sets to the cams and then slow down the wear. If you keep flip flopping the bars, the wear pattern starts all over again.

Hope this helps and good luck

John

mrekim wrote:
I'm going to have to read this more carefully tomorrow.... One immediate question though:

JBarca wrote:


Look at the force direction arrows. The WD bar pushes down on the DC from setting up WD. The DC pull down on the chain. When in a turn there is a force that travels up the DC arm right into the front self tapping screw on the frame. There is a force then when straight ahead too, bit "i think" it is less then when in a turn like this.

For the force traveling up the DC arm when turning. I assume that is because of the curve in the spring bar. So, when turning, the the bar is trying to force the cam toward the tow vehicle and the bar prevents it from moving.

If I understand this correctly then on the inside, there would be a pulling force until the bar popped out of the curve.

Yes, you have it about right. There is a force traveling up the DC arm and that force changes constantly in magnitude depending on the terrain your are driving over. It is normal and just happens all the time. The forces and changes in force going on in a WD hitch are really dynamic.

On the DC, when the TT and TV are straight ahead and on the same plane ground, after WD is applied the force up the cam arm is fairly low providing the chain hang is perpendicular to the frame. And yes when you go into a turn, the heavy friction of the DC allows the force in the cam arm to increase. The heavier the chain load, the more the friction and the larger the force is in the cam arm resisting it. The direction of the cam arm force will be tension or compression depending on left to right side of the A frame and which direction the truck is as the WD bar pushes or pulls over the cam.

This force traveling up the cam arm is one of the reasons Reese wants us to make sure the DC frame plate is dead tight up against the bottom of the frame. And why I suggest using a C clamp like you did to hold it tight to the bottom of the frame while drilling on the DC. If there is an air space under the DC frame plate, now that force is working on the bracket itself and yanking on the infamous self taping screws, fatiguing it back and forth all day long towing down the road. Sooner or later those self tappers will rip out.

Later I will work on calculating the forces going into chain, the DC and the cam arm. They will only be hand calc's and it will be an approximation however it should help shed some light on the "league" of forces we have going on and how they change.

At this point I will do it for my camper and truck as I have the values needed to start with. I will vary the TW from 1,200 to 1,600# and we can see the differences. Your EX and camper will not be exactly the same unless you can tell me this data. However yours will not be totally different.

Truck wheel base
Truck rear overhand, rear axle to tow ball
Tow ball to TT axle distance
TT axle distance on the tandems
How you adjusted the WD on the truck. In my case I will use, returned the front end very close to unhitched weight
Loaded TW
WD bar size
I know the WD bar length.

This is my setup, your EX has a shorter WB but the rear overhang should be close. Your camper is a little longer and the wheels may be positioned different, however my rig and yours are not that far off other than the fully loaded TW




Be back later

John

I'm going to have to read this more carefully tomorrow.... One immediate question though:

JBarca wrote:


Look at the force direction arrows. The WD bar pushes down on the DC from setting up WD. The DC pull down on the chain. When in a turn there is a force that travels up the DC arm right into the front self tapping screw on the frame. There is a force then when straight ahead too, bit "i think" it is less then when in a turn like this.

For the force traveling up the DC arm when turning. I assume that is because of the curve in the spring bar. So, when turning, the the bar is trying to force the cam toward the tow vehicle and the bar prevents it from moving.

If I understand this correctly then on the inside, there would be a pulling force until the bar popped out of the curve.

mrekim wrote:

JBarca wrote:
The set screw drug the frame and headed towards the "bottom" of the frame. In order for the dig marks to go that direction the DC arm had to be lifted "up". Agree Yes/no?

I originally wrote that the chain was pulling up.... but went back and changed it.

When the WD bar is under tension, it's trying to pull the chain down. If the WD bar was centered exactly under the chain, there would be no twisting action. Since the WD bar is to the inside, there's a down force somewhere on the cam and the chain is resisting that force on the end of the cam. I think this creates a twisting action. This is why a small movement can be observed when the bars are snapped up (or when the tongue is let down - I'm not sure when it showed up).

JBarca wrote:

Now the frame crush at the DC frame plate. This pic aligns with the set screw rotation. The DC arm had to rotate "up" in order to crush the frame in. Both the set screw and the frame inward crush support an upward force doing this damage.

Yes, counterclockwise when facing the trailer from the coupler.

JBarca wrote:

If we determined the snap up area failed from the chain force pulling "down" on the snap up, and the DC area pulling "up" on the cam arm, then the 2 areas of failure happened at different times and from different force directions. Agree yes/no?

I was all ready to disagree, but I see your point. So I went back and changed my story some - to discuss this twisting action with the bar pulling down in one spot on the cam and the chain out at the end.

What if the spring bar is loading the cam at the inside keeper flange, basically as far away from the chain as possible. Also assume that since it's all new and not worn in, that the bar is only contacting the cam on a small portion of the bar - at that flange. I'm stacking the deck here to see if my idea is even remotely possible. So, the bar is pressing down on one side of the cam, and the chain is resisting that force on the opposite side of the cam. This would produce a twisting force, but I don't know how much.

I don't have the bar here, or else I would get a photo to see where it's starting to wear....

Well, here goes. Until tonight I could not figure out exactly how the "up" force came to be that crushed the DC frame plate inward. I knew it had to be "up" but how??

You are correct, there is a hard down pull on the chain, we know this as it took out the snap up. So how can there be an "up" force to bend the and twist the DC frame plate up and inward? The chain connects the snap up and the DC so how can the DC lift? Well the DC is not lifting, but the force is upward into the frame.

We have talked about the heavy WD bar loads that can occur on one side of the A frame and the other side unloads a lot or is at 0. The compound angle turn in addition to possibly a level of back flex in the hitch from terrain changes may creates the perfect storm that your thin A frame tube can't handle with those size WD bars and loaded TW on this setup.

The heavy force is coming from the loaded spring bar pushing down on the DC arm. So now I am starting to connect the dots on how the DC is tied to the snap up failure and how the DC frame plate crushed the frame. These 2 events which may have happened at 2 separate times or both at once.

See if this fits. The damage in your pics tell the story. Good pics by the way. We have a lot to work with.

This first pic told the story of the end result of the DC arm being pushed up and rotating. Note the pic is flipped from the angle you took it. The ball coupler is to the left so we know which is the front self tapping screw hole and which is the rear.


If you look closely, the front hole closer to the ball coupler is pushed in when the DC frame plate pushed the frame in. The flat washer you had behind the frame plate left an impression and indentation in the frame when it collapsed. Yet the back hole towards the TT has the threads still pulled out and the frame is not pushed in much if any at this hole like it is on the front hole. This is confirmed by the bottom view you took. The front hole is pressed in, the rear hole swedged out from the self taping screw.

This pic mocks up a back flex where an angle is between the truck and the TT from the road surface being in 2 different planes. I could not mock up the compound angle turn in combination with this back flex with the pics I had to work with. I'm not totally sure if the back flex was a lot or not much at all. The compound angle turn alone could of done it all. The one side of the A frame, the drivers side, was under very high load from the WD bar being highly loaded pulling down on the chain. The opposite side of the A frame had a lot less.


Look at the force direction arrows. The WD bar pushes down on the DC from setting up WD. The DC pull down on the chain. When in a turn there is a force that travels up the DC arm right into the front self tapping screw on the frame. There is a force then when straight ahead too, bit "i think" it is less then when in a turn like this.

This WD bar force traveling up the cam arm into the frame is the "up" force along with a twist. That front bolt took the blunt of all the force and pressed the frame in. That action then rotated the DC frame plate and drug the locking set screw like it did.

Here is the top view. Look at the washer you have behind the front bolt. That put all the load in one spot. And now seeing this view you can envision how the DC frame plate can rotate with that heavy force coming up the DC arm stopping a the front bolt.


So, does that fit? Like I said the entire damage at both areas could of come from 1 event or 2 now that I see how the forces could move to the frame.

mrekim wrote:

JBarca wrote:

Keeping an open mind to this, after all this review is there anything else on that very short trip you made that sticks out to cause forces in the directions we are talking about? A hard bump from a pot hole etc?

I can think of two compound angle turns

One was a left out (and then back in later) the driveway.

The other was a compound angle right turn, leaving my neighborhood out onto the main street. I'm pretty sure we've done that turn a few times as well. It's not a hard angle, but the trailer is higher. If I had to pick a turn/event candidate that would be it.

When coming back we did not do the reverse (left turn) into that compound angle turn.

In light of this new realization, if it holds water that is, you will have to retrace you total trip in your mind on where did the truck riding surface create any level of back flex and did it come with a compound angle turn at the same time? We know the damage occurred on the drivers side of the TT. You or I really need to know the amount of level or uneven ground and which turn direction was the kill shot that created the high WD forces. Or there where several turn events. Pending the amount uneven ground you drove on I can build a case for a left or right turn doing this.

If I have figured this out correctly, then the higher loads connected with DC did aggravate your snap up failure. Now we are back to what is so different with your A frame then all the other DC users running a 3/4 ton truck, 1,200# WD bars with a DC and 6" tubing A Frame??

OK tell me what does not add up with my thought process?

Hope this helps

John

TUCQUALA wrote:

John, do you know if the cams have been changed, like maybe widened (??), since my purchase of the DC in '04??? Too late now to call Cequent out here on the left coast.

I have one here that's 1.5" wide.

Well, back from an unsuccessful trip to DC adjustment land!!!

After centering the detents, took 2 right turns in parking lot which produced 2 pronounced bangs and associated shakes in Ex. Straightened out to remove bars for trip back to stable, and found that either side would not release. Don't think it was totally the detents hanging up, 'cause the chain hangers would not rotate when the chains were loose. Took a few whacks with brass hammer to dislodge the bars and remove. Now I have a slight indentation in the right side frame from the snap up pinch bolt, but the snap up looks unhurt.

Parking lot is fairly flat other than drainage slope at the ends toward a flat center. The turns probably were close to a flat turn without much up or down to either of the TV or the TT during the turns. But I would bet that if I was in a compound angle turn, the head rotation may have made the binding even worse, only speculation.

FYI, I have not done any reinforcing on the frame, and maybe the new HD snap ups would not have dented the frame if used, don't know. Have to step back and think and decide what to do next. I am thinking of going back to the old welded round bar head and my 750# bars and recheck how the combo works. Maybe look for a couple of used 1K bars for the old head.

John, do you know if the cams have been changed, like maybe widened (??), since my purchase of the DC in '04??? Too late now to call Cequent out here on the left coast.

Throwing my thoughts into this again, concerning the bars and possible binding in the cams, either on flat turns or compound angles.

My orig 750# round bars are narrower than the 1000# bars that I used to use. The 1K bars had normal wear, since my son had used them for around 5+ yrs. The new assy 1200# round bars are really thick in the area where the u-bolts would attach for non-DC use. They are flattened out there and just barely fit between the cam side and the chain hanger. My memory of the old 1K bars (returned!) is that they were just as stout and possibly as wide as the new ones.

Just thinking that there may be binding against the cam wall and chain hanger when the head tilts a bunch. ????

About to mount up the old hangers, and go out and check all adjustments. I have brushed off paint in the wear areas, ground flat some high spots on the bars in the detent areas, and cleaned up the cams. Will see if my banging and snapping is going to show up after new adjustments. I guarantee that I will not be towing back to the driveway with the bars in place if it is still acting up!!! Will report back later!!!