Request your help RE pin box movement

[pulpwood007]

Larry,

In your OP I'm still trying to figure out how you measured your absolute movement at the tip of the pin. Seems like your laser attached to pinbox pointed at front storage compartment would give you an "angle" of flex not an exact measurement in inches. In other words the the laser doesn't really move up and maintain the same horizontal plane, it moves up at an angle and points at a lower point on the storage compartment door. Hopes this makes sense.

cruzr4's method seems it would give the best measurement of pinbox movement depending on how much front cap movement takes place during the test.

Also, as to his inside bedroom measurement, his reference point (the laser mount) is on the fixed part of the frame, not the bedroom part that will move. If the laser is in the bed compartment it will be setting on a part of the frame that flexes also. In addition he is shooting a measurement all the way to the front wall inside the closet. This would yield the total flex of the front end of the trailer beginning at the rear of the storage compartment.

All the above (as well as the other thread on this forum) good info. I'm still struggling a little with the descriptions and how the measurements are made.

Without hijacking this thread, hope the next thing we can discuss is the long term effects of this problem, if any.

Jerry

[Dayle1]

Jerry,



In my original post, my measurement #1 was to an external fixed point. In my case, I used two steel studs suspended horizontally between posts in my RV port. Another option would be to hang a tape measure from a roof or tree branch. Regardless of how the external point is defined, you can't use the landing gear because that moves the trailer up and down. I used the truck's air bags, 'rcflyer' used a bottle jack on a platform. My absolute movement data was 1-1/8 inches but limited by the travel of my air bags, so I judged it up to 1-1/4 inches and it might be more.



I used the laser attached to the pin box as a second data point and you are right I had to calculate angular change and horizontal change from the other measurements to confirm what the laser measured. I really didn't know what I would find, so I took as much data as possible with a single setup, and then checked one piece of data against another to increase confidence.



Regarding laser placement inside the trailer. If you read the description of my location and look at the frame inside the front storage compartment, you will see that the front of the laser is above the landing gear and there is a 1-3/4 x 5 inch steel tube running wall-to-wall directly under the laser and above the landing gear. Also, the entire laser is over what has to be the most rigid part of the entire frame, the roughly 2 ft overlap of the lower 8 inch I-beams and the upper 5 inch rectangular tubes. So, this location should be immune to flex and also important, it will work with any floorplan. Center hallway plans or reverse hallway plans do not have a clear line of sight that can support a longer distance. Finally, the elevated hallway/bathroom floor behind this location is aluminum studs/joists and may not be as rigid. Since distance matters when measuring angular movement, if everyone uses the same distance, then there is no need to make adjustments on anyone's data.



Finally, using the front wall of the trailer as a "target" could introduce unnecessary error. The wall studs are poorly secured, just enough to support the interior wall paneling. It is angled and can bow or move depending on how the front cap moves vs. the frame. And on units w/o a front closet (like Lloyd's) it is difficult to hit with a laser beam.



I hope this covers your questions adequately. There are probably other owners with questions or other thoughts as well. It is difficult to provide enough detail w/o making the post extremely long.

[happycampers]

Larry, I hitched up today as we are heading out in a couple of hours so I got a few numbers for you:
The pinbox (measured from the bolt head thru the rubber block up to the clearance light bar) measured 3/4" flex.
The bedroom floor (with the laser sitting at the edge of the carpet near the bathroom aimed at the step in the floor under the closet) showed 1/2" flex.

Edit: Keep in mind that mine has the flush floor thru out the upper level...






Edited by: happycampers

[Dayle1]

Originally Posted by happycampers

Larry, I hitched up today as we are heading out in a couple of hours so I got a few numbers for you:The pinbox (measured from the bolt head thru the rubber block up to the clearance light bar) measured 3/4" flex.The bedroom floor (with the laser sitting at the edge of the carpet near the bathroom aimed at the step in the floor under the closet) showed 1/2" flex.Edit:Â* Keep in mind that mine has the flush floor thru out the upper level...

Matt,



Thanks for taking this data on a newer unit. The 3/4" you measured to the clearance light is exactly what I measured and reported on June 14th. And the bedroom floor flex of 1/2" is nearly identical to the 9/16" I reported on July 19th.

[Lloyd]

There is a lot of questions on pin box measurement along with the taking of the laser measurement.
This is what I did for the pin box check. (did it last Wed. hottest day of the year)

I hung my tape measure from a

ceiling rafter right in front of the pin box. There is a line of white

finger nail polish to reference to. I backed the truck under the pin,

put plywood on the floor of the bed, and then a bottle jack under the

pin. This was so I didn't have to use the landing jacks. I Put my floor jack under the hitch on the truck to eliminate all the

travel when I took up the load with bottle jack in the bed.
Measured

93 in. or 93 1/16 in. it was close either one. Then I run the bottle jack up that was in the bed until "one"

jack had a foot that I could wiggle, the other one was pretty tight yet,

(rig must be a little heavy on the slide side) but anyway, that is

where I took my measurement. 93 5/8 in. So if that works out to be the

correct way to measure how much flex there is in the pin box--I've got some more then I had originally thought.
">
unhooked picture
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Same as if it was hooked up to the truck.


Edited by: Old Farmer

[Dayle1]

Today I met a buddy at the lot where his 325CK is stored for some measurements. We had previously measured from the pin box to the amber clearance light and his number was slightly more than my 3/4� reading. Measured the bedroom floor flex with the same setup and 45 inch distance I used. First picture is when hitched up ( sorry it is out of focus but the batteries died after this pic)







Second picture is un-hitched and it shows a 1/2� difference.







Prior to the inside measurements, we used my truck (due to the lower sides) and like Lloyd used a bottle jack to raise and lower the trailer. I set up the laser on a ladder next to the truck and a “target� wedged into his Rotoflex pin box. This picture shows the laser spot with the front landing gear just lightly off the wood blocks. The bottle jack is also visible under the king pin.







Final picture shows the laser spot after lowering the trailer using only the bottle jack. The difference was 1-11/16�. This measurement technique should be equivalent to the fork-lift method as done with Hank’s unit.

[hhh]

Larry,

Did you happen to look at the pinbox mounting bolt holes to see if they were moving in relation to the underskin?






Edited by: hhh

[Dayle1]

Originally Posted by hhh

Larry,Did you happen to look at the pinbox mounting bolt holes to see if they were moving in relation to the underskin?

Hank,

No we didn't but I'll have Dr. Fletcher take some pics next time he hooks up.

[Dayle1]

Today I took measurements on my 32MK identical to what we did last week on our friends 325CK. First picture is with the king pin jacked up and both landing pads very slightly loose.







Second picture is with the bottle jack removed, difference was also 1-11/16 inch. I ran the bottle jack up and down twice and difference in readings was about 1/32"

[rcflyer]

Originally Posted by Dayle1

Today I met a buddy at the lot where his 325CK is stored for some measurements. We had previously measured from the pin box to the amber clearance light and his number was slightly more than my 3/4� reading. Measured the bedroom floor flex with the same setup and 45 inch distance I used. First picture is when hitched up ( sorry it is out of focus but the batteries died after this pic)



Second picture is un-hitched and it shows a 1/2� difference.



Prior to the inside measurements, we used my truck (due to the lower sides) and like Lloyd used a bottle jack to raise and lower the trailer. I set up the laser on a ladder next to the truck and a “target� wedged into his Rotoflex pin box. This picture shows the laser spot with the front landing gear just lightly off the wood blocks. The bottle jack is also visible under the king pin.



Final picture shows the laser spot after lowering the trailer using only the bottle jack. The difference was 1-11/16�. This measurement technique should be equivalent to the fork-lift method as done with Hank’s unit.

There is a problem with the pin box measurement you did. As you jack up the pin box with a bottle jack weight is transferred from the landing gear to the trailer axles. As a result the trailer springs are compressed and due to the piviot action on the landing gear the pin box will raise and the tail or back bumper of the trailer will lower. The trailer will piviot on the landing gear until this weight transfer has completed. Thus the measurement youmade is not all pin box deflection. The OP wascomplaining about relative movement of the pin box and the trailer cage frame. When I did this I made my measurements from the nose of the pin box to the mirror on the front of my trailer. My result was 1/4 of an inch.

[hhh]

I haven't uploaded this before but I have a video of the movement with the underskin and front cap removed. It is far from a great video but you can see how much it is moving. Best to view it full screen (use the link and then make it full screen) and look at the front of the pin box area near the lower aluminum frame rail of the front cap. It is easiest to see it when they lower the fork lift and take the weight off the pin.

http://youtu.be/px_Dto8t6ZQ?hd=1

[TUBE]px_Dto8t6ZQ?hd=1[/TUBE]






Edited by: hhh

[Dayle1]

Originally Posted by rcflyer

There is a problem with the pin box measurement you did.Â* As you jack up the pin box with a bottle jack weight is transferred from the landing gear to the trailer axles.Â* As a result the trailer springs are compressed and due to the piviot action on the landing gear the pin box will raise and the tail or back bumper of the trailer will lower.Â* The trailer will piviot on the landing gear until this weight transfer has completed. Thus the measurement youÂ*made is not all pin box deflection.Â*

rcflyer,

I thought I addressed your concern with an earlier post when I said.

"You are right there is some affect due to spring sag when comparing to an external reference point. But using your 7/32 inch drop at the springs and a distance of 172 inches from the equalizer to the landing gear vs. say 88 inches from the landing gear to the tip of the pin box, the error would be about 50% less or 7/64 of an inch."



When Crossroads checked Hank's Cruiser at the factory, I don't think that they adjusted for any weight transfer and I'm trying to duplicate their technique w/o the benefit of a fork-lift. But even so, if I subtract the 7/64 inch error from 1-11/16 inch, I still have 1-9/16 inch of absolute movement. Either way it is significant.

[Dayle1]

I took my Cruiser to the dealer earlier this week and today Lippert performed the same repairs that Hank’s 285RL received at the factory.



Cruiser prep’ed by the dealer.





This picture shows how the bottom of closet floor has been pushed up due to frame movement. This has only affected the front of the closet. It may not be visible in the photo, but there is no gap at the closet opening, adjacent to bedroom (right side of photo).This is consistent with measurements and pictures I took from under the pin box. I decided to leave the floor as is.





This diagram shows the frame design better than the rough sketch I posted. The pin box structure has a lot more substance than frames on many other fivers.



The two rear crossmembers have been spot welded and gussets added under bedroom floor to increase stiffness between the pin box portion and bedroom floor portion of the frame.







Great welding job done with minimal damage to the plywood floor.



















Frame extension with additional wall bolt.









Since this was a field repair, there were a couple of communication issues. The Lippert tech made one adjustment on the spot, a call to Randy took care of another and the dealer went after some special countersunk screws that had been overlooked for the wall hangers. I am very pleased with how the repairs went, and the hard work that the Lippert tech and dealer’s staff did in 100 degree weather. I will go back on Saturday to pick up the trailer and when I can, I will measure the improvement in pin box movement.

[Lloyd]

Larry:
Looks like they had some one there that knew how to use a wire feed. Great pics , thanks for posting them.
Was there any stress cracks found?
I bet you are happy to have this ordeal over with.

[hhh]

Looks like they did a good job Larry. Will be interesting to see the difference in the flex once you get some measurements.

[cruzinfools]

[cruzinfools]

So I am wondering how many of us out here has the same problem with our new units. I told the wife the day we brought this home how bad it was moving up and down compared to the old one. This won't be good on down the road. Going to check mine after get back from vacation. Thanks everyone.

[Hunter11]

I would think any floor plan with the new notched frame would be suspect.

[cruzinfools]

I would hope Crossroads or Lippert would step up to the plate and address the issue so we all could know what is up before the warranty or a bad thing happens. Have a trip planned will check mine when I get back as it moves quite a bit compared to my old one. I wish that I would have done more research on this new trailer as I am not at all happy with it.

[Lloyd]

If I was you, I think I would take some measurements before leaving on a long haul.