Old Goat's corner. Dr. Jekyll and Mr. Hide

[phoenix2013]

The subject of proper loading and designing trailers has been discussed ad infinitum, but new examples keep popping up. Spent considerable time with couple of gentlemen, both own DRV Full House rigs, almost identical with the exceptions of the axle suspensions, one behaves on the road the other one does not.

The other subject discussed ad infinitum is the need to have sufficient pin weight in your fifth for proper tracking, handling and balance, 20% of the GVW being the "magic gate". 20% or more good, less than 20% not good. The industry has been in the "not good" territory for a long time. Greed and the need to sell enormous fifths to guys with pickups driving it. 

The reason I got intrigued and involved with this rig, because it's a Dr. Jekyll and Mr. Hyde. Driven with an empty garage it's a perfect Dr. Henry Jekyll, when the owner loads his RZR in the garage it turns into Edward Hyde. Anything over 60 mph and the rigs starts swaying all over the road. Normally when figuring out the pin weight of the fifth I ask for two CAT scales readings, one with truck only (front and rear axle), the other with truck and trailer (truck front and rear axle and trailer axles). In this instance I asked for three CAT scales readings, one with truck only, the other with truck and trailer but no RZR and truck and trailer with RZR. The owner delivered the other day.

Here's the math

No RZR (middle ticket) Truck rears 15840-10620= pin weight 5220       5220 pin + 18180 trailer axles = GVW of 23400      5220 pin is 22.3% of 23400 GVW, nice Dr. Jekyll

With RZR (end ticket)   Truck rears 15020-10620= pin weight 4400       4400 pin + 21560 trailer axles = GVW of 25960      4400 pin is 16.9% of 25960 GVW murderous Henry Hide

Without the RZR it's a very well balanced rig, load RZR into the garage and it takes off 820 pounds off the pin weight and into ugly territory,  anything under 18% can turn ugly going  down hill and braking, down hill, braking and in the rain, too fast, etc. The moral of the story is that the toy haulers garages are not designed for serious loads, why? They got the axles in the wrong locations. And, longer the rigs, worse the problem. There is an industry that has gotten it right.

Regardless of length, look where they placed the axles, where the load is. Regardless how many tons of horses you load, the pin weight will stay the same, or maybe increase some. It must be that the "horse sense" hasn't made it yet to the RV guys.

 

[rpsinc]

And the math doesnt lie.  So after many conversations with you and Curtis, it seems that the math lead us to the place that indicates why that trailer is not "happy" when the garage is empty.

Given that the other trailer is similar but the truck is not(tandem with duals), did you also get weight tickets for that rig?

I can surely see that at increased speed the "tail wag" increases as a reaction to the issue of too little pin.  I wondered if running the trailer tires at lower pressures might affect some of that as well.  Thinking that pressures at tire max would reduce the tires contact patch esp since the loaded weight for those tires did not exist, so reducing said pressure might increase the contact patch and perhaps improve handling(by affecting rolling resistance).  This is purely an OPINION and is not based on any data other that the common sense that bounces around in my head as a result of living for some significant amount of years.

I will add that in my situation, I replaced my hitch due to increased pin weight(different trailer, NH) beyond what my former hitch could handle, and while I was at the hitch change, I also moved it back 26".  The handling of the rig improved in this current condition.  The greatest caveat is that now I am LONGER.

[rickeieio]

Henry, you're just teasing us.  What is the GVWR of the trailer, and what is the loading of liquids (fresh and waste water)?

If the owner still has some cushion in within the GVWR range, they might travel with a full fresh tank when the RZR is on board, possibly curing the hitch balance issue.

[Danfreda1]

Isn’t the highest drv gvwr 24000. 

[Wrknrvr]

   Just thinking about truck axle, lowering the .Try different pressure settings to see if that makes a difference.

   Or the rear truck tires.

  We put new tires on in Florida. Made it to Texas, and had them replaced.   When using the brakes, the truck wanted to leave the fifthwheel lead. Almost lost it once. When I had wanted to leave a commercial truck out in traffic. He was working, and we were just on vacation.

  The truck did act odd without the fifthwheel on back. But was just thinking it was new tires.

 Thinking 

Edited November 8, 2023 by Wrknrvr

[phoenix2013]

The owner is reading this thread, perhaps he can answer. Incidentally the other rig which part of discussion has Moryde suspension which provides different suspension reaction and is higher off the ground (Moryde requirement). I don't believe he carries the same load in the garage. There is also an issue of the the hitch locations. Copy of his email to me below.

Henry, I did read the article. It is accurate. I am still nose low on my trailer. I have spoke to DRV, it is like pulling teeth, but I finally got them to tell me what hitch height is to make the trailer level. That number is 51 inches. My et hitch is at 48 inches but my truck settles 1 inch when I hook the trailer up. Some people tell me is should not settle at all. What are your thoughts about it settling? If I don’t worry about the truck settling, I can raise my hitch 4 inches. I have room to do that in the frame rails. Everyone says nose low will add hitch weight. They also say trailer must be level. If I level the trailer is my pin weight going to get lighter? Have you give any more thought to “tricking the et to make it think I have more pin weight”?

[rickeieio]

This is all for naught. You’re over gvwr already.  Don’t throw bandaids at it. 

[SuiteSuccess]

21 minutes ago, rickeieio said:

This is all for naught. You’re over gvwr already.  Don’t throw bandaids at it. 

Wonder how many don’t consider gvwr?

Edited November 8, 2023 by SuiteSuccess

[Wrknrvr]

   Just thinking about truck axle psi.    Try different pressure settings to see if that makes a difference.

   Or the rear truck tires.

  We put new tires on in Florida. Made it to Texas, and had them replaced.   When using the brakes, the truck wanted to leave the fifthwheel lead. Almost lost it once. When I had wanted to leave a commercial truck out in traffic. He was working, and we were just on vacation.

  The truck did act odd without the fifthwheel on back. But was just thinking it was new tires.

 Thinking 

[Wrknrvr]

   I think my fingers did not listen to my brain when I posted awhile ago.

 

  I meant to say, change tire pressure in the rear drive axles. That is a easy thing to try.

  Your bed settling, most likely because the suspension leveling valve is not working properly.

    Or I have lazy fingers.

[Darryl&Rita]

Levelling valve to start with, then eyeball the tanks and juggle levels to get more nose weight. Nose down won't necessarily add enough pin weight to make a difference, assuming the equalizers are working properly. 

[jenandjon]

The truck should not squat at all. But one inch could be tire squat. We are still harvesting so I will have one of the guys measure the nose of his grain trailer empty and loaded. Just out of curiosity. I will report back tomorrow. 

 

I don't know if I would start jacking with the leveling valve. You change that and you start messing with the driveshaft angles. 

[lappir]

2 hours ago, jenandjon said:

I don't know if I would start jacking with the leveling valve. You change that and you start messing with the driveshaft angles. 

You will most certainly have issues with driveshaft if you start messing with the leveling arm. When I got my truck the top rubber broke on the way home with it. Did a roadside fix and got the new "Kit" on my arrival home. I don't know why they won't just  sell the parts that break and insist on selling everything needed to do a complete replacement. Oh, and you have to cut the steel arm to match what it was.....

Anyway, I found a level spot put the new to me truck and trailer together and cut the piece to keep everything level. OOPS, suddenly slowing down there would be a big Bang at times. I'd messed with the drive shaft angle and it put a bind in the U joint. Thankfully nothing ever broke and I had a professional reset the ride height. 

Rod 

[Case20hp]

Someone may have already thought of this, but backing the RZR into the garage instead of driving it in will distribute the weight closer to the axles and should add more hitch weight. There is generally more weight on the rear axle on a side-by-side than the front.

[Steve from SoCal]

The issue of the trailer being over gross aside, the nose low attitude loads the front trailer axle and tires may be the point of instability?     Trailer sway is more likely with light contact on the rear trailer axle.     The tire load capacity may be well over the rated limit?     A Cat scale can't break out close tandem axle weight, I would start with leveling out the chassis.     As Case 20 mentioned above loading tail first may help greatly as well.     

[phoenix2013]

Interesting developments in the industry.

https://www.google.com/search?sca_esv=3564cec2bd599925&rlz=1C1CHBF_enUS918US920&tbm=vid&sxsrf=AM9HkKnCNYI7kAibUJfesEu4kgVnbPKMZw:1699714656350&q=trailer+sway+control&sa=X&sqi=2&ved=2ahUKEwiBsb7CmryCAxXWVTABHQhnDDUQ8ccDegQIPBAJ&biw=1536&bih=715&dpr=1.25#fpstate=ive&vld=cid:cc16b255,vid:K-sNjpsdUk8,st:0

Basically boils down to the system recognizing that you are going too fast for the way you loaded the trailer and slow your ass down.

Edited November 11, 2023 by phoenix2013

[rickeieio]

Sway control isn’t new. My 2015 had it.   But it won’t fix stupid. It’s the operator’s responsibility to understand how to safely load and tow. 
 

Some people say “ya can’t fix stupid”.  Well, you can, but it will leave a mark.