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Old 08-23-2005, 09:56 PM   #1
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visited CAT scales - the numbers are in...

hi folks

just back from an 8 state 2 week loop that included 4 days at the mother ship for service and tours.....i have lots to post and as soon as i figure out how to upload pictures, i'll share some really neat stuff.

about 2 hours from home today i stopped for diesel and there was the scales......staring at me and me back at them. i looked at them for 15 minutes and no trucks boarded, so......

paided for my fuel and asked,

"how busy are the scales" and the reply was,

"this time of day they are hardly ever used but in 3 hours they'll be really busy. wanna weight that pretty trailer?"

"i do but i've never done this before.....will you be gentle"

the attendant laughed and said,

"go pull your trailer around and i'll send someone out to help you."

so with that i looped the truck stop, weaving between trucks and pumps and people and rolled up onto the platform....or i should say 3 platforms.

i explained to the young fellow that came to help that i wanted to weight the whole thing 3 times while i adjusted the load bars......"not a problem", he replied because the 3 platforms measure steering wheels, drive wheels and trailer wheels weights individually and as a total for all 3.

i could do all of this without moving off the

now for the players:
---2005 f250 psd 4wd supercrew long bed with long camper, shell bed liner, a full load of gear (generator, 12' ladder, bikes, tools, 3 chairs, 3 tables, gas grill, 20# lpg, more tools, gas can, diesel can, bike repair stand, dog and me and 38 gallons of fuel. oh and ENKAY flaps, hensley bar and lots of other stuff! factory curb wt approx 7400 before adding STUFF....gwr 10,000, gcwr 23000, max trailer wt 12,500.
---hensley hitch....i think this adds 250# to the truck/trailer link and 1000# load bars.
---05 classic 34 limited (the kingsford edition) with 800# of options and 60 gallons of water, 80# lpg, 1/2 tank of gray and 1/2 of black. i can't estimate how much gear i've loaded into the trailer........but there are 48 empty walmart bags and 19 empty camping world bags, so whatever was in the bags is in the trailer along with gear for 12 wks of travel and all but 2 doors in the bedroom full of stufffffffff.

engine running; me and the dog and a big gulp on board...

roadking moe would be proud.

so now on to the scales........and the numbers are:::

1. first measurements were done with bars adjusted by trial and error over the last 4 the mid point between 1 and 2 on the cylinders.

steer axle 4680, drive axle 4800, trailer axel 9360, gcw 18,840

2. next was with the load bars complete relaxed......

steer axle 4400, drive axle 5120, trailer axel 9340, gcw 18,860

3. next was with the load bars maximally tightened (0 mark)

steer axle 4740, drive axle 4760, trailer axel 9360, gcw 18,860

the best way to look at the numbers is to draw 3x4 table and fill in the boxes....for each row with unloaded bars, maxed bars, and driver adjusted bars.

go ahead it'll make it easier to see the weight shifts.

comments anyone?

everyone needs to do this at least once and i for one plan to do it again in a few only took 5 minutes to do every thing above. i also weighted the truck f/r without the trailer and the trailer hitch/axles with out the truck...i'll save this data for another day.

i've learned alot about my combination of mass and will post more later in the thread.


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Old 08-24-2005, 04:06 AM   #2
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That looks about right on the numbers. Mine is vintage and I keep track of what my wife stuffs in there...of course at the moment I am sure mine is lighter....half the interior is out


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Old 08-24-2005, 05:14 AM   #3
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Originally Posted by 2airishuman
comments anyone? ... i also weighted the truck f/r without the trailer and the trailer hitch/axles with out the truck...i'll save this data for another day.

i've learned alot about my combination of mass and will post more later in the thread...
Way to go! - Now you KNOW where you are weight wise.

I would think that 5 minutes was a very wise investment.

I'm surprised that the Hensley was able to transfer 340# (or 360#, depending on how you place the "base line") from the rear axle to the front without adding any (only 20#) to the trailer axles. IMO, a 20# error from weighing to weighing on a scale of this magnitude is perfectly acceptable.

Looking forward to the REST of your story with the individual weights.

Did the numbers come out where you thought they were prior to weighing?

BTW, congratulations on your 100th post and your third rivet!

"Suck it up, spend the bucks, do it right the first time."

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Old 08-24-2005, 07:04 AM   #4
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Thats some great info.

What I found interesting was that the trailer didn't seem to move much (and not at all in some cases) in terms of the hitch weight being shifted to the coach.

Clearly your trial and error pretty much hit it right on. The steer wheels and drive wheel weights with your setup seemed very balanced (until you took it off your trial and error settings) if I read it right.

One thing I noticed too is that with the added weight on the front, it might also not be a bad idea for a powersteering cooler as well. If anyone has a GM 3/4 ton with hydroboost brakes, I think you already have one.
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Old 08-24-2005, 07:14 AM   #5
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Ideal Balance?

What would be the ideal for weight distribution?

Does this effect sway? I would think so.

The thought of going on a long trip with a check on the scales sounds so good, thanks for letting us know about it.
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Old 08-24-2005, 07:52 AM   #6
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Great info, 2air. Thanks!
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Old 08-24-2005, 10:37 AM   #7
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Your # 1 test is close. Most owners would be in great shape if they were that close.

However, your # 3 test is PERFECT.

Caravanner Insurance proved way back in 1970, a front and rear axle weight balance is absolutely perfect.

The formula we established back then is easy to work with.

There cannot be more more that 10 percent of the total tow vehicle weight difference between the rear and front axle weights, and then only on the rear axle.

Your tow vehicle weighs 9500 pounds. Therefore the maximum weight difference would be 4300 pounds on the front axle and 5200 pounds on the rear axle. Again these are "maximum" differences.

The closer you get to an equal balance, the better the rig will handle, as you have demonstrated.

But, there are owners who will disagree, especially those that tow with just a "ball". Obviously, they never went to a truck scale or rode in the back end of their trailer while being towed at 60 mph.

Safety, unfortunately, is in the eye of the beholder.

You have absolutely maximized yours.

Great job. Your rig (unfortunately) because of how well you have it balanced, is in a vast minority.

Sad for most owners.

Great for you and your family.

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Old 08-24-2005, 02:37 PM   #8
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hi folks

didn't even notice the milestone or extra rivet.....neat.

thanks for reviewing the numbers and thinking out loud (on the forum) about the results....

it really was a relief to do this after 12 weeks of travel in a big new trailer, wondering the whole time.......where the heck is the weight load; am i over, what do the load bars do...really, and how much does this big ol' rig weigh, and do i have my tires properly inflated.

i really had no idea what to expect and yet the rig drives so nicely....also i was affraid to max out the bars for fear of under weighting the drive andy points out that is near perfect i'll try that on the next trip for the smoothest road sections...

i think others may be intimidated by the prospect of using the CAT scales too, so i hope the post encourages folks to get the data. it's easy, it's inexpensive and now a copy of mine is in the important documents case i get stopped or my insurance folks need it......heaven forbid.

like andy preaches safety should be maximized and based on what is actually known (research data, engineering knowledge and carefully filtered personal experince or population data like that collected by insurance and accident investigations), combined personalized measurements. while each rig is unique (with lots of variables) many of us do have the same or similar rigs. factory guidelines and vehicle marketing are often weak and the folks we buy from sometimes aren't very helpful.

my trial and error setup involved measureing truck height at the wheel wells, hitch receiver and front end, several times before hooking up the trailer. i drew little truck pictures in a notebook and recorded the 6 numbers over several weeks. then i repeated this process when adjusting tire pressures with full fuel and near empty and before/after bed shell and cargo was loaded. on the day i picked up the trailer ( i actually spent 3 nites with the dealer) i redid all the measurements after the hensley install and with the trailer hooked up.

then as silly as it sounds i'd go drive for 5 miles to the next exit and return. adjust the load bars remeasure and drive again. i did this about 8-10 times over 3 days and recorded how the rig 'felt' to me at each setting along with the new numbers.

i had never towed a trailer before, was coming from an airstream class a, and wanted to feel comfortable towing......i also wanted my heart rate under 100 when i finally head out for the maiden trip.

twink and 87mh....

a 20# error seemed ok at the 19,000 range.

i too wondered about the small about of weight transfer aft. seems to me that with a longer trailer less weight will move as far back as the wheels but rather may be dispensed along the frame.....the lever arm is pretty long on a 34 footer. just a guess.....

also i went with the 1000# bars and not with the 1400#ers which is the other hensley choice. the truck has a pretty stiff suspension and anti sway bars fore/aft so my assumption was the lighter bars would flex more. hensley assured me they were not going to break even at max setting.

so perhaps if i had the 1400s on the tranfer rearward would be greater? but the trailer ride would be stiffer too? i think this is how i've read it explained here.....andy?

the 1000# bars are made by drawtite.....and i think they make a 1200# which would be a smaller gain than the 1400s.

another reason for wanting to know the steering wheels and drive wheel numbers when fully rigged relates to tire pressures. the 250 is normally about 58/42 on weight distribution with the diesel, so i run front tires 2-4 lbs higher.....for towing i have been running front/rears at the same pressures.

wondered about the front cooler too twink but the front axle is rated at 6600lbs and the rear at 6000lbs so i'm still under that by 20%. that's also with tires inflated to 80psi and i run 76 or so cold.

again thanks for reading this and offering insights.....

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Old 08-24-2005, 03:24 PM   #9
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Thanks for putting in the time and effort to bring this to our attention. I've always toyed with the idea of pulling up to one of the scales but it seemed somewhat intimidating to pull up with a van and a 20 footer.
I'm using Reese equiptment, and have also spent time out in the middle of the street with a tape measure (much to the amusement of my neighbors). Maybe now that the interior is done I'll give it a try.
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Old 08-24-2005, 03:30 PM   #10
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Actually, you should be using a 750 hitch, but certainly not a 1400 pound rated hitch.

The stiffer the torsion bars, the stiffer the ride for the trailer. If you add to that a stiff suspension system on the tow vehicle, then the trailer winds up being punish by considerable road vibration.

Some early warnings of an excessively rated hitch are shearing of rivets, especially at the front of the trailer. You will also see markings on the walls where the furniture is moving as you travel. Some other signs are a groove cut into the entrance door lock striker bolt, and black marks around the wall attachment extrusions.

I would also suggest that you soften the tow vehicle ride by reducing the tire pressures down to perhaps 55 psi. The stiffer the tow vehicle tires are, the more the road vibrations are transfered to the trailer.

Airstream trailers like a "soft" ride. When the ride changes to rough or stiff, then strange things happen to the trailer, that are usually expensive to repair as well.

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Old 08-24-2005, 04:34 PM   #11
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Originally Posted by Inland RV Center, In

Actually, you should be using a 750 hitch, but certainly not a 1400 pound rated hitch.

Andy we've talked this subject before but I think we need further clarification here. A 34' unit, non slide, is rated for 820 lbs. of hitch weight. I would guess that the weight rating of the bars you use would also depend upon the brand of hitch? Since there are many different brands each having their own characteristics, its probably unwise for a person to assume that each bar has the same operating characteristics.

Example in hand. A Reese dual cam sway control bar is much different from an Equal-i-zer bar. I find the amount of bend and "spring" of these bars are much different. My assumption is that based on my conversations with Reese customer support, a bar which is too light may end up flexing much more that design limits on dips and other road conditions which can cause the trailer to temporarily go into a nose down position. If you exceed that bend limit the bar will snap. In Reese's advice they tell you to go to a heavier bar if your hitch weight gets to less than 75 lbs of the bar capacity. They note that the equivalent force that occurs on a downward moving of the hitch on a dip could exceed the capacity of the bar.

I can tell you that even with a heavy duty truck, some of these road dips are down right scary. I hit one yesterday on I-55 southbound just after getting past the bridge over Lake Springfield in Springfield Ill. I saw the vehicle in front of me start to bounce and I coasted down to about 50 mph. What occurred in the next few seconds was simply scary as we hit these dips in the road. The bounces (4-5) were pretty nasty as we dipped up and down up and down in quick succession. We pretty much guessed that we would find the hanging clothes in the closet on the floor (we didn't). Bottom line I was glad with my 1,125 lb. hitch weight on the Classic, that I was using the 1,400 bars on my equally rated Equal-i-zer hitch. Even with the stiffer spring capacity of my 3/4 ton van, I wonder if we would have had that nose of the trailer closer to the ground if we had used a lighter bar.

All food for thought. Its those extreme situations that get folks into trouble. Your hitch and its components better be up to the task.

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Old 08-24-2005, 05:46 PM   #12
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jack and andy

i'm not planning to make any equipment changes just now....i think it's dialed in pretty closely.

i do understand airstreams like soft rides.....and if the air bags on the rear of an airstream classic mhome ever deflate.....well there will be loose rivets everywhere rearward, gray dust on the head liner and little cracks everywhere in only about 400 miles.......ask me how i know.

the 1000# bars flex nicely, like a bow when the string is drawn. another fellow with an 06 34 with slide pulled with a 3/4 ton chevy had the 1400 bars.....they are much much meater, didn't visually show much flex and he commented on how stiff this set up was riding. we camped together last week at the factory.....more later on this adventure.

while softness is good, other issues, hensley and airstream ALL advised 1000 or 1400 bars so anything less might be a libability issue for the customer and a warranty problem on a new trailer.

i've mulled over the tire air pressure issue for many years and since i regularly run cars on a closed track course am keenly aware of what a few lbs can do for ride, comfort, handling, suspension wear, economy and side walls.

the problem is on the truck which has e rated tires that "e" rating is only valid IF the tires are properly inflated which means 65-75 at a minimum.

and for the full load rating they need to pumped up to 80!!!

while i'm not planning to roll the truck/trailer combined, many truck rollovers can be directly traced to under inflated tires....for the bf's on the truck 55 would be significantly under inflated.......but i do realize the trailer would like the softness.

also these big trucks are prone to rollover rates higher than cars....i'd be very cautious about removing one of the leafs from the rear end.....that might increase instability during emergency manuvers and would certainly spook any insurance related issues of who's liable. ford or me.

so later in this adventure i may consider the mor-ride setup or firestone air bags or the hetchens-like rear suspension set up i've seen.

none of these increase the axle capacity but all do soften the high frequency vibration and dampen the shock that andy is warning us about.

in seems that airstreams really do like rubber suspensions..

cheers all and take that rig to a CAT scale!!

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Old 08-24-2005, 06:02 PM   #13
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Unfortunately there is no "absolute" formula, only basic guide lines.

I agree that under hitching must also be a consideration.

What we proved in the early 70's was that basically, and using a Reese full sway control hitch, the heavier duty tow vehicles should use lighter bars, with the same tongue weight.

If not, then the heavier bars would not bend adequately to take maximum advantage of Reeses dual cam sway control, since a bend of a minimum of one inch was required.

As always there are exceptions, but those cases are exactly that, and not the rule of thumb.

Different manufacturers hitch bars, indeed, must be looked at differently. A direct comparison would be difficult to do at best, except for their weight rating.

A heavy duty tow vehicle equiped with a very heavy duty hitch, unfortunately, will eventually cause some damage to the trailer. The up and down dipping, according to tests, when the resiliency is hampered by heavy duty everything, will increase since all or most the give has been eliminated, causing the very heavy duty bars to throw the front of the trailer back up into the air, as opposed to softer bars absorbing some of the shock, but not kicking back at the rig.

Jack another way perhaps to look at this question, is to consider the wing structure of commercial aircraft.

The recip engine days had wings that were very rigid. Jet aircraft wings flex. If they didn't they would break. Therefore when a jet aircraft hits a vertical movement of air, the wings flex, which minimizes the shock to the fuselage.
Same is true with softer hitch bars, on heavy duty tow vehiches. The softer bars absorb more of the shock, instead of transfering it the front of the trailer, and minimzing the vertical movement of the trailer tongue.

Again, food for thought.

Safety is the real issue, that unfortunately some chose to ignore, to this day.

Can we obtain perfect safety? I don't think so, but I do believe that we can come reasonably and acceptably close.

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Old 08-24-2005, 06:58 PM   #14
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2air' ...

Congrats on taking the time and interest in weighing your truck and trailer. I'm on the road full time ... so this is something I do every 6 months.

Our numbers are pretty close!

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