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Old 08-14-2014, 04:48 PM   #393
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Originally Posted by Jim Flower View Post
One of the benefits of learning how to drive in the frozen north is that you learn fairly early that a balanced vehicle is more directionally stable than a vehicle that is loaded, say, tail heavy, where the back end wants to pass the front end in a loss of control situation.---
Jim, the condition you describe ("where the back end wants to pass the front end") is called, "oversteer". Oversteer occurs when the front tires produce relatively too much lateral force toward the center of the turn and/or the rear tires produce relatively too little lateral force toward the center.

When you move the vehicle's center of gravity forward to "balance" the axle loads, you reduce the tendency toward oversteer.
Moving the CG foward increases the load on the front axle, but it also decreases the distance from CG to front axle.
The product of tires' lateral force times distance from axle to CG gives a steering torque which tends to yaw the vehicle about its CG.

If the tire's cornering stiffness coefficient (ratio of lateral force divided by vertical load) were a constant, the vehicle would remain in "neutral steer" -- the steering torques produced by front and rear axles would be equal magnitude and opposite direction. However, cornering stiffness coefficient decreases as the vertical load on the tire increases.

Therefore, moving the CG forward to "balance" the axle loads causes the front axle to produce relatively less steering torque and the rear axle to produce relatively more steering torque. This tends to keep the back end from wanting to pass the front end -- IOW the tendency for oversteer is reduced. In short --moving the TV's CG forward tends to decrease oversteer.

Now, let's attach a trailer to the TV. When rounding a curve, the trailer exerts an outward-directed lateral force on the ball. The trailer tends to make the TV turn toward the center of the turn -- increasing the tendency toward oversteer.

Fortunately, the trailer's tongue weight removes load from the TV's front axle and adds load to the rear axle. Since the location of the TV's CG does not change, the reduction of load on the front axle and the increase of load on the rear axle both tend to make the TV understeer.

If a WDH is used to add load to the front axle and remove load from the rear axle, the effect is to increase the tendency toward oversteer. If the WDH adds too much load to the front and removes too much from the rear, the TV might end up in an oversteer condition -- which is not desirable when towing a trailer.

In your "frozen north" scenario, we saw that moving the CG forward reduced the tendency toward oversteer.
When a trailer is attached to a TV, we see that reducing the amount of WDH load transfer also reduces the tendency toward oversteer.

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The conclusions reached by the various manufacturers on the correct way to distribute weight on a long wheel base vehicle are puzzling.---
It is important to keep in mind that "weight distrubution hitch" is a misnomer. A WDH does not distribute weight or mass. A WDH distributes load. If a WDH could magically redistribute some of the TV's mass, it could move the location of the TV's CG. Since a WDH cannot redistribute mass, the location of the TV's CG does not change.

You are correct that having a "balanced" vehicle tends to promote directional stability. However, "balanced" in this context, does not include the effect of tongue weight -- it only includes the effect of the distributed mass of the TV and its cargo.
Your desire to have a balanced TV, and the TV manufacturers' desire to reduce the amount of WDH load redistribution, are aimed at the same objective -- to improve the TV's directional stability.

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It would be interesting to see some actual test data that supports the opinions.
I don't know if the test results to which Richard Klein and the Progress Mfg. (Equal-i-zer) representative alluded are available for public distribution. If they are, they might be in an SAE report which could be purchased.

Ron
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Old 08-14-2014, 07:18 PM   #394
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Ron, thank you for your very thoughtful analysis of a condition that is difficult to understand. It's almost like a person where perfect does not exist but trying to get close is most likely good enough. Physics aside, once we through a human behind the wheel, perhaps attitude is the best ingredient for balance. I think SilverCabin will be just fine with his set up based on his methodology, attitude, and past performance. Jim


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Old 08-14-2014, 08:14 PM   #395
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Equal-i-zer Hitch Thread.

So, here's the tale of the scale for my rig. I went to my dealer and had the hitch adjusted, followed by a visit to the CAT scales.

So, here's what I'm seeing with nobody in the truck as we frantically measured and recorded data:

Measurement No TT TT no bars TT with bars
Front Bumper 24" 25.5" 24.5"
Front Wheel 36.5" 37" 36.5"
Rear Wheel 38" 35.25" 36.5"
Rear Bumper 29" 24.5" 26.75"

The truck had a nearly full gas tank and no cargo. The TT had full propane tanks, 1/2 full fresh water, empty grey/black tanks, and no food/clothes, etc. I was in the truck when weighing the rig, below.

When traveling, we'll be adding a couple of bicycles, my slim spouse and our golden retriever to the truck. We'll of course be adding clothes, food and water to the trailer. We will hit the CAT scales again after we load up for a camping trip as we head out for the weekend.

Here's the CAT scale ticket for my TV/TT shortly afterward. Looks like we have plenty of weight to play with and we're pretty well balanced. Previous weights (not on a CAT scale) indicated we had too much weight on the drive axle and that the front axle was 80 pounds lighter than without the TV. Given the other scales weren't CAT certified I won't cite them directly, but I will note that the relative values (e.g. various axle weights on the same scale) should be close enough to have given me useful information.

CAT values today:
Steer Axle 3,440 lbs (GAWR = 3,900)
Drive Axle 3,640 lbs (GAWR = 3,900)
Trailer Axle 5,960 lbs (Max acceptable trailer weight = 7,600)

Here's what we did that really changed the game for our truck: Lowered the hitch ball by one slot on the shank and added one washer.

We figured out today that the hitch ball was an inch or two higher than the coupler when the trailer was level. Our Ram has coil springs so it settles fast and looks OK once connected, but this mis-alignment must have caused the truck to carry more weight than ideal.

Adding the single washer pushed a bit more weight to the front of the truck and perhaps back to the trailer, giving us a more even distribution than before.

On the "before" config our trailer wasn't visibly nose-up, but the mis-alignment of ball height to coupler height must have caused the combined rig to put a lot more weight on the truck than it should have, while also lifting the steer axle of the truck enough to produce a noticeable high-headlights syndrome, even with the EQ hitch hooked up.

Lastly, the towing experience has improved dramatically. The headlights seem normal while towing, and the ride is considerably smoother. The ride continues to feel steady with no discernible sway even when being passed quickly by a double dump truck on a steep downhill run (e.g. I'm going 60 mph and he's going at a much higher but undetermined speed).

So, we're hopeful that we've dialed in the EQ hitch for our truck and trailer.
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Old 08-14-2014, 09:37 PM   #396
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Originally Posted by Silvery Moon View Post
CAT values today:
Steer Axle 3,440 lbs (GAWR = 3,900)
Drive Axle 3,640 lbs (GAWR = 3,900)
Trailer Axle 5,960 lbs (Max acceptable trailer weight = 7,600)
Did you also measure the TV's axle loads today with the trailer unhitched?

Ron
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Old 08-14-2014, 11:46 PM   #397
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Great question.

Answer: No, though I knew it would be a good idea. I was flying solo and the truck stop was so crowded that I couldn't unhitch in their lot and try again. We'll catch that when we're loaded for the trip, probably on Saturday.

Uncertified weight for the truck alone from the other day, similarly equipped:
Steering axle: 3,420
Drive axle: 2,940
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Old 08-19-2014, 01:02 PM   #398
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I'd like to thank Ron publicly, for another very informative, explanatory post (#393). After carefully reading through that, I can understand why the current thought is to have more load on the rear of the TV than the front. Even though my setup seems balanced, in an emergency maneuver I can see how the trailer could drive the rear forward and cause a jackknife. Therefore, I have decided to remove a spacer washer.

I was a little surprised that I could get the head bolts loose with only two breaker bars. They were tight, but it didn't seem like 320 ft-lbs. Hope I can get them as tight as they need to be when I do the final tightening again.

I hitch-up and tow Monday. I'll be making measurements and a scale stop with a truck and trailer loaded for travel. Stay tuned for my next report.

Randy
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Old 08-19-2014, 08:16 PM   #399
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Well, this has been very interesting, not to mention educational. I have read almost every post on this very long discussion. I have learned many things about my hitch.

I purchased this hitch at the dealership when I bought my 2002 31' Classic in June of this year. It was the one they recommended. They installed and set it up.
It does seem to tow very nicely, or did. Lately, I've noticed more popping and groaning.

I have not weighed my axles, but the tire footprint lengths, front and rear are about the same. Tire pressures are the same. The whole rig is nice and level.

To start, I have an E2 hitch with round bars that fit up into cylindrical sections of the hitch head. On the bars there is a label that says they are 1,000 lb. bars for a 10,000 lb. GVWR trailer. My Classic has an 8,000 lb. GVWR.

When I unhitched my AS a few weeks ago, I noticed that the L brackets were loose. They will move back and forth 1/2 to 3/4 inch. The holes behind the poly lock nuts seem to be ovalized. The holes that are being used are the ones at the farthest end from the L.

My engineering senses tingled as I thought it rather dumb to bolt a lever from its farthest point.

Then I saw one of your lovely pics, it seems that my bracket is on up side down!

So, if I turn the bracket around and reinstall the L at or about the same height, I should be in the holes closest to the L. Perhaps I could fabricate a bolt and spacer to lock down the other end of the L bracket also.

As for the bending of the attachment brackets, I'm thinking spacers and extra bolt and spacer at the top end should cure that. (Grade 8 bolts are the way to go here.) If that is not enough, I would suggest welding a 3/8" X 1 to 1 1/2" bar along each side forming a C channel. (Or I could re fabricate the whole thing out of stainless steel) Yes, I have a machine shop.

Now, if any of you experts (I'm not trying to be funny here, you guys know a whole lot more than I do about this) are still available for comment, I would love to have your advice on this.
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Old 08-20-2014, 01:00 PM   #400
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Post #9 is how I got my L-bracket link plates to stay still.

30,000 miles later, they still work fine.

I have the E4, but similar concept.

http://www.airforums.com/forums/f464...ort-34484.html




See you on the road
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Old 08-23-2014, 08:38 PM   #401
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Originally Posted by JimGolden View Post
Post #9 is how I got my L-bracket link plates to stay still.

30,000 miles later, they still work fine.

I have the E4, but similar concept.

http://www.airforums.com/forums/f464...ort-34484.html




See you on the road
Yup, read that. That seems to be the simplest way to fix the problem that I have seen.

I took my brackets off and turned them over, so that the studs for the L brackets are at the bottom. Using the 3rd and 4th holes (from the bottom) in the L brackets, I have effectively lowered them one inch.

Hitching up I find that the front end of my truck is now 7/8" higher than it would be with no load, and the rear is 2" lower.

It seems to drive just fine. In fact, I don't really notice any difference. However, if that 7/8" is a problem, I suppose the only recourse is to add washers.

Or, I could raise the L bracket 1 hole and subtract washers.

Either way I have to remove the ball, right. That might be a problem for me right now. I'm pretty sure I do not have a socket that big.

My parts are in at Reliable RV in Springfield, and I need to hit the road. So, unless you feel that the 7/8" rise in the front is dangerous, I'll leave it as is for the time being.
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Old 08-24-2014, 07:52 AM   #402
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You'll probably be fine with it as-is, though I might move the L-brackets up one notch. I wouldn't fool with the washers, unless you have a good flat parking lot and an hour or two to play with it. Not a big deal, but when you add a washer, you often wind up having to adjust the L-brackets too. Kind of a domino thing.

For 7/8", one L-bracket movement would probably bring you close to level. But, I still think it'd probably be OK as-is to get you home on, and you could fine tune it all when you have a little more time.

See ya on the road,
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Old 08-27-2014, 05:53 PM   #403
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You'll probably be fine with it as-is, though I might move the L-brackets up one notch. I wouldn't fool with the washers, unless you have a good flat parking lot and an hour or two to play with it. Not a big deal, but when you add a washer, you often wind up having to adjust the L-brackets too. Kind of a domino thing.

For 7/8", one L-bracket movement would probably bring you close to level. But, I still think it'd probably be OK as-is to get you home on, and you could fine tune it all when you have a little more time.

See ya on the road,
I am back home now. On the trip to Springfield I left everything as it was. (I took a 1/2" socket set with a big breaker bar along, just in case, tho).

You were right. I had no problems on the road. Joyce and I both felt the ride was better than before I lowered the L brackets, although not day and night better.

I think I may raise one L bracket when I go back to get the AS in a couple of weeks, just to see how that works.

I do have a question tho. My Chevy Quadrasteer heavy half ton has a button on the dash for trailering, bumpy roads, and heavy loads. I'm not sure just what it really does, but it does seem to smooth out the ride on a bumpy or choppy highway. Is this good for the trailer?
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Old 08-28-2014, 01:12 PM   #404
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Terry,

Glad to hear you made it safe and sound.

I'm not certain, but if I had to guess, I would say that button controls the shock absorber valving. I had a Thunderbird Super Coupe that had a switch like that...basically "Sport" or "Touring" modes. If that's the case, it would firm things up a bit by stiffening up the shocks.

Now whether or not that is enough to hurt the trailer, I don't honestly know. They say the 3/4 ton trucks are plenty stiff enough already for an Airstream, but it may be that your model has a special soft suspension so that it rides more like a 1/2 ton and you can stiffen it up as needed.

Others on here may know more on this. If it does handle a lot better with it switched on, i would probably try it and just keep an eye out for signs of rivets popping, etc.

Hope that helps a little
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Old 08-28-2014, 06:45 PM   #405
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I have a question for the experts. After arriving to camp at dinnertime earlier this summer I proceeded to annoy/entertain the entire campground as I passed by seeking my campsite. AREEEEEEEEEE!!!!!!, ERCH ERCH ERCH ERCH, AREEEEEEEE!!!!!, CLUNK. Repeat.

To end it promptly ordered and installed the Teflon L Bracket jackets. I also completely disassembled, cleaned, and re-greased (w/equalizer grease, light blue color). After one 10 day 900 mile trip the noise is somewhat back and the hitch head grease is really black. How often do people clean and grease the hitch head?
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Old 08-28-2014, 08:03 PM   #406
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The hitch head grease will get black fast because it picks up road dirt. I clean it off and put on new every day or two or three days, or around that, depending how far I go and whether I unhitch. Grease and a few paper towels are cheap and keep those little dirt particles from wearing the coupler and ball.

But you have to clean out the coupler from time to time—it isn't all that easy to get under there and around the parts inside. One way is to spray WD-40 in there after unhitching and some of the grease will drip down and you can try to get the rest out with paper towels or rags. But dry it well so the new grease doesn't get too watery.

My solution to the noise from the hitch is to close the windows and turn up the radio. Noise problem solved. I think that since the hitch uses friction for sway control, using grease or teflon covers reduces the friction, thus reducing sway control.

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