Need More Help Understanding Weights

[ROBERT CROSS]

"I am still going to re-weigh but its looking more and more like the setup from the dealer is bad."
__________________

Not all that unusual, many do not take the time to do it correctly.

I also suspect the scales,(operator), if your weights are/were done correctly the 127lb light isn't really too far off the mark, IF the TV and Airstream are level with WD set.

Bob

[slowmover]

Originally Posted by Msmoto

I love these confusion states....because I do not feel so bad about trying to get the weight distribution gig figured out...



However, I am still in process of getting my unit fully adjusted, so I sent a question to Life As A Trucker asking about when the truck scales are least busy. It is my opinion, that the "set up" should be done by weighing once, driving off the scale and readjusting, then returning to the scale for the next weigh in. There is some "settling in" of the hitch after a few feet of driving and this can be accomplished in the weigh return route at a state inspection site.



If there is minimal traffic at the weigh station no one will get upset. I would avoid trying to cut into a line of truckers.....



More to come when I get this figured out....LOL

We've answered that question around here several times. It is that there may not be an ideal time due to a variety of factors. Scale use is fast, but avoiding truckers bent on food and fuel during lunch is about it. Traffic at the truck stop is the thing to watch for.

Yes, drive off scale immediately upon being advised by scale master that the reading is done. It is pretty much instantaneous. Pay for each reading after parking. Effect changes at that parking spot.

[Pat Cassity]

So, I just got off the phone with Blue Ox. They feel that my set up is good. However, they also feel that the Denali's automatic leveling system is interfering with the WD. They suggested that I deactivate the auto leveling system when towing. I am now trying to find out from GM if there is a way to do so. I have checked the manual but it doesn't address deactivation of the system. It only states that it is recommended to allow the shocks to inflate prior to adjusting the hitch. Any of you with Denali's out there had similar issues?


Sent from my iPad using Airstream Forums

[Msmoto]

Just a note, after asking a friend, who owns a very large trucking company, about weighing rigs, I find out that the initial weight is $12, but that each re-weigh is only $2 and this is true at most CAT Scales.

So, I will be heading down to a scale about fifty miles away to set up my unit more like i want it.

Currently I am 7380 lbs steer wheels, 7300 lbs, drive wheels, 7240 on trailer wheels. So, I will attempt to adjust a few pounds from front to rear, hopefully coming to about 7350 each axle of the truck.

[ROBERT CROSS]

Originally Posted by Pat Cassity

So, I just got off the phone with Blue Ox. They feel that my set up is good. However, they also feel that the Denali's automatic leveling system is interfering with the WD. They suggested that I deactivate the auto leveling system when towing. I am now trying to find out from GM if there is a way to do so. I have checked the manual but it doesn't address deactivation of the system. It only states that it is recommended to allow the shocks to inflate prior to adjusting the hitch. Any of you with Denali's out there had similar issues?


Sent from my iPad using Airstream Forums

Pat,

If I haven't lost too many grey cells.....

Set the WD with the key off. When started the Autoride will activate. It should stay level.

Bob

[dznf0g]

Originally Posted by Pat Cassity

So, I just got off the phone with Blue Ox. They feel that my set up is good. However, they also feel that the Denali's automatic leveling system is interfering with the WD. They suggested that I deactivate the auto leveling system when towing. I am now trying to find out from GM if there is a way to do so. I have checked the manual but it doesn't address deactivation of the system. It only states that it is recommended to allow the shocks to inflate prior to adjusting the hitch. Any of you with Denali's out there had similar issues?


Sent from my iPad using Airstream Forums

I have towed with Denalis and Escalades. Pull the fuse for the auto level control. Get your WD dialed in...maybe a bit too much WD High. Then re-install the fuse. The back will rise a bit (maybe 1/2" or less). This takes out the extra WD you dialed in in the previous step.

You don't want to run for extended periods of time with the fuse out. The system is an integral part of the overall rear suspension...not just add on air shocks. The system will leak down over a period of hours, eventually leaving you with little or no air pressure in the system. That's not good for the system, not to mention sacrificing some of the designed in rear suspension engineering.

[slowmover]

Originally Posted by Msmoto

Just a note, after asking a friend, who owns a very large trucking company, about weighing rigs, I find out that the initial weight is $12, but that each re-weigh is only $2 and this is true at most CAT Scales.



So, I will be heading down to a scale about fifty miles away to set up my unit more like i want it.



Currently I am 7380 lbs steer wheels, 7300 lbs, drive wheels, 7240 on trailer wheels. So, I will attempt to adjust a few pounds from front to rear, hopefully coming to about 7350 each axle of the truck.

Just go for FALR, or front axle load restoration. Same weight solo or towing. Limits on an 08 Dodge will be around 6k or less per axle.

[Ron Gratz]

Originally Posted by Pat Cassity

So, I just got off the phone with Blue Ox. They feel that my set up is good. However, they also feel that the Denali's automatic leveling system is interfering with the WD. They suggested that I deactivate the auto leveling system when towing. I am now trying to find out from GM if there is a way to do so. I have checked the manual but it doesn't address deactivation of the system. It only states that it is recommended to allow the shocks to inflate prior to adjusting the hitch.---

GMC also says:
"When using a weight-distributing hitch, the spring bars should be adjusted so the distance (Ground to Front Wheel Well) is the same after coupling the trailer to the tow vehicle and adjusting the hitch."

When you attach the TT and then allow the TV to level, the rear will rise to the preset level, but the front of the TV will be unloaded by the TW and the front will rise.

If you then apply load to the WD bars, load will be transferred to the front suspension, and the front will drop.
The rear will tend to rise, but the leveling system will try to keep the rear at the preset height.

The goal should be to keep the front end at the same height (same front axle load as when unhitched).
IMO, there is no reason to deactivate the auto leveling when towing as long as you follow GM's instructions -- 1) attach trailer, 2) allow TV to adjust rear height, and 3) adjust WDH to return front to unhitched height/load.

Ron

[SSquared]

Originally Posted by ROBERT CROSS

SS,

I was always told to install the chains with the open end toward the trailer.



Bob

Bob,

Thanks, I've never been told to do it either way.

[SSquared]

Originally Posted by Pat Cassity

So, I just got off the phone with Blue Ox. They feel that my set up is good. However, they also feel that the Denali's automatic leveling system is interfering with the WD. They suggested that I deactivate the auto leveling system when towing. I am now trying to find out from GM if there is a way to do so. I have checked the manual but it doesn't address deactivation of the system. It only states that it is recommended to allow the shocks to inflate prior to adjusting the hitch. Any of you with Denali's out there had similar issues?


Sent from my iPad using Airstream Forums

I don't think the auto leveling is a problem. To me, setup is best done with the truck scales. If you make an adjustment to the chains while your rig is parked in the parking lot, by the time you get onto the scales, the auto leveling will have done its thing, and you will have valid data. With the modern Sway Pro hitch, you have no head angle adjustment, so your setup has only one adjustment to make--the chain length. A little experimentation at the truck stop and you should be good.

By the way, if you want to be a perfectionist on the chain length, you can adjust by a fraction of a chain link by inserting a bolt into the chain such that it captures two adjoining links, and shortens the chain by the diameter of the bolt. I never did that with my Blue Ox, but on my current other brand hitch, 1/2 inch bolts are the right size.

[rostam]

Originally Posted by ROBERT CROSS

Yep....re-weigh.

TV alone loaded for camping.

TV & AS with and without WD set, (with full camping load), rig must be LEVEL when WD set properly.

Notice I'm within 100lbs of the TV alone steering axle weight.




Bob

This ticket is very informative. Thanks for sharing it.

I noticed that applying the WD, adds 660# to the TV front axle and only 160# to trailer axles. This means that roughly 75% of weight moved by WD goes to TV front axle and only 25% to trailer axles. Do you think these ratios are specific to your setup only or are rough estimates in general?

Applying the WD returns the front axle to (almost) its original weight, but does not seem reduce the the load on the TV much (160# only).

[slowmover]

2 to 1 ratio is correct. And 20 to 25% off of ball. This is per formula.

[rostam]

Originally Posted by slowmover

2 to 1 ratio is correct. And 20 to 25% off of ball. This is per formula.

The above ticket shows a 4 to 1 ratio (660 to 160) for weight added to front axle and trailer axles. I am sure the overhang/wheelbase ratio can change this, but was curious what is the "general" rule.

[slowmover]

As stated. 75-80% off of rear axle and weight distributed 2 to 1 steer axle to trailer axle.

[Pat Cassity]

Ron, per the Yukon manual one should let the shocks inflate before attaching WD. However, Blue Ox has told me that auto leveling will interfere with the WD process, resulting in poor handling and increased sway. In regards to pulling the fuse to disable the system, the fuse does not just disable auto leveling but is also involved in other stability and safety features. The GM service manager suggested that I pull the power plug from at the shocks.


Sent from my iPad using Airstream Forums

[Ron Gratz]

Originally Posted by Pat Cassity

Ron, per the Yukon manual one should let the shocks inflate before attaching WD. However, Blue Ox has told me that auto leveling will interfere with the WD process, resulting in poor handling and increased sway. In regards to pulling the fuse to disable the system, the fuse does not just disable auto leveling but is also involved in other stability and safety features. The GM service manager suggested that I pull the power plug from at the shocks.

Pat, if you adjust the WDH FIRST and THEN allow the auto leveling to raise the rear of the TV --
the raising of the rear will cause load to be removed from the WD bars, and the amount of load transfer to the front of the TV will be decreased.
I'm guessing this is the scenario envisioned by Blue Ox when they say that load leveling will interfere with the WD process.

Many people have reported successfully using a WDH in conjunction with automatic leveling or with manual air leveling.
If you follow the instructions in the Yukon manual, you should not have a problem.

Ron

[Pat Cassity]

After talking with the Blue Ox folks again today, it has been determined that the head should have been installed 2.5 to 3" lower to compensate for the rise of the back of the Yukon from the auto leveling system. Ron, you were, in fact, correct. With the current setup, once the auto leveling system raised the rear of the Yukon, all of the pressure was removed from the WD bars.


Sent from my iPad using Airstream Forums

[dznf0g]

Originally Posted by Ron Gratz

GMC also says:
"When using a weight-distributing hitch, the spring bars should be adjusted so the distance (Ground to Front Wheel Well) is the same after coupling the trailer to the tow vehicle and adjusting the hitch."

When you attach the TT and then allow the TV to level, the rear will rise to the preset level, but the front of the TV will be unloaded by the TW and the front will rise.

If you then apply load to the WD bars, load will be transferred to the front suspension, and the front will drop.
The rear will tend to rise, but the leveling system will try to keep the rear at the preset height.

The goal should be to keep the front end at the same height (same front axle load as when unhitched).
IMO, there is no reason to deactivate the auto leveling when towing as long as you follow GM's instructions -- 1) attach trailer, 2) allow TV to adjust rear height, and 3) adjust WDH to return front to unhitched height/load.

Ron

Ron,
This is a surefire way to overload the rear axle by "masking" the true rear squat and thus the WD applied to return the front to proper height. I guarantee, with this method you will not have enough WD applied.

The only way I found, by weights and measures, to accommodate the auto level control is this:

1) Empty TV; cycle ignition so the auto level control adjusts to the proper ride height. (this might take 30 seconds or more)

DO NOT CYCLE IGNITION UNTIL ALL THE FOLLOWING STEPS ARE COMPLETE. OR, IF VEHICLE MUST BE MOVED DURING THE HITCHING AND LOADING PROCESS, REMOVE AUTO LEVEL FUSE.

2) hitch up AS

3) fully load trailer and TV with all gear, food and supplies including water, if needed.

4) Apply WD until you return the front height to FALR height.

(Note) at this point the rear will probably be squatted enough to activate the auto level control at TV startup.

5) Apply a bit extra WD to compensate for auto level control activation at TV startup. I recommend one link (or one notch of head tilt...1/2 link would be good, but...) on chain systems and about 1/2" more jack lift on PPP.

6) At startup, you probably will still get some very minor activation of auto level control, but if it more than about 5 seconds, or 1/4 - 1/2" lift, you haven't applied enough WD for your setup.

Any ignition cycle (with fuse in) before significant loading is complete and WD is properly applied will result in the auto level control setting a new "baseline" height at a partial load status and will mask true load height and result in rear axle overloading.

Once done at the beginning of a trip, you will be close enough for the remainder of that trip, and for subsequent trips with similar loads.

The danger here is not so much rig handling as it is about durability of the rear axle. However, sway control on those hitches which rely on spring bar pressure can and will be affected masking true loaded ride height and, subsequently, by not enough WD application.

[Ron Gratz]

Originally Posted by dznf0g

Ron,
This is a surefire way to overload the rear axle by "masking" the true rear squat and thus the WD applied to return the front to proper height. I guarantee, with this method you will not have enough WD applied.

Rich,
As long as step 3 (adjust WDH to return front to unhitched height/load) is done with the leveling activated,
the WDH will have restored the proper amount of load to the front
and will have removed the proper amount of load from the rear.

Ron

[dznf0g]

Ron,

True. My point here is to make sure that a true baseline is set when each person sets up their particular trailer and loading circumstance. IMPO, as a GM Rep, the baseline WD setup must be done without activation of the system. And there should not be significant activation after proper setup, or WD needs to be increased as described above. Again, if your particular load changes over time, or the system activates without a loaded setup, you will not have the proper WD and, at a minimum, you will have more severe rear axle overloading than normal. Remember the large SUVs are marginal with regard to RGAWR for those of us with....say 25' and up trailers (>750 - 800 lb tongue weight.)