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Old 07-16-2017, 02:33 PM   #1
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3/4 ton truck, equalizer WD hitch - calibration

I am running a 2017 30' international and had my equalizer with 1000 pound WD bars "dialed in" for my 1/2 ton SUV. With my 1/2 ton suv (independent suspension) I was able to restore 100% of the front axle load with my equalizer hitch so that steering feel was restored and rear axle remained within GAWR specs.

Well I've since upgraded my TV to a 2017 GMC 2500 (3/4 ton) with a duramax diesel. I'm looking to "dial in" my equalizer hitch for the new TV and I'm looking for advice. The duramax diesel engine adds a ton of weight to the front axle (about 700-800lbs more than the 6 liter gas version of the truck), and specifically I'm looking for advice on "how much" weight I should try to restore to the front axle with weight distribution, given there is such a slant towards front axle weight when the truck is unloaded in the first place.

I've been over the CAT scales, here is where we stand:

No trailer, full fuel, no passengers, no cargo, no trailer (truck only, so this is actual curb weight measured at the CAT scale):
  • FA: 4,740lbs (FAWR is 5,200)
  • RA: 3,240lbs (RAWR is 6,200)
  • Total TV weight: 7,980lbs (GVWR is 10,000)

I calibrated my equalizer hitch this morning. Adjusted ball height, put "moderate" pressure on the WD bars using 4 washers, and Trailer sits level with WD bars attached. Was seeing about 1/2 inch of front fender "rise" W/O WD attached and with four washers I am bringing that down to about 1/4" - so 50% restoration (thereabouts - not scientific) but we are not talking about a lot of movement up front. Rear sagged 1 3/4" without WD and sags 1 1/2" with WD applied with 4 washers.

So I moved the front axle down 1/4" and lifted the rear axle up 1/4" with a moderate amount of WD applied.

With the equalizer calibrated per the above I ran back through the CAT scale and here is the after measurements:
  • FA: 4,420lbs (-320 lbs - not sure I like that.... FAWR is 5,200)
  • RA: 4,540lbs (+1,300lbs - not sure I like that even though RAWR is 6,200)
  • Total TV weight: 8,960lbs (added 980lbs of tongue weight with WD attached, GVWR is 10,000)
  • Total trailer axle weight: 6,740lbs (so the trailer is sitting at 7,720lbs with a full tank of water. Axles are rated to 8,800lbs).

(NOTE: I did not do a 3rd pass with TV+trailer but no WD bars - but I may go back to do that at a later time)

So here is my question: the "heavy-front-end-diesel" TV is actually quite nicely balanced (albeit without any passengers or cargo) at 4,420lbs front axle and 4,540lbs on the rear axle.

But I am thinking that maybe I should get more aggressive with WD and try to restore more weight to the front axle as I am accustomed to shooting for 100% restoration with an independent suspension 1/2 ton SUV.... but this new truck is a different animal in that it is seriously biased / heavy in the front end with a heavy Diesel engine without any payload / trailer attached.

I'd certainly appreciate the advice and wisdom from others who have a 3/4 ton with a heavy (~1,000 lbs) tongue weight and have been through the CAT scales. Interested in how you have calibrated your setups and thoughts on pushing more weight back to the front axle.

Thanks Airforums!
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Old 07-16-2017, 03:51 PM   #2
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You probably only need 750 pound bars.
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Old 07-16-2017, 04:26 PM   #3
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3/4 ton truck, equalizer WD hitch - calibration

Equalizer only has 400, 600 or 1,000, 1,200 and 1,400 lb spring bar options. 1,000 feels good (actually pretty smooth with 900+ lbs of tongue weight)

I set a slightly less aggressive head angle on the hitch so that there wasn't too much tension on the bars and hence a softer ride / less stress on the trailer given the 3/4 ton leaf spring suspension.... but at the sacrifice of load transfer.

I towed for 25 miles or so and things where pretty smooth - the gmc 2500 definitely wants some weight on the rear axle - the truck rides much better with a trailer in tow that has 1,000 lbs of hitch weight vs no load.....
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Old 07-16-2017, 04:54 PM   #4
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I would use 400 pound bars.
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Old 07-16-2017, 05:10 PM   #5
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3/4 ton truck, equalizer WD hitch - calibration

I don't think 400 lb bars will move the needle regarding weight transfer on a 20' long 8,000lb curb weight 3/4 ton truck with 1,000lbs on the receiver... also the hitch assembly for the 400lb bars have a hitch head that is too weak / not rated for the hitch weight.

Back to my original question

Regardless of how I accomplish weight transfer (hitch selection, bar selection, etc..) should I even attempt to move more weight forward or is a balanced TV (near 50/50 weight distribution on front and rear axles) what I should be shooting for?
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Old 07-16-2017, 07:53 PM   #6
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I'm not dealing with as much trailer as you are, but I did switch from a Tundra that needed quite a bit of weight distribution to a 2500 Duramax last summer. I'm trying not to think about how I missed out on that cool hood scoop on the 2017s by the way.

I tried to change as little as possible before playing with the weight distribution setup, but did replace my Equalizer shank to go to the 2.5" model to avoid the "slop" of an insert, and also had to go to a longer drop. I have the 1000 # bars.

From there I drove it with everything else the same as the Tundra as a baseline, but did not have easy access to scales. It didn't matter, I experienced what I would call the "pogo" effect. I could tell that things were too stiff on that initial drive, not a surprise.

I tried the fender measurements but as you observed, it takes a lot of weight to get those fenders to move.

I ended up going from 5 washers down to 4, and that is where I have left it. It doesn't feel too stiff when driving and we don't have anything strewn about the trailer after long tows. We just returned from our annual 2 week fly fishing sabbatical in SE Montana & Idaho and things felt pretty good. That one washer made a huge difference. Another bonus is that I don't need to use the tool to get the bars on the L brackets.

I did go to the scales after I had removed the washer last summer.

Weight distribution applied:
FA - 4560
RA - 4420
Trailer - 5540

Weight distribution off
FA - 4420
RA - 4620
Trailer - 5480

Truck only
FA - 4780
RA - 3360

Clearly from the weights, I haven't made it to a perfect 50% return to the "untrailered" weights, and I may tweak things further when I have time. What I can tell you is that the comfort of the the ride and the handling of the trailer at highway conditions (including high cross winds on I90 in Easterm Wyoming) has been very good, so much so that my wife took some turns driving, and she wasn't comfortable doing so with our previous TV.

Hope that helps.
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Old 07-16-2017, 08:35 PM   #7
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3/4 ton truck, equalizer WD hitch - calibration

Those data points help a lot - thank you!

Based on your numbers if the math in my head is correct you have added back 140lbs to the front axle with WD applied but are still 220lbs reduced front axle load with vs your (unloaded?) 2500 duramax with a 6,380lb trailer that generates 840lbs of tongue weight with WD applied.

Looks like we are in similar situations (+/- 100lbs of front axle load) assuming you took your measurements without additional / significant weight in the TV.

Good to know that the rig is behaving nicely for you with those metrics.

I might add 1-2 washers (a little more weight transfer) to restore a bit more weight to the front axle and see how it rides. Yes I like that you don't necessarily need to use the pry bar to mount the spring bars with less tension in the system

Btw - the hood scoop goes hand in hand with the re-tuned duramax ... they claim it is "functional" and provides the necessary increase in airflow for the small bump in HP / torque but now the 2018s have a new grill! Ah! But the redesigned new platform for 2020 GMC HD trucks is right around the corner tough decisions in life!
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Old 07-17-2017, 02:40 AM   #8
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I like to shoot for FALR. I'm looking for the range I can work with. The high and low. With it is TT load. How much added? That said, in the end the Drive Axle "should" be heavier than the Steer. 10% is usually cited.

What are the GM recommendations? Use them as well. Find the range of adjustments and record them.

No reason not to continue to experiment:

1) Split the trailer axles. How well balanced?

2) Do individual wheel weights.

Too much TV tire pressure isn't a friend. Thus, according to door sticker range, get TV tires close to load of heaviest wheel per Axle. Test by running an easy 1.5-hrs steady state and glide to a light stop where pressures may be checked. 5-7% pressure rise is fine. 10% needs more air.

One doesn't tune truck suspension with tire air pressure. How does rig feel as TT comes around? Degree of wheel turn and duration is partly getting used to it. Without a VPP hitch, it gets slower (longer) than the first side to side in lane changes. Both vehicles lean.

How representative is Load in truck and trailer? Closer to actual is better.

3). Brake testing. Lockup on hard and loose surfaces (needs an observer). Note brake controller settings. Ck drum temps for variation.

Etc.

Start where you are. Unless there are other adjustments with an EQ brand hitch (forward head tilt maximization), numbers look okay to start within given representative loading

WDH and tires: where is the top and the bottom? Record.
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Old 07-17-2017, 03:59 AM   #9
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(Not enough requisite coffee above)

Max rear tilt on head.

Leave TT tires at sidewall max to test combo

While Steer vs. Drive looks good, the thing to focus upon during/afterwards is TT tire load equalization.

It's damned near a one to one relationship I see a one ton with an AS behind it bouncing along on the front" axle. (This is pretty much all one needs to know about the claims of such being "superior" TV: the operator never knew how to set lash-up in the first place. Scale tickets, or no dice).

Full truck fuel plus permanent gear and driver is TARE weight.

That plus loaded for camping is SOLO weight. (Items in bed must be secured against movement. You can bet this problem has pushed at least one rig the rest of the way over).

TT needs max propane, fresh water, all normal gear aboard for TARE. Specific load for a trip after that is SOLO (TW check); simulate if need be.

The TT may be at .85 of max, it may be at .92. But it's unlikely to be at 1.0

TT loads needs to be on axle centerline or within four feet, ideally.

Dig up the chart I linked here about seven years ago from RV.net that Ron Gratz posted there. Fill in the numbers.

A Sherline gauge is your friend. Range should be with TW at center thereof.

Better shocks on truck always a good first move. KONI or Bilstein.

Good luck.
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Old 07-17-2017, 04:51 AM   #10
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We run a one ton F350 6.7 Diesel with crewcab and 6.9 bed. We tow a 2017 30'Classic. I could not get the front end to move with the Equalizer I use and have used for about 8 years on other Airstreams. I called Equalizer and talked to a tech with my questions. He stated to add one washer at a time, further that they have no "number" guidelines but go only on front fender movement from top of tire to gauge acceptable balance. He said if one can down to 3/4" or better one is fine. I called back another time, talked to another tech, receive same answers, so this is correct from their perspective or it's a script, but did not sound like a script.

Mine moves 1/2", I think in our off travel time, now, I will play with it a bit and try to secure either zero rise in front fender over top of wheel or down to a 1/4".

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Old 07-17-2017, 04:57 AM   #11
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Quote:
Originally Posted by wulfraat View Post
Those data points help a lot - thank you!

Based on your numbers if the math in my head is correct you have added back 140lbs to the front axle with WD applied but are still 220lbs reduced front axle load with vs your (unloaded?) 2500 duramax with a 6,380lb trailer that generates 840lbs of tongue weight with WD applied.

Looks like we are in similar situations (+/- 100lbs of front axle load) assuming you took your measurements without additional / significant weight in the TV.

Good to know that the rig is behaving nicely for you with those metrics.

I might add 1-2 washers (a little more weight transfer) to restore a bit more weight to the front axle and see how it rides. Yes I like that you don't necessarily need to use the pry bar to mount the spring bars with less tension in the system

Btw - the hood scoop goes hand in hand with the re-tuned duramax ... they claim it is "functional" and provides the necessary increase in airflow for the small bump in HP / torque but now the 2018s have a new grill! Ah! But the redesigned new platform for 2020 GMC HD trucks is right around the corner tough decisions in life!
No doubt, first world problems. I like the features of the new Fords too . . .

I'm hesitant to add the washers back due to the very stiff conditions I felt when I had that washer in line. I don't want to beat the trailer up too much.

I also am going to take a look at the hitch ball height again, as the trailer may leaning forward a bit, though better that than tipped towards the back. I do think another overall assessment is due as the suspension has some miles on it and of course, with all of the miles we've now put on, I have a better idea how it 'feels" while moving down the road than I did when we first bought the truck.
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Old 07-17-2017, 06:38 AM   #12
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No doubt, first world problems. I like the features of the new Fords too . . .

I'm hesitant to add the washers back due to the very stiff conditions I felt when I had that washer in line. I don't want to beat the trailer up too much.

I also am going to take a look at the hitch ball height again, as the trailer may leaning forward a bit, though better that than tipped towards the back. I do think another overall assessment is due as the suspension has some miles on it and of course, with all of the miles we've now put on, I have a better idea how it 'feels" while moving down the road than I did when we first bought the truck.
TT perfectly level. This is worth the time and the effort. If one gets nothing else right, get this right. (Other stuff falls into place after this).

Use a 2' level across the doorway entrance.

FWIW, EQ brand is least acceptable WD hitch having integrated antisway.

.
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Old 07-17-2017, 11:34 AM   #13
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I went thru this 1500/2500 upgrade. Using the original 1000lb bars. Adding a drop stinger to re-level.
I went from the third or fourth chain link to the second or third link reducing total equalization force. The variable is additional bed weight.More/heavier stuff = more equalizer tension. I have run without the bars and pitching was too severe. Experiment to find your sweet spot.
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Old 07-17-2017, 12:10 PM   #14
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Thanks all for your input. I very much appreciate it and I am still digesting.

My trailer is dead level as it currently sits (front vs rear of the frame rails are within 1/2 inch height difference as measured using a dead level concrete pad) and I completely agree this is a minimum requirement.

I was at my storage facility the other day getting everything setup and a guy showed up with a SOB trailer that was wildly pitched down to his ball... I was like - dude what the?! rotate your shank 90 degrees and get your ball heigh correct. 101. I should have taken a picture, it was kind of funny looking.

Not sure I understand the comment that the equalizer is least desirable. For what it is worth I've had good success with it for both weight distribution and sway control after 25,000 miles of towing, so I chose to keep it for my 30' and 3/4 ton. I am sure there are other hitches out there that work just as well or better, they all seem to have pros and cons. Regardless of hitch selection I am a believer that correct configuration is what counts most regarding weight transfer and sway prevention, hence soliciting community feedback on how others have their weight distribution setup for 3/4 ton trucks that a front axle heavy.

After giving this some more thought I feel like the current weight balance of the TV is OK (Front vs. Rear axle weights with TV and WD attached) - slightly biases to the rear axle to help keep the rear planted but the heavy Diesel engine helps to ensure there is also significant weight on the steer axle to maintain steering feel and overall control, even though some of it is reduced by rear sag with the trailer attached.

I will likely get a little more aggressive with weight transfer (1-2 washers perhaps, we'll see) based on anticipated additional loading of the trailer and TV truck bed a little more with camping gear. I'm installing a 220lb bed storage solution tomorrow which will add a little extra to the leaf springs...

I'll keep everyone posted as to where I land after some additional loading and adjustments. I've got a 9 day trip coming up to tour around Colorado and will see if I can't get it slightly more dialed in.

BTW both my gross axle weights, GVW and tire load ratings are all within specs by a healthy margin - I'm really not close to any limits as it stands - nice to have some good overhead on load ratings.....
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