Adjusting bars on a weight distributing hitch

[rodsterinfl]

Greetings

I finally decided to check into the hitch adjustment. I followed the manufacturer's instructions on setting the height of the receiver and ball. Then I spent quite a bit of time playing with measurements of the top of wheel wells on the TV and then after each link was used on the hitch and bars. I need some opinions on which link is best. One set of directions I have says to go with the link that lowers both front and rear about the same on the TV and uses the dead weight wheel well measure (trailer lowered onto hitch w/no bars) as a starting point. The other set of instructions says to use the truck's original wheel well height and work toward keeping the front wheel measure within a half inch of the original measure while working to get the rear to as close as original as possible but no closer than 1".

Here are my measures (in inches):

Original (level ground nothing attached to TV)
front 35.43 rear 37.75
Dead Weight (w trailer and no bars)
front 36.06 rear 35.31

Link 5 front 35.56 rear 35.93
Link 6 front 35.96 rear 35.56
Link 7 front 35.93 rear 35.19
Link 8 front 36.00 rear 35.12

The first set of directions would seem to lead me to use Link 7 as that one is the link that lowers both front and rear nearly the same amount.

The second instructions seem to lead to the Link 5 as they state that I would be adjusting the truck most closely to original. The rear is raised .62 from dead weight and the front is lowered by .50".

With Link 5, the front of the truck is lowered by .13" and the rear is lowered by 1.8" from ORIGINAL.
With link 7, the front of the truck is .50" higher than ORIGINAL and the rear is 2.56" lower than Original. What link would you use?

[HowieE]

Looks like none are right. You want the front axle to come down some.
Depending on the TV springs set I generally look for a 60/40 ration for the rear axle drop to the front axle drop.

Link 5 seams to be raising your front end not lowering it

I will attempt to send you a PM with the instruction I use.

[rodsterinfl]

All of them have some rise to the front end; however, Link 5 has the least, basically only an eighth of an inch higher. The directions say to get as close as possible without going lower than original height on the front. Also, is 1.8 inches a lot of rear squat for an F150 with a tongue weight of 860 lbs?

The reason for my questioning is that there seems to be two ways and, two results. I did find that Ford says that whatever rise is added by dead weight, that at least 50% must be corrected for front end safety.

Ford specs for 2009 and newer trucks say the w/d should be adjusted to eliminate about 50% of the front end RISE... IOW, if the front rises 1.5" initially, the RISE should be reduced to around 3/4"...

When setting the weight with the handle, is there supposed to be quite a bit of resistance even with the trailer and truck lifted up a bit by the jack?

[rodsterinfl]

By the way Howie, do you really have a five axle Airstream? That is a beast in that picture.

[dwightdi]

I am not sure how you are counting links. I try to get the front and back to go down equally (indicating 50%of the trailer tongue weight has been shifted to the front axle). None of the settings you have listed do that. It would seem that 3 or 4 links (as you count them) might be the best for you.

[idroba]

I use, and have used in the past, the wheel well measurement system. But if you want to really see what is happening, take your rig to a scale and weigh each axel until you get the amount of weight transferred to the front and rear of the TV in a way that makes sense. That is, you want to put some of the tongue weight on the front TV axel, some on the drive axel and some back on the trailer axels.

[rodsterinfl]

Thanks for the replies. I believe that the way I am describing it is not making sense to others. Bascially my system requires that you leave at least 5 links between the bar and the clamp. From the bar I am counting the links. Link 5 is the shortest length I can go before adjusting the hitch head again on the angle to gain more weight on the front. My point is that the front is only an eighth of an inch higher than original now. That is pretty close but the bars, although at five links between (said to be ok) are not parallel to the ground they angle slightly upwards. Everything else is in the correct tolerance. The towing was great before all of this adjustment I have already made. It should really be good now even with these slight "off" settings. Of course I hear you on the scale weighing too. They say that the bars SHOULD be parallel to the ground or have a slight downward stance. Well, it seems that every adjustment I do makes either the bars wrong or the weight balance wrong. It is not cut and dry. I have found that one cannot assume that because link 6 changed the front this much that link 7 will change it the same amount. I got an email from the hitch company telling me to basically ignore the rear squat and focus on getting the front end to as close to original height as possible that is, supposedly the correct setting - they say. Hitch science 101 right?

[rodsterinfl]

Update, today I visited a CAT scale. Here are my actual weights with a full tank of gas and two full LP tanks AND the trailer loaded with everything but food and clothing.

Truck front axle weight: 2820 lbs
Truck rear axle weight: 3380 lbs
Trailer axles weight: 5360 lbs

Previously I worked on angling the hitch head leveling the spring bars and I was able to correct the front end within and eighth of an inch of original height. So, in lowering terms, I lowered the front end 3/8" and the rear was corrected by nearly the same amount.

[rodsterinfl]

New update,

I got my Trailer Life magazine last month which had some information about weight distributing hitches. It mentioned that if your hitch head bar insert holes are egg-shaped that it is time to be replaced. So, I replaced my hitch head and started this process over and there was certainly a change.

First of all, I could not get the hitch chains locked at the original link - too tight. So I backed off two links increasing the number of links to 7 between (no less than 5 allowed) the bar and the frame. I measured the truck wheel well heights again and found the front at EXACTLY the same height as before hitching up and the rear one inch lower.

I went to the CAT scale and decided to weigh the rig and also detach the trailer this time and weigh it as tongue weight/axle weight. I had already done the truck axles and truck weight.

Basically the book describes a perfect WD hitch setup as one that takes the tongue weight and balances it out to the TV front, rear and trailer axles. The hitch company told me that usually on a half ton, there is some lift on the front. They and Ford recommended that I not go lower in front than the unloaded weight.With that advice (good or bad), I have been working on this.

The new CAT info, just by changing the hitch head: The front axle is 20 lbs lighter than unloaded (was 100), the rear is 680 lbs heavier and the trailer is 380 lbs heavier on the axles. The tongue weight of the trailer was dead-on 1000 lbs. The perfect balance would be 300/300/400 on the axles. The front is the issue but I do not seem to be able to get any more adjustment (will try) I have two more links for maximum adjustment on the hitch. So, it looks like I would need to shift 320 lbs from the rear to the front for perfect balance. It may not be possible with this hitch setup.

[RLS]

First of all, I could not get the hitch chains locked at the original link - too tight

This remark has me wandering if you are using the tongue jack to raise the trailer and back end of truck up so the bars can be hooked up. There is no way I would be able to put enough force on the pry bar to hook it up without doing this

[rodsterinfl]

Thanks for responding. Yes, I have to do that. I would barely be able to start tightening otherwise.

I also found a great article on this topic, "TT Hitch Set-Up Procedure":

RV.Net Open Roads Forum: Towing: Travel Trailer Hitch Set-up Procedure

From what he is saying, it sounds like my system is set - original height on front, level truck and trailer. The only thing that is different in his directions is that I set the ball height at 1.5" higher than the trailer height. He said that he starts lower. That might be a difference as to why I have my ball angled to the max angle to gain WD balance. Note too what he says that manufacturers are now saying. GM wants 100% correction, Ford wants front wheel correction to original well height but no lower with up to 50% of rise correction acceptable. That would mean that slightly "lighter" conditions would be ok it seems.

[HowieE]

If you are using a Reese hitch the adjustment is NOT in the link count but rather in the head adjustment. The head can be tilted with each adjustment about equal to one chain link. You will never get the same weight increase on the front axle as the rear simply because of the different lengths of the moment arms. It is more likely the ration will be something like 4 or 5 to 1 depending on the tongue weight and the truck springs.

The most important factor in setting up a multi axle Airstream is that the trailer has to ride parallel when finished. This is because of the type of axles used. Second would be weight applied tot he front axle should cause the front axle to drop below unloaded weight. This amount will be a function of the springs of the tV. Heaver spring set will drop less but there has to be load applied to the front axle to retain steering control.

I can not understand why anyone would suggest you start adjustment with the ball lower than the coupling.

If you PM me I will send a more detailed set up instructions.

[rodsterinfl]

Updated to manufacturers' specs on adjustment of WD hitch:

1. Park vehicles on level ground.
2. Level the trailer using tongue jack
3. Measure from ground to top inside of trailer coupler- record.
4. Set ball height on hitch head to 1/2" to 1" lower than trailer coupler height.
5. Measure all four truck wheel well heights unhooked - record.
6. Hook up trailer and snap up bars picking a link that makes the bar near level to ground.
7. Measure truck well height again. If the front truck well height is the same as #5, you are done. Otherwise continue.
8. If front is high, decrease links between bar and clamp but do not go beyond the minimum spacer links required by hitch manufacturer. If more adjustment is needed, increase the angle of the hitch head and continue adjustment. If the front is low increase the number of links to increase the front well height.
9. Trunion bars should be parallel to the ground (round ones) or slightly angling downward (flat ones) if not, increase hitch head angle and repeat steps 8 and 9.
10. Check for level trailer and adjust ball height if needed. If a change is required, repeat steps 8 and 9.

There are a slew of vehicle manufacturer comments on this. Suffice it to say that newer Ford F-150 do not want adjustments to lower the front end any more than the unhitched height and only require 50% rise correction (dead weight hitched-unhitched front end well measure) while GM trucks require 100% correction to same height as a minimum. I did not see anything regarding lower squat height. This applies to newer vehicles. I reference the second repost of the Les Adams article- the update.

[rodsterinfl]

I know this is beating this topic to death but it is so important to safety. I just want it done correctly and I know that others may benefit from all of this posting. Here is a quote from the first article I mentioned:

At this point some will set the hitch head ball height about 1/2 to 1" higher than this measurement as a starting point... Some start with the ball height 1/2 to 1" lower (including myself)... At this preliminary stage it doesn't make much difference which way you go, up or below as you'll more than likely readjust it again before your through with the procedure...
(Note: On older vehicles, the procedure was to have the WD system lower the whole vehicle evenly, front and back (equal squat) but newer recommendations have changed that procedure. The following steps are aligned with the newest recommendations from the various hitch and vehicle manufacturers.)

I believe a lot of this has to do with suspension changes. I too do not understand the lower hitch ball height part. The only thing I can figure is that it may have to do with the bar and hitch head angle adjustment. I am still digging and gathering information. I have spent so much time adjusting that grabbing the rachet will not happen until I have a clear reason to do more changes.

[HowieE]

the procedure was to have the WD system lower the whole vehicle evenly, front and back (equal squat

I don't know the origin of this idea but it is completely wrong. Trucks are made to carry the load on the rear axle. There fore the SQUAT will not drop equally as you apply a load. The rear springs are designed to take the load while retaining close to original fender height. The front springs are designed to remain in as close to original height as possible in order to retain the steering geometry. If you were to drop the axles equally under load you would drastically change to front end alignment and wear the tires. This factor is less important with front leaf springs but very important with A frame front ends.

[rodsterinfl]

That's what I thought too. The RV handbook says to take your tongue weight (mine is 1000 lbs) and work toward a distribution of 300lb/300lb/400lb for that weight BUT consider the squat I would have on my front with 300 lbs added to it. That would go against Ford's recommendation of no added lowering for sure.

[slowmover]

The "old" WDH procedure had to do with cars (1960's forward) where the distribution of TW was 1/3 - 1/3 -1/3 on FA - RA - TA. Scaled weight values were the finishing touch then as today since fender height measurements are prone to repeatable error. Easily located three-pad certified weight scales make this much easier (and can be checked nationwide).

Nice job, OP

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