Rear suspension sag question

[CollinP]

My current TT has 600 lbs tongue weight (I weighed it) this is 100 lbs more than the advertised dry tongue weight and I have 2.5" of rear suspension sag with my current setup. I am considering a new TT with a dry tongue weight of 775 lbs. I am going to upgrade my spring bars for my hitch from 800 to 1000 or maybe 1400 lbs if there is a benefit. Based upon my current setup I am estimating 875 lbs of tongue weight. My questions are: 1) How much sag is considered acceptable? 2) Will new spring bars help compensate for the increased tongue weight preventing too much sag?

[Flagstaffer06]

What size spring bars do you have now?

It also might be helpful to list what type of hitch you have as well. Is it something with chains or is it more like the equalizer 4pt, reese pro series with the sway control, or the reese dual cam setup?

My bars are rated for my current tongue weight and setup properly I get about .5 inch or rear sag. One more notch up with the bars or take one more washer out of my hitch head (I have the equalizer 4pt) it actually throws enough weight to lift the rear end instead of sag.

Check the manual for the hitch too, it should say in there what they would deem acceptable for rear sag. Some say no sag, some say a little is ok.

I'd think as long as you have bars rated for your current tongue weight or if you decide to upgrade, bars that would cover that tongue weight (I'd go 1000lb bars if you get the other trailer) you should be able to get it all adjusted to no sag or a half inch or less once setup properly. Sometimes it takes alot of playing around with it.

[CollinP]

I have a Eaz lift elite with chains and 800 lb bars.

So, it sounds like I should expect better performance from my hitch. Checking my TT with a level the trailer is level right now. If I get less sag I would be raising the front of the trailer...I assume I would have to drop the hieght of the hitch.

Could I upgrade my hitch and get better performance or is it simply adjustments?

[Flagstaffer06]

I would try getting your current hitch dialed in a little more. If you upgrade trailers the 800lb bars won't do it.

Try adjusting your hitch height. Then to get less sag tighten the links.

You want the trailer level or slightly nose down.

Good luck but I think you can dial it in a bit.

[Platokidd]

It would be helpful to know what kind of unit and tv you have.
It's helpful to place that info in the sig line

[CollinP]

Added TV and TT to sig line...don't judge me; it's not a Forest River product...yet.

[RollingDownTheHighway]

I would adjust your hitch height first, then tweak the bars some. I had a slight sag in my '10 Silverado and we adjusted the hitch height and the sag was gone

[AquaMan]

Are you describing "sag" as height below no load height or below level? I've seen trucks "sag", being nose high, which is a hitch adjustment. I also have had trucks "drop" about 2" from no load and are now level, which could be acceptable depending on your truck. Measure the height at the center of your fender openings(front and back) to see what the real attitude of your truck is, (nose up, nose down, level). I usually adjusted my hitch so that I used half the distance to level from no load height.

[MtnGuy]

The current WDH setup may need to be adjusted. If you are not getting the proper weight back onto the front axles, then the rear of the truck is going to sag, and the front raise a bit. Fender measurements and/or a trip to the scales (with 3 weigh-ins done) might been needed to make sure the WDH is setup correctly.

Another thing is that I think RAM still uses coil springs on the rear axle. Leaf springs can be "staged" so that as the load increases, the springs pack gets stiffer. Can't do that as well with coil springs.

1000 lb. spring bars should be a good fit with a listed dry tongue weight of 775 lbs.

[CollinP]

Here is how I measured. No load to the bottom of the draw bar 19 1/4" trailer hooked up it dropped to 16 3/4". Truck appears to be level. I will do as you suggest Aquaman and measure the fender height with and without trailer. I suspect I need a little more tension because the trailer feel heavier than it should.

This hitch was set up on a different truck and I didn't change anything because the camper was still level when hooked up to the new truck.

Mtnguy the truck is coil springs; I have added timberen helpers to it because I didn't like the way it felt stock. I may have needed the hitch adjusted from the beginning and didn't realize it.

[Platokidd]

You need to measure at the fenders. Front fender should be back to stock height when the camper is hooked up. For me , it worked best to have my ball height 1" above the campers hitch height. Then to get the lift I needed I tipped he hitch head back creating more lift or transfer of weight onto the front wheels. The camper should also be level within a 1" or 1-1/2". I measured at the front n rear of the camper for this.
In the end my trucks front fenders are at stock height, rear has a 1" or so of sag and my camper is within 1- 1/4" of level.

[MtnGuy]

Originally Posted by CollinP

Here is how I measured. No load to the bottom of the draw bar 19 1/4" trailer hooked up it dropped to 16 3/4". Truck appears to be level. I will do as you suggest Aquaman and measure the fender height with and without trailer. I suspect I need a little more tension because the trailer feel heavier than it should.

Measuring at the draw bar gives you skewed measurements....you need to measure at the fender wells inline with the axle. As the back end of the truck goes down, and if the front of the truck raises, the receiver hitch will go down much further than the fender at the rear axle.

Originally Posted by CollinP

This hitch was set up on a different truck and I didn't change anything because the camper was still level when hooked up to the new truck.

Getting the trailer level has to do with the ball height, not the load on the spring bars.....though the spring bars will affect the trailer attitude to a certain extent. Once the spring bars are set-up properly, then the ball height may need to be adjusted (lowered ?). After that, then spring bars may need to be adjusted again. It takes several adjustments of both to get things right. Many owners start with the trailer low in front, knowing that when the spring bars are added, the front of the trailer will come up some.

Originally Posted by CollinP

Mtnguy the truck is coil springs; I have added timberen helpers to it because I didn't like the way it felt stock. I may have needed the hitch adjusted from the beginning and didn't realize it.

IMHO, not saying that Timbrens might also be needed, but correctly setting up the WDH should be the priority. Timbrens may be needed if the truck still sags after the WDH is setup correcty. If Timbrens are added after the initial setup, then the WDH may need to be readjusted because of the rear of the truck being raised......it is an almost endless cycle.

[CollinP]

Originally Posted by MtnGuy

Measuring at the draw bar gives you skewed measurements....you need to measure at the fender wells inline with the axle. As the back end of the truck goes down, and if the front of the truck raises, the receiver hitch will go down much further than the fender at the rear axle.



Getting the trailer level has to do with the ball height, not the load on the spring bars.....though the spring bars will affect the trailer attitude to a certain extent. Once the spring bars are set-up properly, then the ball height may need to be adjusted (lowered ?). After that, then spring bars may need to be adjusted again. It takes several adjustments of both to get things right. Many owners start with the trailer low in front, knowing that when the spring bars are added, the front of the trailer will come up some.

So if I understand this correctly the spring bar tension is determined by using the sag or drop of the truck suspension. Once you have this set as desired (.5" to 0"or 1/2 way to level are the 2 mentioned in the thread) you adjust the trailer to level or slightly nose down using the hitch hieght.


IMHO, not saying that Timbrens might also be needed, but correctly setting up the WDH should be the priority. Timbrens may be needed if the truck still sags after the WDH is setup correcty. If Timbrens are added after the initial setup, then the WDH may need to be readjusted because of the rear of the truck being raised......it is an almost endless cycle.

WOW...this is way more complicated than I realized! I think I will wait until I decide whether or not to get the new trailer then tackle this with the new rig and new spring bars or my current trailer...either way it needs some TLC. I will set it up with the timbrens since they are on the truck.

[CollinP]

So if I understand this correctly the spring bar tension is determined by using the sag or drop of the truck suspension. Once you have this set as desired (.5" to 0"or 1/2 way to level are the 2 mentioned in the thread) you adjust the trailer to level or slightly nose down using the hitch hieght.

[MtnGuy]

The spring bar tension is determined by how much weight you get distributed to the front end of the tow vehicle. The front axle weight should be near the weight of the front axle weight without the trailer hooked up. Mine runs about 60 lbs. over the weight with the trailer not hooked up.

[AquaMan]

Originally Posted by CollinP

So if I understand this correctly the spring bar tension is determined by using the sag or drop of the truck suspension. Once you have this set as desired (.5" to 0"or 1/2 way to level are the 2 mentioned in the thread) you adjust the trailer to level or slightly nose down using the hitch hieght.

Partly. The bar tension is mostly affected by the tilt of the head. Get the height right, then adjust the tilt to get the tension on the bars. It's easier than it seems.


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[CollinP]

Originally Posted by AquaMan

Partly. The bar tension is mostly affected by the tilt of the head. Get the height right, then adjust the tilt to get the tension on the bars. It's easier than it seems.


Sent from my iPhone using Forest River Forums

So, what about the length of the chains?

[MtnGuy]

Originally Posted by CollinP

So, what about the length of the chains?

Yes that also affects the weight distributing for those WDHs that have chains. Many WDHs require that the spring bars be parallel to the tongue frame, others not so much. The head assembly tilt would be the main adjustment to get the bars positioned to the manufacturers requirements.

AquaMan can take over here......I gotta get some errands done.

[CollinP]

Originally Posted by MtnGuy

Yes that also affects the weight distributing for those WDHs that have chains. Many WDHs require that the spring bars be parallel to the tongue frame, others not so much. The head assembly tilt would be the main adjustment to get the bars positioned to the manufacturers requirements.

AquaMan can take over here......I gotta get some errands done.

Thanks, you have been a lot of help.

[jk510]

There are some very informative videos posted at etrailer.com on setting up different brands of WDHs as well as some general WDH info.
Weight Distribution Videos | etrailer.com