Test with simulated tongue weight - yikes! No wonder the RAKE

[TheWingman]

‘This should be a helpful comparison without having to go all out with the car hauler. This is making me dust off some of my load analysis from engineering school. Don’t underestimate the effect of those last two blocks being another 9 inches or so back from the virtual ball. That leverage gain is not insignificant. 8 x 60lb blocks with two of them further back along with the weight of the carrier, I think your simulation is likely topping 500 and change.

‘Your towing needs may still require additional stiffening, but really, couldn’t we all benefit from that?

My thoughts exactly. That hitch carrier is a lever and the moment of force is the ball. You are multiplying force on the ball with that setup.

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[TravisH88]

I have a storm water run-off issue on a part of my property so I need sand bags. Sounds like a great idea for a video, so tomorrow I'm going to start throwing sand bags in my truck until it hits maximum payload (1,511 lbs. in my case). I will take before and after measurements to see how far the Max Tow suspension will sag.

Additionally maybe you can drop the tailgate and put 400 pounds or so on the end of that to better simulate hitch weight.

 

[ShadowsPapa]

Additionally maybe you can drop the tailgate and put 400 pounds or so on the end of that to better simulate hitch weight.

I had thought of doing the same test I did with the 6 blocks on the platform - which would be centered over where the ball would be so would be an exact simulation, then add the other two on the tail gate to put some of it a tad more forward.
According to measuring a ball mound, the front 6 blocks were centered over the point the ball would be.
So I need to relocate the other two blocks. In any case, it dropped too much for a truck that says it can handle 600 pounds of tongue weight.

 

[ShadowsPapa]

My thoughts exactly. That hitch carrier is a lever and the moment of force is the ball. You are multiplying force on the ball with that setup.

ONLY the back two blocks. The front 6 were centered over where the ball would be. I measured by putting my ball mount and ball in, measuring back from the pin hole, then putting the platform in and measuring that, too - the front 6 blocks were NOT behind the ball. They were centered over it.
Only the back blocks were too far back.
I guess no one read my post where I stated that the front 6 blocks were actually over the ball area. The front half of the front blocks were ahead of the ball center, the back half of the front blocks were just back of the ball center. Only the back two blocks, only the back 100 pounds was too far back.
I sort of know about levers and such, being a student of science. My big mistake was having the back two blocks back instead of putting them on top or even on the tail gate (and perhaps posting the pictures here at all)

 

[ShadowsPapa]

Maybe put in max payload minus your weight to show how it would be if you were driving?

Trying to find out how much he weighs, eh, when he says how many sand bags he used to get there.

 

[TheWingman]

ONLY the back two blocks. The front 6 were centered over where the ball would be. I measured by putting my ball mount and ball in, measuring back from the pin hole, then putting the platform in and measuring that, too - the front 6 blocks were NOT behind the ball. They were centered over it.
Only the back blocks were too far back.
I guess no one read my post where I stated that the front 6 blocks were actually over the ball area. The front half of the front blocks were ahead of the ball center, the back half of the front blocks were just back of the ball center. Only the back two blocks, only the back 100 pounds was too far back.
I sort of know about levers and such, being a student of science. My big mistake was having the back two blocks back instead of putting them on top or even on the tail gate (and perhaps posting the pictures here at all)

Agreed.

 

[WXman]

OK so right now I have 1300 pounds sitting 100% behind the rear axle on my Max Tow and I measured exactly 3" of sag.

Went from 24.5" unloaded to 21.5" completely loaded behind the axle.

 

[ShadowsPapa]

Sport S max tow - that's reasonable for that sort of JT - it's got the springs to support that. I see quite a bit of that weight is back of the bumper as well. Maybe 2-300 of it at the bumper area?
I bet if you centered that over the axle it wouldn't drop but maybe a couple of inches. That's a pretty good load for these trucks. It should handle that well if centered.

My plan at this point - max tow springs under the rear. Rubicon springs up front. Fox shocks all around.
Max tow springs shouldn't "sag" as much as the Overland springs, and Rubicon springs up front may take some of the rake out, perhaps half an inch to three-quarters of an inch.
Looking for less drop, not more capacity as I've said before but I know some won't go back and read that part ;-)
I have no plans to load over 1100 pounds or tow over 5,000 pounds, likely will not even get to the 6,000 tow rating with my stuff.

 

[TravisH88]

OK so right now I have 1300 pounds sitting 100% behind the rear axle on my Max Tow and I measured exactly 3" of sag.

Went from 24.5" unloaded to 21.5" completely loaded behind the axle.

OK so right now I have 1300 pounds sitting 100% behind the rear axle on my Max Tow and I measured exactly 3" of sag.

Went from 24.5" unloaded to 21.5" completely loaded behind the axle.

Coopers? Change up the tires already?

 

[WXman]

Coopers? Change up the tires already?

Long story... but a video is coming this evening.

 

[BlueCT]

I hope I can add a some perspective that might be helpful. 1) You shouldn’t be overly concerned with the amount of rear drop alone. While the amount you are seeing is more than I would like you really should prioritize getting your tow vehicle level. When you are actually towing I’m guessing it will be you and your wife in the truck maybe more people and some gear. That will put weight on the front which will level the vehicle load more and you have the natural rake of the truck. I would do the same test with you and your wife in the truck and have a 3rd party take the measurements to see if you are level. I’m sure you know this but it’s worth pointing out the max payload is about 1,100 lbs. If you put 450 lbs on the hitch that leaves you with about 650. 2 adults in the truck probably gets you to only 200-300 remaining payload. Any truck that is within 200 lbs of its payload is going to sag a bit. Maybe a max tow package is a better option to correct your situation. Good Luck
Thanks
Chris

 

[ShadowsPapa]

I hope I can add a some perspective that might be helpful. 1) You shouldn’t be overly concerned with the amount of rear drop alone. While the amount you are seeing is more than I would like you really should prioritize getting your tow vehicle level. When you are actually towing I’m guessing it will be you and your wife in the truck maybe more people and some gear. That will put weight on the front which will level the vehicle load more and you have the natural rake of the truck. I would do the same test with you and your wife in the truck and have a 3rd party take the measurements to see if you are level. I’m sure you know this but it’s worth pointing out the max payload is about 1,100 lbs. If you put 450 lbs on the hitch that leaves you with about 650. 2 adults in the truck probably gets you to only 200-300 remaining payload. Any truck that is within 200 lbs of its payload is going to sag a bit. Maybe a max tow package is a better option to correct your situation. Good Luck
Thanks
Chris

Assuming you are referring to my blue Overland sag - I don't travel with much in the truck aside from myself and an overnight bag (maybe 20 pounds tops), and a cooler (maybe 40 pounds). Once a year at most might have my wife with me.
My simulation was not even close to the payload - let's round the payload to 1100 - it's a tad under but we'll use that.
Assuming I had 500 pounds on that rack - 8 blocks times 60 pounds each. I wasn't half of payload.
Granted it was not in the box, but I was trying to simulate tongue weight. So I tried to stack the block close to where the ball would be (and got close except the last two blocks so I need to try again, moving the last or back two blocks forward)

Adding her, her sewing machine (she hates car events) and her clothes, all total we'd add another 200 pounds or so depending on what she took. And that would not all go on the front axle - it would go to the rear some, too. So that would not help.
Normally when I have my car hauler and car hooked up, it's me, one cooler, one leather duffel of clothes. That's it.

The rear sags badly because the Overland springs are soft - the softest used on these.
Getting the vehicle level means better springs in the rear - lifting the rear - Not loading more stuff up front.

Anything I would put in the box will settle the rear even MORE. The box on these is centered over the axle, not forward of the axle like other trucks, so weight in the box would add to the troubles and cause the truck to sag even more than shown.

Can't add "max tow package" to a truck already bought and paid for....
A little late for that, and I assumed with a 6,000 pound towing capacity that only 500 pounds on the rear wouldn't drop the truck THAT much.
But I AM adding the max tow springs to the rear to help prevent the sag. That will hold the rear up better.
I'll be doing a complete blow by blow write up on that - how it does as it is, how the m-t springs help hold it up, then adding Rubicon shocks and front springs, etc.
I can't change the payload or the towing capacity, but I can change how badly it sags under load.

 

[BlueCT]

I wasn’t suggesting you add a max tow package I was suggesting maybe you should have purchased one to begin with. While the truck sagged 4 inches there is a rake to being with so you are probably about 2 inches out of level. When you put 200-300 lbs pounds in the front seats you will probably be less than 2 inches out of level. For a truck that is towing at more than 75% of capacity I would find that an acceptable amount. You are looking at total sag not total out of level which is what is important when towing. I’m guessing you are making more out of this than it needs to be. I’m sure Jeep did enough testing to ensure you can safely tow the 6,000lbs the vehicle is rated for. You might be solving a problem you don’t have. My advice would be to have someone with a lot of experience setting up tow vehicles look at your setup before you spend any time or money fixing this issue.
-Chris

Assuming you are referring to my blue Overland sag - I don't travel with much in the truck aside from myself and an overnight bag (maybe 20 pounds tops), and a cooler (maybe 40 pounds). Once a year at most might have my wife with me.
My simulation was not even close to the payload - let's round the payload to 1100 - it's a tad under but we'll use that.
Assuming I had 500 pounds on that rack - 8 blocks times 60 pounds each. I wasn't half of payload.
Granted it was not in the box, but I was trying to simulate tongue weight. So I tried to stack the block close to where the ball would be (and got close except the last two blocks so I need to try again, moving the last or back two blocks forward)

Adding her, her sewing machine (she hates car events) and her clothes, all total we'd add another 200 pounds or so depending on what she took. And that would not all go on the front axle - it would go to the rear some, too. So that would not help.
Normally when I have my car hauler and car hooked up, it's me, one cooler, one leather duffel of clothes. That's it.

The rear sags badly because the Overland springs are soft - the softest used on these.
Getting the vehicle level means better springs in the rear - lifting the rear - Not loading more stuff up front.

Anything I would put in the box will settle the rear even MORE. The box on these is centered over the axle, not forward of the axle like other trucks, so weight in the box would add to the troubles and cause the truck to sag even more than shown.

Can't add "max tow package" to a truck already bought and paid for....
A little late for that, and I assumed with a 6,000 pound towing capacity that only 500 pounds on the rear wouldn't drop the truck THAT much.
But I AM adding the max tow springs to the rear to help prevent the sag. That will hold the rear up better.
I'll be doing a complete blow by blow write up on that - how it does as it is, how the m-t springs help hold it up, then adding Rubicon shocks and front springs, etc.
I can't change the payload or the towing capacity, but I can change how badly it sags under load.

 

[ShadowsPapa]

I wasn’t suggesting you add a max tow package I was suggesting maybe you should have purchased one to begin with. While the truck sagged 4 inches there is a rake to being with so you are probably about 2 inches out of level. When you put 200-300 lbs pounds in the front seats you will probably be less than 2 inches out of level. For a truck that is towing at more than 75% of capacity I would find that an acceptable amount. You are looking at total sag not total out of level which is what is important when towing. I’m guessing you are making more out of this than it needs to be. I’m sure Jeep did enough testing to ensure you can safely tow the 6,000lbs the vehicle is rated for. You might be solving a problem you don’t have. My advice would be to have someone with a lot of experience setting up tow vehicles look at your setup before you spend any time or money fixing this issue.
-Chris

Sorry, you apparently missed my posts where I stated why we went this route - so I won't rehash that other than there was at the time no way at all to get our options with a Sport S. In fact, for some of them it's still not possible. You are coming into this months late.

Total sag is an issue because among other things, the headlights are aimed for driving at curb height. The load took the rear down 4" and raised the front at the same time (yes, the front DID rise some as expected) you change the difference more than 4". The truck pivots on the front axle, it's a lever and the front axle the fulcrum.
I posted only how much the rear went down, not how much the front came up.

I have been towing for decades - with various trucks.
Springs will be the solution. As has been discussed here at length, with some suggesting air bags to reduce or even eliminate the "sag".
In the past we had overload springs, helper springs, air shocks, air bags and so on. You can't use the overload springs with this vehicle, helper springs are for leaf springs, and I won't use air shocks to support weight. I'd prefer not using air bags.

You mention again about adding weight to the front seats - that won't take the front down enough because it's BETWEEN the axles and the point isn't to LOAD the truck down with more weight - it'ts to prevent the sag. And like I say - on these 200 pounds in the seat does not "level it", all that does is add more payload, reducing what I can carry.
That's totally silly as if I'm at a swap meet and want to buy an engine or a couple of transmissions, I'd be screwed because I'd be over payload.
The solution is not to add weight to the vehicle to level it out.
Your solution would mean I'd take off already maxed out with payload - to add weight just to drop the front to level it?
The solution is to not allow the back to drop AS MUCH. Not keep adding weight until it's "level".

 

[TheWingman]

The truck pivots on the front axle, it's a lever and the front axle the fulcrum.

I hate to be a contrarian but the front axle can’t be a fulcrum because a fulcrum is a fixed point and the front axle is unsprung weight under suspension.

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