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I measured the suspension compression while loading camping gear and hitching my trailer. I measured the height of both front and rear wheel Wells at the center of the tires unloaded - both measured 32 1/2”. I then loaded about 280 lbs of camping gear using both the rear and the third tow seats down. The rear dropped about 1/2” and the front remained at 32 1/2”. I then connected my trailer with 310 lbs of tongue weight. The rear dropped to 31” and the front still remained at 321/2”. Previously I have measured the same 1 1/2” rear compression but never measured the front. This surprised me as I would have thought the front would have gone up. Am I missing something?
 

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The Ascent is designed to handle the weight up to the limits without substantially affecting balance like with many vehicles, This is why a WDH isn't permitted/needed with the Ascent.
 

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I measured the suspension compression while loading camping gear and hitching my trailer. I measured the height of both front and rear wheel Wells at the center of the tires unloaded - both measured 32 1/2”. I then loaded about 280 lbs of camping gear using both the rear and the third tow seats down. The rear dropped about 1/2” and the front remained at 32 1/2”. I then connected my trailer with 310 lbs of tongue weight. The rear dropped to 31” and the front still remained at 321/2”. Previously I have measured the same 1 1/2” rear compression but never measured the front. This surprised me as I would have thought the front would have gone up. Am I missing something?
Just curious if the front suspension has some stiction going on.

Next time you load up, try pressing down and up at the front of the Ascent and let the car rebound to it's at rest level, then measure.

When I was a mechanic, after doing an alignment, I'd always bounce the car and re-check. Some cars have more stiction than others.
 

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In hindsight I should’ve measured the squat. The front wasn’t noticeably different but you can see the rear a bit in this picture:
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27 bags of mulch at about 40lb each = a bit over 1000lb + a full tank of gas and 200lb of me. I hit some rather large bumps on the way home but never bottomed out and it even accelerated nicely too!
 

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This surprised me as I would have thought the front would have gone up. Am I missing something?
As long as your rear suspension was not bottomed out, or at least not to the point where the spring rate is sufficient to act as a fulcrum, then there really wouldn't be any forces that would LIFT the front of the up. As you add weight to the rear of the car, you're shifting the overall weight distribution to the rear, yes (% of rear axle weight to the entire weight of the vehicle), but you're not removing any weight from the front. Now, if your suspension was bottomed out and you kept adding weight AFT of the suspension, then you'd be using the rear suspension as a fulcrum and could literally lever the front of the car up into the air. But I don't think this would be a common scenario.
 

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Next time I am tempted to try to explain that in 27 paragraphs, I am just tagging you, @hokiefyd! 🤣
 

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As long as your rear suspension was not bottomed out, or at least not to the point where the spring rate is sufficient to act as a fulcrum, then there really wouldn't be any forces that would LIFT the front of the up. As you add weight to the rear of the car, you're shifting the overall weight distribution to the rear, yes (% of rear axle weight to the entire weight of the vehicle), but you're not removing any weight from the front. Now, if your suspension was bottomed out and you kept adding weight AFT of the suspension, then you'd be using the rear suspension as a fulcrum and could literally lever the front of the car up into the air. But I don't think this would be a common scenario.
Close, but not quite. The suspension acts as a fulcrum even if not fully compressed. Any force applied behind the rear axle (tongue weight, cargo, whatever) will unload the front suspension by a certain amount. Load on the rear suspension will increase an amount equal to the applied force plus how much the front suspension is unloaded. That's kind of odd to think about actually. You can add 500 in tongue weight and your rear suspension could get an extra 600 while your front suspension gets -100 (just theoretical numbers).
 

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Close, but not quite. The suspension acts as a fulcrum even if not fully compressed. Any force applied behind the rear axle (tongue weight, cargo, whatever) will unload the front suspension by a certain amount. Load on the rear suspension will increase an amount equal to the applied force plus how much the front suspension is unloaded. That's kind of odd to think about actually. You can add 500 in tongue weight and your rear suspension could get an extra 600 while your front suspension gets -100 (just theoretical numbers).
I'd been taught that it's once you exceed the counterbalance effect of the front. The front is weighed down heavier than the rear (54/46) by an overhanging weight (most of the front subframe, the entire engine, and a chunk of the front differential and CVT. I actually bought a four shock RC car to test it with, and a few little food scales. Never got around to it.

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Close, but not quite. The suspension acts as a fulcrum even if not fully compressed. Any force applied behind the rear axle (tongue weight, cargo, whatever) will unload the front suspension by a certain amount. Load on the rear suspension will increase an amount equal to the applied force plus how much the front suspension is unloaded. That's kind of odd to think about actually. You can add 500 in tongue weight and your rear suspension could get an extra 600 while your front suspension gets -100 (just theoretical numbers).
I had to really get my brain exercising, which is really doesn't like to do. :)

Think about this with me in simple terms -- if you apply a 500 pound weight to the exact center of a notional car with 50/50 weight distribution, then both the front and rear suspensions should be sharing 50% of the weight, right? 250 pounds would be applied to both. If you apply that 500 pound weight EXACTLY over the rear suspension, then I suppose that ONLY the rear suspension would be bearing the load, and the front would not feel any difference. But applying the weight AFT of the rear suspension necessarily removes weight from the front, right? I don't think that could be a linear relationship -- there's probably some complex curve in terms of how much weight could ever be unloaded from the front from a theoretical perspective (assuming you don't compress the suspension enough until it bottoms out).

If I'm thinking in the same lines as you above, then I imagine the situation becomes even less clear when you add things like spring rates, existing weight distribution, and even weight distribution "around" each of the axles (the front has a bunch of weight cantilevered forward of the axle).

Subject to the nuances regarding weight distribution and such, if there is an unloading of the front suspension, I suspect it's not enough to overcome the stiction noted earlier to result in actual jacking of the front end. Car suspensions today are far less "motioney" than they were in the past. Even completely worn struts don't really "bounce" anymore. Forget the "bounce test" on anything from the last 15 years or so (at least in my experience). Stuff is just much tighter today than it used to be.

To the OP, it'd probably be interesting to take a static measurement (as you did) and then drive around the block or up and down the road for a few miles, slowly come to a stop, get out, and measure again. I wonder if the front would be any higher then?
 

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I'd been taught that it's once you exceed the counterbalance effect of the front. The front is weighed down heavier than the rear (54/46) by an overhanging weight (most of the front subframe, the entire engine, and a chunk of the front differential and CVT. I actually bought a four shock RC car to test it with, and a few little food scales. Never got around to it.
I'm not sure which "when" you're referring to but I think what you're describing is when the front suspension is completely unloaded and tires are airborn or nearly so. You'd never be able to apply enough tongue load or cargo for that to happen while standing still. The front is a little heavier but that just shifts the center of gravity forward.

I had to really get my brain exercising, which is really doesn't like to do. :)
For real. I understand.

Think about this with me in simple terms -- if you apply a 500 pound weight to the exact center of a notional car with 50/50 weight distribution, then both the front and rear suspensions should be sharing 50% of the weight, right? 250 pounds would be applied to both. If you apply that 500 pound weight EXACTLY over the rear suspension, then I suppose that ONLY the rear suspension would be bearing the load, and the front would not feel any difference. But applying the weight AFT of the rear suspension necessarily removes weight from the front, right? I don't think that could be a linear relationship -- there's probably some complex curve in terms of how much weight could ever be unloaded from the front from a theoretical perspective (assuming you don't compress the suspension enough until it bottoms out).
That's a very logical way to think about it and makes perfect sense. I'm not sure what the curve looks like but it's a balance of the torques (force x distance) about a given axis (rear axle). See below.

If I'm thinking in the same lines as you above, then I imagine the situation becomes even less clear when you add things like spring rates, existing weight distribution, and even weight distribution "around" each of the axles (the front has a bunch of weight cantilevered forward of the axle).
It really doesn't have to be that hard. Remember that springs can still react forces. They'll just compress in the process.

Here's a quick free body diagram.

The main equations to consider are
Balance of vertical forces:
G = Rf + Rr (no load applied)
G + L = Rf + Rr (load applied)

Balance of torque about rear axle:
L x dist(L-axle) + Rf x dist(Rf-axle) = G x dist(G-axle)

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There's almost no weight in the back, compared to the front and the entire engine, battery, cooling systems and a chunk of the transmission forward of the front axle. If I am correct, the engine alone weighs more than the tongue weight. It's not a transverse mounted drive where that weight is mostly balanced above the axle. When we studied bridge design way back, we learned that a cantilevered force on one side can be overcome by one on the other side, supported by two or more support mechanisms. In this case, with the supports being wheels on axles that rotate, things change. Then, you add springs. Things change even more. It's a lot more complex than the forced you indicate.

So, before the same tongue loading principles that lighten the front, the rear is affected by the loading and spring compression of the front's overhanging weight. Add in stiction, rotation and more... and it's pretty complex. The results so far, of multiple weights posted to this forum, are that, until the tongue weight is exceeded, the front does not unload.

When you add 500 pounds to the tongue, the car is about 50/50 balanced and the center of gravity is in the center of the axles. When you exceed 500 pounds, the center of gravity shifts rearward and the front unloads.

I want to test that in real life.
 

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I think you're overcomplicating. Sure, the load is distributed and not a point load at the CoG. For this case, all it does is determine the location of the CoG, which should be shifted a little forward of between the axles. CoG is a good estimation here since we're not talking about bending stresses or moments of inertia.
 

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The simple version is the normal COG is forward of the center point because in a curb-Ascent, the front is decently loaded before the axle (by engine, etc), while there's literally nothing behind the rear axle. A proper tongue weight centers the COG between the axles equally (front to back). Once the COG moves farther backwards, weight unloads from the front at a quicker rate.

The more complex version is; in addition to that point, spring rates are extremely important in figuring out how, when, if and what weight transfer occurs at any given weight. For instance, I can put springs in the back that will make almost any weight transfer to and lift the front.
 

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I wish I had a shop central to all of us (and time, and parts, and more tools, and a spare Ascent to tinker with, lol)... there's some important factors we don't know. It would be really fun to test all of this, with different springs, different tongue loads, different loading scenarios, etc. I have a feeling some of you, like me, would not mind knowing what exactly happens when.
 

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Free body diagrams. CofG shifts with new load, springs make it tricky to figure out without FEA...there is nothing left for an old engineer like me to add.
 
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