21+ IRS SAG issues when towing product design (looking for someone in Michigan)

[tagexpcom]

I have a 2021 Yukon Denali 6.2L but it doesn't have the air ride. My trailer's tongue weight is 650lb and with a Blue Ox Trac Pro weight distribution the rear sags 1" + front up 1/2" and towing is stable.

Without WD the rear sagged 2+ inches and front was up 1+ inches and towing was not nearly as stable.

So I'm wondering... If I got the 'heavy duty' spring option mentioned above - https://www.hdcoilsprings.com/produ...burban-tahoe-yukon-yukon-xl-rear-coil-spring/ - would this eliminate the 1" (and front rise) for the 650lb tongue weight with WD? Or to ask another way - what would one expect in terms of less drop?

 

[olyelr]

I have a 2021 Yukon Denali 6.2L but it doesn't have the air ride. My trailer's tongue weight is 650lb and with a Blue Ox Trac Pro weight distribution the rear sags 1" + front up 1/2" and towing is stable.

Without WD the rear sagged 2+ inches and front was up 1+ inches and towing was not nearly as stable.

So I'm wondering... If I got the 'heavy duty' spring option mentioned above - https://www.hdcoilsprings.com/produ...burban-tahoe-yukon-yukon-xl-rear-coil-spring/ - would this eliminate the 1" (and front rise) for the 650lb tongue weight with WD? Or to ask another way - what would one expect in terms of less drop?

It would no doubt help with the rear squatting. But up front, that will most likely still rise…thats what the wdh’s are for.

 

[olyelr]

I think the biggest challenge is finding shocks/struts with valving that will match the increased spring rate.

While it may be a 35% increase in load capacity, it is possible that the spring rate % increase may not be nearly as much as the load capacity increase. Maybe if the spring rate is only 10-20% greater than factory, a Bilstein 5100 would be appropriate.

Yes, that is very possible.

 

[dbphillips]

It would no doubt help with the rear squatting. But up front, that will most likely still rise…thats what the wdh’s are for.

I think part of the front lifting is caused by the rear squatting, so it should help. But that's kind of the whole challenge, no one knows. Someone has to do it, since none of the air shock guys are committing to even investigating the solution.

 

[dbphillips]

I think the biggest challenge is finding shocks/struts with valving that will match the increased spring rate.

While it may be a 35% increase in load capacity, it is possible that the spring rate % increase may not be nearly as much as the load capacity increase. Maybe if the spring rate is only 10-20% greater than factory, a Bilstein 5100 would be appropriate.

My thought is the damping needs shouldn't increase. The shocks should already be adequate for the increased load, and the spring reduces the amount of travel. I suppose you could get unlucky and end up with a weird harmonic, but otherwise should be fine.

 

[olyelr]

I think part of the front lifting is caused by the rear squatting, so it should help. But that's kind of the whole challenge, no one knows. Someone has to do it, since none of the air shock guys are committing to even investigating the solution.

Through my personal testing, the front lift is simply caused by all the extra weight on the back of the vehicle, essentially “unloading” the front (taking weight off the front end), and lifting the rear up does not change the lifting up fromt. Ive proven this to myself with the airbags on my truck. Regardless if i put a bunch of air in the bags and lift the back of the truck up to factory height (or even over it), the front is still unloaded and higher (unless i am using the weight distribution hitch).

 

[Chad G 1979]

Do you know if the WHD is set up properly or out of adjustment? I wouldn't think an inch sag in rear and 1\2 inch rise in front is bad, but i dont tow anything needing WDH yet so i dont have one to know for sure.

 

[tagexpcom]

In my case, the 650lb tongue w/WDH pulls my 2021 Yukon rear down 1 inch and front raises 1/2 inch. My model doesn't have air bags. This is perfectly stable towing and no complaints but I'm just wondering.....

IF I add the 35% stronger rear springs and let's say the rear only goes down 1/2 inch instead of 1 inch - will the front still go up 1/2 inch? or less? A recent comment suggests the front will still go up the 1/2 inch and this is consistent with some youtubes I saw.

Bottom line, for me, just wondering if adding stronger rear springs would have significant benefit. How about down the road and I have an 800lb tongue weight trailer (with WDH) instead of the current 650lb? What if we load the full 1400lb worth of cargo (tonque + us = room for ~450lbs of junk)?

 

[Chad G 1979]

You could likely test if the front raises more if you have someone stand on the wdh while you measure the front and rear to see if that changes things. Showing you a but what a heavier tongue weight would look like.

Im not certain adding stronger springs will address the rise on the front. Physics even using a whd dictates that the front will rise when the rear drops. As the rear is still going to drop some, the front will still rise. It might not be as much as with stock springs but it will still rise. It all comes down to how much it would cost you to add stronger springs and if the cost to reduced rise (if any) is worth it for your purposes.

 

[olyelr]

In my case, the 650lb tongue w/WDH pulls my 2021 Yukon rear down 1 inch and front raises 1/2 inch. My model doesn't have air bags. This is perfectly stable towing and no complaints but I'm just wondering.....

IF I add the 35% stronger rear springs and let's say the rear only goes down 1/2 inch instead of 1 inch - will the front still go up 1/2 inch? or less? A recent comment suggests the front will still go up the 1/2 inch and this is consistent with some youtubes I saw.

Bottom line, for me, just wondering if adding stronger rear springs would have significant benefit. How about down the road and I have an 800lb tongue weight trailer (with WDH) instead of the current 650lb? What if we load the full 1400lb worth of cargo (tonque + us = room for ~450lbs of junk)?

With my personal experience, stiffer rear springs that sag less will not change the front from raising. The only thing that combats that is a wdh, which literally removes weight from the rear of the vehicle and places it on the front.

However, the stiffer rear springs may help with the overall drivability when towing. But, unloaded ride quality may suffer some ?? Thats the beauty of bags or some sort of air adjustability…no negative effects when not aired up.