Get rid of massive Chevy overload leaf?

[peteco]

Originally Posted by Luv2Go

Still love them. Pressure of 65PSI seems to provide the best ride. Still glad I removed the overloads also, the only time the "bang" came back was when I was experimenting with lower air pressure, at 45PSI big bumps caused the suspension to hit the bump stops and "bang".

Is the "bang" a hard grounding? If so, it sounds like the bump stops are a hard material, not like the material in timbrens or Sumo springs.

[booster]

Originally Posted by peteco

Is the "bang" a hard grounding? If so, it sounds like the bump stops are a hard material, not like the material in timbrens or Sumo springs.

If the overload is not there it is very possible that the bang could be shocks bottoming out.



It is very important to have shock travel and airbag mounting height closely matched to your desired ride height so you stay within all the travel specs for them.


Our van will go onto the airbag with no air in on it without bottoming out the Bilstein shocks.


Of course, there could also be something loose in the van that doesn't like the sudden big travel and quick stop. The frig? Something like the jack in the storage? The grille you carry? Lots of noisy things in our van that I would check.

[peteco]

Originally Posted by booster

If the overload is not there it is very possible that the bang could be shocks bottoming out.

It is very important to have shock travel and airbag mounting height closely matched to your desired ride height so you stay within all the travel specs for them.

Our van will go onto the airbag with no air in on it without bottoming out the Bilstein shocks.

Of course, there could also be something loose in the van that doesn't like the sudden big travel and quick stop. The frig? Something like the jack in the storage? The grille you carry? Lots of noisy things in our van that I would check.

I don't recall our RT 210 ever banging (either sensation or noise) in a terrible sense. Last year we drove from Virginia to Indiana. My elderly inlaws were in the rear sofa seat. Other than getting bounced up in the air on a few large bumps they seemed comfortable.

After reviewing all this great discussion (thanks to all) I have decided to stay with the Firestone airbags. I may try adding sumosprings (if I can find a good deal) under fairly low load nominally to provide some level of failed airbag support like the Airbag jounce provides. The Sumos might also provide a small level of sway control enhancement. Sway has not been an issue, except at low airbag pressure, but perhaps I am used to it and just don’t know the difference a swaybar would make. Would have to switch to Airlift in order to install swaybar. Tough call as Airlift with internal jounce along with swaybar sounds like the best way to go in the rear.

I just ordered Firestone airbag replacements as the current ones are 12 years old with some noticeable cracking and wear.

I did some checks and I do have about 1/8" clearance between the overloads and the main spring at about 70 psi airbag pressure.

Measured the fenderwell heights (LF, RF, LR, RR)
Airbags at 70 psi: 36-3/8, 35-7/8, 36-4/8, 35-5/8
Airbags at 35 psi: 36-3/8, 35-7/8, 35-7/8, 35-1/8

So the lift is where I want it. But a big difference left to right at the rear, with smaller difference up front. The van doesn’t look or feel noticeably tilted.

[booster]

Originally Posted by peteco

I don't recall our RT 210 ever banging (either sensation or noise) in a terrible sense. Last year we drove from Virginia to Indiana. My elderly inlaws were in the rear sofa seat. Other than getting bounced up in the air on a few large bumps they seemed comfortable.

After reviewing all this great discussion (thanks to all) I have decided to stay with the Firestone airbags. I may try adding sumosprings (if I can find a good deal) under fairly low load nominally to provide some level of failed airbag support like the Airbag jounce provides. The Sumos might also provide a small level of sway control enhancement. Sway has not been an issue, except at low airbag pressure, but perhaps I am used to it and just don’t know the difference a swaybar would make. Would have to switch to Airlift in order to install swaybar. Tough call as Airlift with internal jounce along with swaybar sounds like the best way to go in the rear.

I just ordered Firestone airbag replacements as the current ones are 12 years old with some noticeable cracking and wear.

I did some checks and I do have about 1/8" clearance between the overloads and the main spring at about 70 psi airbag pressure.

Measured the fenderwell heights (LF, RF, LR, RR)
Airbags at 70 psi: 36-3/8, 35-7/8, 36-4/8, 35-5/8
Airbags at 35 psi: 36-3/8, 35-7/8, 35-7/8, 35-1/8

So the lift is where I want it. But a big difference left to right at the rear, with smaller difference up front. The van doesn’t look or feel noticeably tilted.

If you are comfortable with what you have, there is no real reason to mess with it, I would agree.


If the height of the Sumos is close or even on the frame all the time a bit, you should see some slight amount, but quite progressive, of spring rate increase and that will reduce sway a bit, I think.


I am not all that surprised that you don't notice the sway after all these years as you can get used to it.


Swaybar changes are funny in general because they do reduce sway some for sure, but you tend to feel it at different places. For us it was very obvious on tight right turns when the right side wheels go low into a curb gutter and then quickly back out, and the rocking when coming out of a driveway at an angel. But the real benefits are indirect and have more to do with weight shift and distribution, I think. When the wind hits the side of the van in will move straight over, but front and rear together rather than have one end move more than the other and create a large correction need. The big thing for me is that the rear bar improves the steering response so it takes much smaller corrections to stay in line or to turn into a corner. And it is pretty non instinctual that adding a big bar in the back, increases the front traction to improve the steering response.


I am a bit surprised with you being higher on the left rear than the right. I think most Chevies are lower on the right. You are also lower overall in the back than we are at the wheelwells, but they is part of the fiberglass body, I think, so it could be anywhere and may be why the heights are different side to side also. I think we would have to compare trim heights measured at the axle to frame to know for certain.

[peteco]

Originally Posted by booster

Swaybar changes are funny in general because they do reduce sway some for sure, but you tend to feel it at different places. For us it was very obvious on tight right turns when the right side wheels go low into a curb gutter and then quickly back out, and the rocking when coming out of a driveway at an angel. But the real benefits are indirect and have more to do with weight shift and distribution, I think. When the wind hits the side of the van in will move straight over, but front and rear together rather than have one end move more than the other and create a large correction need. The big thing for me is that the rear bar improves the steering response so it takes much smaller corrections to stay in line or to turn into a corner. And it is pretty non instinctual that adding a big bar in the back, increases the front traction to improve the steering response.

Rocking when crossing a dip at an angle is the most noticeable, but reduced with higher bag pressure. It would be nice to drive a 210 with the swaybar to feel the difference. I have to say though that after the lift (12 years ago) the van drives and steers really well. Of course I drive it very conservatively, and in an emergency maneuver the differences would be more apparent.

[/QUOTE] I am a bit surprised with you being higher on the left rear than the right. I think most Chevies are lower on the right. You are also lower overall in the back than we are at the wheelwells, but they is part of the fiberglass body, I think, so it could be anywhere and may be why the heights are different side to side also. I think we would have to compare trim heights measured at the axle to frame to know for certain.[/QUOTE]

Agree that the 210's fiberglass body may not be as consistent as the frame. Where would you suggest measuring to the frame?

[booster]

Originally Posted by peteco

Rocking when crossing a dip at an angle is the most noticeable, but reduced with higher bag pressure. It would be nice to drive a 210 with the swaybar to feel the difference. I have to say though that after the lift (12 years ago) the van drives and steers really well. Of course I drive it very conservatively, and in an emergency maneuver the differences would be more apparent.

I am a bit surprised with you being higher on the left rear than the right. I think most Chevies are lower on the right. You are also lower overall in the back than we are at the wheelwells, but they is part of the fiberglass body, I think, so it could be anywhere and may be why the heights are different side to side also. I think we would have to compare trim heights measured at the axle to frame to know for certain.[/QUOTE]

Agree that the 210's fiberglass body may not be as consistent as the frame. Where would you suggest measuring to the frame?[/QUOTE]


The factory service manual shows a specific place to measure the trim heights, both front and rear, but I don't recall where it is on the back offhand and am far away from the manual right now. For just side to side I think you could go from the axle tube top vertical to the frame, though, just to see the difference.

[sadpanda]

I may have an alternative for this problem.

My rig weighs 3,640 lbs front, 3,420 lbs rear with full fuel and 200 lbs driver. I'm sure this is far below most of you guys, despite that even I am sitting on the helper.

Looking at truckspring.com, stock rear spring pack is a 5 leaf rated for 2,485 lbs. - 1st Stage 3/380 1/360 ,2nd Stage 1/999

The Suburban SKU 22-907 spring is rated for 2,900 lbs. - 1st Stage 1/380 2/401 2/380 2nd Stage 1/1.063

If my understanding is correct, the second stage would not be engaged until after 3,884 lbs yes? That would be 884 lbs more than the 3,000 lbs on the Express spring - likely enough to improve my application. Is that enough to help you guys? The only issue I see is the arc is 1/4 lower - may not matter given the extra capacity and different stack.

Recommended bags are $478 on amazon, springs are $600 ish new. If you are already have bags or were planning on them, probably not be worth it.

[sadpanda]

Originally Posted by booster

The factory service manual shows a specific place to measure the trim heights, both front and rear, but I don't recall where it is on the back offhand and am far away from the manual right now. For just side to side I think you could go from the axle tube top vertical to the frame, though, just to see the difference.

Here ya go. Pro tip - throw a laser level under the front and simply measure down to it and do the maths.

image.HJIU71.jpg


Z Height Measurement

The Z height measurement determines the proper ride height for the front end of the vehicle. Vehicles equipped with torsion bars use an adjusting arm to adjust the Z height. Vehicles without torsion bars have no adjustment and could require replacement of suspension components.

Important:
All dimensions are measured vertical to the ground. Trim heights should be within 12 mm (0.47 in) to be considered correct.

1. Place hand on the front bumper and jounce the front of the vehicle. Ensure that there is at least 38 mm (1.5 in) of movement while jouncing.
2. Allow the vehicle to settle into position.
3. Measure from the pivot bolt center line (2) down to the lower corner (5) of the steering knuckle (1) in order to obtain the Z height measurement (4).
4. Repeat the jouncing operation 2 more times for a total of 3 times.
5. Use the highest and lowest measurements to calculate the average height.
6. The true Z height dimension number is the average of the highest and lowest measurements. Refer to Trim Height Specifications See: Suspension > Mechanical > Trim Height Specifications.
image.ULYE71.png

D Height Measurement

The D height measurement determines the proper ride height for the rear end of the vehicle. There is no adjustment procedure. Repair may require replacement of suspension components.

Important:
All dimensions are measured vertical to the ground. Trim heights should be within 12 mm (0.47 in) to be considered correct.
1. Place hand on the rear bumper and jounce the rear of the vehicle. Ensure that there is at least 38 mm (1.5 in) of movement while jouncing.
2. With the vehicle on a flat surface, lift upward on the rear bumper 38 mm (1.5 in).
3. Allow the vehicle to settle into position.

Important:
Measure the metal to metal contact points of the rear axle to the frame on the inboard side of the leaf springs.

4. Measure the D height by measuring the distance between the rear axle tube or rear axle bracket on vehicles with 7300 GVW rating and the frame.
5. Repeat the jouncing operation 2 more times for a total of 3 times.
6. Use the highest and lowest measurements to calculate the average height.
7. The true D height dimension is the average of the highest and the lowest measurements.

image.LU2Q71.png

[booster]

I guess I don't get why you need a laser level. My floor is plenty flat. I can see that if you are on a drive on lift because the floor is a long ways away, but not at home. Just put my small square on the floor to show me vertical under where I am going to measure and measure down to the end of it and add on the square height. It is a bit more accurate than using the tape only, but that works also. Best I think is to use a plumb bob and just hold the string at the top with the weight just touching the floor and then measure from where you are holding the string to end of weight in an easier to do it place.

[booster]

Originally Posted by sadpanda

I may have an alternative for this problem.

My rig weighs 3,640 lbs front, 3,420 lbs rear with full fuel and 200 lbs driver. I'm sure this is far below most of you guys, despite that even I am sitting on the helper.

Looking at truckspring.com, stock rear spring pack is a 5 leaf rated for 2,485 lbs. - 1st Stage 3/380 1/360 ,2nd Stage 1/999

The Suburban SKU 22-907 spring is rated for 2,900 lbs. - 1st Stage 1/380 2/401 2/380 2nd Stage 1/1.063

If my understanding is correct, the second stage would not be engaged until after 3,884 lbs yes? That would be 884 lbs more than the 3,000 lbs on the Express spring - likely enough to improve my application. Is that enough to help you guys? The only issue I see is the arc is 1/4 lower - may not matter given the extra capacity and different stack.

Recommended bags are $478 on amazon, springs are $600 ish new. If you are already have bags or were planning on them, probably not be worth it.

If you are going to replace the springs you are way, way better off to not buy springs with an overload leaf. Class b's operate in a very narrow range of weight compared to empty cargo or passenger vans so you can get a spring that does not suddenly get way to stiff. Are those springs rated as individuals or as a pair?



That said, I would still take the bags over a spring replacement because you can tweak the height if you need to and we have found having a weak lower rate spring like the stocker 3500 van one is without the overloads and picking up about half the weight on the air bags give a much smoother ride that a spring replacement would because the bags are less progressive.


All of this changes if you plan on towing a trailer as then having stiffer rear springs is probably needed.

[sadpanda]

It looks like the springs are rated each.

Regarding the heavier spring, I do have to contend with wide variations in weight and I will be towing - usually under 5,000 lbs.

My brother tows very heavy with 2500 dmax. With weight distributing hitch he still ended up bagging it to keep it off the helper. The soft spring / bag combo may be enough.

The only alternative without overload is the 9 leaf cargo spring rated at 3,700 lbs - 1/473 6/499 2/473

[sadpanda]

Replacement springs also cost more than bags so I went bags.

Along with removing the helper I installed new springs/bump stops up front with 2in leveling spacers. The ride is vastly improved; not 1500 smooth but close. Wife and canines even noticed.