Steer axle air suspension

[GlennWest]

I agree. I have one.

[usbusin]

What is wrong with an air bag suspension front axle versus leaf spring front axle?  Do I suspect "mushy" steering and handling?  I would think the ride would be smoother.

[Vegas Teacher]

On 8/30/2020 at 8:38 AM, HERO Maker said:

Cory, this is a warning!

What is the warning for, don't understand? I only asked a question?

[Parrformance]

I believe he means if you change the ride height of the leveling valve at the tandems, the drive line will grenade and destroy everything in a four block radius.

[GlennWest]

4 hours ago, usbusin said:

What is wrong with an air bag suspension front axle versus leaf spring front axle?  Do I suspect "mushy" steering and handling?  I would think the ride would be smoother.

You got it. Mushy. My ride is good. 

[Av8r3400]

I love the air ride front on my truck.  It handles fine and rides like a dream.  If you guys are chasing the steering on your truck, have the king pins, tie rods, steering box and steering shaft checked.  If these are in good working order the air ride front drives awesome.  

This isn't just stupid me making this comment, a good friend and professional driver with several million miles experience (now retired) helped me inspect and test drive my truck when I first got it.  He stated that he loved the way the truck drove, handled and wished his brand new Freightliner drove half as well.

 

As to changing the ride height, the major question is WHY?  These trucks are engineered to ride with a certain distance from the axle to the frame.  The leveling valves maintain this.  Changing that height changes not only the driveline angles, introducing wear and vibration, but also the alignment of the chassis possibly leading to tire issues or even handling quirks that could be dangerous.

Edited August 31, 2020 by Av8r3400

[GlennWest]

Had kingpin bushings put in. all tie rod and joints good. Still mushy. Had 4 wheel alignment too. I might need to tighten steering box some more.It is drivable now but not pleasurable.

[Av8r3400]

2 minutes ago, GlennWest said:

Had kingpin bushings put in. all tie rod and joints good. Still mushy. Had 4 wheel alignment too. I might need to tighten steering box some more.It is drivable now but not pleasurable.

Obviously it isn't a Corvette handling vehicle, but I can drive with my fingertips and it tracks wonderful down the road.  I did replace the steering shaft u-joints a little while back and that cleaned up some slop in the steering wheel.  If you do this yourself be aware that there is a steering angle sensor (in the column) that needs to be recalibrated afterward.

[GlennWest]

Now I doubt this old freightshaker has that.I have to have both hands on the wheel. 

Edited September 1, 2020 by GlennWest

[Parrformance]

11 hours ago, Av8r3400 said:

I love the air ride front on my truck.  It handles fine and rides like a dream.  If you guys are chasing the steering on your truck, have the king pins, tie rods, steering box and steering shaft checked.  If these are in good working order the air ride front drives awesome.  

This isn't just stupid me making this comment, a good friend and professional driver with several million miles experience (now retired) helped me inspect and test drive my truck when I first got it.  He stated that he loved the way the truck drove, handled and wished his brand new Freightliner drove half as well.

 

As to changing the ride height, the major question is WHY?  These trucks are engineered to ride with a certain distance from the axle to the frame.  The leveling valves maintain this.  Changing that height changes not only the driveline angles, introducing wear and vibration, but also the alignment of the chassis possibly leading to tire issues or even handling quirks that could be dangerous.

Because it was set at the very top limit by the former owner operator.  This caused the rear Tandem's bags to be so hard the truck rode like Glenn's Freightshaker.  Moving it down softened the ride considerably. 

The height also caused the leveling valve to be outside the sweet spot, and could hear it leak after the truck was shut off, until it came down an inch or so.

I can tell the truck was likely set in the middle hole originally.

I am simply correcting an error by a previous owner.

I will likely move it back up this weekend to the center hole. Where it was likely at when it left the Southwestern Virginia factory.

[GlennWest]

My truck rides smooth. No complaint. The drive ability lacks a lot.

[Lance A Lott]

Does anyone have experience with Donvalves front airbag kit?

[Hot Rod]

The first and cheapest point I would start is tire air pressure.  That can make a HUGE difference in ride quality when lightly loaded as is typical in rv service.  I just took a quick look at michelin's website for reference and a given 22.5 tire shows recommended inflation ranging from 75 psi to 120psi depending on the load and single/dual.  Scale your axles and inflate appropriately.  Each tire manufacturer should have a load/inflation chart on their website.  When we first swapped from a dually to a mdt with 22.5 tires, I automatically set them at max inflation like on the dually and it rode like a brick.  Drop from 110 to the 75 psi on the chart and big difference.

Any difference in mileage due to rolling resistance on a lower air pressure is going to be largely theoretical and not noticeable at the pump unless it is severely under inflated.  And you are probably driving it several thousand miles a year, not several thousand a week like the over the road guys, so it would not add up to anything anyway.  Happy wife, happy life!

[jenandjon]

I had a 2015 KW T-800. It had 50,000 on it when I got rid of it. I'm pretty sure the King pins and stuff were fine. I dont know why but it rode like absolute crap. Now my new truck is a 2021 T880 with spring suspension 16,000 lb steer axle rides like a dream.

[ALLOY]

What about changing the seat to something that suits the weight of the person....and if the cab is on air what pressure is it at?

[porky69]

Changing ride height does very little to change ride quality unless you are going to the very extremes(too low and it will constantly bottom out or way too high will over-extend the shocks and eventually blow the air bags out). It will change driveline angles which may cause vibration and accelerated u-joint wear and possible alignment issues. As others have indicated the factory engineers this stuff very precisely.

 

Worn out seats or seat suspensions(seat shocks) can ruin a good riding truck.

Next I would look at some upgraded shocks front, rear and cab- did this to a Pete 379 I used to own and it turned it into a whole new machine. Check with the dealer for your VIN #'s engineered ride height and have it checked/set. Tire pressures can be adjusted (so long as it is within the tire manufacturers specs- most have a load vs psi chart online for each model of tire), but this can cause mushy handling and funny tire wear if not careful. 

 

I haven't driven a newer truck with front air-ride suspension but any of the older ones handled like crap and were un-holy expensive to repair when they wore out. 

[DJohns]

Thanks to all who responded. Looks like I need to get my rig weighed to set rear tire pressure. I check my tire temp this summer with heat gun, I can tell you the fronts run about 130 and the rears run about 117 on 90 degree days.

I will check ride height.

Truck only has 40000 miles so seat is not worn out but wife only weighs 108 so that could be the problem.

[porky69]

Don't think that just because the truck only has 40,000miles on it that stuff isn't worn out......Volvo/Pete/KW/FL/WS aren't any different than Ford/GM/Ram, they use the cheapest stuff that fills the need(which if the original purchaser is smart will spec upgrades). I had to replace shocks on my Pete at 20,000miles.

Seats are a finnicky thing, some seats just about cannot be set comfortably if you have certain combinations of body attributes.  I for example have relatively short legs, larger than average waist and average height and I find if I adjust some seats so it doesn't bottom out on every bump it puts me way to high in the air and then I can't reach the pedals without sliding the seat against the steering wheel which is uncomfortable. If I lower the seat so I am able to reach the pedals and steering wheel comfortably then the seat constantly bottoms out. Some seats are worse than others. I have learned to love sitting flat on the floor (no air in seat suspension), that way the seat doesn't move.....

Being lightweight is a tough one for a lot of seats....they seem to be designed for hefty folks.....

 

 

Edited September 4, 2020 by porky69

[GlennWest]

8 hours ago, porky69 said:

Don't think that just because the truck only has 40,000miles on it that stuff isn't worn out......Volvo/Pete/KW/FL/WS aren't any different than Ford/GM/Ram, they use the cheapest stuff that fills the need(which if the original purchaser is smart will spec upgrades). I had to replace shocks on my Pete at 20,000miles.

Seats are a finnicky thing, some seats just about cannot be set comfortably if you have certain combinations of body attributes.  I for example have relatively short legs, larger than average waist and average height and I find if I adjust some seats so it doesn't bottom out on every bump it puts me way to high in the air and then I can't reach the pedals without sliding the seat against the steering wheel which is uncomfortable. If I lower the seat so I am able to reach the pedals and steering wheel comfortably then the seat constantly bottoms out. Some seats are worse than others. I have learned to love sitting flat on the floor (no air in seat suspension), that way the seat doesn't move.....

Being lightweight is a tough one for a lot of seats....they seem to be designed for hefty folks.....

 

 

I aire up my seat until my upper leg is straight or level. So blood flows better. With mine down, no air, knees up in the air.

[chief916]

On 9/1/2020 at 2:01 PM, Lance A Lott said:

Does anyone have experience with Donvalves front airbag kit?

Yes sir.  We drove to Sturges from NC last year and them roads beat us up pretty bad.....bad enough that it snapped the mounts on both my after market side boxes.  Completely destroyed my right side box.  We made home finally and I got to looking at my front suspension and all I had was leaf springs and shock absorbers.  This is a 1997 Volvo WIA64 with 640 k on the frame.  Researched the Donvel suspension system and called them up.  Terry I believe was his name with a British accent walked me through the process of measuring for after market airbags for the front and rear bag air restrictors.  Once installed we left for California for a month.  BIG difference in handling and ride.  The nice thing about this was that I can change the air pressure to the front airbags while I'm driving to adjust to different road conditions.  Nice setup, was not expensive and it was easy enough that even a person who has rudimentary tool skills can install the bags.  Many many thanks to the guys at Donvel for there assistance.

[Lance A Lott]

Thank you I have the restictors for the rear and the cab bags I have considered the front kit. I may look into it more. 

[DJohns]

On 9/4/2020 at 9:56 AM, chief916 said:

Yes sir.  We drove to Sturges from NC last year and them roads beat us up pretty bad.....bad enough that it snapped the mounts on both my after market side boxes.  Completely destroyed my right side box.  We made home finally and I got to looking at my front suspension and all I had was leaf springs and shock absorbers.  This is a 1997 Volvo WIA64 with 640 k on the frame.  Researched the Donvel suspension system and called them up.  Terry I believe was his name with a British accent walked me through the process of measuring for after market airbags for the front and rear bag air restrictors.  Once installed we left for California for a month.  BIG difference in handling and ride.  The nice thing about this was that I can change the air pressure to the front airbags while I'm driving to adjust to different road conditions.  Nice setup, was not expensive and it was easy enough that even a person who has rudimentary tool skills can install the bags.  Many many thanks to the guys at Donvel for there assistance.

Did you get the system that remoes one leaf spring?

[chief916]

1 hour ago, DJohns said:

Did you get the system that remoes one leaf spring?

No sir.  I filled out a work sheet about what I had on the truck and they built the bags and all the hardware to attach  and provided the air lines and the pressure gauge that's attached to my dash down and out of the way.  Hope that helps.