front air ride

[davehummell]

I took my buddy for a ride in my b and he said it did ride better with the air ride in the rear he say's i should put air bags in the front. He is good at getting me to do stuff i didn't know i needed. Anyone ever do this on a b 61? I figure you would have to remove a few leafs and get the right bag that will carry the weight you shouldn't run more than 100lbs in the bag i was told.

[Freightrain]

Yes, this was done before.  A fellow many years ago on here did it.  Same scenario, remove a couple springs and add bags.  Not sure if anyone around here today remembers Dale Hamilton?  He restored a beautiful B67 and then sold it.

I've had the same thoughts.  That stiff front axle really pounds on you.

[Rob]

21 minutes ago, Freightrain said:

Yes, this was done before.  A fellow many years ago on here did it.  Same scenario, remove a couple springs and add bags.  Not sure if anyone around here today remembers Dale Hamilton?  He restored a beautiful B67 and then sold it.

I've had the same thoughts.  That stiff front axle really pounds on you.

Dale was a nice guy and worked on high end boats professionally. I felt him harshly treated which limited his participation.

[Rob]

100psi in the bags will make it ride like a brick. More like 35-45 would suffice but it does matter with bag selection. The double convoluted take up less space but higher pressure to carry the load. It may take some experimentation to achieve the ride quality you are looking for and ratings are online.

I would double up your front shock absorbers on the steer axle to minimize the "porpoising" this modification causes.

[Freightrain]

42 minutes ago, Rob said:

Dale was a nice guy and worked on high end boats professionally. I felt him harshly treated which limited his participation.

Yes, I agree.  His plan was to use the truck to move the boats around.  He was not around for long, especially once he changed directions and sold the truck.  He contacted me about driving it to the new owners.

 

If you keep the majority of the spring pack, then you would not have to rely on so much air pressure to support the front end, which in turn would allow the bag to "move" easier and absorb some of the motion.  I remember talk of leaving the springs alone, and just using enough air pressure to just raise the front end slightly.  That would allow some spring action from the bags.  Definitely need something better then the factory shocks!

[davehummell]

I was referring to maximum pressure that is allowed in an air bag. I am running 15 lbs in the rear bags just enough to keep the truck setting at the right height. I installed a manual valve in the cab to change the air pressure in the back bags. i used to run about 40 lbs. in the brockway's lift axle. The right diameter bag will change the air pressure needed in the front. I was just going to take out the  the short leafs and run all the long leafs.

[Quickfarms]

I wanted to do this to front of my Ford FT900 and the spring shop recommended rebuilding the front spring pack so it was designed for your normal or unladen weight, upgrading the shocks, and using the air bags for excess capacity or to raise the front end for leveling when camping.

They said it is very difficult to get the air ride front end to really ride and handle good.

I will say now my air ride seat barely moves and my wife does not need a sports bra to ride in the truck!

[j hancock]

Here is a front axle air bag thread.

 

[Freightrain]

Just a side note.  Originally I cut my rear leafs down so it would move withy race trailer on the back.  After a few years one side broke.  Guess those 50 yr old leafs weren't suppose to move that much?  So if you plan on removing leafs so the remaining move, watch as they may break over time.  May want to get new springs made?

[harrybarbon]

Here is a picture of our front axle air bag with parabolic springs, kit comes with a pressure gauge and valve dial to adjust air pressure, improved road handling and less pressure does give some ride help and drop tyre pressure some as well. Kit comes with mounting/fitting plates, air bags, gauge, valve to adjust air pressure, air lines, bolts etc. We had to make a couple of plates to sit on top of the air bags which bolted to the vertical frame plates. And we retained the shock absorbers.

[Aussie Greg]

G'Day guys and hello from Australia. i have a 1999 CH Mack. Single drive short wheelbase that i'm going to use as a toy hauler. (meaning it will never go back to heavy work), instead pulling a 48 foot drop deck trailer around with very little weight in / on it at all. 

I would dearly love to "soften" the front end ride. It has 3 parabolic springs on the front and Hendrickson air on the rear. The rear i can play with when i get her on the road. My thoughts are simply removing the the bottom leaf on the front end. The 2 upper leafs have the "wrap around" the shackles, so I'm not touching them. 

Just wanting to know others thoughts because my beautiful little truck rides like an Australian Bush Pig. (Not good at all). I've seen others in the US of A especially on the long wheelbase Peterbilts remove 2 of the 3 parabolic leafs from the spring pack and install airbag. I wouldn't be adverse to this either. Just want some others thoughts?

Thanks

Greg

[Geoff Weeks]

Ok, you asked for it.

I am expecting to be called "not fit to burn" by some, but many years ago I had to design a lift axle suspension with some very tight specs.  While none of that directly applies to your application one part does. I had to research and understand air bags as they relate to spring rate at different heights and loads.

 Simply put the more deflection under a given load the "softer" the ride will be.

 If you look at some air suspensions, the ones with the longest swing arm with the bags away from the axles, tall bags with rolling lobe type are the softest riding.

Pancake bags have the highest spring rate (smallest deflection for load change) of all the types, and single convoluted bags are the stiffest of all "pancake bags".

When you remove a leaf, you add more deflection for a given load, but when you add an air bag directly over the axle, you put that stiffness back in.

In an ideal situation you would want the air bag more toward the shackle end of the spring to allow more deflection, but this makes a sharp load point somewhere on the leaf spring and will eventually break the leafs.

Steel can have a soft spring rate or hard depending on how the spring is made.

Tandem axles have an advantage in that some of the dampening can be done by shifting the load between axles. Single rear and steer don't have that luxury. 

 A single convolute bag is just like a tire on its side, but much smaller diameter, and we already know how well tires dampen rough roads. They are better that solid rubber tires but far from what we expect.

 Ideally you would have the front axle spring deflection rate (spring rate) and that of the air bag you are considering and try and work out what removal of one leaf will do the the spring rate and adding the new air bag rate at the given ride height.

 All in all, I doubt any airbag placed directly over the axle is going to have much effect on ride. Double convolute would be better than single, but doubt there is room for such a bag.

The smaller the bag the stiffer it is at a given height, and the higher pressure required to maintain that height.

In my case, even with a deep dive into the way air bags worked, it took some trial and error in bag selection in both type and size, to get it as close as I could, and still was not ideal.

[Joey Mack]

Volvo did something with air ride on the front axle. Theres probably a break down of how its set up, i beleive the air bag is NOT over the axle, as GW states..

[70mackMB]

2 hours ago, Joey Mack said:

Volvo did something with air ride on the front axle.

Joey, Did you say a Volvo broke down because an air bag fell off the axle?      .....Hippy

[Geoff Weeks]

There were/are a few that mfg air ride for steer axles, and it is a complex setup.  steel leaves are great at taking side force as well as vertical load, Air is not!

[Geoff Weeks]

3 hours ago, Joey Mack said:

Volvo did something with air ride on the front axle. Theres probably a break down of how its set up, i beleive the air bag is NOT over the axle, as GW states..

https://www.truckcomponentsonline.com/NEWAY-ASASB-BUS-AND-MOTORCOACH-FRONT-STEER-SUSPENSION-FOR-I-BEAM-STYLE-AXLES_c_1515.html

https://www.hendrickson-intl.com/products/airtek/airtek-nxt

Edited Wednesday at 06:11 PM by Geoff Weeks