Air Shocks on Class 8 "D" Truck

[sweetbillebob]

I tuned into Keven Rutherford last week and caught the last part of a discussion regarding putting air shocks on a class 8 tractor. Has anyone tried or know of using air shocks on their C/D truck? We are front axle heavy and have to increase air ride height to max to keep from bottoming out. This makes for a very stiff choppy ride. I was thinking that by adding air shocks, if they are available, I could reduce ride height on front axle to nominal, making life a little smoother.

 

[guido4475]

My truck was a class 8 that had a c-15 cat with 400 gal fuel capacity,so you can imagine why the empty weight on the front axle was at 14,200,full of fuel.I took it to Certified Alignment in Detroit, and we replaced the springs and added a leaf also, giving it a capacity of 18,000#. You would think it would ride rough, but it actually rode very well, not choppy.And I also put 16-ply front continentals on the steers also.There is a tire that Prevost coach uses, but it requires a rim 1 inch wider than standard.It is a 12-inch wide tire, instead of the usual 11.Check your road atlas, and you will be surprised at what different states give you on the front axle for weight capacity.But your tires had better be able to handle the weight for what you have on the axle at the time of inspection by the scalemaster.And Michelin makes a tire that says "nominal width tire" that also is legal for heavier front axles, without using floaters.I dont think I would trust air shocks.What if one of them blew out?The sudden drop in suspension height on one side could cause dome seroius problems going down the road.

 

[greg334]

Read this;

Air shocks are not shocks, they don't have the ability to control movement in the suspension system because they are an medium pressure air cylinder and nothing else.

AND

The use of air bags which give added support to the frame for any given load, is recommended over any thing else. It allows the shocks to do their job without changing the geometry of the suspension or altering the alignment.

 

[moose]

Call Hendrickson from Wisconsin,
they have the best tech advisers :

Tractor Suspension Systems - Hendrickson

the after market kit , will do the job , its have a remote controlled valve that you can adjust from the cab for changing road conditions ,and you can take it to the next truck .

there are other products out there .

 

[guido4475]

Read this;

Air shocks are not shocks, they don't have the ability to control movement in the suspension system because they are an medium pressure air cylinder and nothing else.


I do agree with you here, Greg.
AND

The use of air bags which give added support to the frame for any given load, is recommended over any thing else. It allows the shocks to do their job without changing the geometry of the suspension or altering the alignment.

But here, I cannot agree.There are proper ways to add leaf springs to a vehicle, especially the front, and maintain the proper ride height as well as alignment and characteristics.

 

[layoutshooter]

OK, it's I have NO idea stupid question time. My current front end capacity is 13,300lbs. NOW, IF I change and add springs as mentioned above, put on the different rims and tires, do I STILL have to change the axle itself to a heavier axle? I am ready for all the laughing you care to do but I NEED to learn and this forum is one of the better places for that!!! LOL!!

 

[greg334]

But here, I cannot agree.

But here Guido, I am not talking about leafs in the springs but air shocks......... and air bags....

Using an air shock, to replace the regular shock removes the damping effect of the shock. The OEM shock has a specific valving that allows the shock to react to the 'vibration' of the axle or frame.

An air shock is a big old fat cylinder that is filled with air and the only thing that happens there is the compression of the air when there is a load put on it which prevents it from contracting when it should - make sense.

IF you replace an shock with an air shock and charge it to say 150 psi, it is the same as lowering your air bags, the shock is now hard enough to prevent that air bag and the suspension from functioning properly.

Air bags on the other hand are made in such a way where they act not as a hard support for the suspension but is allowed to expand and contract.

As Moose pointed out, I would think the Hendrickson Air-Tek system is the best if anyone wants to get an air bag ride. If I was going to buy another truck, I would put that on it.

The leaf thing is very doable, I had them added to some of my trucks in the past.

 

[layoutshooter]

Did you have to change axles?

 

[greg334]

Did you have to change axles?

Who me?

NO I had 12k axles on the trucks I ordered, but the trucks were rated below 10k GVW. The reason I added leaves was because we always loaded them to capacity when we would clean out a warehouse or store and always busted springs on one truck.

 

[layoutshooter]

OK, my total front end capacity is 13,300. IF I want to up that I would have to change the following: the axles, wheels, tires and springs. Am I correct? I get confused SO easy.

 

[greg334]

OK, my total front end capacity is 13,300. IF I want to up that I would have to change the following: the axles, wheels, tires and springs. Am I correct? I get confused SO easy.

Yep, check out the link moose posted and look at their axle replacements.

 

[layoutshooter]

Thanks, Greg.

 

[RETIDEPXE]

We have Donvel air springs on the front leafs and they have a patented valve that you put in the airlines that prevent the snap back affect air springs produce, works very nicely on my FL M2, they do everything their web site states; DVI - Donvel Ride Control Systems.

Not sure about increasing front load capacity, i have a 12k# frnt end and it rides smooth enough with the 96" sleeper, Cat C-9, class 7 so not too heavy. The folks at Donvel can answer any questions you might have, i found them to be affordable as well.

Just my 2 cents,
Retidepxe