M35a3 air steering issue

[HFDm715]

how well is the air assist on your m35a3? for normal road driving its ok, but when we (fire dept) take ours in the woods for Fires, it just seems as bad as manual steering, Im thinking its the nature of the beast but wondering if Im correct?

Duane

Helmetta Fire dept.

 

[Hoefler]

Few things to do.
First, look up under the frame near the steering box. There is a pressure regulator-take the cap off and set it for full pressure. Follow the line where it exits through the frame-there is a hose that is prone to leaking that goes from the bulkhead fitting in frame and to the pitman arm. Most leak-put some soapy water on this and check it. Last-check that the air valve on the firewall (driverside)-top is full open. If its partial open, it will restrict flow to system.
The hose I mentioned-its probably there where you will discover the issue.
If its none of the above, it could be a bad cyclinder.
If its not bad cylinder, may be an armstrong issue. Solve this by lifting large objects repetitively!

 

[gimpyrobb]

In addition to checking the air supply, you can always find a larger diameter air ram to replace the one you have. The original system had 3 size options.

 

[Hoefler]

Didnt know this-where does one find info on this?

 

[gimpyrobb]

Check the installation links at the bottom of this link.

Air-O-Matic: Maradyne

Edit, the "AOM service document" shows 5 different cylinders with 2 different bores.

 

[rrrr]

My air o system works great at low speeds. I did not install the regulator on mine since its a high failure item. Do a search lots of info on the subject.

 

[3dAngus]

I thought mine was great when I sold it to Riddle1.

He found an adjustment for the air steering and said you could move it with a pinky finger after he adjusted it, with tires sitting flat on the ground and not moving.

I would contact Tripp for the adjustment. I asked him to picture and post, but not sure if he did.

PM Riddle1.

 

[Hoefler]

The system operates fine at the maximum pressure the air comp puts out. I did notice that the regulator mounted to frame is very small. Regulators and solenoid valves used in comp air systems have a "CV" value. CV value refers to flow. The greater the size of valve and ports-the greater the flow. Judging by the air cylinder size and the size of the pressure regulator, I would say there is a flow problem through the regulator. Running without the regulator will help to increase flow to air cylinder.
I have two A3 trucks-one steers easy, the other is a little harder. I do notice the easier steering truck affects the air pressure guage in the truck much more-when turning, the pressure goes down quicker. While on the harder steer truck, the pressure guage is more lazy when turning. Indicates issue with regulator and flow. If air cant get to cylinder, the compressed air reading wont be affected as much.
My two cents worth.
Pete

 

[Deuce007]

while we are on the topic I have a question also. When I turn the wheel it turns a few inches then it has a tough spot then I turn it a few more inches and it is easy but when I turn it more there is another tough spot and so on. any ideas or is that how it is for everyone?

 

[Hoefler]

Not sure but that sounds like flow.
It acts sort of like a fuel filter that is plugged. Turn a little and the reserve air volume in piston is able to move the steering wheels until that compressed air volume is expanded in cylinder-when you are hitting the hard spot-perhaps the flow through system is "catching" up then when air cylinder is replenished with compressed air, it is able to assist in the steering until it is fully expanded...
Check your valve on firewall-it may be partially closed (restricting flow). It could be you have some junque stuck in the orifice of your regulator. Seems like my truck sort of does this.
Pete

 

[gimpyrobb]

Could be a rust spot(in the cyl) too. Have you added oil to the system at all? The compressed air contains moisture. Also, when you were talking about "flow" Those PDFs in the link I posted showed some with 1/4 air lines and some with 3/8 air lines. You might want to look at that too.

 

[Hoefler]

1/4" port is way to small for a cylinder of this size. Smaller the port-the slower the piston extension. Add to the possibility of crud in the port-and you have issues keeping the air cylinder charged.
The stuff we build here uses 3 and 4" air cylinders. We have found small regulators really affect the speed of an air cylinder.
I was surprised at the size of the regulator on my truck-it looks like a 1/4" size. My truck didnt power steer at all becasue of leaking hose-barely leaking that went to the pitman arm. I replace and cured the leak-steering got better but still not good-its a good bet that the regulator is clowning my steering up.

 

[gimpyrobb]

I agree, 1/4 would be too small, just pointing out "some" of them might be.

On a side note, I got an air assist kit from an A3 and it doesn't seem to have the low-air-saftey valve. I looked in the A3 TM and didn't see one listed. Do the A3 truck's air assist not have the low air cutoff valve?

 

[camp9]

This is great, you guys have covered everything that my truck is doing, what a big help. When it warms up I'll have another project. Thanks!!

 

[Hoefler]

Not sure about the low air cut off switch-didnt know there was one. If it does have one, it could also contribute-perhaps it holds air in when pressure drops and lets air out when full pressure. Given the air cylinder is a two way unit-if air cant get out-it cant get in (assist).
There sure are a lot of bits and pieces to these trucks-it is fun discovering them and understanding how they work. Some of the design features are more seemingly committee designed as opposed to practical engineered.
Pete

 

[HFDm715]

sounds like I have a good starting point to diag, will hopefully find some time this weekend, I have a pinewood derby car to finish for sunday so that takes priority for this week, but will post if i find anything or not.


Thanks

Duane

 

[a1abdj]

Add me to the list of those who simply took the regulator off. Works much better now.

 

[Rustygears]

The stock regulator, when not leaking, supplies plenty of air to run the steering. It has more than enough capacity to bleed down the truck air faster than the compressor can refill, even at high rpm. There is no need for larger hoses or setting the pressure higher than that indicated in the TM. My A3 has a replaced stock reg and steers with one finger with TM spec pressure. I installed a schrader valve in the plugged monitor port so I could set/check the steer system pressure. Check the posts for info and pictures.

The most common reason for dead zones and flat spots in steering is crud/corrosion in the drag link control valve. Tons of posts on this. It's an easy fix. Disconnect the air supply from regulator to drag link at the link valve side. Pour a little air tool or Marvel Mystery Oil into the drag link inlet and reattach the air supply. Air up and work the steering wheel in both directions to actuate the control valve thoroughly. Repeat a few times as necessary. This will usually free up and clean up both the drag link control valve and the ram actuator.

Next, fix the root cause. Confirm the regulator and fittings aren't leaking (often are). Fix as necessary. Then service the Haldex air dryer next to the spare tire. These are usually poorly maintained and gummed up with snot. Replace the filter and desiccant cartridge. After this is done you will likely never see liquid drain from the wet side air tanks again. It will stop corrosion of the steering, CTIS and brake packs.

 

[tco3129]

I have a pinewood derby car to finish for sunday so that takes priority for this week, but will post if i find anything or not.

HFDm715 Let us know in CONVERSATIONS how the race went. BTW kids particapating is the real win.

 

[HFDm715]

ok, will post the race AAR. LOL

Duane