Air assist steering

Timkar · February 11, 2007, 04:57:38 PM

I have just brought my Eagle 5 with air assist steering home. Works fine at low speed, but get up over 30mph and it seems very "choppy" when turning. I have the brochure from the previous owner stating it is an "Air-O-Matic" unit from Sycon corporation. Anyone familiar with these or have a troubleshooting guide?
TIA

NJT 5573 · February 11, 2007, 07:16:55 PM

Tim, I've got a similar unit on one of my KWs. They are pretty basic. Mount to drag link. I guess if the mount bolts were loose you could notice some problems with it jerking the steer axel around. The brain is pretty fail safe, mine has been in service 20 years without a problem. I suggest if the brackets are not loose you start by checking the toe. You can use a tape measure and go side to side front and back of the steer tires and get a pretty good idea if you are out. The front and back on the side to side should not show more than 1/8 inch difference. If you don't find it there, jack each steer wheel up togather or seperately and use a long bar (like 6 or 8 feet) to insert into the wheel holes and pry on each wheel in all 4 directions. Also look at the shim packs where the top A frame bolts to the frame to make sure that it has not lost a shim pack. When the tires are jacked up spin them and make sure they are round and that you don't have a ply liner failure. (The tire failure is my first guess).

TomC · February 11, 2007, 10:35:02 PM

I had the same air steering on my transit when I bought it. It worked fine around town below 50mph. But when at freeway speeds had to do a lot of steering to keep things running straight (didn't bother me since that's the way my first truck drove-but bugged the wife). Also, the steering was painfully slow (translated-lots of wheel turning to go around corners). I checked all fittings on the front-all were tight. What was the slop was just the actuating valve for the air cylinder. Well with 8 1/2 turns lock to lock, it took 3 or 4 tries to back into my warehouse. I scored a Sheppard power steering unit and changed it over to full time hydraulic steering. Now the steering is 3 1/2 turns lock to lock and I can back into my warehouse on the first try with one finger steering. My steering box is mounted on the axle-I believe the Eagles are mounted on the frame like a truck with a drag link to the axle. If that's the case, you could get a truck box and change it over (heard a Mack truck steering box is what you use-but don't quote me). It has made driving the bus truly fun. Out of all the mods I've done, changing to hydraulic steering was the most dramatic-very glad I did. Good Luck, TomC

Dave Siegel · February 12, 2007, 09:06:14 AM

Tom, would you be willing to share how you made the swap? Right now our PD3751 has "Armstrong Steering" and it's really what you call "painful" steering. I would love to be able to change the steering to hydraulic.

The set-up now is: The steering column attaches to the steering box which is under my feet. I guess it's mounted to the frame. There is a steering arm at the bottom of the box that is attached to a drag link. (Leaf spring front suspension)

That's our set-up......think it would work?

Dave Siegel

pipes · February 12, 2007, 10:30:04 AM

Hi Tim...I am glad that you found yourself an EAGLE!!! When you were here, looking at my eagle 05 did you notice that I had installed power steering ? If you want to stop by or call me I might be able to help you.
three six zero 629 4308.............Ken Turner

Timkar · February 12, 2007, 07:24:14 PM

Thanks to all for the reponses.
Ken..yes I remember, I'll check the pictures I took...This is the second Eagle..the one I got last year was a 15. I ended up with this 5 because the guy had a lot of spares (from maintaining a fleet over the last twenty years) and it was buy it all or nothing....

TomC · February 12, 2007, 10:57:43 PM

Dave- since your steering column is directly attached to the steering box, you might have to change out the whole thing. Then you have to consider your column shifter!? If it is just clamped to the existing steering column, then you could do the swap. I would look into scoring a Freightliner steering column, match your manual steering box to a power unit, then the steering column and steering box can be attached together by a custom length made drive shaft.
I would first see what the make and model of your steering box is now and do some research to see if there is a steering box that could be directly connected to the steering column. I don't know since most trucks use the steering column-drive shaft-steering box set up. Give me a few clues and I can do a little research for you. Good Luck, TomC

Runcutter · February 14, 2007, 01:36:04 PM

Tom, I'll second Dave's request for more information on your steering upgrade. Our 4107 also has, at least, Armstrong steering - and sometimes I think it's TMSB steering (Two Men and a Small Boy). I've seen archived posts, heard comments about retrofitting Sheppard power steering (if I recall, some have mentioned stripping the ps out of an RTS.

Lack of power steering sure does limit the "fun factor" - it wasn't an issue when I was driving non-ps transits, but I was in my 20's then (ahem).

We don't have access to a shop (hoist, pits, etc), so I couldn't do the work myself (and, after a recent hernia operation, my wife probably wouldn't let me anyway). So, I'm interested in experience, costs, and any recommendations for who could accomplish such a retrofit.

Thanks for your help

Arthur

Busted · February 14, 2007, 05:31:18 PM

Air o matic suggested putting a switch to shut the air off when underway, which we would do. We used to use the old bifold door switch on the 05 since it was right there. Check into it, there might already be one there.
That reminds me of hot wiring the high idle, the old time cruise control!
Good Luck

TomC · February 16, 2007, 03:51:55 AM

Runcutter- I believe your steering setup is the same as mine in that the steering box is mounted on the axle. Part of the increase in steering speed comes from changing the 90 degree gear box (or miter box as it is sometimes called) at the base of the steering column that changes the direction of the driveshaft for the steering box by 90 degrees. My manual steering box equipped bus that had Air-O-Matic steering had a miter box with a 1.5:1 ratio that made the steering a little easier, but boy did you have to turn the steering wheel alot. What was changed was the actual steering box on the axle, changed the miter box to the 1:1 ratio, the drive shaft from the miter box to the steering box had to be shortened since the Sheppard box is much bigger, run two hydraulic lines to the rear of the bus, install a steering fluid reservoir, install the hydraulic pump on the back of the engine. I too have the 8V-71, and luckily my engine already had the steering pump drive on the back with just a plate over it. I had the steering box overhauled, and bought a new Vickers hydraulic pump since the old pump that came with the steering box did not put out enough pressure (towards 2000psi). It cost about $2500 (I had other work done at the time, so just an estimate). EXTREMELY worth it. If you have to post pone other projects to get the power steering installed. It makes driving the bus really enjoyable. Good Luck, TomC

Runcutter · February 16, 2007, 04:05:42 PM

Tom, that's just the information I was looking for. I remember driving 4905's in downtown Boston, which makes the non-ps 4107 seem that much more uncomfortable. Your experience is also in the price range, and I want to get the work done (along with new tires) before the next major trip next Summer.

Now, I'm shopping for someone to do the work.

Arthur