1997 Expedition Steering/suspension

[Guest]

Ok, I am going to sound like a idiot here. I need some info.

I replaced about 90% of the steering and suspension components on my Truck.

All new Eurethane bushings (yes, upper and lower control arms)
New Ball joints
New shocks, Rancho 9 position with cockpit control
Steering stabilizer Rancho
all new tie rod ends
new pitman arm
new idler arm
New steering box.

The box was replaced because the aluminum cover at the top of the steering box was cracked during the removal of the pitman arm.

Now, the steering is very precise, and has absolutely no play, but it is too easy to turn. To put it in simple turns, the power steering has too much power! It makes the truck anoying to drive at highway speeds.

How does Fords Speed Sensitive steering work on the Expedition? Is it a function of the steering box, and the box I got does not have this feature? Is it an adjustment I can make on this to lessen the power assist?

Has anyone done such work on their truck, and what results did you have?

Thanks for any help which can be provided!

Vincent
1997 Expedition 4x4 5.4

 

[Tibiko]

This is how it works:
The power steering system is a hydraulic assist to the mechanical linkage. The power steering system is equipped with an electronic variable orifice (EVO) integrated in the power steering pump. As the vehicle speed increases the EVO closes to reduce the hydraulic power assist to the steering system.
Vehicles with air ride suspension use the air ride suspension control module to monitor steering control for the electronic variable orifice steering (EVO) system. Vehicles with base suspension use the EVO control module to monitor steering system. Both systems on a panic or aggressive turn will default to full power assist. If there is any electrical system failure in the EVO system the system will default to full power assist.

I have the same high sensitivity on my 97 / 5.4 but I just got used to it. I do not know if there any adjustments you can do through the EVO control module.

 

[b_salgado]

Hello vincent..... I am assuming that you are saying that the Expedition is very jittery on the highway. Now this is gonna sound like a stupid question but here it goes..... Check your front tire pressure. Is it 35 PSI? If it is open your drivers door and look on the sticker. You will see that the front tire pressure is supposed to be 30 PSI and the rear is supposed to be 35PSI. This little difference in tire pressure will dramatically increase how the truck drives! I had the same problem in mine. I lowered the pressure in the front and all is fine in the world! The truck drives great! Just don't forget..... after tire rotations you will need to readjust your tire pressures! Hope this helps!

 

[Tibiko]

This is something I have never heard of.
My door decal speicifes all tires for 30 PSI, however is 35PSI - at cold - that means when temperature outside is below 30 .
I am not aware of different tire pressures for front/rear.
Maybe you misread the label.
Anybody on the list with any suggestions. I can take a picture of my decal but there is no doubt about the fact that pressure is 30PSI for all 4 tires.
Another mistake many are making is going with the pressure listed on the tire wall. That is the MAXIMUM pressure the tire was rated for. There are some cases when that matches car mfg. specs but in over 95% of the cases tires are to be inflated at a pressure lower than one on the sidewall.

 

[b_salgado]

Go look at your label again. I can assure you that it is 30 psi front and 35 psi rear. This has been discussed in great depths in the FTE and FTW forums. All tire pressures should be checked when tires are cold.... this means that you will not get an accurate reading of tire pressure after going down the road at 60 MPH for any length of time. Cold pressure simply means that the tires have been sitting and are at normal temp.... which would be the outside air temp. If you have a heated or cooled garage they would be the temp of the garage.

 

[PaulC]

I concur with Bryan's observations regarding tire pressure. On my 1999 Expy 4x4, it's 35 psi rear, 30 psi front. You definitely can feel a difference in steering feel at 30 psi.

BTW, when they refer to a "cold" tire, they mean one that has not been warmed up through use. In other words, the truck has been parked for several hours or more. It has nothing to do with the weather.

 

[b_salgado]

Thanks Paul I didn't think I was losing my mind. And you're absolutely correct... cold tire pressure has nothing to do with weather! LMAO!

 

[Tibiko]

I have to admit that you were right.
The Tire Decal for canadian cars is quite confusing with all the bilingual (engl/french) info and also metric/imperial values.
Actually, I took 2 of my co-workers out in the parking lot and show them the label. None of them could figure it out. However, your comments on this make more sense so from now on I would go by 30front and 35 rear.

 

[rwinch]

One more point folks, any change to the tire from the stock brand/type will effect what pressure to use.

Example: I have BFG tires on that are LT (light truck) not P (passenger car) type tires, which come stock on the Expy's. I keep front and rear inflated to 50psi, with an excellent ride (albeit stiffer, but that is to be expected).

So if you have changed tire brands/types, check the sidewall ratings, and keep them properly inflated.

Remember, Ford has had a notorious past with tire inflation pressures (remember the Explorer fiasco?). Ford commonly keeps the front tire pressures low to "improve the ride" i.e. nice and soft.