1998 concourse drifts to the left

[Flame]

This past weekend we took our longest trip yet in our new 1998 concourse. 600 miles round trip. Drove real good with 65 psi air in front and 58 psi in the rears but...I noticed I had a constant"drift" to the left no matter what road I was on. Not arm breaking but annoying. Had to keep a little right hand tension on the wheel at all times. More noticeable when you brake but not bad. Do you think swapping the front tires might straighten it up or do you suspect front end alignment? Tires still look like new and no bad wear pattern anywhere. Need advise from you guys who have owned and driven yours a lot more than me. Thanks

[b6fischer]

1) unequal air pressure
2) alignment

Getting the alignment correct early before tire wear issues is an important step.

Bill
1997 Concourse

[Kirah]

+1 for inflation and alignment. I take mine in for a tires check-up before every significant trip (more than a couple of hours each way), and before the first trip of any kind after it's been sitting around doing nothing on my off season. It's been much more pleasant to drive since I started doing that, and the tires are wearing better.

[Blue~Go]

I can't see any reason that over-inflation would make it pull to one side, but just as an aside, you might want to try it with the recommended pressure just for grins. Here is an inflation chart for the stock tire size. As you can see, you take the axle weight (which is a very good figure to have - I weighed right after I bought mine and many times since), divide it by the number of tires on the axle, and then find the pressure. You can deviate from this, but it's the recommended pressure so a good baseline.

BTW, you don't run different pressures on each side, if, say, the coach is unbalanced. You just divide the total axle weight by the number of tires and run the same pressure in every tire on that axle (then try to balance the coach by moving weight). Chinook seems very well balanced side-to-side as stock, which is nice.

Probably this isn't your problem, but just mentioning it.

BG

PS: When I was in stock form, I ran around 3100# on the front axle, with driver but no passenger - so that's probably a starting point for you. (I now have my spare on the front, a newer front end, and a larger sway bar and run around 3400#.)

Tire inflation guide.pdf

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[Flame]

Well Blue, I took my 98 concourse to the scales at our local sawmill yesterday and with me in it and 5/8 tank fuel,gray and black empty,fresh water 2/3 full it weighed in at 9640....soooo with my wife and a little water in other tanks and maybe a full tank of fuel I should come in at 9900-10000 lbs. Please help me figure out by your chart what air I should be running. If I read the chart right I would be running way less than my 65 front and 58 rear that I am presently running.

[Blue~Go]

I thought 65 sounded a bit high for typical weight. I still don't think that should make it pull, presuming both sides are inflated equally; but knowing weights and tire pressures is still good.

So for the chart, you need to know your front and rear axle weights. If you went to a CAT scale they may have them listed as "steer" (front) and "drive" (rear).

For comparison, here is the weight I did on my way home from picking up my Chinook. I did have all the stuff from my camper van loaded into it, so not empty by any means (I could barely clear a place to sleep!).

As you can see, my total came to 9,940# at this weighing. If you don't have your axle weights broken out, you could probably use these weights until you can do so. So in this case (my Chinook back in 2014), I had 3,060# front, and 6,880 rear. Note that I did not have a passenger, and I'm not a big driver.

So let's go through the steps of using the chart. First, we divide each axle's weight by the number of tires on the axle. So front axle has two tires, and 3,060# ÷ 2 = 1,530#.

Using the green line on the chart (single wheels) we see that the recommended pressure for the front tires at 1,530# load on each tire is actually below the minimum chart rating of 40psi. That doesn't necessarily mean you should run them at 35psi though, I don't think. I take that to mean that I should start at 40psi and then add pressure until I like the way it handles. Being at the very very bottom of the range obviously makes it a bit different. Also now I'm at closer to 3,500# (1,750#) on each front tire, so now I'm theoretically at like 44#. You are probably a bit higher in front already due to having a passenger. So not knowing your precise front axle weight, I'd say start at 45# and see how it feels. Nothing wrong (IMO) with adding some psi above that, but clearly you likely don't need 65#.

Okay, now we'll do the rear (for my original scale weight). I was 6,880# on the rear axle. So dividing by number of tires we do 6,880 ÷ 4 = 1,720# Now we look at the blue line on the chart (because that is for dual wheels, which are de-rated a bit due to heat I think), and for 1,720# we see they recommend about 48psi per tire. One thing to note especially is the fuel level if you weigh without a full tank. That's because a full fuel tank in our rigs weighs about 250# (in fuel) and it's behind the axle. So it would add something like 75# per tire. Same with black and grey tanks (way back there) vs. potable water tank (up forward of the axle). Upshot is that unless I'm chock full when I weigh, I add some additional psi to the rear tires.

Hope that helps explain the weighing/chart/psi. These are guidelines put out by the tire mfgrs, btw. There are also psi recommendations on the door jamb but they are only listing what they *think* your weights may be, because they are making up the stickers while the rig is being built and they have to estimate something. Scale weights are just exactly what you DO weigh.

I don't know how it works in Texas or nearby states, but some states (eg Oregon and Washington) leave their public highway scales on even when the scales aren't "open" for trucks. So anyone can drive in during those off hours and use the scales. It's fantastic and oftentimes you can be there for 30-45 minutes without anyone else pulling in. I've used these to not only weigh the axles, but do the left and right sides, plus weigh my trailer(s) tongue and axles. Super handy. It's usually a bit more rushed at a CAT scale and you can't do all the permutations.

[Flame]

Blue they don't have a way to do individual axel I guess. I drove up on it and a lady walked out and handed me a yellow sticky note with my total weight on it. They didn't charge anything and the nice part is it is only 2 miles from my house. I realize no matter what pressure I run as long as they are the same it should not pull to the left. I also know if I am going to get a front end alignment I need the vehicle loaded approx. with the weight I will be travelling with. They don't make 2 tires exactly alike either. They are radials and there could be some variences. I checked inflation and they are all still even. That is why I am thinking of trying a old trick and just swap the two front tires to see if that brings it back to center. I have seen that work many times over the years.

[Blue~Go]

I think that even if it's one single scale, you might be able to just pull the front wheels onto the platform, have them weigh, then pull ahead so just the rear wheels are on and weigh again. Or else you can always go to a CAT type scale - they're at many Flying J, Pilot, Love's, etc. They do steer and drive as a matter of course without asking. Just the one figure doesn't help too much with axles/tires, but it's still interesting.

[dougm]

That is incorrect... do you think ford takes the time to load each van or cutaway with tonnage prior to doing an alignment at the factory? Improper toe will cause the vehicle to pull, worn out ball joints, worn out tierods, worn out gear box. Caster will also cause the vehicle to wander, a bad tire, can cause a pull. Take it to a reputable shop (good luck) tell them you want the maximum amount of caster they can put in it and have them check the tierods, ball joints, ect..... Aligning twin I-beam fords is a compromise when setting camber and caster because the same eccentric bushing is used for setting both.... Dont bother with the dual eccentric alignment bushings because you wont find a shop that has an employee smart enough to figure out what he is looking at let alone actually use one. Before you walk out of the shop you want a print out of where they placed all of the settings for your records.... Also take the time to look up the OEM alignment specs on a Ford E-350 superduty cutaway van before taking it in, that way you know when you look at that print out if they did it correct or not..... also keep in mind that just beause the print out numbers appear in green does not mean its properly aligned...... lets say the book call for 1- 6 degrees of caster, the mechanic sets one side at 1 degree and he sets the other side at 6 degrees, theres going to be a problem driving this vehicle because there is to much variance from side to side even though his machine is telling him he is within spec and he is telling you that its all within spec.... the reality of it is that there are very few mechanics that actually have a full understanding of what they are doing when it comes to alignments. You would be best served to skip the tires plus, kmarts, walmarts, tire shops and take it directly to an actual medium duty truck shop because they work on these types of suspensions all the time. Ford builds trucks with the assumption that you the consumer arent going to overload the vehicle and exceed its manufacturers load carrying capacity. If you modify the vehicles suspension then you open up a different can of worms.

[Flame]

dougm, Thanks for your input. I was going based on when I used to do front end alignments myself although 30 years ago. But my concourse is 20 years old!! Anyway, we were taught to first check all front end parts for wear and replace before aligning. Then make sure you had 4 good tires. Then make sure you had at least even air pressure. The reasoning behind getting it aligned with your full load is simple. If you line it completely empty and then take it out and load it down with everything you will totally change the level of everything and the added weight especially on the front axel WILL change caster/camber readings!. That is why we recommend you get it lined with a load you most commonly carry. But I totally agree that finding someone that really knows what they are doing (or care) what they are doing is extremely hard to find. And yes Ford has still come a long ways from the old KING PIN set up. I used to hate replacing those!!