Alignment Specs

[High Road Travelers]

Yesterday I had my motorhome aligned because I was getting wear on the outside tread of my front tires. Below is a copy of the report from the truck shop. I am ignorant as to proper alignment specs, so can someone tell me if it looks like the alignment was done properly? It seems to be pulling slightly to the right now, but I only drove it a short distance home. It is too windy to drive it today. GVWR is 24K and wheels are 22.5". I have 25,000 miles.
I have a Safe-T-Plus steering stabilizer; could it need adjusting after the alignment?
Thanks for any feedback.

[mr.tommy]

I have a gas MH on a F53, 22K chassis, with 42,500 miles on the clock and I had the same problem the last couple of years with my front tires wearing more on the outside. I had my alignment checked and it was perfect and at the time I was running 83-86 PSI which was right for my weight. I had Michelin tires at the time which tend to be a softer rubber tire.

Remedy was to increase the tire PSI to 90-95 and not take as aggressive turns—aka slower turns—which prevented the outside of tires to dig in more and therefore wear less on the outside. That fixed the problem. I have since replaced all 6 of my tires to Toyo M122's because my others dated out.

[High Road Travelers]

Thanks Mr. Tommy. I forgot to state that I usually run 80 - 82 PSI in the tires, trying for a less harsh ride, and the tire chart indicates that I can run 70 lbs. for my weight and tires (which are Michelin).
I think I will try moving the psi up towards 90 lbs to see if that helps with the wearing and doesn't produce too harsh a ride. I do a good bit of mountain driving so am doing a good bit of turning.

[TFell]

You have some positive camber, which means the tops of the tires are tilting out slightly if you were looking on from the front. There is not much that can be done to change this except to bend the axle. Positive camber will cause the outsides of the tires to wear.

While adding pressure will help move the wear to the middle of the tire, I expect that you will feel a big increase in harshness at 90. Mine was set at 90 when new and dropping to 80 made it much less harsh. Pressures should be based on your weight and the tire charts, of course.

You have .28* of thrust angle, which means the rear axle is not pointed straight. That can steer the coach one way or the other. Not sure which way yours is pointed though.

You have equal caster on both front wheels. I had a shop give me more caster on the right than the left so that it would compensate for crown in the road. My coach pulled to the right. This is called cross caster. You want to give the right front wheel a “lead” up the hill that is the crown in the road. I believe I have .2 or .3 more caster in my right than left and it made a nice difference in straight line tracking.

[tiffy2000]

It s possible that the SafeTsteer needs to be adjusted, mine pulled to the right and I just loosened up the clamps (with wheels straight ahead) and re-tightend it...it stopped pulling to the right....I think it must have slipped with the rough roads that we hit on our retirement trip. It may take a couple of adjustments with test rides in between

[TeJay]

Wade,

They didn't do you any favors as far as your caster angles. The stock max Caster is 5.4 degrees. We've had many other owners use caster angles closer to 6 and even higher degrees. There's absolutely nothing wrong with setting the caster closer to 6 than where they set it.

Ford has one caster angle for every vehicle they use the F-53 chassis. They don't care if you have to struggle to keep your RV going straight down the road. You've driven enough to understand it's CASTER that brings your front wheels back to the center after making a turn. The weight of the front of the vehicle forces the tires to return to center. Keeping your caster at positive 5.4 degrees is not enough for an RV.

Caster also allows one to drive a bicycle with no hands. The backward or positive angle of caster allows your weight to keep the bike wheel straight ahead.

Some shops refuse to set the angle any greater than the 5.4 that ford states. That just makes them less informed. A good experienced tech would set yours at 6 or better.

[Fiesta48]

My GY G670s were wearing on the outside more than the inside tread. I found I had 3/8" toe in. I simple drag bar adjustment fixed this, I did it myself.
I was at 100psi on my DP. Have gone to 110psi on new fronts to reduce wear.
Added Roadmaster Reflex steering assist for safety and winds.
Drives much better all around now.

[Jpiland]

Questions: Print out?
You have a F-53 chassis. Why are they using an Allegro Bus for your specifications? Shouldn't they have used a F-53? I doubt that the specs are the same, because Tiffin custom builds there chassis. Just my 2 cents.

[High Road Travelers]

I talked with the Service Manager at the truck shop today and he checked the specs that were used for the alignment, and they did mistakenly use specs for an Allegro Bus (I have an Open Road "gas"). He was very nice and apologetic and asked me to bring it back in at my convenience so they could do it right.
Tejay, when I take it back in Monday or Tuesday I will ask them to set the caster at 6.0 degrees.
Is there anything regarding camber or toe that I should specifically ask about?
Thanks for everyone's assistance; I feel much better now.

[TeJay]

Wade,

"Tejay, when I take it back in Monday or Tuesday I will ask them to set the caster at 6.0 degrees. Is there anything regarding camber or toe that I should specifically ask about? Thanks for everyone's assistance; I feel much better now."

They should set the caster to what you want. It is your vehicle and many of us have had the caster set to more than Fords specs call for. One excuse they use is a more positive caster will make it harder to steer. Technically they are correct except name me one vehicle that does not have power steering. The steering wheel gets harder to move because the more positive the caster the more front end weight is being raised as you turn the steering wheel. You are lifting the weight of the front end.

Another excuse they use is, It's beyond Fords recommended specs. Well Ford does not change settings based on the chassis use. They just don't bother. Ask them what's going to happen if they set it to 6 degrees? They won't have a good answer because the RV will just handle better as you drive down the road.

There is no good reason not to set the caster higher. Just insist they set it where you want it. You will be very happy you were insistent.

My alignment guy who had worked in the field for better than 30 years sets all his big rigs to 1/16" total toe in or 1/32" for each side. Setting the toe angle is really a crap shoot. Ideally you want the tires to move straight down the road with the tires not angled in or out. That won't work because as the steering parts wear the tires will move from straight to a toed out position. Setting the toe in slightly allows the toe angle to change from very slightly in to neutral and then to out. The more the parts wear the more the toe angle moves out and then the tires wear.

The thinking is simple. If you begin with the tires toed slightly in the weight of the front will force the tires out very, very slightly which is then actually more to where they should be. If you start with the tires toed out very slightly it gets nothing but worse as more wear occurs.

The suspension wear takes a lot of miles but I think one can see why it's smart to start toed in slightly and why it's done.

Camber is another story. The straight cast iron axle determines how much camber or in and out tilt of the wheel occurs. To change it the axle has to be bent cold as pointed out by another poster. Ford does not recommend they any technician try to bend the axles. My guy did bend our axle using chains and hydraulic jacks. Both side were off. Technically Ford should change the axle but that won't happen. It can be done but most
shops won't even try.

So there's really not much you/they can do about the camber angle if they even bother to measure it. All you can do is monitor the tire wear and if you see tire wear due to a bad camber angle take it to a dealer for warranty work to have the axle bent of replaced. A good point is we don't read much about improper camber angles wearing tires on the F-53 chassis.

[NXR]

Attached is the before and after for my 2019 F-53 22,000 GVWR chassis. Note that at the top it says it's good for everything up to and including the 22K chassis so not your 24K chassis but the numbers cannot be too different.

You might want to print mine out and bring it along to compare to yours.

The Ford Commercial Vehicle Dealer tech who does all of the alignments for the local RV dealers said he had been seeing them come through with above-spec caster for a few years.

Changing the caster requires the addition of physical shims so it likely will not be cheap. I paid $135 two years ago for the alignment only.

The only thing that can be easily changed is the toe. The Ford tech, even though mine was technically in spec, made a slight change to make it drive better in his experience.

Anyway, this should give you a good idea. Honestly, yours does not look too bad so I'm wondering if the tire wear is coming from front end parts wear like the king pins.

Who does your annual greasing and do they grease the kingpins both with full weight on the front tires and with the tires lifted a bit to unload the kingpins?

The Ford dealer tech readjusted the Safe-T-Plus as part of the alignment and his test drive. I would suspect that having a Safe-T-Pus takes the place of adding extra caster.

FWIW,

Ray

[TeJay]

NXR, Thanks for posting. That's all good information for those wanting to have an alignment. Any experience like you had is good to read about. We need all the honest and quality help we can get from the decent shops we encounter.

A price of $100 to $175 isn't to much for sure. I had mine done in 2014 for $160 and that included: toe, caster and cold bending both sides of the axle for proper camber.

Adding shims isn't really a big deal. The metal shims come in degree ranges and all you do is loosen the U-Bolts that hold the leaf springs to the axle and slip the shims in between the leaf spring and the axle. They have all the proper tools so getting the nuts loose then re tightened and torqued is no big deal for a technician.

Some will tell you if you loosen the big leaf spring U-Bolts they need to be replaced with new ones. I really doubt they would do that every time they did an alignment. But I could be wrong. I know I loosened my front U-bolts to install a plate for my steering stabilizer and didn't change the U-Bolts and that was 35,000 miles ago with no adverse issues.

[NXR]

Originally Posted by TeJay

Adding shims isn't really a big deal. The metal shims come in degree ranges and all you do is loosen the U-Bolts that hold the leaf springs to the axle and slip the shims in between the leaf spring and the axle. They have all the proper tools so getting the nuts loose then re tightened and torqued is no big deal for a technician.

Perhaps you have confused the amount of actual work performed with what is charged.

a.k.a."You don't pay me for what I do. You pay me for what I know."

Ray

[TeJay]

NXR,

Absolutely correct. It's a combination of both as you mentioned. The amount of $$$$ charged is supposed to be based on the cost per hour time the number of hours. Plus list price on parts. That cost per hour will vary from state to state as well as location within those states. The flat rate per hour is supposed to be based on the local economy. If you live close to a big city the FR/H will be higher than say a local shop out in the small towns.

I did not work as a line technician but over the years have talked to many who did. In addition I've know manufacturer dealers who charged based on the size of your wallet. There are also those out there who will do work not based on actual needed repairs but based on what they say are needed repairs. That type if dishonest stuff will always happen unfortunately.

If one knows something about what repair is being done they can ask some good questions. Asking to be shown before specs and after can help. Asking a tech to show or tell you why something needs to be replaced can also help. There will always be those who take advantage of folks many times based on sex and age. I've talked to hundreds who were ripped off.

If you are in my area I can advise you of good honest places to have repairs done as some can attest to. When traveling and needing repairs that's another bad situation as well. Many on here do ask for suggestions when folks need help while traveling.

I still believe the best approach for folks is to list the symptoms of needed repairs and ask for some advice. Even the OP for this thread told us he had 25,000 miles on the unit. In MHO king pins should not need repairs with just 25,000 miles but it is possible. That's where a second opinion comes into play.