While setting up to remove the large side to side front end tie rod to remove the aux fuel tank in our 4104 I was running measurements checking front end alignment. Seems like I may have found the culprit of why our pass. side front tire wears the fastest on the outside tread. Da book calls for toe tolerance of 0 to 1/16" max. My measurements put it at 1/4". If I tighten the tie rod as tight as it will thread (+3/4 turn from where its been) it brings the tolerance to 0. Is there anyone versed in alignments that can say the excessive outside pass side front tire treadware could be caused by toe? By tightening the tie rod it closes the wider at the rear of the front tires from 1/4" greater than the front & brings it into spec @ 0" difference. The other perk is I found a hydraulic shop that was able to overhaul the original Vickers Power Steering Booster Cylinder. It's exciting working on a couple of these big ticket items as they have been a long time nuisance (leaky power steering & tire wear). Pulling the aux fuel tank just behind the front axle was a real PITA but glad I did - it needs attention & will also allow me to change out the last two radius rod bushings I couldn't do with the tank in there. Digging a little deeper into the ole' girl trying to ready the bus for a less eventful trip to Alaska this coming spring!
Have you pictures of the tire wear to share?
I'd call Luke at US Coach and see what he thinks.
Order something from him while you're on the phone.
Happy coaching!
Buswarrior
Sure on the photo. The tire closest when viewed is what every tire looks like, the tire farthest is the right front passenger side. The closest side of both tires are outside tread. notice how much of the outside tread on the effected tire has worn - that wear happened in just 12,000 miles. Is it possible that the toe condition created that? One thing I should mention is there is a constant slight pull to the right. All the king pins, tie rod ends, etc. seem to be tight, no slop.
Passenger side front outside tread
Every other tire outside tread
Aren't all GM buses positive camber on the left side and negative camber on the right side ? I know most are all 0 plus or minus a 1/16 th on toe in but not sure about a 4104.Those specs were set up for a 20 inch bias tire you may need to do a trial and error setting to you get where it feels right with no tire wear. The guys with the 4106's and 24.5 wheels I know are always changing the camber and toe in looking for the magic spot
Da book just shows one camber spec for both sides - it is positive, the 4104 is 0 - 1/16" toe. 10-4 on the trial and error, easy for toe but to change camber something would need to be replaced or straightened that is bent - at least that's what I gather from da book.
You are so limited on the camber on old buses it dosen't make much difference anyways you still have to use the steering wheel to get it back to center not like the newer stuff with 8 + degrees of camber
If you run the palm of your hand across the face of your tires side to side does the tread feel sharp when going one direction and not the other? Does the tread have a feathered look to it on one edge and not the other? If you don't have one or both of these conditions toe in is likely not the culprit or at least the main one. Usually one tire being worn off on an edge is not the result of toe issues, it is most commonly caused by improper camber on the same side as the worn tire. A tire that is worn on the outside edge usually indicates excessive positive camber ie the top of the tire is tilted outward too much. You mention that there is a constant light pull to the right - this is a trait of unequal camber between the right and left sides, and will usually cause a pull to the side that has the most positive camber, which fits your case - it pulls to the right and your right tire is wearing off on the outer edge. Camber is not easily adjusted on beam axles as changing it requires bending of the axle with the specialized equipment. I would suggest taking your 04 to a shop that does heavy truck alignments and have them check it. You say that the specs call for the same camber on the right and left sides. They can easily determine if they are in fact the same - I suspect they are not. That much outer edge wear in 12000 miles is definitely indicative of an issue.
On our 4104, an old alignment shop put some bend at outer axle ends to get camber correct. Your kingpins are tight?
Camber on city busses are different from right to left. The right side of the city road are always more curvy that the left side. That's why they compensate with different degres of camber. But i dont think that they do this on hiway busses. If you find a place to rebuild your Vickers cylinder ,be sure that they will be able to ajust it on a bench. It is realy a pain to ajust it in place. 1/16 toe in is a normal setting. Dont go less or more.
It is still a practice to offset the camber on trucks and buses today,I had it done on my DL3
King pins are tight with no play. Easystreet's interpretation seems pretty clear to me that Camber may be the issue. I've gotten a recommendation for Josam Truck & Frame alignment in Orlando FL. When I get the bus roadworthy I'll be taking it in. Thanks for the replies.
Is there a caster setting on a GM bus without heating and bending the axle ?
According to da book only toe can be adjusted everything else is either frame/axle altering or part replacement.
On straight axle vehicles usually the caster off will wear a tire to the inside from years of beating on the pavement and pot holes bending the axle up.Use a dial indicator and check the wheel bearing run out if to loose they cause a tire to wear on the outer edge.I don't think the 1/4 in toe in was your problem with a tire wearing on the outer edge
The 4104 caster cannot be adjusted. If you install the link assy. from a 4106 or4905, then you can adjust it. That is what we did with ours. Before doing that, we used tapered wedges on axle beam
Check also that the steering box and power assist is centered - they often have a "return to center" effect built in, and my wandering problem was down to an off center steering box. I had to center the steering box per the manual, set the front tires in line with the chassis and then shorten the drag link by over an inch to get it all to work out.
With respect to toe-in, make sure you are measuring in the same way as the manual wants you to. When I was racing, we did toe in/out based on the wheel rim. It was repeatable, and we did it by building a string box around the car, and measuring from the string to the wheel rim. My MCI manual says to chalk the tread of the tire, scribe a line, and measure at the tire tread, and 1/16" toe in is the spec. The alignment shop I took it to did it on computerized pads, and did a four wheel alignment with read out in degrees.
The cheap little line lasers are ideal for setting the toe in that all I use now