Help! Allison transmission control problem!

[michaeldterry]

It is on a data plate, typically located next to the driver's seat. It will list individual axle weight limits and maximum gross weight.

Using those weights you now need to look up the tire pressures for each axle.

http://www.michelintruck.com/micheli...ion-tables.jsp

My guess is you are seriously overweight and should start considering how to bring those weights down to something near the limits for your coach, or recognize that you may have to adjust your driving habits to compensate for the additional stresses those excess weights impose on your air bags, brakes, bearings, etc.

Jon - you were correct with your guess. The data plate shows:

• Steer axle - 14,600 lbs
• Drive axle - 20,400 lbs
• Tag axle - 12,000 lbs
• Gross weight - 47,000 lbs

That puts me almost 3,000 lbs overweight! Ack!

On tire inflation table. are the weights listed per wheel or per axle? In other words, do I need to divide the numbers by two (for the steer axle and tag axle) and by four (for the drive axle) to get the weight per tire? I'm confuzzled!

Any ideas on how to shed weight? I'm already on a diet and have lost 18 lbs since December 14th on my way to losing 65 lbs. I don't think I have enough to lose to get Evangeline under weight, though!

[phorner]

Unfortunately, some of the heaviest items can't be moved: generator, refrigerator, fuel tank, etc. so you will need to be creative with both your amount and placement of personal storage items. You can also opt to carry less than a full tank of fresh water while in transit.

Good luck.....

[Steve Bennett]

Michael, when you get a chance have the bus weighed in total. If the area around the scale is not perfectly level it will throw off the individual axle weights significantly. My guess is that your coach is not as heavy as those weights would indicate. If you find that the coach weighs in the 47K range, you could then drop the individual weights proportionally. It is also unusual to have the tag weigh as much as the front axle on a non-slide XLV. If that is accurate you may want to have your ride height checked.

[Kenneth Brewer]

"On tire inflation table. are the weights listed per wheel or per axle? In other words, do I need to divide the numbers by two (for the steer axle and tag axle) and by four (for the drive axle) to get the weight per tire? I'm confuzzled!"

The answer is yes; divide the axle weight you have in actuality by the number of tires on it. And in the case of the drive axle, you need to compare the result against the tire spec for duals, as the weight allowance for a tire mounted as one of a dual is less than as a single. I guess I saw these post thread later on, as I don't see where you state the exact tire model (and make, which I assume is Michelin), size, and rim diameter (I am sure in this case the rim diameter would be 22.5); be sure of what you have, XTA, XZA, XZA-1, and so on, and the size, all exactly as noted on the tire, when you consult the tire table.

If I have mistated anything here, I'm sure be corrected, so watch this thread. Good luck and I hope you can resolve things.

[Jon Wehrenberg]

Important.........The tire pressure charts reflect single and dual wheels.

In the case of the tag and steer axles use the inflation pressures specified for single and on the drive axle use the dual wheel inflation pressures.

All are cold pressures, and as a practice I add 5 PSI just to provide a small cushion of added safety should I develop a leak I do not detect right away. If you have a tire pressure sensor system you don't need that extra pressure because you will get an alert before it becomes an issue.

Remember...if you run a tire at 20% less than the specified pressure you have effectively ruined it and driving on it could compromise safety. That is not me talking but the tire manufacturers themselves all stating that.

As to Steve's comment about ride height and the relation between it and any axle weight I do not understand how that impacts axle weights. We only have 3 ride height vales. One centrally mounted for the two front axle air bags, and one on each side (located ahead of the drive wheels in the wheel well) for the left or right rear. When the ride height valves are in the circuit (they are out of the air circuit when in the level low position) the rear ride height valves supply air flow to or remove air from the 3 air bags (2 drive one tag) on their respective sides. All three rear air bags per side have equal air pressure in them regardless of the height adjustment.

Having said that the drive axle air bags are different than the tag air bags on coaches I am familiar with. It is that diference that maintains the weight distribution in the rear between the tag and drive. The tag air bags are generally the same as the front air bags and are slightly greater in diameter (although described as the same) than the drive air bags. The only way to adjust the relationship of weights on our coach rear axles using the leveling / ride system is to use varying size air bags as Prevost has already done.

There has been a misconception in the past that the ride quality on our coaches can be adjusted firmer or softer by adjusting air bag pressures. That is not the case. Using the ride height valves brings our buses to a specified height by adding or exhausting air from the air bags until the bus reaches the set height. The air pressure increases or decreases based on the loads each set of air bags must carry. A bus with a heavy front for example is going to take a lot of air pressure to rise to the correct ride height, or less if the front end is relatively light.

In the case of the 3 rear air bags on each side they all share the exact same pressure because they are all interconnected when thye system is in the road or driving position.

[michaeldterry]

I guess I saw these post thread later on, as I don't see where you state the exact tire model (and make, which I assume is Michelin), size, and rim diameter (I am sure in this case the rim diameter would be 22.5); be sure of what you have, XTA, XZA, XZA-1, and so on, and the size, all exactly as noted on the tire, when you consult the tire table.

Kenneth - actually, I just put on a new set of Firestone FS400's, load rating J.

To make absolutely sure I understand how to use the tire inflation table, is it correct that I would divide the inflation table numbers by two (single) for the steer and tag axles or divide by four (dual) for the drive axle to get the correct recommended PSI per individual tire?

[GDeen]

Kenneth - actually, I just put on a new set of Firestone FS400's, load rating J.

To make absolutely sure I understand how to use the tire inflation table, is it correct that I would divide the inflation table numbers by two (single) for the steer and tag axles or divide by four (dual) for the drive axle to get the correct recommended PSI per individual tire?

Michael,

See the excerpt below from the Michelin load and pressure table guide - no dividing by 4....in fact, no dividing at all. Technically, they are saying weigh each axle end and inflate all tires on axle to max end inflation indicated. Dividing by 2 works obviously but is still not the same as weighing each axle end. Rounding up 5 or 10 psi should cover any error by using the total axle weight average rather than weighing each end separately:

In the load and inflation tables, SINGLE means an axle with one tire mounted on each end, while DUAL means an axle with two tires mounted on each end. The loads indicated represent the total weight of an axle end in an RV application. When one axle end weighs more than the other, use the heaviest of the two end weights to determine the unique tire pressure for all tires on the axle. The maximum cold air pressure for each axle may vary, depending on their weights. These tables are applicable for all RV axles, whether or not they are power-driven.

[Kenneth Brewer]

Michael,

See the excerpt below from the Michelin load and pressure table guide - no dividing by 4....in fact, no dividing at all. Technically, they are saying weigh each axle end and inflate all tires on axle to max end inflation indicated. Dividing by 2 works obviously but is still not the same as weighing each axle end. Rounding up 5 or 10 psi should cover any error by using the total axle weight average rather than weighing each end separately:

In the load and inflation tables, SINGLE means an axle with one tire mounted on each end, while DUAL means an axle with two tires mounted on each end. The loads indicated represent the total weight of an axle end in an RV application. When one axle end weighs more than the other, use the heaviest of the two end weights to determine the unique tire pressure for all tires on the axle. The maximum cold air pressure for each axle may vary, depending on their weights. These tables are applicable for all RV axles, whether or not they are power-driven.

Gordon is completely right, the Michelin tables reflect the whole axle weight (load) and you do not have to divide. The Michelin tables do it for you, no dividing. You have your axle load already, look up the corresponding air pressure and follow the advice about rounding up. Sorry I misled you. Thanks Gordon.

[Jon Wehrenberg]

The proper pressures from the Firestone chart for Michael's tag and steer axles is somewhere between 110 and 115 PSI. For the drive the pressures would be around 80 PSI.

http://www.trucktires.com/firestone/...loadTables.pdf

I agree with Steve about rechecking the weights because the tag weight seems unreasonable since his chassis air bags and mine are likely the same and I have a hard time understanding how that much weight can have been shifted onto the tag. I don't doubt the steer axle weight. If that tag axle weight is accurate I would guess at some point oversize air bags have been put on the tag axle and someone needs to check to verify nothing is rubbing. If the weight is correct consider that by having that much weight on the tag turns will be much harder and the tag tires will get excessive scuffing. I would expect to see the tag axle weights in the 11,000 pound range, maybe 12,000.

I hope all new owners are understanding that tire pressures must be adjusted to reflect the axle weights and if the coach has not been weighed it needs to be weighed with full fuel, empty holding tank and full water plus all the personal stuff that is routinely carried.

[truk4u]

Michael,

Travel with empty holding tanks and reduce your fresh water to a 1/4 and that will help. Your steer is over because of the golf cart in the front bay.