Jake break? Sometimes.

[phorner]

I would be more concerned about SAFETY than the legal issues!!

Chances are, you will not likely get ticketed for being overweight. The real concern is tire pressures, braking distance and the potential damage to the components of your suspension system....

Simply put, how much risk are you willing to take with full knowledge that you are operating a vehicle that substantially exceeds the safe handling limits?

[Jon Wehrenberg]

Buster,

There are better things in life than driving a coach that may be a handling nightmare.

The way Prevost rates the axles is based on the capacity of all the components, not just the tires or wheels. Air bags, brake pad surface area and application force, bushings, bearings etc. all are a part of the total and while conservative driving and luck may allow you to enjoy years of enjoyment, the flip side is that coach is likely to wear out front end bushings, bearings and brake pads, but it also will be slow to raise to ride height, and with the heft of the front its braking forces on rain slicked roads may be compromised.

I'd walk. There are a lot of choices out there.

[Steve Bennett]

Mike, I would have the coach re-weighed after the ride height, and tag bag pressure had been checked. We have seen some significant variances in scales, and we had a Newell that we sold, and by adjusting the ride height & tag axle pressures were able to correct a 1,500lbs. overweight on the front end. This coach went to Newell, and they also re-rated the front end for an additional 2K lbs. with different front tires. I would also check with Prevost to see if they will tell you what the limiting factor is. It is not a big deal ($4K) to put the 365 upgrade on the front end. That will get you closer but if the axle is a 16K axle you are significantly over. And as John stated you will likely have other components that may be undersized for that weight. If you love the coach, you may check to see what the cost would be to change the front end to the current configuration. If the coach still has the beam front axle (98 chassis & older on an H) it would likely not be possible.

[Jon Wehrenberg]

With all due respect for Steve there is a common belief that air bag pressures can be modified. They are modified constantly while driving, but only to maintain the ride height under the varying road conditions.

The air bag pressures are a function of the weight on a given axle. The unsprung weight is the tire, wheel, brake disc, calipers, etc. The air bag does not lift that, but it does lift the chassis and everything in the chassis including the people. For a given size air bag the air pressure required to position the bus at ride height is dependent upon the weight which must be lifted. The only way to reduce the weight on any axle is to move the weight elsewhere in the bus or remove it from the bus.

The ride height valves only serve to control when the flow of air into or out of the bag is necessary to place the bus at a specific distance above the road. They adjust pressure, but only to the extent necessary to raise or lower the bus height. But in the end, if the bus is sitting on a level surface, and the pressure in an air bag is raised or lowered, the only change will be to the height of the bus. It will have no effect on the weight on a given axle.

[Steve Bennett]

John, on the Newell that we had the tag axle air pressure is adjustable via a regulator in the engine bay. We had the coach parked, and running with the steer axle on the scale. You could adjust the air pressure on the tag axle and watch the weight raise or lower depending on how the tag was set. The drive axle acts as a fulcrum, and the coach will gain weight on the tag & steer if the tag pressure is reset. Remember that the rear ride height is determined by the drive axle ride height valves. There are not ride height valves on the tag axle. That is why you can increase the weight on the tag, which will also increase the weight on the front, and decrease the weight on the drive axle. The front ride height valve, or valves will compensate for the increased weight by increasing the front air bag pressure to bring the coach back to the ride height. In my racing days we would set up our race cars by corner weights. The car would be set on a level plane with individual scales @ each corner. We would adjust the individual ride height via coil over shocks to set the individual corner weights to where we wanted them. You would be amazed at how significant of weight change you can achieve with minimal adjustments in ride height. If we were racing on a predominantly right hand turn track such as Lime Rock we would set the car up asymmetrically to achieve the best balance in right hand turns. A coach is no different if you were to raise the tag axle pressure (same thing as adjusting a coil over spring) on only one side (I know that is not possible with the standard air system) it would transfer weight to the opposite side on the front. The Newell that we were referencing went to Newell in Oklahoma, and I saw the print out of the new corner weights. It was completely different then what we had when we weighed the coach in CA. If you doubt what I say, park your coach on a scale with only the front axle on the scale. Now raise the tag axle, and see what happens to the front end weight. That is the reason that some coaches with heavy front ends need to lift the tag to speed up the achieving of full ride height on the front end.

[Jon Wehrenberg]

Steve, I am well aware of how the tag affects the steer axle weights.

That is how the overloaded Marathons get to raise the front end to road height. They pick up the tag.

However this is not something that is adjustable on our coaches. The rear ride height valves supply or exhaust air from the three rear airbags per side simultaneously. There is no pressure regulator to control air bag pressures anywhere on a Prevost.

[jimshoen]

Steve,
Why does Newell allow the tag axle air spring pressure to be adjusted? Sounds like a formula for disaster. Prevost surely does not allow that, and there must be a good reason. I have heard Newells are heavy and among other things need the 600 hp get down the road? On a Prevost, all three air springs on either rear corner will have the same pressure in them. Both front air springs will have the same pressure. I just can't believe Newell would have a user adjustable air spring pressure.
Jon, Which Marathons are having that problem getting the front to road height? Do you know if it is a particular model or year? Or is it the possibility that the front axle may be overloaded?

[Jon Wehrenberg]

Jim,

There was a period of time when some Marathons exceeded the Prevost front axle limits. At the time they were configured with the generator and I believe batteries in the first bay.

They are not alone. There are other converters whose front axle weights are in excess of the ratings. I do not know if the problem continues to exist but I suspect some, especially with slides are close if not over

In about 1992 or 1993 Bill Campbell, one of the three owners of Prevost at the time gave a dire warning to owners about observing weight limits during a PP seminar. He was cautioning owners not to overload their bays, but he was also sending a not so subtle message to a few of the converters at that time. He apparently got spanked by the converters for doing that because from that time on we never heard a word from Prevost about converters exceeding the limits.

That was when Prevost did a retrofit to larger air bags in the front because some coaches had to come up to full air pressure just to get the front up to ride height. If my memory serves me the four shock absorber set up was also retrofitted because with the excess front axle weight some coaches had so much rebound over bumps they were bottoming.

[truk4u]

Jim,

My 97 Marathon XL would not lift the front end without dumping the tag and it was at gross weight with little weight in the front bay.

My Liberty is also at gross on the front (I thought they did a better job on the weight distribution), but will lift the front very easily.

[Jon Wehrenberg]

40 footers are a bitch to get the front light. There is very little weight cantilevered beyond the rear axles so the front shares every pound in the bays. The 45 footers with the long rear overhang have less of an issue if the converter keeps the heavy stuff back towards the drive axle.

An entertainer coach with the same overhang as a 40 footer in the rear is almost guaranteed to be front axle heavy.