[Peter]

Tim,

Some coaches are fat in the front end. I won’t name names but if you own a coach with the generator and batteries in the front bay or near the front and then have a lot of personal stuff in the bays the weight on the front axle air bags is greater than they can lift because they are sized for the axle weight limits and the bus maximum air pressure.

Since it is not likely anyone is going to start moving their generator or batteries around one possible solution is when you need to raise the front end, lift the tag axle. Raise the front end where it is needed and then adjust the leveling with the rear air bags. If that works, great but if it needs a little more help, lift the tag and with the aux air pressure at its max lift the front. At some point the aux pressure will go down a little. Stop trying to lift the front and get the compressor to cycle the air back to full pressure. Fanning the brakes is a good way to cycle the compressor because it doesn’t take air from the aux system. Only try to raise the front when aux pressure is at or near the 120 PSI.

It may involve a lot of monkeying around to do it but eventually it will work. Do not turn up the pressure on your air system unless it is lower than 120-125 PSI. You can go up to 130 according to Prevost but there are a lot of pressure limited devices in the coaches and some have a 130 PSI limit. Air bags usually have a 100 PSI limit, but I don’t believe that applies to the pressure needed to go above ride height.

[Peter]

Good to know Jon!

I’ll try your suggestions, but at least it sounds like it’s not a defective part.

[Dick]

Tim have you replaced the front air bags with new ones since you have owned the coach or are they the original ones it came with????????

[Tim]

Yep Peter,

Replaced most everything underneath when I bought it.

[Archived]

Do you know the number of the front air bags that you put on ???? It will be a number like 630151

[Peter]

Welcome to Marathon ownership Tim, they’re front heavy. I have to do as Jon explained, lower rear bags, dump tag and keep the engine compressor as close to purge stage by fanning breaks and just before the purge, hit the up button and hold while watching the aux gauge and just keep doing it until at full up in front? You’ll get there, just takes time.

[Chris]

Thanks Tom!

I’m just curious why the front end comes up to ride height with no issues after I had it in low-level and the front end was fully deflated.

Peter,

They are: 630151

[Art]

That sounds like the right number ,I would have to look to check

Tim I had a coach that would do the same thing from the bottom to ride height no problem but to go up past that no way , it had the wrong air bags and pedestals, once I changed them out up it went no problem

[Andre]

I am not sure there have been issues with Prevost supplying the wrong air bags on H model coaches. It has been an issue with the X chassis and that was a problem.

Tim can and should verify his air bag numbers, but if they are the correct ones it is a weight issue. Assuming it is a weight issue and there is no acceptable larger diameter replacement the only option is to do as Tom and I suggested.

If the air bags in the front can be replaced with larger diameter air bags the problem is easily resolved but changing air bags is not something easily done because it brings about other issues such as clearance problems. It is not something to be pursued without getting Prevost engineering involved.

The air bag diameter is the critical value because even a 1″ increase in effective diameter can lift a lot more weight at the same pressure. But if that is not possible then the answer is to get weight off the front axle and by lifting the tag you have that effect. By trying to raise the front by keeping the air pressure in the aux system at max you increase the lifting ability. There are no other options.

[Tim]

Buddy, I am not trying to be a trouble maker … But, here is your chance to tell the God Father that there ARE other options. They are called Country Coach, Royal, Vantare’, etc.

[Chris]

Thanks for the suggestion Boys,

I got it to raise while the Aux Tank was filling in excess of 120psi. Worked like a charm!

[Archived]

Triple F, I hate to burst your bubble but I personally know of Country Coach conversions and at least one Vantare conversion that was in excess of the Prevost steer axle weight limits such that the coach had a hard time even coming up to the driving height.

We, all of us owners, are the problem because the more we ask for, the fatter our coaches get. It is not the best thing to load the front bays with heavy weight like generators and batteries, but as we demand slides, marble or granite floors, and we load up everything we own in the bays we end up overloaded.

The X3 if it is ever converted in large numbers is going to be a nightmare for converters with respect to steer axle weight as are some H models. With less weight cantilevered behind the tag axle unlike the XLII models the weight up front has a greater impact on axle weight. And in the X3 Prevost uses the last bay for AC which is fairly light, so it shifts heavier weight like holding tanks, generators and batteries forward, while having less rear overhang to offset that movement of weight toward the steer axle.

As a result Tim is not and will not be the only one with the problem

[Lacey]

Ok, we have a Marathon and have not had any issue raising the front. Our genny is in bay 1 CS. Maybe ya’ll are carrying way too much shit if the front airbags won’t raise the front end!

[Per]

The XLII also has a greater distance from the rear wheels to the rear bumper so you have more weight overhanging in the rear to offest the weight up front. Assuming the air bags are OK it is all about weight and balance.

[Per]

Last time I weighed the coach, we were about 500 pounds overweight on the front axle, but since I did not have my stock of scotch in the rear bedroom closet when we weighed, I figure we are OK on the front weight!