Community Forums

tomckeon · 02-21-2015, 09:57 AM

Quote:

Originally Posted by CampDaven

If your HD is on the lift, that may be why the front was light. Without the HD you may overload the front. Remember, the drive axel is a fulcrum. Maybe weight with and without the HD?

That's exactly what I was thinking, We pretty much always have one of the bikes on the back.

bobcovey · 02-22-2015, 10:15 AM

"I tried mine up there on the scales and exceeded both the max allowable weight on the tires and the front axle. Even at 42 psi where I run it now I upgraded to 315 tires on the steer axle for a safety margin"
__________________
Mike Canter
"Gunner" USN Retired, Airdale
2004 Monaco Signature 44' Conquest. Detroit 60

Mike,

I am max'ed out on the front, too, and am contemplating the same tire change. What tires did you use? Did you change rim width?

Cheers,

Mike Canter · 02-22-2015, 10:28 AM

I used the Michelin XZA2. I kept the same wheels but Michelin has a special inflation/weight chart when used with our rims. I can send it to you if you need it. I have no clearance problems. The tires radius is half an inch larger than the stock tires. I have heard that on some years/models that the larger tire can barely touch the base of the air bag and they had to trim it. With the 315 tire you actually run less pressure than the stock tire.

bobcovey · 02-22-2015, 06:23 PM

Mike,

Thanks, see PM.

The 295's rub slightly on the control arm at full lock, so I am not going to try the 9" rims either. I just want some margin in the tires that I don't have now.

1mainiac · 02-22-2015, 06:44 PM

My rough numbers are 250 lbs added to the tag for every 1psi added to the bags. This is sprung weight so you also have the weight of suspension axle and tires and brakes to begin with. different bags have different ratios based on how many sqin the bag is and how many bags as well as leverage added due to design of the system.

darstar · 05-25-2015, 08:34 AM

Remember the golden rule, the more air you put to any axle ,the more weight will be transferred to those air bags that are connected to that axle.. That weight has to come from somewhere else. Learned that being in trucking for over 50 years. My guess is transferring more wt to the tag ( bag pressure ) will first take more weight off the drive. In theory this should not effect steering wt. In the case of coaches, the longer the unit the more wt. on the steer. 45 foot as I have , I would have to remove the generator to lighten up the steer. There is little you can do actually other than go to larger tires. Never try to put 315s on 8.25 rims, doing so defeats the capacity rating of the wheel. I have been thinking if I put a solenoid valve on the air intake of the tag , then I could regulate pressure from the driver seat. ( My thinking here would be handy when full of fuel and water ? )

CampDaven · 05-25-2015, 04:00 PM

Raising tag pressure makes the drive axel act as a fulcrum. Weight on the steer axel increases. Physics.
My steer is just under max with full tanks at 14,300 and tag at 28psi (factory setting). Why play with it if it handles just fine?

darstar · 05-25-2015, 11:59 PM

Quote:

Originally Posted by CampDaven

Raising tag pressure makes the drive axel act as a fulcrum. Weight on the steer axel increases. Physics.
My steer is just under max with full tanks at 14,300 and tag at 28psi (factory setting). Why play with it if it handles just fine?

the reason we run so much weight on the steer ,especially 45 foot coaches is the distance factor with so much wt. spread out naturally. the more air you put to any axel the wt. goes up. , and less on the closest axel , its always been that way. one of the reasons we used to control wt in or on each axle with electric controlled valves, which are illegal everywhere. so, are dump valves, yet everyone i knew installed one on the trailer axle, for making short turns, and we also ran spread 10 foot too......if what you say is true,then if a coach does not have a tag , and because of distance to the front putting more air to drive bags does not help take wt off the steer....i guess that is what you mean when you said less air to drive puts more wt. on steer ? i don't see any way to move wt. off the steer axle no matter what you do, just too far away to be effected by rear axles.

Mike Canter · 05-26-2015, 12:06 AM

That's not what the CAT truck scales show when adjusting the pressure in the tag axle airbags. If you can put weight on the steer axle then you can take it off so maybe I am confused at what you are saying. Help me to understand.

vettehead · 05-26-2015, 06:44 AM

I drove my Exec onto a scale before I left home this spring. Adjusted Tag air to 52psi. Ft axle is 13540, Drive axle is 20600, Tag is 8660. I played with tag pressure to get to that weight, weighting each axle at a time. Well within the allowable limits. Tires are Michelin 295/80.

CampDaven · 05-26-2015, 05:12 PM

Quote:

Originally Posted by Mike Canter

That's not what the CAT truck scales show when adjusting the pressure in the tag axle airbags. If you can put weight on the steer axle then you can take it off so maybe I am confused at what you are saying. Help me to understand.

My manual states that "If necessary, you can adjust tag axle regulator to
compensate for payload carried by tag, drive and front axles."
So I adjusting the tag pressure UP will transfer weight to drive AND steer axles. There is a huge section in the manual that goes into much detail on how to weigh by axles, by tire, even by "sleeping weight".
All I know is that the factory tag bag setting is 28, and my drive and steer axles are happy.
Just my view from the saddle.

38 Special · 05-26-2015, 05:17 PM

Quote:

Originally Posted by CampDaven

So I adjusting the tag pressure UP will transfer weight to drive AND steer axles.

No, that is not correct. Increasing the air pressure on the tag increases the weight on the tag and front axle, but decreases the weight on the drive axle.

CampDaven · 05-26-2015, 05:39 PM

Quote:

Originally Posted by 38 Special

No, that is not correct. Increasing the air pressure on the tag increases the weight on the tag and front axle, but decreases the weight on the drive axle.

Well, shucks! You are on the mark. Makes total sense.
I like to think that I simply did not ponder it quite enough.
Do you suppose we have completed the thread discussion together?

I do.
And thanks!

darstar · 05-27-2015, 07:24 AM

Quote:

Originally Posted by Mike Canter

That's not what the CAT truck scales show when adjusting the pressure in the tag axle airbags. If you can put weight on the steer axle then you can take it off so maybe I am confused at what you are saying. Help me to understand.

Sorry about the way I described ......It was late and the gears in the brain were rusty. No excuse, but 38 special answered for me....Now Its all clear...I think....