Individual Smart Weigh results...

[jrugarber]

I thought some may be interested in the final numbers of our Smart Weigh completed this morning on all wheel ends.
17 Cornerstone 45B w/ Hydralift and 1995 H/D Dyna Low-Rider towing a Scion XB (GVWR 3,200 lbs.) 4 down.

Coach GVWR - 50,700lbs. GCWR w/Car 53,900 lbs.
L/front - 7,800 (Driver) / R/front - 9,800 (Pass)
L/drive axle - 9,400 / R/drive axle - 10,200
L/tag axle - 6,500 / R/tag axle - 7,000

Front Axle total - 17,600
Drive Axle total - 19,600
Tag Axle total - 13,500

I'm basing the weight difference of the Tag axle sides on the fresh water tank being full (100 x ~ 8.34 lbs. = ~834 lbs.) in addition to the H/D rear portion of the bike would be positioned slightly to the Passenger side

The 800 lb. difference on the Drive axle I think would be explained by the water tank also

My question is, what could be a cause for the 2,000 lb. difference on the front axle.
My tool box is actually on the Driver's side and cargo bays are loaded closely equal.
The Dometic cooler is only 1/3 full of beverages...
Is the step compartment that much heavier, or the "L" shaped couch on the P/side.
The Weighmaster double checked his scale reading and found nothing wrong.

Has anyone else had similar readings with a large difference between the L & R front sides?
This is the first time we have ever scaled individual axle ends so I don't have a past history of readings other than a full axle weigh done at Spartan back in 2019.

My tire pressures were all within the range needed other than the Tag which I may bump up to 100 psi vs. the current 96 psi based on the 7,000 lb. wheel end.

[Gary.Jones]

Interesting to read and compare. I just bumped into some old axle weights and tire pressures yesterday as I was scanning some old data to be filed away in the appropriate directory of the laptop that I keep on the coach.

I will use your format and give you my weights.


GEJ Coach, 2019 Cornerstone, "B", Weights done at NIRVC with their portable scales 3-18-2021


Coach GVWR - 50,700lbs. GCWR w/Car 49,200 lbs.
L/front - 8,920 (Driver) / R/front - 8740 (Pass)
L/drive axle - 9,760 / R/drive axle - 9280
L/tag axle - 6,320 / R/tag axle - 6180

Front Axle total - 17,660
Drive Axle total - 19,040
Tag Axle total - 12,500

My pressures are ~ 115 # on Michelin 365s, 90# all other 315s

I carry lots of tools in three large toolboxes on passenger side of front movable slide. These weights include Dee and I sitting in proper positions.

Interesting!! Lots of similarities and some differences.

Gary

[777 Driver]

Originally Posted by jrugarber

My question is, what could be a cause for the 2,000 lb. difference on the front axle.

I've had corner weights done on my '18 Anthem 42DEQ at Spartan on two occasions. 360 pound difference the first time and 40 pound difference the second time. Both times, the passenger side was heavier. Both times, the ride height had been checked/adjusted prior to weighing.

Did you have your ride height checked prior to weighing?

I believe that mis-adjusted ride height can have a significant effect on corner weights.

2,000 pounds seems to be a significant difference, to me. JMHO.

Take care,
Stu

[RVFunlovers]

The L / R weight difference on my 17’s front axel was just at 300 pounds with the right being heavier. 2,000 pounds seems significant. If anything your front drivers side seems low. The passenger side is a little high but within range.

Your entire right side is heavier. Maybe a good idea to check air level and get weighed again when you can.

Be sure to weigh with a mostly full fuel tank as well. The 150 gallons (1000 pounds) is significant.

[jrugarber]

Gary, Stu & Hal,
Thanx for the input.
I have an appointment at NIRVC LasVegas on June 14th to have it scaled again, each wheel end, and if needed a possible ride height adjustment. Stu, the last ride height adjustment was completed at Spartan about 2 years ago, although without the full complement of items i.e. tool box etc.

I will post the results when completed.

[777 Driver]

Originally Posted by jrugarber

Stu, the last ride height adjustment was completed at Spartan about 2 years ago, although without the full complement of items i.e. tool box etc.

John, the purpose of the ride height system is to maintain the Spartan designed ride height regardless of load. The system senses the distance of the house frame above the chassis frame and meters compressed air into and out of the corresponding air bag to maintain that height, regardless of load. If you load up a corner enough to cause that corner's air bag to compress (sag), the system pushes more air into that bag to adjust the height back to specs.

That need for adjustment is sensed by a mechanical linkage. You should be able to see that linkage by looking over the top of a tire (right front is probably easiest to see). I've been told that if it's off, even a relatively small amount, it can cause the coach to lean enough to have an effect on a corner weight. You may, or may not, be able to see that lean. That's why it's important to have the ride height adjustment checked periodically. Spartan recommends checking ride height annually. Mandatory first step in any chassis alignment and probably a good idea before a corner weight check.

Take care.
Stu

[Alfalfa1]

Front axle driver 8240...passenger 7780 = 16020 @ #123
Rear axle driver 7840...passenger 8640 = 16480 @#90
Tag axle driver 4820...passenger 5020 = 9840 @#90

total = #42340
2017 Insignia 44W

[alank]

I would first suspect there's something not operating correctly about your air bag suspension system. It sounds like too much of the front end weight is being supported by an over inflated passenger air bag, or not enough front end weight is being supported by an under inflated driver side air bag.

Do you know the detailed working of the air bag system on your coach? If it were on my Freightliner, I would have some suggestions, but I don't know the working detail on a Spratan.

[Cruzer]

The K3 chassis in the Cornerstone uses electronic ride height sensors rather than pneumatic. They are less problematic than the pneumatics. However, they still utilize mechanical links to the suspension and can get out of adjustment. The ride height should be the first thing you check prior to weighing the coach.

FWIW, my 2016 45A weights are:

Front Axle: 9,360 Left, 8,820 Right, 18,180 Total
Drive Axle: 9,230 Left, 10,210 Right, 19,440 Total
Tag Axle: 56,890 Left, 6,130 Right, 12,020 Total

Total Weight: 49,640

I carry a lot of tools on the right side as well as two large freezers on that side as well. That explains the drive axle proportions but my guess for the front axle being heavier on the left is because I have a large custom desk with a heavy quartz top on the driver's side near the front which weighs a ton. Either way, it is beneath the axle capacities and I air up to the pressures for the higher side plus 5 PSI to be safe. It drives and handles great so I'm not concerned.

[Gary.Jones]

I thought that I would add the data of my tire pressures when they were measured HOT immediately after we had traveled ~ 325 miles back home. My "cold" tire pressures are listed first.

COLD
steers drive tag
Passenger........115 ............................90#..........90#
.................................................. ......90#


Driver............................................ ....90#
......................115......................... ....90#..........90#

-------------------------------------------------------------------

HOT
.....................steers....................... ..drive...........tag
Passenger........126#......................... 94#............94#
.................................................. .....96#


Driver............................................ ...95#
.......................124#....................... ..95#.............98#

---------------------------------------------------------------

Finally, steers are 365 Michelins (with Rettrobands) and all the rest are 315 Michelins..

Cheers !!!

Gary

[777 Driver]

Originally Posted by jrugarber

I have an appointment at NIRVC LasVegas on June 14th to have it scaled again, each wheel end, and if needed a possible ride height adjustment.

I will post the results when completed.

Happy Flag Day!

Looking forward to your results.

Take care,
Stu

[jrugarber]

Stu,

Thanx for following up on the results... I apologize in advance for the long response!!!

Visited NIRVC today and the results are as follows,

Gross weight (GVW) - 6.14 - 52,250. // Initial 5.12 - 50,700 (+2,250 lbs. difference)
---------------------------------------------------------------------
Gross - Front Axle 6.14 - 17,600 // Initial 5.12 - 17,600
6.14 - D/S = 8,300 // Initial 5.12 - 7,800
6.14 - P/S = 9,300. // Initial 5.12 - 9,800
(1,000 lb. difference vs. 2,000 lb. on 5.12, weight changed on each wheel)
---------------------------------------------------------------------
Gross - Drive Axle 6.14 - 20,550. // Initial 5.12 - 19,600
(950 lb. difference)
6.14 - D/S = 9,900 // Initial 5.12 - 9,400
6.14 - P/S = 10,650 // Initial 5.12 - 10,200
---------------------------------------------------------------------
Gross - Tag Axle 6.14 - 14,100 // Initial 5.12 - 13,500
( 600 lb. difference)
6.14 - D/S = 6,850 // Initial 5.12 - 6,500
6.14 - P/S = 7,250 // Initial 5.12 - 7,000
100 lbs. OVER the 14,000 lbs GAWR on the tag axle
---------------------------------------------------------------------
Hopefully the information above isn't too confusing, a summary,
I am 1,550 lbs heavier than the 1st weighing
I am still under the GVWR of 54,000 lbs
Steer axle is 1,000 lbs less than the first reading, both wheels affected.
Drive axle weights are similar to 1st weighing
Tag axle is 600 lbs. over the 1st weighing, 100 lbs over GAWR
Black, Grey and Fresh tanks were at similar levels, although fuel may have been a bit fuller, contributing to some added weight.

Ride height was checked and is as follows...
Front height is LEFT - 9 3/8" // RIGHT - 9 3/8"
Rear height is LEFT - 8 3/8" // RIGHT - 8 3/8"
According to the Invoice "Ride height spec" is FRONT - 9 1/4 - REAR - 8 1/4 +/- 1/8"
Everything looked good when inspected by the Tech.

I have an appointment at Spartan on 9.13.2023 for a full Inspection of the Coach based on their "Chassis Maintenance"
Checklist and I may ask them to look at everything again dependent upon the cost and/or need.

[MS60ocb]

Interesting results
My results from June 6, I had my K2 chassis weighed at the factory after service was completed. I drove to Michigan with the Fresh water tank and waste tanks empty. When I arrived in Michigan I filled the Fuel tank. Otherwise I was traveled with a bare minimum.


Front L-R 7240, 7960 = 15200#


Mid L-R 7440, 7780 = 15220#


Rear L-R 5110, 5030 = 10140#


Total L-R 19790, 20770 = 40560#

One thing I do regularly is spot check my tire temperatures after driving a hour or more. I always find the Tag axle tires running 10-15 degrees warmer than the drives. My measurements are taken on the side wall about 2 inches from tread. Should the tire pressure be adjusted? Or would this be normal by the position directly behind the drivers?

My overall acknowledgment of the weight is I know where to put my tool box when the freezer is full.

I will say the Spartan Chassis Techs know their business and what to look for. The Chassis inspection was informative and reqiired some hardware tightening. Also informative of Cummins level 1 oil leak and Entegra front entry air ram air leak.
The cost of the weigh check was 1/2 hour labor

[jrugarber]

Clay,

It is interesting that you mentioned taking a heat measurement after driving.
I also check temperatures, albeit, not every hour but at each fuel stop and random Rest Area stops.
I have found that yes, the Tag runs hotter than the Drives at about the same differential as yours, it makes sense, as only 1 tire on each side (Tag) is supporting weight vs. the tandems. Also, the side of the Coach facing the sun as you drive will also be warmer than the "shady" side. As I do not use a TPMSystem, I watch for any considerable change in temperature comparing each tire to its respective side which could be an indiction of low inflation or other issue needing attention.