Community Forums

mikwallace · 06-11-2019, 04:13 PM

We just traded our 2006 Allegro Bay for a 2013 Allegro Bus 43QGP.

I'm looking for a good Primer for Tag Axle operations. The Cautions, Notes, Warnings, Do's and Don'ts of operating an RV with a Tag Axle.

We're excited to make the Giant Leap from gas burner to DP, all-electric coach. It's currently in the Cummins shop for an emissions recall and then to PDI. We should take delivery next week. I was fortunate enough to park next the our purchase when the previous owners were swapping their goods from their old to new Bus. Actually spent 4 days with them and gleamed lots of info.

I searched this forum for Tag Axle info, but didn't get any hits?

Thanks!

TriMoot · 06-11-2019, 04:21 PM

I'm watching this thread...JUST in case I ever get the chance to move up to DP with a tag.

brandss · 06-11-2019, 04:38 PM

I'm not sure if there is anything to be concerned about. The only thing I can think of is to increase your monthly tire savings for two more tires. Enjoy the ride.

vsheetz · 06-11-2019, 04:41 PM

Proper adjustment of the tag pressure is very important. As it effects front tire loading.

V3600 · 06-11-2019, 04:55 PM

About the only thing to do is not to take tight turns with the tag engaged. There is usually a tag dump switch of some sort to dump the air.

Pigman1 · 06-11-2019, 06:51 PM

Not too much to worry about. The tag sort of takes care of itself. When backing, the tag automatically deflates so you might hear a fairly loud hiss of air as it dumps. Forward, the tag automatically inflates at about 8MPH if you forget to push the switch. To make a sharper turn, dump the tag. The dump switch is on the left side driver panel. Just know that when you do this and go to max steering angle, you have a considerably larger counter swing on the rear overhang. Just watch it closely. Also, depending on your tow bar and toad, it's possible to hit the toad against the rear coach corner on a max turn with tag dumped. It all depends on the towbar arm length, the length of the stinger on the towbar and width of the toad. A few turns in an open parking lot with a friend watching may give you a feel for this.

A few years ago there was a lot of discussion on tag vs drive axle loading. This cannot be changed or adjusted on the '13 43' unless the suspension valve is upgraded. We run the Bus very heavy to Alaska (9 trips) and although our balance is not ideal, the as built configuration gives us no issues. We're nowhere close to max loading on the tag or drive axle. We're at over 105,000 miles now.

Although not directly tag related if you get a chance, weigh the front axle. Tiffin has a habit of overloading it or coming close to overloading it with the 295 tires on it. I was running the fronts at the max 120PSI and had a very rough ride. I replaced the 295's with 315's and wider rims and was able to reduce front tire pressure to 110-115 and got a noticeably smoother ride. The 315's fit fine, but you may have to adjust the steps further forward.

Larry F. · 06-12-2019, 07:46 AM

On ours the tag axle proportioning was way off and it was carrying around 1000 pounds more than the drive axle. See below. It took a visit to Bay Diesel to solve the problem Weight it as soon as possible!

Larry F. · 06-12-2019, 07:49 AM

It looks like picture did not come thru on the last post. On our first weigh, the tag was carrying 10380 pounds and after it was fixed it carries 6980 pounds.

Pigman1 · 06-12-2019, 12:15 PM

Milkwallace, which chassis do you have? I thought all 2013 43' buses were on a Powerglide chassis, but might be mistaken.

Crasher · 06-12-2019, 03:29 PM

If your proportioning valves have not been changed, they have a 60/40 ratio. 60% of the rear weight is on the drive, 40% on the tag. This puts too much weight on the steer and too little weight on the drive. Some have had the rear wheels spin on wet pavement because of this imbalance. There are a couple of remedies. I chose to have manual regulators installed in place of the 60/40 prop valves. I can now adjust to whatever ratio I want. 2/3,1/3 is the best for braking, but the 75/25 I use puts the steer axle 1,000# below it's rating even with full fuel. That also puts the drive axle from 14,000# up to 20,000 for better traction on wet or snow covered roads. It is rated for 22K. Several owners have gone this route. Some are unaware of the issue and have done nothing. Tiffin has recognized the problem and has corrected the problem on the newer 45' Bus. I also had my control modules reprogrammed so that the tag will dump when below 20 mph if the directional is on. The tag will not re-inflate till the coach gets up to 20 mph. This is another improvement Tiffin has done on the 2015 and later after I requested the mod. At the same time, I had them change the "Dump Tag" switch the an "Inflate" function. Now I dump it with the directional and inflate with panel switch at anytime I need to when below 20 mph. I did all of the above when the coach was new after the first time I ran it over a scale and found out how poor the weight distribution was. The ride height valves were also off causing the FR tire to carry 950# more than the FL tire. Tiffin paid for most of the changes. I would advise the OP to learn more about his 2013 43QGP and make the corrections if needed. It makes a good coach into a great better balanced ride.