Tag axle adjustment

[Hardtrigger]

Good evening in Newell land, hoping someone can help me with a question about adjusting the tag axle air pressure! In the passenger side of the engine compartment is three air gauges, two up high on the forward firewall and one lower about a foot off the floor. The manuel says to keep air pressure on the tag axle to 25lbs. and I would venture to guess the bottom gauge is the tag axle gauge and that is what scares me! When the air pressure builds this gauge goes up to 110lbs and has a brass dial on the side of it which reads max on opposing edges with arrows pointing in both directions which does not make sense! If I spin this dial clockwise the air pressure does not change. When I dial it counter clockwise air pressure kepps at 110lbs. I guess I have to ask; is this the correct gauge for tag axle air pressure for 25lbs. hope not showing 110lbs? And if so how do I get this to bleed down to 25lbs as the manuel ask for? I have a 1991 42ft. and any help would be highly appreciated for I am frustrated not being able to figure this out for the manuel does not say what the three gauges are for and how to adjust air pressur to tag axle. Thank you very much Robert :(

[rheavn]

Robert,
There are several folks on this forum with early 90s coaches that I'm sure will be able to answer your question. My vintage coach does not have the ability to adjust air pressure on the tag axle other than raising & lowering through a switch on the dash. You might start with a call to Newell and speak with one of the service managers. (888) 3-newell

[tuga]

I had a 1987 Newell and the air pressure on the tag was adjustable. Trouble is that was so long ago I can't remember how to do it.

Call Newell service 1-888-9NEWELL and ask for one of the service managers, they will walk you thru it.

[Wally Arntzen]

I have an 88 and the tag air is adjustable. I have a black knob at the bottom of the guage and I don't recall if you push the the knob in or pull it out and turn it to the amount of air you want to make the adjustment. I then put it back to the neutral position and it holds. On my 88 I was told at Newell to keep my tag at 40 pounds. They probably have different preasures for newer coaches.

[fulltiming]

Hardtrigger, on my 1992, the top gauge is the transmission air shift pressure gauge, the center gauge is the system pressure gauge (non-adjustable) and the lower gauge is the tag axle air. To adjust the tag axle pressure on mine you pull out on the plastic knob and rotate. Assuming the engine is running, the gauge should change with a small movement of the knob.

If you actually have 125 psi in your tag the rear of the coach would look high and the rear wheels would have very little weight on them. I would check for a stuck air gauge. Does the gauge drop to 0 a couple of minutes after you release the tag dump switch on the dash?

[Hardtrigger]

Thankyou very much for the replys! Fulltiming yes the tag axle looks as if it is taking on much more of the weight! The drive axle tires looks like it has much less of the weight! I will see if the brass screw on the bottom gauge will pull out so I may reduce air pressure! Im much concerned on not moving thenbus til this is corrected! Again thanks for the replys and have a great day!!!

[Hardtrigger]

I guess I am a little disappointed to have the best built coach in the world and hardly any manuels to support the user on such a technical coach as far as I'm concern! The manuel claims the air pressure gauge is with the regulator and should be set at 25lbs. and no more or may damage the components and frame. Thats it, thats all nothing on how to adjust air pressure or which gauge out of all of them is the air gauge!! Anyhow I think the tag axle gauge is the bottom off a elbow and sits about 5 inches horizontly coming off the firewall! It has a brass nob on the side of the air line which has two curve arrows going both ways which says max both directions which counterdicts itself! The brass flat nob will not pull out nor adjust air pressure when spun! The gauge still reads 125lbs. before the cutoff kicks in! Im kinda stuck til I get this adjusted for I have no intention for the coach to move with a tag @ 125lbs. and the drive wheels barely on the pavement! Anyone please have any similiar set up! Thank you very much! Robert Oh by the way this botton gauge mimics air pressure of the 2nd gauge up high on the firewall between the upper most gauge and botton gauge I cannot adjust!

[busnut]

Here is a case of a picture is worth a thousand words.

Our '93 has a pressure regulator with a black knob. You push it in (maybe pull out) and rotate it to change the pressure. This regulator is available anywhere you can get air tools or supporting supplies.

[Hardtrigger]

Busnut thank you for your reply! This gauge I am talking about seems to reflect supply gauge in dash as far as air pressure goes though it does have the adjustment knob that turns and turns without any adjustment to the air pressure gauge! Im going down to the supply house and swapping out regulator and gauge and see what this will do! Other night I started the coach and again the air pressur built up to 125lbs and sprung a leak in a hose I believe behind the generator 5 feet back from the opening! Air pressure wont build above 70 lbs. and when I slide the generator out it really bleeds air quickly. I have no way of getting behind the generator for the clearance is too small and now have no idea on what to do! Bought this Newell month ago and just cant seem to get on top of the problems! Really nervous on the last issue for it looks as if I am going to need to pull off the generator just to have access to the air leak. Wow I say Wow Have a great day!

[fulltiming]

Air leaks can be a real bugger to track down and fix. That is true on any air operated coach. The pressure regulator you are talking about is somewhat different than the ones I have seen on Newells in the age range of yours. I wonder if it has been replaced. I have heard of a few cases where someone had a leaking regulator and put a screw into the orifice to stop the venting. That would result in an inability to reduce the pressure once it was increased.
http://www.newellclassic.com/forum/picture.php?albumid=58&pictureid=588

[Jimg]

Top gauge with regulator in line is the transmission modulator air supply and should be set at 60

The middle gauge show's air supply pressure it will very from 0 – 120 psi.

Bottom gauge is the tag axle regulator that should be set to 25 psi

[fulltiming]

Sorry, I added gauge location info to the photo in the gallery but didn't add it here. Thanks for also adding setting information.

[Wally Arntzen]

I have an 88 and when I got it I was frustrated with air leaks as you are. A friend of mine who manages a bus repair garage and I decided to fix it all. We replaced every check valve, air switch, air guages, air motors and two air tanks (which had leaks in the welded seams) and to this day when I am parked and living in the coach, my 110 air compressor goes on approx 2 to 3 times in 24 hours. This is primarly due to the fact that I have an air operated toilet. It cost a bit of money for all of this equipment but it was well worth it to eliminate the problem. The air switches I replaced were for the generator slide, the step slide, the windsheild wipers and they were the most expensive.
In most cases you don't find cracked lines, it's just the check valves, switches, etc that get all gumed up over time and fail due to lack of use or moisture that causes the gumming up.

[Hardtrigger]

Fulltiming this gauge comes off the bottom center row where yours is capped off in your pic then from the gauge if is yubed over to the bottom right solenoid.Where you bottom gauge is I have nothing bit a 1/8# hole that bleeds when I hit the dump as well as the gauge will go from 125lbs. to 0 when I release tag switch! I e-mailed pic to myself but cannot figure how to move to this message so as to show the layout of mine! Thanx for everyones help! Robert

[Hardtrigger]

1146 hopefully this opens

[Hardtrigger]

Nice it opened! Can you see where the gauge comes off of center bottom row solenoid then feeds solenoid to the left? Where your gauge is I only have a hole that bleeds when I dump my tag! The gauge mimics air pressure of gauge top right and suppose to adjust but doesnt! Thank you for any ideas! Im suppose to go on vacation Sunday but refuse to move until I reduce air pressure to tag axle! Thanks again

[HoosierDaddy]

Hardtrigger,
It appears to me that the air pressure regulator in your system is different than those in Michaels and my systems. Ours are like this:
http://www.grainger.com/Grainger/SPEEDAIRE-Compact-Manifolding-Regulator-4ZM16?Pid=search
Ours has a diaphragm and spring in it and are rebuildable. I do not know how yours works but I think it could be replaced very economically. It is probably letting air pressure leak by. A call to Newell will probably get the part you need.

[fulltiming]

From the photo, I don't see a way to vent the setup that has been installed other than through the tag dump. Definitely has been changed out from the original setup. I would concur with Dean, I would look at changing the out the regulator.

[Hardtrigger]

K I bought some solenoids from Newell and replaced as advised from Newell and this had no reflection on the 125lb. going to the tag axle. I then replaced the valve and regulator that was rengineered before I purchased as shown in picture and was able to regulate the air pressure perfectly. The regulator and gauge are used to adjust air pressure for paint gun and total investment equals to air solenoids fron Newell with freight $210.00. Investment from Harbor freight for regulatoe and gauge $2.25. I now am in Oregon and stopped at there scale house when closed and following weights with 60lbs. in tag axle equals steering axle is 14,205lbs. drive axle is 19,825lbs and tag axle is 8300lbs. with 60lbs. psi. in tag axle. Now I understand Newell advises 25lbs. psi in tag axle but when I reduced my tag from 60lb psi to 25lb psi my steering jumps to 14,920lbs. drive axle is 21,425lbs and tag reduces to 6200lb. My main concerns are the following with my past experience in owning a trucking firm legally I cant exceed 12,000lbs on steering and I should be able to transfer up to 10,000lb onto the tag axle off of steering with my drive axle absorbing some of this also of course. With my fuel tanks(325 gallons x 6.50lbs) and my water tank (300 gallons x 8lbs.) directly behind my steering axle I am over weight on steering with full tanks no matter what I do with my tag. So I increased my tag axle psi to 60lbs. to asorb steering weight the best I know how and with that done I still in excess of 12,000lb legal by law the best I know having 14,205lbs. Anyone else have this situation or give advise on how to lighten up steering axle with full fuel and mostly full water tanks?? As always thank you and hope I did not confuse anyone

[Hardtrigger]

Oh and one other thing. As mentioned above adjusting weight to tag axle is not a problem but from time to time when I dump tag to make a hard turn when I switch back to on on tag to replenish the air to axle I get a different psi to reading on axle and I need to readjust air pressure to tag when I park to get back to 60psi. I would think thought I dump air for turns when reactiate switch it should go to previous settings? I mean no a major concern for I can keep readjusting the air but it would be nice to be done with it. Thanx Robert

[Hardtrigger]

Wow to much whiskey in the casino last night @ crap table!!Head hurts. Kinda hard to read my threads above and apologize. If anyone is able to comprehend what I was trying to ask above and have any resolution I would be appreciative of both getting through that mess and having a solution. Thanx in advance

[GORDON HUMMEL]

http://www.newellclassic.com/forum/showthread.php?t=1471&highlight=AXLE+WEIGHT

When you are feeling better, you might want to review the above thread. I have a similiar coach to yours with similiar issues. Mine was fixed with changing to "H" rated steer tires, 14,400 lbs @120 psi. While this is greater than the listed cap for the coach, I believe, the tag on the coach is incorrect. If you stop @ Newell, you might want to ask them about that.

I can't for sure answer as to why the tag axle pressure does not return to the previous setting after being dumpted. If it wasn't new, I would say it is the regulator & considering it came from HF that is probably the problem.

I don't understand how reducing the tag axle air pressure will increase the weight on the front axle. This is backward to my way of thinking.

In all honesty, I like your weights @ 60lbs in the tag; better than mine with 30 lbs.

Have you checked the ride height? There are a few recent threads discussing that topic.

All in all I suggest a trip to Miami, to establish a valid base line.

As to front axle capacity limited to 12K, most if not all the Mack trucks I am familiar with have a 20K front axle, & need it. New Newells also use a 20k axle !

My 2 cents

[fulltiming]

I concur with Gordon. I had access to a full set of wheel scales in Kerrville, Texas several years ago and I found that it can be challenging to get the numbers to make sense when shifting the tag axle pressure as it takes some time and movement of the coach to get it to readjust to the new air pressures. I did find that as the tag pressure was DECREASED the major change was a redistribution onto the drive axle and off of the tag axle AND a much smaller DECREASE in the load on the front end. The weight on the front axle is controlled much more in the early 1990's coaches by the amount of fuel on board. Fuel is just behind the front axle so almost the entire load is transferred to front axle with a small amount added to the rear.

I also found that moving heavy objects (like tool boxes) from the bays close to the front axle into the bays toward the rear of the coach helped.

I don't think you will find any way to get the front axle weight close to 12,000 lbs on a 1990 or newer Newell. Typically a tag axle early 90's Newell had a front axle rated at 14,200 lbs because that was the limit of the tires rather than the axle or the brakes. While no one advocates overloading tires, the 11R24.5 H rated Bridgestones (I do NOT recommend using G rated Bridgestones on the front axle) gave excellent service even if somewhat overloaded. If you are running the front axle significantly over the limit, change the front tires to 305/75R24.5 tires which carry a rating of about 1400 pounds more per front axle. In California, for example, 12,500 pounds is the maximum weight for the front axle. However, there are numerous exceptions including buses and motor vehicles that are non-commercial (such as RV's).

Having an axle over 20,000 pounds will cause you grief on some of the weight controlled toll roads in northeast with in road scales so playing with the tag pressure to insure you stay below 20,000 on the drive axle is important. The front axle weight of 14-15k will not likely cause you problems.

[Hardtrigger]

Thanks for the replies guys. The scale house was closed but the weight board outside was on and I was able to park the coach on the scale and with the tag on the scale I was able to add and delete air out of the tag and noticed that when I added air to the tag it added weight to the tag also but at the same time the steer axle would subtract 200-300lbs every 10 lbs or so! Havindg the experience with class 8 trucks we would adjust our fifth wheel slide to add or subtract weight off of the steer axle sort of the same way I guess. The more weight one axle takes on would reflect less weight of the opposite axle! Kid you not sliding the fifth wheel on class eight truck each inch over the drive axle would alter steer axle weight couple hundred pounds. Im fine with tag axle at 8000 lbs. or so if the steer axle is engineered to handle the 14000 lb. weight and great advise with upgrading the load rating on the tires. I was reading somewhere on this board that Newell suggest running 130 lbs. in the steer axle tires which I am hesitate on doing for the manufacture suggest 110lbs. What are your thoughts guys on having 20lbs. over manufacturer specs. I mean if that is cool than I would add air right away. Thanx again, Robert

[fulltiming]

See this thread, posts 20 and 22, for some additional tire information. http://www.newellclassic.com/forum/showthread.php?t=987

If you are running H rated tires, they should show a max inflation of 120 psi rather than 110 psi. If you are running G rated tires on the front, they should be changed out for H rated tires as soon as you can. The G rated tires will not take the weight you have on them safely.

For everyone reading this thread, please remember that inflation advice for the 11R24.5 or 305/75R24.5 is NOT relevant for the Newells with the newer, heavier models that changed to 22.5" wheels and 315/80R22.5 tires.