Visit our Popular Forums

Mr Sunshine · 10-10-2017, 11:10 PM

Hi: I am new to this so I need advice about the tag axle on a 1986 345. I need to drive it 800 miles home and am not sure about the tag axle. This has been siting so the tag axle probably does not work, I have researched this topic here and need to know if I will hurt the drive axle if the tag axle will not apply pressure to the ground. Should I have more air in the drive axle air bags? I think the drive axle should be 70 on 80 psi off? I believe the tag axles are available from Andy but the drums are unobtainable. I plan on being as light as possible for the trip home, drain water tanks etc, but what should I do to keep damage to a minimum? Thanks in advance. PS I will have many more questions in the future but right now I just need to get it home. I will check all the usual stuff before I depart.

Grosspoluter · 10-10-2017, 11:56 PM

Sooo here's what I know about the tag axle's
The drive axle is held up by the airbags
if you researched it here, I believe you'll find that the airbags should be about 10 1/2 inches tall from the top of the airbag to the bottom of the airbag. I run about 100 pounds PSI in the air holding tank
I don't know if there's a way of knowing how much pressure is actually in the bag itself
(I would like someone to chime in on this)
I do know that the airbag height is adjustable there is, for the lack of a better description an upside down L bracket made out of a threaded rod that you can adjust to put more or less pressure in the airbags to raise or lower the axle
I do know you will damage the rear tag axle if those airbags don't have enough air in them. too much weight on the tag axle WILL bend the axle. I believe this is what happened to my 345.
With my bags at 10 1/2 inches on the drive axle, I still have a negative camber of about 2° on each wheel. This puts the tag axle tires only about one or 2 inches from the inside of the wheel well. It gets much worse if the airbags are only 7 inches tall, the negative camber goes to about 4° this makes the tag axle tires rub on the inside of the wheel well.
I've had my 345 for about four years now
it's still a learning curve for me.
I'm sure more people, with more knowledge will respond
I would like to add the question:
is there is a way of knowing how much psi is in each air bag?
I've noticed on my 345 when adjusting the bags. adjusting the left one affect the height of the right one.
Are they tied together and equal out some how?

mehes · 10-11-2017, 04:46 AM

On my 86 345 there is a leveling valve sensing off the tag axle wheel on each side of the coach. These valves feed air to the air bags that adjust the height of the drive axle. Everything is tee’d together which is counter intuitive. You would think each side would be independent. I know on other years there was a single leveling valve off the center of the drive axle. The point of the whole system is to limit the load on the tag axle to about 3000 pounds total. If your bag height is somewhere around the 10-1/2” area you should be OK for your trip. Note in the Airstream manual the height may vary from 9-1/2” to 10-3/4”. Take it easy, pull over and check your tires and ride height occasionally and you should be fine.

WayneG · 10-11-2017, 06:56 AM

For what it is worth, on my 84 270, only a single axle, the control rod length is fixed with no adjustment. Also if yours is adjustable, be aware that the valve has a time delay to operate. It may take more than a min. to get the height change.
Be careful if you are under the vehicle while working on the springs or valve or adjusting. On mine the gas tank could crush you if the valve releases its air.

rem3006 · 10-11-2017, 03:27 PM

Blow it up to 80psi & go. Both air bags will be at that pressure. That tag axle won't get hurt. If you have to much pressure on te tag axle your duals will lighten up & you won't have any traction. It's a dumb ass system which has caused me a few headachecs. Just monitor the air pressure in the air bags, which of course is hard to do because the pressure gadge is praobably ba k in the bedraoom. Have fun with that s.0.b.

bkahler · 10-11-2017, 03:28 PM

Here's some links to the service and owners manuals for the 84-86 310/345 coaches. The service manual has some good information on the air bag suspension system.

345 service manual

345 owners manual

Brad

Mr Sunshine · 10-11-2017, 08:30 PM

Thank you all for the great info. I am new to AS and new to this site so I may have problems navigating the site, but already I have got a great deal of knowledge from you guys. Thanks again.I have a Peterbilt with air bag suspension so I know a little about the leveling system etc, it's the tag axle that I don't fully understand. I will put 80 lbs in the air bags and hope for the best. This 345 has been sitting since 2010 so from what I understand the rubber cords in the tag go bad from sitting therefore I assume that they are bad and will check as per the info on this site when I get the 345. I bought this sight unseen so any other tips on what to check before I drive it home would be appreciated. I will check the usual stuff, oil water tires etc, but the specific things for this 345 is what I need to know. The tag axle seems to be the biggest problem with the 345. I really do Love it though and I haven't even seen it. Thanks again to everyone.

WayneG · 10-12-2017, 04:35 AM

Quote:

Originally Posted by Mr Sunshine

This 345 has been sitting since 2010 so from what I understand the rubber cords in the tag go bad from sitting therefore I assume that they are bad and will check as per the info on this site when I get the 345.

If it has been setting for 7 years untouched, I would be nervous about driving it on tires that are going to be over 7 years old!
You are going to need new tires anyway, you may want to take it to a nearby shop to have the tires, brakes, and bearings inspected. While it is in for tires, have them look over the rest of the undercarriage & drive train.
It is so much easier checking it all out on a lift than on the ground. If they let me, I get right in there too, so I can see how everything is laid out.

tevake · 10-12-2017, 05:47 AM

Welcome Mr Sunshine to our zany group.
Sounds like you are on the right track, focusing on the running gear and brakes for your first trip.
Also a good tip on checking the tires closely at that age, and keeping the speeds down if driving on older ones.

Another chronic issue in our 454 powered beasts is engine cooling. Tight quarters in the engine room and extra effort pulling all the weight, make for cooling challenges. Often the bottom of the radiators get clogged and other restrictions make for high engine temps.

After sitting for so long the fuel will be suspect, and should be drained, tank flushed, filters changed. Should be two filters, one near the tank another midway forward near the battery drawer.

Lots to deal with getting one out of a long hybrination like that.
Do keep us posted on how things go for you getting it going again.

I was looking for a 310 when my 345 came to me, and Im very happy with it, great layout and nice on the road.

Cheers Richard

Mr Sunshine · 10-18-2017, 08:55 PM

I am not sure if this is a reply to my previous posts or not. But I got it home 800 miles, no real issues. Needs lots of small stuff and I need to learn a lot. I have the owners manual and it is not much help. Is there a salvage yard that specializes in the AS motorhomes? If I can figure out this forum I will have lots of questions. This 345 has Gear Vendors overdrive and banks exhaust. Ran real good coming home. Gas mileage seems good also.