early prevosts tag dump

[gmcbuffalo]

This feature of the early Prevost to dump the tags axle bags when the Aux pressure gets below 35 PSI is something I am thinking of changing.

Has anyone done this and specially has anyone done it like Joe C recommends in this post?

http://prevostmotorhomes.ning.com/forum/topics/reconfiguration-of-the-tag

As someone post PrevostCar wants around $1000 in parts and $2000 in labor. Joe C says his method is around $10 in parts and 4 hours of your time.

[rahangman]

I am guessing that if your 92 has this feature, then my 90 does also....

[gmcbuffalo]

Rodger that.

[Jon Wehrenberg]

I'll try to explain this so it can be understood by all. There is no f*****g way a $10 fix is going to cure that design issue.

Prevost engineers have designed a fix that works and makes the suspension system function as it does on later models and the key is that they have not compromised all the features the suspension system must have. If you choose to make the modification for free and only choose to eliminate the ability to dump air in the tag axle so it can be lifted, just take the 2 three port Norgrens from between the tag and drive axle and connect the air line coming from the aft drive axle air bag directly to the tag axle air bag. Problem solved, less than $10.

[truk4u]

Why on earth would anyone want to take a chance on a cheap unapproved fix for such a vital part of the bus suspension? I looked into it when I had my Liberty and Prevost calls the job "Reverse Tag Logic." All you have to do is get the part number for the kit and look at what all is involved and then I think you'll have a better understanding as to why you wouldn't want to spend just 10 bucks.

[stevet903]

Here's the link to the Prevost modification instructions - http://prevostparts.volvo.com/technicalpublications/pdf/Sb96-14B.pdf

It's confusing at best, because it covers many different models and configurations. As the coaches get newer it takes more hardware and time to get the job done right. I did this on my 89 and it is indeed simple and cheap. Block the coach up so it won't fall, get out your stubby wrenches, and swap the locations of 8 air lines on the rear suspension Norgrens, 4 on each side. You then need to make a wiring mod to make the tag indicator light/buzzer work correctly (if you don't, the light/buzzer will be on when it is down, off when up). Works great, and took me about 4 hours total in the driveway - a pit would easily cut 1-2 hours off. If your serial number is between G-192 and L-580, you lucked out.

The later models, starting with L-583, require more hardware, the installation of an inversion valve, and welding on a bracket to hold it, so the job is not nearly as simple.

[gmcbuffalo]

On my year I would need to add a Inversion valve or some way to turn off the Brakes to the tags when up like they presently do. But by swapping the lines on the Norgren's I have not figured out why this function is eliminated. What happens to that valve?

Question: Why does the inversion valve do and how does it work?

[Coloradobus]

Anyone,

If your coach has, say, a house leveling system with a house compreesor (HWH), if I understand correctly we wouldn't dump air out of the tags, if the compressor keeps air psi over 35. Is this correct? If so, then those Beaver Busses equipped with HWH Leveling shouldn't have issue of sinking. ? We have learned that out of the 22 Beaver Busses we have identified, not all have HWH Leveling. Chris has noticed that our tag comes several inches off the ground when I dump, So, without looking underneath, but will be soon to see, we must have those hydraulic lifting rams.

[dreamchasers]

I also have looked at the various ways owners are dealing with this issue. My 1995 was probably one of the last Prevost made, without the updated valve logic. My tag will release if my aux air pressure get low. The complexity of the modification for my coach, using the Prevost supplied kit, is one reason I tolerate the suspension as is.

The way I manage the issue is the keep my leaks manageable. It take time, but it can be done. I use the famous "Texas Bubbler" to find and eliminate pesky leaks. I had an opportunity to show a POG member, Nolan Bedford, the device in action. i was trouble shooting a leak in my right rear suspension (most of my leaks have been in improperly installed fittings and couplings). He liked the "Texas Bubbler" it.

I had hoped of having a leak finding party at the Austin Rally, but at this time, business conflicts are keeping me attending the rally questionable.

Hector

[gmcbuffalo]

Jim
I think you found the easiest and cheapest modification for this problem, add a compressor to keep the Aux tank air above 35 PSI.
Thanks.

My Beaver doesn't have HWH leveling