Air Bags - Testing

[gene]

I am no expert on the bags but the group thinking is that the cracks do not
tell the quality of the bag. Also might be better to install the one new
bag because some times the new bags have leaks that you would not be able
to determine unless they are installed. That way, your old bag that you
removed you know does not have leaks now and you could keep it as the
spare. Almost every one says do not carry a spare because you cannot tell
if is going to be ok when it is installed. Most carry a bolt or a block of
wood that they can use if the air bag goes down.

I know of no diagnostics that will tell you the quality of your current
bags. They do last a long time and normally do not burst, however, they
certainly do blow out as you have probably read. About the only thing that
is done to increase the life of the bags is to rotate them 180 degrees
every year so that they do not get a permanent bow in them called "hot dog"
effect. Sorry this is not much help

gene

>Salutations:
>
>I'm trying to fix up some of the basics on our elephant before moving onto
becoming a complete nut and spending the kids college fund on the total
restoration that will ultimately, unfailing come.. It's a sickness -
Anyway, I've gotten through the front end ($900 Canadian and still
counting) and am now addressing the rear.. which brings up a question about
air-bags..
>
>I know that I should replace them if I have any suspisions at all..
However, at $350 CND+ taxs per bag (plus shipping) in Canada - I'm trying
to make sure that they need attention this year.. Like - after new tires,
fresh brakes, Onan work, roof air conditioner replace/fix/ or rewire.. etc.
etc.
>
>They are kinda cracked at the ends (about 1/16 of inch deep - but not
long) and I can see hints of white canvas (or whatever materail it is) but
am assured by others that exterior bag cracks are not serious.. There is no
history as to when these were last changed and they seem to hold air well
enough (They'll hold pressure over a couple of days parked at our elephant
stable - when I start it up the compressor runs for a couple of miniutes
and thats it)..
>
>So, what I'm wondering is: is there a loose measurement around the
circumfernce of the bag or a pressure test that will tell me anything
useful? Should I be looking for anything in the shape of the bag that is
meaningful? I have bought one brand new spare (just in case) and they don't
seem that different around the waist - but given how suddenly crappy this
kinda thing can turn out if something goes wrong I thought I'd check and
see if there was anyway to test these bags.. Anyone here ever work for
Firestone and have lots of details about these things?
>
>If new bags are installed, is there anything I can do to make bags last a
little longer? Wrap them in web to avoid rock damage and the like, coat
them with something to keep the rubber fresh?
>
>I have found the original '73 Pop. Sci. test drive report in my Magazine
collection (they loved it - but burst both bags on the test run).. I'm not
likely to go for 4 bag system as, if I have to rebuild, I would likely work
out a replacment using a more standard (cheaper) 5 ton truck bags and lose
the 'automatic leveling' systems in favour of easier to find parts..
>
>your pal
>J Dexter
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/

 

[j dexter]

Salutations:

I'm trying to fix up some of the basics on our elephant before moving onto becoming a complete nut and spending the kids college fund on the total restoration that will ultimately, unfailing come.. It's a sickness - Anyway, I've gotten through the front end ($900 Canadian and still counting) and am now addressing the rear.. which brings up a question about air-bags..

I know that I should replace them if I have any suspisions at all.. However, at $350 CND+ taxs per bag (plus shipping) in Canada - I'm trying to make sure that they need attention this year.. Like - after new tires, fresh brakes, Onan work, roof air conditioner replace/fix/ or rewire.. etc. etc.

They are kinda cracked at the ends (about 1/16 of inch deep - but not long) and I can see hints of white canvas (or whatever materail it is) but am assured by others that exterior bag cracks are not serious.. There is no history as to when these were last changed and they seem to hold air well enough (They'll hold pressure over a couple of days parked at our elephant stable - when I start it up the compressor runs for a couple of miniutes and thats it)..

So, what I'm wondering is: is there a loose measurement around the circumfernce of the bag or a pressure test that will tell me anything useful? Should I be looking for anything in the shape of the bag that is meaningful? I have bought one brand new spare (just in case) and they don't seem that different around the waist - but given how suddenly crappy this kinda thing can turn out if something goes wrong I thought I'd check and see if there was anyway to test these bags.. Anyone here ever work for Firestone and have lots of details about these things?

If new bags are installed, is there anything I can do to make bags last a little longer? Wrap them in web to avoid rock damage and the like, coat them with something to keep the rubber fresh?

I have found the original '73 Pop. Sci. test drive report in my Magazine collection (they loved it - but burst both bags on the test run).. I'm not likely to go for 4 bag system as, if I have to rebuild, I would likely work out a replacment using a more standard (cheaper) 5 ton truck bags and lose the 'automatic leveling' systems in favour of easier to find parts..

your pal
J Dexter

 

[darren paget]

IMO, the cracks in the bags are the same as weather checks, or cracks in old tires. The money you spend on new bags is good preventative maintenance. You could do a lot more, costly, damage by having a bag blow out while on the road. Even just sitting in your drive way. Damaged wheel wells and suspension components will add to the cost of the bag if this happens. The unfortunate side of these motor homes is the fact that some replacement parts are expensive. If you spend the $1200.00 U.S. and get the four bag system, replacement bags are readily available
and are considerably cheaper, but the initial outlay hurts. If you find a good, less expensive alternative you will also, more than likely, find a market for it. Good luck. Darren

> Salutations:
>
> I'm trying to fix up some of the basics on our elephant before moving onto becoming a complete nut and spending the kids college fund on the total restoration that will ultimately, unfailing come.. It's a sickness - Anyway, I've gotten through the front end ($900 Canadian and still counting) and am now addressing the rear.. which brings up a question about air-bags..
>
> I know that I should replace them if I have any suspisions at all.. However, at $350 CND+ taxs per bag (plus shipping) in Canada - I'm trying to make sure that they need attention this year.. Like - after new tires, fresh brakes, Onan work, roof air conditioner replace/fix/ or rewire.. etc. etc.

- --
Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com

 

[chuck blanford]

>
> Date: Mon, 19 Jun 2000 16:26:49 -0400
> From: J Dexter
> Subject: GMC: Air Bags - Testing
>
> If new bags are installed, is there anything I can do to make
> bags last a little longer? Wrap them in web to avoid rock damage
> and the like, coat them with something to keep the rubber fresh?
>
> your pal
> J Dexter

My old bags were also abraded at the front and rear radius. I installed the
stainless steel air bag protector plates to protect the new air bags from
the road detritus thrown by the tires. I believe these plates may also
limit damage to the air bag in the event of a tread separation. The plates
are made by Jim Demares (sp?) and advertised in GMCMHM.

Chuck
77 Kingsley
North ID

 

[emerystora]

> I have bought one brand new spare (just in case) and they don't
>seem that different around the waist - but given how suddenly crappy
>this kinda thing can turn out if something goes wrong I thought I'd
>check and see if there was anyway to test these bags.. Anyone here
>ever work for Firestone and have lots of details about these things?
>
>If new bags are installed, is there anything I can do to make bags
>last a little longer? Wrap them in web to avoid rock damage and the
>like, coat them with something to keep the rubber fresh?

J Dexter -- If you have already bought a new one, instead of using it
for a spare you should install it on the side that looks worse and
use the old one for an emergency spare. Don't wait until you have a
blowout to replace the bag as you might incur a lot of fiberglas and
wheel well damage. I had a pressure switch go bad once and it blew
up a bag. I bought two new ones and just put one on the GMC. Three
years later I had a leak in the other bag and found that the new
unused one had a pin hole. It had never been used and was not in
warranty at that point. I had to buy another.

The best thing to do with the bags is to keep them clean. Use car
wash soap and a brush once in a while to get the road oil off them.
Inflate them all the way and clean the ends where they wrap around
the cones. The one that I had go bad from a leak was due to a tiny
sharp pebble that had gotten onto the cone and the bag had folded
back over it. Eventually it wore a hole into the bag. If I had
cleaned that area once in a while I might have prevented the problem.

Some have recommedned rotating the bags 180 degrees to prevent "hot
dogging" or a permanet curve that can set into the bags.

Do you have fender skirts to shade the bags? They will last longer
if you do. You can also coat the bags with a rubber lubricant or
rubber tire dressing which is a polyglycol base. It will not harm
the rubber. It is sold at auto parts stores to make tires look shiny
and new. DO NOT use anything with a petroleum base as it can degrade
the rubber.

Emery Stora
77 Kingsley
Santa Fe, NM

 

[steve clevenger]

>From: tom warner
>you mean the bags for the 4 bag system are available NOW. But will they in
>10 years?

They are standard Firestone bags used in several applications & I feel sure
they will be much more available than the stock GMC bags will in 10 to 20
years. And lots cheaper, too.

Steve Clevenger
76 Transmode 230
Tulsa, OK.
On Digest

 

[marlene meineken]

Emery
In town and looking for tire dressing and everything I found was petroleum
base. What brand's are you referring to?
Marlene Meineken
*****************

if you do. You can also coat the bags with a rubber lubricant or
rubber tire dressing which is a polyglycol base. It will not harm
the rubber. It is sold at auto parts stores to make tires look shiny
and new. DO NOT use anything with a petroleum base as it can degrade
the rubber.

Emery Stora

 

[emerystora]

>Emery
>In town and looking for tire dressing and everything I found was petroleum
>base. What brand's are you referring to?
>Marlene Meineken
>*****************

Marlene - let me get back to you on this. I'll have to see if I
still have any in the garage. Should get to you tomorrow.

Emery Stora
77 Kingsley
Santa Fe, NM

 

[paul bartz1]

Marlene:

One such petroleum free product is Meguiar's Vinyl & Rubber Cleaner /Conditioner.
If you're unable to find it in your local auto parts store, etc., try an auto body
shop supply store.

Paul Bartz

From: owner-gmcmotorhome
[mailtowner-gmcmotorhome]On Behalf Of Marlene Meineken
Sent: Wednesday, June 21, 2000 10:04 PM

Emery
In town and looking for tire dressing and everything I found was petroleum
base. What brand's are you referring to?
Marlene Meineken
*****************

if you do. You can also coat the bags with a rubber lubricant or
rubber tire dressing which is a polyglycol base. It will not harm
the rubber. It is sold at auto parts stores to make tires look shiny
and new. DO NOT use anything with a petroleum base as it can degrade
the rubber.

Emery Stora