Air bag upgrade

darylleemiller

New member
Apr 8, 2019
2
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We need to upgrade our airbags on our 1973 GMC motorhome. Any advice on what we should be looking for and other considerations before purchasing them
would be greatly appreciated.
Thank you, Daryl Miller
 
Hey Daryl:

I’m going to share what I’m using, and why. There will be many opinions on this, and I think it’s best to share my experience.

I do have the math to back this up, but let’s just say this works for me.

I just went through this exercise, with the goal being the handling I wanted.

After completely rebuilding the front end, I was still getting wander.

I had a great ride, but not the handling I wanted, and we use it as a touring coach.

A long time owner has warned me a while back that larger bags with greater volume would present handling challenges, and he was completely correct.

So I learned a lot about spring rate (they really are being used as springs), and deduced that I likely wanted air volume not to exceed the stock bag, and pressures +/- 15% of the original. What amplifies the effect on the steering is the wheelbase of our coaches, which is considerable.

What’s on the coach now is Alex Ferrara’s solution. I’m completely thrilled with them. Simple and straightforward, and it handles like the 26 foot hot rod with plumbing (comment borrowed from Jim B) that I wanted.

Your mileage my vary. Batteries not included.

Let the discussion begin.

Dolph

DE AD0LF

Wheeling, West Virginia

1977 26’ ex-PalmBeach
Howell EFI & EBL, Reaction Arms, Manny Transmission

“The Aluminum and Fiberglass Mistress"

>
> We need to upgrade our airbags on our 1973 GMC motorhome. Any advice on what we should be looking for and other considerations before purchasing them
> would be greatly appreciated.
> Thank you, Daryl Miller
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
My GMC has had Jim K's 4 bagger for over 12 years.

When I picked up the GMC, the SOB that sold me the coach had done some "restoring" to her. He didn't touch the
the Air bags, which were original. He didn't know anything about them and assumed they were good.

At the time these bags were still obtainable but only certain places had them for purchase. There were getting '
harder to find.

When I had the bags inspected, we found that the back side, where you cannot see, of the bags were deteriorated.
Asking what the options were, I could have replaced with the OEM bag but with availability getting more and more
difficult, they offered a different option. The 4 bagger that jim offered has a robust frame that bolts on.
If you needed to, you could install them yourself in a day or so.
They use a common air bag that is found everywhere making them very easy to find.
The ride is the same as the OEM bags, stable and proper.

The only difference that I can see, is the OEM bag had the full movement between the left and right mounting
points. This is why when GMC demonstrated the ability to drive over 4x4 posts with little bounce, the GMC
hardly noticed. The 4 bagger cuts the original bag in half so you might experience a little bounce when
you drive over those 4x4 posts, but will you do that often.

With two bags on each side, one on each axle, you do have the option of being able to move the coach if a
bag for some reason may fail. This was not an option with the OEM bag.

On the highway she rides straight and true. I have had no problems at all with this system, it came highly
recommened and I recommend it. Do talk to Jim K about it and get all the info first hand.

This was a product that was designed just for the GMC motorhomes.

Thanks Jim for a great product.

slc
--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
Daryl,
A few years back I had the OEM airbag on the drivers side blow out at speed. My oversized tires immediately began grinding away at my wheel wells, but control of the coach was never an issue. Fortunately a safe pulloff place was across and just down the highway. I got on the phone to jim K. and had the quadra bag system sent to one of my intended destinations. At the time, I made the choice to avoid a repeat of the bag blowout scenario, though I repeat, control wasn’t an issue.
It took me two days to install the quadra bag system with my dexterity roughly equivalent to a lobster. Straightforward, good instructions, with only one change with a hand grinder to avoid contact with an oddly placed brake line.
Now, many miles down the road, I am more than satisfied with the system. It handles well, gives me good leveling travel and is one of the few “systems” on my project coach that doesn’t keep me awake at nite.
As Dolph has so eloquently stated: “Your mileage may vary, Batteries not included.” To which I would add… “...some assembly required."
Doug

Douglas & Virginia Smith
dsmithy18 at gmail
Lincoln Nebraska
’73 “Canyonlands” since ‘95: “Wanabizo”, Anishinabe Indian for “He gets lost driving” Yes, really.
Quadrabag/6 wheel disks/3;70 final/Paterson QuadraJet/Sundry other
P&W PT6, no wait, that's the wish list...

>
> Hey Daryl:
>
> I’m going to share what I’m using, and why. There will be many opinions on this, and I think it’s best to share my experience.
>
> I do have the math to back this up, but let’s just say this works for me.
>
> I just went through this exercise, with the goal being the handling I wanted.
>
> After completely rebuilding the front end, I was still getting wander.
>
> I had a great ride, but not the handling I wanted, and we use it as a touring coach.
>
> A long time owner has warned me a while back that larger bags with greater volume would present handling challenges, and he was completely correct.
>
> So I learned a lot about spring rate (they really are being used as springs), and deduced that I likely wanted air volume not to exceed the stock bag, and pressures +/- 15% of the original. What amplifies the effect on the steering is the wheelbase of our coaches, which is considerable.
>
> What’s on the coach now is Alex Ferrara’s solution. I’m completely thrilled with them. Simple and straightforward, and it handles like the 26 foot hot rod with plumbing (comment borrowed from Jim B) that I wanted.
>
> Your mileage my vary. Batteries not included.
>
> Let the discussion begin.
>
> Dolph
>
> DE AD0LF
>
> Wheeling, West Virginia
>
> 1977 26’ ex-PalmBeach
> Howell EFI & EBL, Reaction Arms, Manny Transmission
>
> “The Aluminum and Fiberglass Mistress"
>

>>
>> We need to upgrade our airbags on our 1973 GMC motorhome. Any advice on what we should be looking for and other considerations before purchasing them
>> would be greatly appreciated.
>> Thank you, Daryl Miller
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I just went through this tap dance a few months ago.

I bought a set of Alex Ferrara's air bags from Sirum GMC and am very happy with the performance. That they can be installed in about 20 minutes per
side (I'm not the fastest wrench in the world) without removing the T-skirt is another benefit.

JWID, YMMV
--
Bob Heller
1974 X-Canyonlands 26ft
Original 455 exc for timing chain, Rockwell intake, valve covers.
AF air bags. 145k miles.
Winter Springs FL
 
SO....................

when you were performing this TAP DANCE,

Did you have the obligatory straw hat and bamboo cane?
--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
No.

Soft shoe.

Dolph Santorine

DE AD0LF

Wheeling, West Virginia

1977 ex-Palm Beach TZE167V100820
Sullybuilt Bags, Reaction Arms, Manny Transmission

>
> SO....................
>
> when you were performing this TAP DANCE,
>
> Did you have the obligatory straw hat and bamboo cane?
> --
> GatsbysCruise. \
> 74GMC260 Former Glacier Model style. \
> Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
> UBUNTU VOYAGER - Berzin Auto Center
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I have the Jim K Quadra Bag system on my coach. I like it for all the reasons mentioned in previous posts. The Alex Bag system looks good as well.
Whichever system you decide on, My feeling is that it is important to have the air system operating as it should. That way you don't need to worry
about dragging your rear end on the pavement when negotiating driveways and rough/uneven surface streets. I can turn my valves to full raise on urban
surface streets and not worry. The Quadra Bag system also allows full suspension travel, within the limits of the shocks, when leveling for camping.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
I too have the Quadra Bag system from Jim K at Applied. Extremely happy. I think it helps some with high side winds. Plus I really like the idea that the coach will stay up if anything happens to a bag. Then for my application. It was the only one that I could use. As we carry a $1200, 3 ft wide, and 8 ft long aluminum ramp under the coach frame. That hangs down below that frame. 5-1/2 inches all the time. I just don't have much ground clearance. Been doing it that way for 11 years now. ( And you thought yours was low pulling into some drives. ) GRIN. Bob Dunahugh 78 Royale
 
Thank you all for your advice and reasoning behind your choices for the systems you have installed on your motorhomes. We have decided to go with the
Alex Ferrara system. It looks like a very solid and cost-efficient answer to our requirements. Does anyone have advice as to who we should order them
from? We are in Scottsdale AZ. You guys are awesome!!
 
> Thank you all for your advice and reasoning behind your choices for the systems you have installed on your motorhomes. We have decided to go with
> the Alex Ferrara system. It looks like a very solid and cost-efficient answer to our requirements. Does anyone have advice as to who we should order
> them from? We are in Scottsdale AZ. You guys are awesome!!

I know Jim Kanamota at Applied GMC carries them.

Since you are in AZ, consider joining s at a Saguaro Jetset rally sometime next rally season. It's a fun, knowledgeable group.

gmcsj.com
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member