Quad Airbag suggestions?

Scotty

Scotty

Active member
Apr 29, 2021
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Minnesota
New user here. Just purchased a 1978 GMC Royale (rear bath model).
As all you veteran GMC owners know, I have a very long list items to check, repair/replace, update and so on.

First order of business is replacing the original airbag system with a quad bag system.

I know of California Quad Bag system from Alex Sirum, appears to be the same as the the system offered from Applied GMC MH
Then there is the Quad bag system from the Co-Op.

I do not know if there are other systems to choose from, so I will start with these two.
Any recommendations as to which one and why?
 
The Quadra bag does not transfer the road shock of a bump to the opposite wheel... it transfer the shock directly to the bogie mount and to the frame. Look at any tandem axle, they use a pivot point between the two springs to balance the load between the wheels and to transfer shock. The quadra bag does none of this.
 
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RF_Burns said:
The Quadra bag does not transfer the road shock of a bump to the opposite wheel... it transfer the shock directly to the bogie mount and to the frame. Look at any tandem axle, they use a pivot point between the two springs to balance the load between the wheels and to transfer shock. The quadra bag does none of this.
Click to expand...
I’d truly never considered this. I was considering a quad bag system but that ends it for me. I think I’ll buy a couple of spare standard bags instead.
 
Glad I asked.

Are there any comparisons of the single airbag options?

Repro bags from Cinnabar?
Hensley?
Mother-in-law?
others?
 
Here is a spreadsheet, but I'm not sure when it was last updated. It doesn't mention the Cinnabar OEM reproductions and has several that I believe are not longer available.

My current airbags are a single bag from Applied, I believe were called "Silvertone" at the time (~2010). I'm not sure if they are a current model, but I would not recommend them because if they deflate the internal opening for the inflation air gets covered by the opposite side of the airbag. This prevents you from re-inflating the airbag until you lift the coach a bit using a jack, then you can re-inflate the airbag.

When I replace them, I will go with Cinnabar reproduction OEM or the Alex Ferera aingle bag.
 
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Are your airbags shot?

If you're in need of bags anyway, then I've considered the Sully bag as a reasonable replacement .

But mine are still in decent shape. I don't carry a spare bag but someday I'll bring along a piece of threaded rod for an emergency in case one gives out.

Since you're a new user, if the bags are working ok, I'd move them to the bottom of the list. Priority one is to use the coach and enjoy it. Don't let the rehab project make the coach unusable for very long or else you won't end up enjoying it and you might even let it go.
 
Hi, what’s the Sully bag? On the applied site it has the original design bag with aluminium cones
www.gmcrvparts.com

ORIGINAL DESIGN BAG WITH ALUMINUM CONES - GMC MOTORHOME

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.
www.gmcrvparts.com
And the Firestone replacement for the sully system
www.gmcrvparts.com

REPLACEMENT BAG FOR SULLY SYSTEM AND MONO BAG SYSTEM

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.
www.gmcrvparts.com
Which is recommended?
 
gerryg said:
Hi, what’s the Sully bag? On the applied site it has the original design bag with aluminium cones
www.gmcrvparts.com

ORIGINAL DESIGN BAG WITH ALUMINUM CONES - GMC MOTORHOME

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.
www.gmcrvparts.com
And the Firestone replacement for the sully system
www.gmcrvparts.com

REPLACEMENT BAG FOR SULLY SYSTEM AND MONO BAG SYSTEM

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.
www.gmcrvparts.com
Which is recommended?
Click to expand...

You must be a Brit.
Anyhow, the original design bag bolts right in to the mounts you have. The Sully system requires buying new mounting plates as well as bags. The bags are much cheaper and available than the OE design though.
 
gerryg said:
Not quite. An Aussie. What gave it away?
Click to expand...
Aluminium.
It loses a syllable in North America. Forgot Aussies pronounced it that way too.
I' m in a similar quandary about airsprings, I have one good and one bad one, I might got to a Daytona Ferrera single bag system, still deciding.
 
The OEM airbags have a tapered cone on each end which gives a better spring rate than other choices. But its been over years since I replaced mine so I don't recall if I could tell the difference.
 
For the record - I love the way the Aussie's and Brit's pronounce Aluminium
my dang spell check wants to change it to aluminum

One bad bag. but both look to be original, As such, I will replace them both regardless.

Order of priority for now...
1) maximum travel (lower/lift),
2) most universal (replacement parts availability)
3) Ride comfort/stability
4) Price
 
gerryg said:
Hi, what’s the Sully bag? On the applied site it has the original design bag with aluminium cones
www.gmcrvparts.com

ORIGINAL DESIGN BAG WITH ALUMINUM CONES - GMC MOTORHOME

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.
www.gmcrvparts.com
And the Firestone replacement for the sully system
www.gmcrvparts.com

REPLACEMENT BAG FOR SULLY SYSTEM AND MONO BAG SYSTEM

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.
www.gmcrvparts.com
Which is recommended?
Click to expand...
I found this link for the sully bag system:

 
Ok- to answer your first question-
1. Applied and coop quadbags are the same.

2. sirum quadbag I think is different.

but in my opinion you are in the right direction now- i have never heard a bad thing about the alex ferrerra/daytona single bag system. Easy install.

Sullys are worse then the daytona bag. But still fine. Just a little soft I personally think.

But as christo said! Cinnebar has stock bags that are great and keeps everything working stock and fine.

i think travel on stock is greater then the others. But others are fine and work for most.
 
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LQQKatJon said:
"i think travel on stock is greater then the others. But others are fine and work for most."
Click to expand...
navigating in and out of my driveway requires an angled approach in the motorhome to prevent/reduce dragging.
so every fraction of an inch of lift helps.
sacrificing elsewhere (ride/cost/other) is secondary if I can't use the coach without damaging it.

I looked on Cinnabar's web site - (certainly not much to offer other than a place holder with a phone number).
Do they have a custom air bag system or sell replacement OEM bags?
 
Yes- cinnebar website is poor. The other vender sites are not much better- best to call.

i do not deal with Cinnebar too often, but they will surprise me how good they are when I do.

cinnebar has reputation of keeping things stock and not modified.

so cinnebar carrys direct replacement parts. And they carry a stock airbag replacement for $400 something??? Some say expensive, but not really when you look at alternatives.
 
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My coach came with a quad bag setup, likely very expensive, and I viewed it as a disappointment. For all the reasons Bruce mentioned. Those bogies were designed to oppose each other. Just look at the way they handle speed bumps in succession. It was a great design, and I'm bummed that it was defeated on my coach. I'd have much preferred that the PO spent $800 on stock replacements instead, rather than getting sucked into the hype of the quad bag setup.

Of course, I could limp the coach around short distances on 5 wheels, for whatever that's worth. And really, compared to my last Class A coach, this thing still rides like a dream.
 
I just got off the phone with Mr. Caughlin of Cinnabar. What a fantastic wealth of knowledge!
Not only will I be sticking with the OE style airbag setup, but I will be upgrading my wheels to 16's (replacing the 16.5's) - and much more.
 
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