Quad Airbag suggestions?

[Kendra]

Larry, greatly appreciate the detailed info - your experience running all three types. Based on what you've written I'll hang onto my Harrison quad parts for awhile if I go with the Sully.

Richard - I know I should have carried a spare bag but didn't. I was surprised to find the Harrison system will run with zero psi on one entire side (rough, but got us home). Majority of this drive was in remote areas.

I've never driven or ridden in GMCs equipped with other types of bags, but the ride in my quad-bag (when it's working) seems slightly harsh and I'd prefer a smoother ride. Just a preference.

 

[tmsnyder]

I have a single bag system and decided against carrying a replacement bag. It's going to be old when I pull it out of storage.

To me, that was the attraction of the replacement bag system. The bags are supposed to be readily available, and new instead of hard to obtain, and old.

If one does blow, I do carry the pipe/threaded rod to keep from being completely immobile. My plan is to then buy one (or two) brand new bags at the nearest truck shop and be back on the road without too much delay.

 

[Kendra]

Recent Firestone quad bag failure was my fault. I was running 80-90psi (a habit since my previous bags were cracked from age) and should probably have been 110+ psi. Tire nicked an under inflated bag at full speed.

After re-reading every post - especially post #51 on page 3 - I've decided to remove the quad bags and get closer to OEM with Todd Sullivan's system. I am not okay with road shock and stress transferred to bogies in ways the original engineers never intended.

Quad bags can theoretically run with a missing tire but I think that would be insane on the remote roads I drive. One of the first things I did when buying this coach is add a spare tire mount and 7 new tires (previous owner eliminated the spare).

 

[Richard RV]

Recent Firestone quad bag failure was my fault. I was running 80-90psi (a habit since my previous bags were cracked from age) and should probably have been 110+ psi. Tire nicked an under inflated bag at full speed.

I'm not that familiar with the quadrabag clearance and had to go look at one. With 225/75/16 tires and the bag riser bracket that raises the airbag a couple or three inches there's inches of clearance. Are you running larger tires, not have the bag risers, or maybe a different quadrabag system?

I've decided to remove the quad bags and get closer to OEM with Todd Sullivan's system.

Was the Alex Ferrara double convoluted single bag in the running? Why did you settle on Sully bags?

I am not okay with road shock and stress transferred to bogies in ways the original engineers never intended.

All engineers think they're better engineers than the other engineers.

 

[LarryW]

Recent Firestone quad bag failure was my fault. I was running 80-90psi (a habit since my previous bags were cracked from age) and should probably have been 110+ psi. Tire nicked an under inflated bag at full speed.

After re-reading every post - especially post #51 on page 3 - I've decided to remove the quad bags and get closer to OEM with Todd Sullivan's system. I am not okay with road shock and stress transferred to bogies in ways the original engineers never intended.

Quad bags can theoretically run with a missing tire but I think that would be insane on the remote roads I drive. One of the first things I did when buying this coach is add a spare tire mount and 7 new tires (previous owner eliminated the spare).

Kendra, sorry if I missed this in a previous post, but what brakes are you running on the rear?

 

[JPB]

I nave the Harrison quad bag setup. One nice feature is that a rear tire can be changed without a jack. Getting the bogie in the right position for the new tire was a bit challenging. When one side is supported on one tire the whole side drops about an inch. Both the tire and the bag were compressed. Only in an emergency would I consider driving on one rear tire and then not too far or fast.

I'm not aware of any bogie failures as a result of using quad bags.

 

[Kendra]

With 225/75/16 tires and the bag riser bracket that raises the airbag a couple or three inches there's inches of clearance. Are you running larger tires, not have the bag risers, or maybe a different quadrabag system?

I'm not familiar with the concept of quad-bag risers - my quads were installed by previous owner. My outer Michelin diameter is 30.3”. OEM 8.75 tire = 29.5”, so I am within 3/4 inch of stock diameter. Low pressure (anything under 80psi) will collide with the rear tire.

Was the Alex Ferrara double convoluted single bag in the running? Why did you settle on Sully bags?

At this point I want a monobag - I want something closer to OEM with bags that aren't difficult to obtain. For Alex-Ferrara, is there a recommended reseller or source? Didn't see Alex-Ferrara at Applied, but I checked just now and see Sirum has them.

Kendra, sorry if I missed this in a previous post, but what brakes are you running on the rear?

4 rear discs installed by previous owner, mid-1970s Monte Carlo. Good brakes but I'll be making changes to gain a parking brake.

 

[LQQKatJon]

I'm not familiar with the concept of quad-bag risers - my quads were installed by previous owner. My outer Michelin diameter is 30.3”. OEM 8.75 tire = 29.5”, so I am within 3/4 inch of stock diameter. Low pressure (anything under 80psi) will collide with the rear tire.

At this point I want a monobag - I want something closer to OEM with bags that aren't difficult to obtain. For Alex-Ferrara, is there a recommended reseller or source? Didn't see Alex-Ferrara at Applied, but I checked just now and see Sirum has them.

4 rear discs installed by previous owner, mid-1970s Monte Carlo. Good brakes but I'll be making changes to gain a parking brake.

Kendra- sirum has the ferrerra bags as the only suppler.

I have a copy of sully bags on my coach.
My friend has the daytona/ferrera bags. His drives better. I think the sully style are fine. But they can be a nut soft in the spring rate and body roll a little more then a daytona bag. In my experience. Also the sully style bounces more when parked.

I personally would go with the daytona over the sully. But there really is not too much wrong with a sully.

 

[sailor man]

I nave the Harrison quad bag setup. One nice feature is that a rear tire can be changed without a jack. Getting the bogie in the right position for the new tire was a bit challenging. When one side is supported on one tire the whole side drops about an inch. Both the tire and the bag were compressed. Only in an emergency would I consider driving on one rear tire and then not too far or fast.

I'm not aware of any bogie failures as a result of using quad bags.

How did you raise the flat tire? I have asked Jim Bounds and he never told me.

 

[JPB]

How did you raise the flat tire. I have asked Jim Bounds and he never told me.

.Good question. My tire wasn't flat. It had a slow leak after I inserted two plugs. Even with all the air out of the bag and tires it required a shovel to lift it from the ground and get the tire off. After propping up the bogie it was easy to put the new tire on by sitting in a lawn chair and lifting the tire/wheel with my toes. Shoes on of course. IIRC Some of the newer quad bag setups I've seen have a hinged center post.

For plan B I have a bogie jack hook and a couple of old mower blades to hold both wheels off the ground. Others use a section of leaf spring.

Bogie Supports

<p>Made with the old blades from my riding mower. Supports the bogie arms when rear wheels are jacked up. The rubber blocks engage the bogie arms ~3-1/2 inches from the center of the bogie pins. The brackets are ~12" long. Using both I can raise all 4 rear wheels at once.</p>

www.gmcmhphotos.com

JP

 

[pvfjr]

Recent Firestone quad bag failure was my fault. I was running 80-90psi (a habit since my previous bags were cracked from age) and should probably have been 110+ psi. Tire nicked an under inflated bag at full speed.

I'm going to argue with you about it being your fault

Since you have a tire size so close to stock (and I'm assuming an appropriate wheel/offset), you should be able to go through full range of suspension motion without issue. Something is off with the kit--either design or installation.

 

[Kendra]

I have 7 Ions from Applied with the correct offset. Co-Op installed this particular Harrison system in 2016, but I'm starting to wonder if that was old inventory (pre-2012) or a prototype.

On the topic of flat tires I always carry a jack, block and stands ...most GMCs also have front tires ;-)

 

[LarryW]

Larry - how bad was the rear-brake lockup with the relatively soft Sully system (and a strong brake system)? Something rare for a panic stop, or quite often while dealing with with typical traffic and road conditions?

I am planning for a reaction-arm upgrade but have found the issues with my quad-bag frustrating (bags should last more than a couple years). I've been running Firestones, so I know bag quality isn't the problem.

The quad and 4bag systems, by design, have a solid mounting plate between the bags. The nature of this setup allows both bags to be inflated equally to...say... 110psi. When under hard braking, while the single bag systems may unload the rear tire (sometimes called "pole vaulting") leading to that tire loosing traction (skidding), the quad/4bag systems have a single bag for each arm and keep a full 110PSI of down force on both bogie arms, with no pole vaulting effect and little or no transfer of weight to the front arm, thus significantly reducing rear wheel loss of traction. This becomes significant when going to the heavy duty disc systems that can be installed on the front axle (of the rear). So really, if you keep the Harrison 4bag, IMO, you don't need a reaction arm setup, because the 4bag does not allow lifting of the 3rd axle.

It could be said that the solid plate between the two bags does not allow for a smooth ride over bumps like speed bumps. I have noticed no difference in coach handling between the original or Sully systems as compared to the 4bag over speed bumps. Felt the same to me, and I've tested this at speeds exceeding 30mph. A smooth ride back there.

If you have further questions about the operation of the 4bag when used with the big brake and 4bag systems, talk to Dave L. When buying his big brake system, he recommends a 4bag system to keep that 3rd axle down.
JMHO.

 

[Carl Stouffer]

I have both the quad bag system and one of the original reaction arm, six wheel disc brake systems on my coach. That, along with Dave Lenzi's hybrid metric brake booster and the quick take up master cylinder, makes for some incredibly effective brakes. I did not notice much of a difference in the ride, going from the factory air bags to the quad bags. I DID notice a bit more stability on the highway.

I don't know how much more effective the stock brakes were with just the quad bag system, I never really noticed, or didn't have to make any emergency stops in between installing the quad bags and the reaction arms. I mainly went with the disc brake/reaction arm system at my good friend, Dan Gregg's suggestion. I'm glad I did. It has saved me several times, and living in the West, I don't have to worry much about brake fade in the mountains that I frequently drive in.

 

[sailor man]

.Good question. My tire wasn't flat. It had a slow leak after I inserted two plugs. Even with all the air out of the bag and tires it required a shovel to lift it from the ground and get the tire off. After propping up the bogie it was easy to put the new tire on by sitting in a lawn chair and lifting the tire/wheel with my toes. Shoes on of course. IIRC Some of the newer quad bag setups I've seen have a hinged center post.

For plan B I have a bogie jack hook and a couple of old mower blades to hold both wheels off the ground. Others use a section of leaf spring.

Bogie Supports

<p>Made with the old blades from my riding mower. Supports the bogie arms when rear wheels are jacked up. The rubber blocks engage the bogie arms ~3-1/2 inches from the center of the bogie pins. The brackets are ~12" long. Using both I can raise all 4 rear wheels at once.</p>

www.gmcmhphotos.com

JP

When Jim Bounds was actively selling the system, he kept saying that you can raise a flat tire and drive the coach like that to a tire repair place without using the spare,

He also said that with the quad bag you could also take one of the good rear tires and use it to replace a flat front tire, so you really don't need to carry a spare.

Dos anyone know anything about this?


I installed this Roadmaster spare tire carrier so I would never have to lift the spare or the flat. See hoe the lever is extended to provide the mechanical advantage to reduce the human effort. Just roll the spare over to where it is needed and roll the flat back and raise it.

It is supported by the through the bumper tow.
Here it is always ready to be deployed. The Thule storage box rotates backward to provide enhanced access to the spare.

 

[JPB]

When Jim Bounds was actively selling the system, he kept saying that you can raise a flat tire and drive the coach like that to a tire repair place without using the spare,

He also said that with the quad bag you could also take one of the good rear tires and use it to replace a flat front tire, so you really don't need to carry a spare.

Dos anyone know anything about this?

Jim told me something to that effect also and it is possible. I understand that others have done so successfully. Only in an emergency would I do what he suggests. As a test isolate the bags, let all the air out of one bag and watch what happens to the coach. It sags enough to make me think twice about driving very far on one rear tire.
Maybe other quad bag setups are sturdier than mine.

I always carry a spare tire. Not to mention roadside service but sometimes it can take a long time until they arrive. That Roadmaster spare tire carrier looks cool.

 

[Tom Katzenberger]

You just need to get off the highway to a safe location and replace the tire. I don't think that jim expected anyone to finish their journey with a missing tire.

 

[Larry Davick]

I've been missing a lot, it seems. I have a 4-bag system - Ken B mentioned "quiet recall" but I guess I never got the notice! My 4-bag system has a pivoting center plate between two smaller bags - each attached to a bogie. The concern is that as you turn and the bogie arms flex that the center pivot will fatigue and break. I suspect that the tru-trackers on my coach will save me from this malady, but the thing that has really saved me is that the coach has just sat for too many years...

One of the fittings on the driver's side front bag is cracked and I'll need to replace it. It is a simple thing to do, although with Jim K just down the street years ago, I almost never got my fingers dirty. This will be a fun thing to try, and if not, well, a landoll can take her down to Jim, now in San Jose...

If I were to replace I'd likely go with the Sully bag. It has many advantages (it's cheap) and I might be able to do it myself.

 

[Richard RV]

I've been missing a lot, it seems. I have a 4-bag system - Ken B mentioned "quiet recall" but I guess I never got the notice! My 4-bag system has a pivoting center plate between two smaller bags - each attached to a bogie. The concern is that as you turn and the bogie arms flex that the center pivot will fatigue and break. I suspect that the tru-trackers on my coach will save me from this malady, but the thing that has really saved me is that the coach has just sat for too many years...

One of the fittings on the driver's side front bag is cracked and I'll need to replace it. It is a simple thing to do, although with Jim K just down the street years ago, I almost never got my fingers dirty. This will be a fun thing to try, and if not, well, a landoll can take her down to Jim, now in San Jose...

If I were to replace I'd likely go with the Sully bag. It has many advantages (it's cheap) and I might be able to do it myself.

We've been missing you a lot, Larry, so I guess we're even.

That center swing bracket quad bag setup was sold by Sirum, not sure if others as well. Interesting design, didn't know about the bogey twisting causing problems with the fixed bracket.

It would be pretty easy to modify the bracket so it was free to turn a bit, just don't tighten the bolt all the way! Seriously, though, allowing the bracket bottom mounting to twist a few degrees either way is all that it'd take. I'm not familiar with the details of the swing bracket - please post a photo of the top and bottom mounting points.

I do like Alex Ferrara's single convoluted bag design with the two cone shaped end pieces. Simple, direct replacement. The only thing that is given up is some of the range for campsite leveling.

 

[Larry Davick]

We've been missing you a lot, Larry, so I guess we're even.

That center swing bracket quad bag setup was sold by Sirum, not sure if others as well. Interesting design, didn't know about the bogey twisting causing problems with the fixed bracket.

It would be pretty easy to modify the bracket so it was free to turn a bit, just don't tighten the bolt all the way! Seriously, though, allowing the bracket bottom mounting to twist a few degrees either way is all that it'd take. I'm not familiar with the details of the swing bracket - please post a photo of the top and bottom mounting points.

I do like Alex Ferrara's single convoluted bag design with the two cone shaped end pieces. Simple, direct replacement. The only thing that is given up is some of the range for campsite leveling.

I'll have to take off the T-Skirts to take some pictures. Squeezing between parked rigs was so much easier 30 lbs ago! I'm a believer in the tru-trackers ever since somebody posted a video of the rear end wheel flex during a U-turn.