I need a smoother ride.

[drewskiren]

Just generally speaking, what things make for a harsher ride and which things would make it smooth?

Tall sidewall tires or shorter tires- duh
Springs or airbags?
Poly bushings or rubber - duh
Body mounts.....
.....

Fill me in with all the alternatives.

[N2TRUX]

Harsh ride= Short sidewalls and stiff shocks.
Smooth ride= Taller sidewall and softer shocks.
Best ride= Bag it and enjoy

[VA72C10]

I know poly cab mounts make the ride harsher (transfer the energy more than stock rubber) as do bushings of course....

You're talking about frankie...right? So you have the bags....


How much pressure is in the bags? That makes a huge difference from everything I've read...

what brand shocks/part number (compressed/uncompressed length vs actual travel)? I can't check the whole humungous thread again

How is the angle on the shocks?

Brand of tire can make a difference also....I had a company ford explorer and the first set of tires rode horribly...when they changed them at 65K miles it was like a totally different ride...much smoother...

[big_al_71]

+1 on the "Bag it" and enjoy it!!!

[gringoloco]

Originally Posted by VA72C10

How much pressure is in the bags? That makes a huge difference from everything I've read...

This. I know there is not much travel out back on Frankie, so between low pressure and possible frame/axle contact, you have a formula for less than stellar ride quality.
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[502ms]

Ok, I agree with pressure in bags comment... But the Frankie thing went over my head. What thread is that in?
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[gringoloco]

OP's truck...
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[drewskiren]

I feel like I know the basics, but I'm hoping someone makes a lightbulb go off.

Yes this is my Crewcab truck.
I have about 3 inches of rear down travel with sleeve type bags which supposedly ride smoother. They do.
I have about 2.5 inches of down travel in the front with big Firestone double convoluted bags.
In the front I have a factory bumpstop which is very squishy and I actually am in contact with it at rest.
The rear shocks are pretty soft and the truck will drop a lot when you have a seat on the tailgate.
I don't think I have a problem with the rear ride, it is clearly softer than the front. Although I think a lot of trucks are softer in the rear? My 2002 Sierra squats down about the same as my 72 Crewcab when I plop down on the tailgate. (not very scientific)
The front shocks are very hard to compress by hand to install them. I took them off to see - hoping it would be a drastic difference. It wasn't. Better, but not near my 2002 Sierra ride.
Without the shocks I can get the front end to bounce some by pushing on the bumper. Not as bouncy as the rear, but then again the tailgate length acts as longer leverage for me for me to push down.
Air pressure in the rear bags is around 90 psi. 80 psi - on the bumpstops, 100 psi - sky high.
Air pressure in the front is 92 to 95. Much less, you are too low and fully riding on the squishy bumpstop which finally gets firm when fully compressed. 100 psi starts getting pretty stiff and high. 105 -forget about it.
I am riding on 20's, but they are take-offs from a 2007 Suburban - 55 series and those new burbans ride pretty nice. But my 2002 Sierra is riding on 17's and that is my main comparable. I might swap them and see if it helps.
I mounted my body with part of the rubber mounts from the 2002 truck, but it is not completely isolated by rubber. There is rubber between the frame and body, but the head of the bolt touches the cab and the nut touches the frame. This effectively means a direct metal connection, even though it doesn't seem like much.
I'm willing to do most anything to get it to ride like a new truck. It should since that's what it is - until I bagged it.
Would factory coil springs from the junkyard with tired factory shocks ride smoother? I'd be willing to swap back and use a dropped spindle to lower it a little.

[oldspowered67C10]

Heres your problem. You said on the front that its riding on the bump stops, that right there is guaranteed to give a terrible ride. Either trim them down or cut them off and make a new bump stops so theres some travel in there. If there no travel before you hit the bumps tops than you can make changes to the springs and shocks all day and it wont matter, all of the work is being done by the bump stop.

[gringoloco]

Agreed. Even with those super squishy ones, my Yukon rides much better with them trimmed.
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[drewskiren]

If I cut them or remove them I will not be able to drive it if my bag deflates. Also when I deflate my bag I drop 3.5 inches - Travel that my bumpstop does not stop. So I feel like I have good play here.
I am planning on removing them to see if it helps, but I'm not sure what I would do as a permanent solution for bumpstops. With no shocks now, I am able to move the truck up and down pretty easily and the factory suspension is also normally in contact with this bumpstop. Also, this bumpstop is mounted way inboard - near the pivot of the lower control arm,- there is a lot of leverage to compress it. If it was out at the wheel and had a 1 to 1 ratio it would be very stiff when contacted (like a snubber on a rear axle hitting the frame rail), but it isn't like that.

Thanks for helping, keep thinking of ideas I can try.

[VA72C10]

They make shorter bumpstops or...as mentioned...trim that one...that definitely will improve the ride even if it's soft...it's still hitting it....

After that, I'd look into the front shocks as well...what brand/type?

And on the cab mounts...I'd work on getting rid of any metal to metal contact.

I think the three of these together will make a big difference.

Someone else can speak to bag pressures and how those compare....but what I've seen on here is 70 front and 30 (unloaded) -60 (loaded) on our trucks...might want to consider a cup for the front and rear since your problem is the truck is too low with lower air pressure...if you add a cup (or put in a larger one if you have one already) it'll raise the truck up...allowing you to lower the air pressure in the bags to lower the truck back down....

There are recommended ride heights for every spring out there which I found out a year or so ago...post how tall your bags are currently at ride height....maybe you have them too tall for their optimal ride (too much air in them) The cups would help that and be a relatively simple and inexpensive solution....

[502ms]

Originally Posted by VA72C10

They make shorter bumpstops or...as mentioned...trim that one...cup (or put in a larger one if you have one already) it'll raise the truck up...allowing you to lower the air pressure in the bags to lower the truck back down....

There are recommended ride heights for every spring out there which I found out a year or so ago...post how tall your bags are currently at ride height....maybe you have them too tall for their optimal ride (too much air in them) The cups would help that and be a relatively simple and inexpensive solution....

Bingo.
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[drewskiren]

Some more testing reveals that my rear is definitely is softer than a 2003 Silverado half ton. (Leaf springs). We sat on the tailgate of both trucks and mine went down an eighth inch more. Couple that with the fact that his is a LWB, his "lever" (tailgate) is longer to give my body weight more effectiveness of pushing down his suspension. Translation: the 2003 truck should have gone down more, but instead went down less.

[drewskiren]

I pulled the bumpstops out of the front and maybe it is better??? It has to be, because anything holding the truck up makes it stiffer. Now with no front shocks and no rubber bumpstops in constant contact I can really get it bouncing in the front. Seems a little better, but still not as smooth a new truck.

[N2TRUX]

Seriously? You have no front shocks and your wondering why it rides like poo? Get some shocks mounted and build bump stop stands. I don't have pics on this computer, but my 77 has stops built to limit the travel where I can still roll aired out.

[oldspowered67C10]

No use trying to make any decisions with no shocks, re-install shocks and give it a try.

[SCOTI]

Originally Posted by N2TRUX

Seriously? You have no front shocks and your wondering why it rides like poo? Get some shocks mounted and build bump stop stands. I don't have pics on this computer, but my 77 has stops built to limit the travel where I can still roll aired out.

Re-read the info shared.... The shocks & bumpstops were removed only to try & isolate the cause of the rough ride quality.

Drew, I can't remember. Did you also install drop spindles? If not, I think I'd try the OE coils trimmed as required & dropped spindles. It appears that for whatever reason, the bags are limiting your ride quality within the pressure/height requirements for optimal operation.

[drewskiren]

Originally Posted by SCOTI

Re-read the info shared.... The shocks & bumpstops were removed only to try & isolate the cause of the rough ride quality.

Drew, I can't remember. Did you also install drop spindles? If not, I think I'd try the OE coils trimmed as required & dropped spindles. It appears that for whatever reason, the bags are limiting your ride quality within the pressure/height requirements for optimal operation.

First, thanks for answering the previous 2 posters.

Second, I think you are right on. Today I spoke with a crew chief friend of mine and he and I came up with the same answer. Rolling sleeve bags ride pretty nice and are not very progressive in respect to their "Spring Rate". However they must travel in a straight line and cannot be used on a front suspension that travels in an arc. Double convoluted bags can ride smooth over small bumps, but by their design they get firm real fast - their spring rate ramps up very quickly and they become very stiff over medium and larger bumps. When double convoluted bags are installed on a long lever (rear control arm) this problem is lessened because the bag can stay in its sweet spot for a longer amount of actual wheel travel. In my front suspension the bag is near the actual wheel and is less leveraged which means with medium sized bumps my bags get compressed a lot which gets them into their stiff zone.

Another thing of interest: We hear lots of talk about all 18 wheelers ride on air bags now for a smoother ride. This is true, but look at what type they use - Rolling Sleeve type. Also it was pointed out to me that on an 18 wheeler, air bag suspensions weigh a lot less than those huge leaf packs. The manufacturers are shaving weight for better mileage, not just for a smoother ride for your goodies on the truck.

Also take a look at the car manufacturers that have air bag suspensions, most all use rolling sleeve. I can't think of any with double convoluted bags.

Lastly what comes to mind are Baja race trucks with those enormous travel suspension systems. Those trucks can soak up the most gigantic bumps and the drivers are hardly affected. It seems to me that the smoothest ride is achieved with the most travel possible. Factory coils springs for the front allow for the most travel utilizing the factory control arms and suspension design. If you could design and build a long lever type front suspension and place a double convoluted bag somewhere in the middle of that lever you could get the best of both worlds, smooth ride because of long travel and air bag adjust-ability. Ford's old twin I beam comes to mind.

As is stands now, the smoothest ride for my truck will be long, soft factory coil springs in the front with a soft shock. I will lower it some with a dropped spindle if I need to which will not affect my ride at all. In the rear I may keep my rolling sleeve bags or I may look into long coils. Either way, I will need much more travel than the 3 inches I now have which means frame and bed floor modifications. I want this thing to ride so well that people comment on the smooth ride. To get there though I may also need to have a taller tire sidewall.

[VA72C10]

Originally Posted by drewskiren

My point here IS that I want to help guys understand and have an honest assessment of before and after. I searched high and low and asked many and never could really get a straight answer. Now that I have finally found engineers and other smart people in the industry willing to explain the dynamics of suspensions systems, I want to share that knowledge with others.

Also I have read Firestone's own technical sheets on applications of their bags and design strengths and limitations. There are several tech sheets available on the web at Firestone.com available for download.

What it all boils down to is that the double convoluted bags that are small enough to work for our applications have a very small effective range of low pressure/soft enough ride. In Firestone's own application manuals they detail this and show multiple applications using the bag mounted on a lever arm to maximize their throw -or in our case - wheel travel. The rear suspension system on our 67-72 trucks is exactly how this bag is intended to be used. Our front suspension double A arm is not a long enough lever to keep this bag in it's sweet spot. Picture a blow up rubber kickball, push your thumb down on it 1 inch. Easy (soft) how about the next inch down? Harder! How about the next inch?- so hard that it hurts your thumb and it can't be done. This is what is happening inside the double convoluted air bag. As the bag is compressed, the air pressure goes up exponentially (multiple times). When you design the air bag system you are always searching for the lowest air pressure that will keep the truck at the correct height to give the smoothest ride. When you hit a medium to large bump the air bag absorbs the first little part but then the pressure rises so high in the bag it is all of a sudden very hard, like you were cruising around with 30 psi more. Try adding 30 psi to your bag and see how hard it rides. These double convoluted bags are very soft and smooth in the bags first inch or so of travel. depending on your suspension set-up this could equate to 1 to 3 inches of travel depending on how long your lever/control arm is and where the bag is placed on it. The closer to the wheel or axle, the less travel and the less sweet spot of smooth travel you will have. Beyond that these bags get very stiff very fast

The next part comes from suspension engineers:
Longer travel equates to a better chance for a smooth ride, but it must be engineered with a soft, long traveling spring and shock. Long travel with a stiff shock will be stiff, don't bother. Again, look at a Baja race truck video and watch a proper long travel suspension soak up huge bumps with very little truck body movement. Fortunately we don't have to design for this extreme, just potholes and speed bumps.
Truck rear suspensions by nature are designed with longer travel in mind and respond well to soft springs and shocks be it air spring or leaf or coil. The problem in the rear though becomes how to have a soft rate with no load and a firm rate when you have a load. Some leaf springs on trucks have a upper helper leaf that comes into play when the truck is weighed down, some coils springs use a progressive rate design with tighter and wider spaced coils. Using an air spring (airbag) can be the best of both worlds with soft and firm at the touch of a button.
Truck front suspensions, and most all vehicles for that matter, have severe space limitations when it comes to the front suspensions. Long travel suspension arms are hard to make room for and most front suspensions make do with less travel, shorter arm setups. For that type of suspension it is impossible to get a double convoluted bag far enough away from the tire to have much lever action which would give the front more travel at the low pressure sweet spot of this type bag. So in the front, you end up with the first inch or so of travel really smooth, the next inch of travel a bit firmer, the next inch of travel really hard and not much any travel after that.

In summary, double convoluted bags in the front suspension will not be as smooth a ride as a factory coil at normal factory height.

That being said, if you lower your truck with short stiff springs in the front which many people do, going from that set up to bags WOULD end up riding better than it had with the short aftermarket springs. This is usually how it goes- lower your vehicle on a budget at first with lowering springs, love the look, but hate the ride. Then someone says to bag it and it will ride like a dream (compared to how it is now). This statement ends up being true and furthers the myth that double conv bags ride soft in the front. They don't when compared to a standard factory coil suspension, but that's usually not what people are talking about.

If you needed your truck to be low AND ride well then a dropped spindle on the front is the way to go. It leaves your factory engineered coil spring geometry and the longer travel alone, but just makes the wheel/tire higher in the wheel well - thus lowering the truck. For the rear with long control arms a double conv. bag works well and is capable of delivering enough travel smoothly if it is set up right, and you can raise the pressure to handle a heavier load. Short aftermarket springs in the rear will most likely be much stiffer than factory and result in a poor ride.

I hope all this helps!

didn't want to clutter your build thread but wanted to keep the discussion on this going because I think it's a good one to look at...

First...did you ever try the truck without the bump stops in the front but with the shocks installed? And what travel did/do the shocks have...thinking that might have had something to do with it also...

I totally agree that static lowering leads to a harsher ride than stock. And I will fully disclose....I've never driven a 67-72 bagged in the front. I had one that was bagged in the rear with double convoluted bags and lowered in the front with drop a-arms and springs and it actually still rode better than either of my 70's did with factory (original) springs....both with newer replacement shocks. Could have been the springs were worn...haven't ever driven on new stock height coil springs...but I was going to add 2" lowering blocks to the rear on the truck with bags so I could run more air pressure because they were almost on the bump stops and below their recommended pressure for best ride quality and still were more comfortable than stock coil springs...

The main point I was making is you may have a 67-72 looking body (an awesome one at that )
...but your frame is completely different all the way around so it really has nothing to do with how 67-72's ride bagged. No disrespect intended and not trying to argue...but it's apples and oranges....2002 engineering vs 1967 engineering...shockwaves would have probably been a better choice for the front instead of double convoluted bags with the large hats on them. They are almost a bolt in for that year frame from other builds I've read on modern trucks. (and have 4 1/2" of adjust-ability instead of 2 1/2")

Looked at the firestone specs and it appears the recommended "ride height" of the bag (depending on actual model bag) is 5.5-7"...what were your air springs at when driving?


Also, on 67-72 trucks the front bags have nearly 10" of adjust-ability (depending on brand) from max to min so that greatly improves the ride quality....the 2 1/2" of travel isn't enough as you have surmised...no way to dial in the "sweet spot" of the bags...

On the 67-72 front end with a cup and drop spindles the "sweet spot" for most guys with bags and drop spindles is right about the stance of your maxed out no pressure in bags picture and they can still drive and steer at that height...and from what I've read it's around 75-80 psi in the bags at that stance...

[Hart_Rod]

Good discussion Gents! Drew what's the difference in weight from the factory truck your chassis came from and Frankie?
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[tubbedII]

^Good question. I'm thinking some tweaking of the bag mounts could possibly help since putting 80+ psi in the bags barely pulls them off the bump stops. I'm going to have to search for the Franky thread...I don't think I've ever seen this build.

[drewskiren]

Yes, I am of course speaking of my 2002 front geometry and I have never ridden in a bagged 72 to know what that feels like. My point is though longer travel on any suspension equals smoother ride, double conv bags don't have much play on their sweet spot, so if you are looking for smooth you better be able to lever them at least 2 to 1. I don't know how much lever action you can get on the 72 suspension. When you can, get them away from the wheel as far as you can for more lever action. For the record, I had about 2.5 to 3 inches of down travel - depending on whether I had the bag inflated between 5 to 5.5 inches of height (yes I remade my hats so the bag would be at it's perfect design height). Up travel was even greater at around 4 inches, so I had a total travel of around 7 inches. Also keep in mind that the main design flaw of using a double conv bag is that the bag does not have a LINEAR spring rate. The bigger the bump the harsher the ride.

Since I drive my truck everyday, a smooth ride is way more important than getting it low. If I did need it low I would start with spindles no matter what year I had.

The shocks I had were making it even stiffer and I couldn't tell any difference with them and no bump stops. The bump stops were not my issue.

I have no experience with Shockwaves, but since I know that the bigger the bag and the more air volume you have the smoother the ride will be I wouldn't think they would be that great. But I have NO CLUE - they may be the greatest things ever. A quick call to Ride-Tech could answer that.

I haven't weighed it yet, so I don't know yet.

[SCOTI]

My suggestion is to swap in drop spindles & try an OE coil trimmed to suit for ride height purposes. It won't have the adjustability of air-ride but should offer an OE quality ride.

Along w/that, I would be optimizing the shock travel w/the revisions.

[gringoloco]

Originally Posted by SCOTI

My suggestion is to swap in drop spindles & try an OE coil trimmed to suit for ride height purposes. It won't have the adjustability of air-ride but should offer an OE quality ride.

Along w/that, I would be optimizing the shock travel w/the revisions.

Sage advice. I think this is exactly what he has done now with positive results.