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MarvinG · 02-06-2020, 05:59 PM

Yes we got the rain! And looks like I bragged to soon to TeJay, we are having about the same temp as you tomorrow, but I will be surprised if we get more than a flurry or two.

TeJay · 02-06-2020, 06:42 PM

We got lucky so far guys. We were supposed to get 3" to 6" and got about 1/4". The temps were down in the high 20's but no bad roads. That works for me. We're a few hundred miles further north than you guys are.

I'll post pics of what I'm building this weekend. It's causing me some issues. The company in CA didn't send suggested expansion springs to contain the AB. I sent another text today and no answer. That may be OK. I checked on prices of some springs and they want about $10 or so per spring. I'm not going to dump $100 worth of springs into something that I'm not sure will work.

Maybe I'm over thinking this thing. If my AUX AB has a max of 12" (Which I'll limit mechanically) and a minimum of 4" just let it float. When I fill the stock AB with 35 lbs of air so will the AUX AB get filled with 35 lbs of air. That will expand the AB to it's max. It won't be hard as it will become when it absorbs road shock. Just picture the AB getting hard then soft. Do I really need to pull it down to say 5" and then allow the road bumps to raise it up and down up and down. Would it really hurt to just allow it to fill up and down naturally? It wouldn't be any different than a ping tank compressing the air then allowing it to decompress naturally.

The question is will an AUX AB work better than a ping tank? Will the AB give a softer ride or not. I really don't know for sure but we should find out soon. Will the air inside an AB also compress some as it is compressed by road bumps?

If all I have to do is assemble what I've got going so far then it won't take me long to finish this. Finding some springs to work were going to be time and $$$$ consuming. Maybe I don't need them after all? I've got 4 plates ready to be drilled and enough 1/2" rod to finish a set for the front of the RV. I think I got all the fittings and tubing as well. Maybe I'll get it done before we head to FL.

DENSHER · 02-06-2020, 07:35 PM

Quote:

Originally Posted by TeJay

We got lucky so far guys. We were supposed to get 3" to 6" and got about 1/4". The temps were down in the high 20's but no bad roads. That works for me. We're a few hundred miles further north than you guys are.

I'll post pics of what I'm building this weekend. It's causing me some issues. The company in CA didn't send suggested expansion springs to contain the AB. I sent another text today and no answer. That may be OK. I checked on prices of some springs and they want about $10 or so per spring. I'm not going to dump $100 worth of springs into something that I'm not sure will work.

Maybe I'm over thinking this thing. If my AUX AB has a max of 12" (Which I'll limit mechanically) and a minimum of 4" just let it float. When I fill the stock AB with 35 lbs of air so will the AUX AB get filled with 35 lbs of air. That will expand the AB to it's max. It won't be hard as it will become when it absorbs road shock. Just picture the AB getting hard then soft. Do I really need to pull it down to say 5" and then allow the road bumps to raise it up and down up and down. Would it really hurt to just allow it to fill up and down naturally? It wouldn't be any different than a ping tank compressing the air then allowing it to decompress naturally.

The question is will an AUX AB work better than a ping tank? Will the AB give a softer ride or not. I really don't know for sure but we should find out soon. Will the air inside an AB also compress some as it is compressed by road bumps?

If all I have to do is assemble what I've got going so far then it won't take me long to finish this. Finding some springs to work were going to be time and $$$$ consuming. Maybe I don't need them after all? I've got 4 plates ready to be drilled and enough 1/2" rod to finish a set for the front of the RV. I think I got all the fittings and tubing as well. Maybe I'll get it done before we head to FL.

Pressure will be equal throughout the system so whatever you inflate the suspension air bag the aux bag will have the same thus work like a ping tank. Only difference is possibly some flexing of the rubber side walls.

What is the diameter of the aux bag? If it is 6" diameter @ 12" extension would equal 1.47 gallon. 7"X 12" equals 1.99 gallon.

I have been wondering how you were going to calculate the mechanical spring tension resistance to match the weight main AB was carrying. Too light of spring the Aux bag would fully extend before main AB started to lift any weight off leaf spring and too high spring resistance and the Aux bag would not flex.

TeJay · 02-06-2020, 09:18 PM

Densher,

I am not a mechanical engineer. I called a spring company and spoke with an engineer who explained to me how the springs would work and what could and could not be done with springs. I'm thinking she did not respond because maybe there was no good solution. I sent a message to her today and still nothing. If I don't her tomorrow I'll call call and see what's going on. As I said earlier at a minimum of $10 per spring maybe I don't really need them. I was thinking of maybe 8 to 10 springs per wheel.

Here's what's going through my head. With stock AB's when a bump is hit the pressure goes way up and the bags don't blow up. That action occurs the entire time we drive using AB's. We constantly take the pressures way up and they don't blow apart. They do become stiffer with the rise of the air pressure.

With an AUX AB not having a frame and spring to limit the expansion as long as I mechanically limit the height they will act the same as they do when installed between the frame and leaf spring with one important difference. The AB is free to collapse or relax and expand as pressures rise and fall.

However when hitting a bump the stock AB is held down by the frame so the AUX AB is free to expand and soften the ride. Yes it will move up and out. Will it exceed the bags limits and blow apart? If they don't when between the frame and spring why would they?

And they can expand more than the stock AB when the pressure rises. That will/should work as well if not better than a standard ping tank that is just using the compression of the air to soften the ride.

Maybe there's a good reason why this has never been done before. Maybe there's a reason why one company is using a liquid to soften the ride. That is at a significant cost compared to this idea. Then again maybe it's not been done because nobody thought it would work or maybe they just didn't think of it. Well it's been thought of now and we'll find out if and how well it does or does not improve the ride.

This much I do know. If it gives a minimum of a 10% improvement in the ride I'll be happy. It will cost me maybe $150 a set or $300 for both axles. Not to shabby considering I paid $750 for Koin shocks and $400 for a steering stabilizer.

leadman · 02-07-2020, 06:54 AM

Tejay, would a brake pod off an air brake system work if modified? The dual chamber type have a spring that is pretty stout as it sets the axle brakes when the air is released from that chamber. Usually takes at least #75 pounds to start releasing this chamber. Spring could be cut to lessen the tension.
The other chamber is for the service brakes and is what works with the foot pedal. This chamber has a weaker spring in it to return the connecting rod that goes to the S cam bracket to the off position so the brake does not drag.
Might be able to find one cheap at a truck junkyard.

TeJay · 02-07-2020, 07:55 AM

leadman,

Thanks, that might help but I'm not familiar with it so something to look at if just an AB does not work.

MarvinG · 02-07-2020, 08:20 AM

Interesting possibility Leadman.

We know from Densher’s work that adding more volume helps, we should know in just a few more days if we can enhance the results with even more air volume and/or flexible ping tanks. I am eager for that first test drive!

MarvinG · 02-12-2020, 10:21 AM

Here are a couple photos of my test setup. I’m still awaiting a fitting to complete the other side.

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MarvinG · 02-12-2020, 10:22 AM

MarvinG · 02-12-2020, 10:37 AM

So the ballast side of the tank has 35 lbs as a preload as it came prepared for it intended use. Let’s assume I am going to run about 25 lbs airbag pressure, which lifts my front end about 3/4” higher than the springs alone. What preload pressure do ya’ll think I should try?

DENSHER · 02-12-2020, 11:59 AM

I suggest same pressure on both sides of the diaphragm/bladder for most amount of volume change when the air bag suddenly compresses due to bump.

TeJay · 02-12-2020, 12:22 PM

MarvinG,

Glad you're making progress. Had to get tires on the TOAD today and heading to Tulsa Friday to get them on the RV. Couldn't find a tire store in NWA (North West Arkansas) worth their salt so had to go to Tulsa. Same Toyo tires are $800 cheaper in Tulsa. 150 miles drive and it's still cheaper.

I will post pics later today or tomorrow of what I'll have set up with the AB's.

We're still not sure if I'm heading to KC next Thursday. If that cancels I'll have time to mount this set up maybe. I've only got one set up close to being done since it changes so often.

Anxious to hear how your first ride works out.

TeJay

Mark_T · 02-13-2020, 01:56 AM

Maybe you should install something like roadbounce on your smart phone . This will give you some numbers to compare instead of going by it feel better.

MarvinG · 02-13-2020, 07:25 PM

That is a good idea, I didn’t know such existed, however the bumps we are dealing with are primarily transition bumps to bridges, or similar, not sure how well the app would measure but I’ll look into it. However, if the ride is a whole lot better, I don’t know if I will want to bother letting the air back out to get “before” readings!