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Discussion Starter #1
I know that Progressive has a kit to allow to you fill both rear shocks at the same time with air also allowing you to have equal air pressures. The price seems a little high to me. Was wondering if anyone has got the parts seperatly and did it. I know I just need to replace the shocks period, but I can't swing it right now.
 

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Calif Rider
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I bought the kit over 3 years ago and I am very satisfied with it. Like you said it is a little pricey. I tried myself to find something that would work but could not find anything. I think you would have to have your own machine shop, or know somebody that works in one.
 

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Super Moderator
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23 bucks is a high price?

http://tinyurl.com/rxxkyo


You can buy the various fittings form one of several companies that makes air fittings for air driven components, but you will likely end up spending about the same money when it all adds up.

I didn't put one on my Vulcan cause I thought the way the tubes stuck out and looked were kinda cheezey, but I did have a simular kit on the air shocks on my 76 El Camino SS...which worked well...and on the front forks of my RD400.

My thoughts were adding more fittings to the system would just add more places to develop leaks, as the hoses could get caught or kicked by a passenger getting on/off the bike.

But 23 bucks is a fair price.



Gadjets write up:
http://www.gadgetjq.com/airshockbalance.htm

KM
 

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Discussion Starter #4
it seems pricey considering what it is. seems like there were would be parts for cheaper.
 

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To me the biggest problem is airing them up without putting too much in, and then losing it all when you remove the hand pump. There's a hand pump in the J&P cycles catalog that has a built in guage and an inline check valve that supposedly keeps you from having either problem for around $50. IMO that would be a better buy cause you need a good hand pump anyway for this and then you could match the pressure in both sides without adding other fittings/hoses. Again, just my opinion!
 

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You could probably fab one up with some scrap air pumps and some vinyl hose. One nozzle for each shock, a T connector, and a valve cut off a bicycle tire.

Or look on Ebay for a bicycle shock fork. They're small, have gauges and should go for around $15-20.
 

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Love My Baby
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I'm very apprehensive about these types of systems that allow you to fill more than one shock (or tire) at the same time because they don't always deliver equal pressure to all shocks (or tires). Many things can affect the distribution of air into something, such as weight, resistence, rust, lubrication, etc.. If you are only measuring the air pressure at the pump, you don't know for sure that there is equal pressure in both shocks. I put nitrogen in all 4 car tires on several vehicles. The dealer deflated/inflated all 4 tires together and measured the air pressure at the pump. I drove off thinking all was well, but my vehicle pulled a bit to one side. So I checked the pressure in all 4 tires and one tire was WAY OFF. I made them due it again and check all tire pressures, same thing. So they did just the one tire by itself after that. I think you're better off doing one shock at a time or rigging something up that includes a gauge for each shock.
 

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Concert connoisseur
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I dont have a hand pump, I do have a cigarette lighter powered tire inflator that takes forever to fill up even a front lawnmower tire. do you think a couple quick shots with it would be too much for the shocks?
 

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I'm very apprehensive about these types of systems that allow you to fill more than one shock (or tire) at the same time because they don't always deliver equal pressure to all shocks ......


Actualy that is the very advantage of the system. I am not familar with whatever micky mouse device your guys filled your tires with, but I do know that if you take a tube and connect it between two seperate air chambers, the air pressure in each chamber will be exactly the same as the other. This is simple physics and kinda impossible to argue with.

The problem with our air shocks is the volume of air they hold is so small, so attempting to put the exact amount of air in each one is a bit troublesome.
Having a tube that connects between them with one schrader valve to add the air makes it pretty foolproof.

I would guess that in some garage where they use a multiple tire filling tool like you describe, it would be prone to wear, folks stepping on it and other misuses. A clear plastic tube you install new on your bike , actualy use infrequently and have controll of would likely not have these factors to contend with and should work as advertised.

I had such a system on my front of my race bike and it performed flawlessly. The simple physics of it meant that I had the EXACT amount of pressure in each fork, and that is almost impossible to achive with seperate fill valves.

KM
 

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Old Truck Junkie
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Two ways that I know to get close to the same amount of air is; 1) use and air tank fill tank to what pressure you want and air up one shock and repeat for the other. 2) use a pressure regulator on the compressor and set as dessired pressure and air up shocks.
 

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The problem with using anything but a hand pump is that you have little to no control and if you overfill, it could be game over. It is a pain with a hand pump cause removing the pump can easily let off all the pressure you just put in since the chamber is so small. There is a $50 tool made for this and I'd call around to various shops to see if anyone has it. It has a check valve built in and you can open the valve stem while adding the correct pressure, then close the valve stem before removing the fitting, thus, no air is lost in the removal of the fitting. I've been tempted to buy this pump, but would have probably used it twice now in the three years I've been looking at it. Not really a good investment, especially if a shop can do it accurately for you and for a small charge.
 

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Love My Baby
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I went out an purchased a shock pump at my local bicycle shop. Paid a whopping $40 for it but it is worth it. Virtually NO AIR LEAKS when disconnecting. There's a built-in gauge and a pressure relieve button in case you overfill. Mine lets you add tiny increments of air with each pump, or larger volumes, with a turn of the pump. I can use it as my spare bicycle tire pump or use it as a shock pump, that's what it's designed for.
 

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Linkmeister Supreme
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I'm very apprehensive about these types of systems that allow you to fill more than one shock (or tire) at the same time because they don't always deliver equal pressure to all shocks (or tires). Many things can affect the distribution of air into something, such as weight, resistence, rust, lubrication, etc.. If you are only measuring the air pressure at the pump, you don't know for sure that there is equal pressure in both shocks. I put nitrogen in all 4 car tires on several vehicles. The dealer deflated/inflated all 4 tires together and measured the air pressure at the pump. I drove off thinking all was well, but my vehicle pulled a bit to one side. So I checked the pressure in all 4 tires and one tire was WAY OFF. I made them due it again and check all tire pressures, same thing. So they did just the one tire by itself after that. I think you're better off doing one shock at a time or rigging something up that includes a gauge for each shock.
The difference here rubyrick, is that the hose stays connected to the two shocks while you are riding and they are in use. The tire dealer only has it hooked up long enough to for the gauge to read #35, or whatever pressure he chooses. If they are in a rush to unhook the filler hoses, and don`t let all 4 tires equalize pressure, you can get the situation that you encountered.
 

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Love My Baby
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Good point OlHoss. Since the connection is continuous there would likely be an equilization of pressure within a reasonable period of time. BUT...

could someeone sitting/leaning way to one side also cause a differentiation in pressure between the shocks during the lean?
 

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I don't know how that would work, since there's one wheel on a single swingarm and both shocks would seemingly have to compress equally, no matter what side the lean is on. I've heard that you could have handling problems though if the two shocks aren't equally balanced, so I don't know. But my limited knowledge or maybe my logic tells me leaning one way or another wouldn't matter???:confused:
 

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Discussion Starter #16
and if that was going to happen it would regardless of the equalizin device. plus any changes in pressures resulting from leaning would have to be extremely minuete (small) that it would hardly make a noticeable change. specially with these crap shocks
 

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could someeone sitting/leaning way to one side also cause a differentiation in pressure between the shocks during the lean?

No. If the two shocks are joined buy a connecting tube, even if you took one shock off the bike and compressed it all the way...the pressure in both shocks would be the same. ..Because you basicly have one air chamber, not two.

Slight differences in pressure do have an effect on the "smoothness" of movement in the swing arm, but even if you put 10 psi in one shock and 30 in the other I really doubt you could tell the difference.

Some bikes even have front forks that do seperate jobs..one having the dampening system in it and one the spring.

Alot depends on the overall stiffness of the system...large diameter forks with heavy duty steering bracing can get away with split systems. ...and a very beefy swing arm linkage can even work with only one shock. (Think of the bikes that have one sided swingarms)

Folks get a bit anal about this whole "equal pressure" thing when they would never be able to tell the difference if the shock were 10 psi off from each other in the first place.

The wonderfullness of having a "balancing tube" on the rear shocks is just having one place to add air and never having to worry about the shocks being "unbalanced"...even when it is not horribley important that they are.

On a race bike that pushes it's suspension to the limits you might encounter more "flex" if the shocks pressure were uneven, and have premature wear in the swing arm bushing...but I doubt any of this would ever come into play on the Vulcan.

As a matter of fact one could make a case against running the same settings on the shocks due to drive shaft induced flex. The bottom line here is the engineers that built the bike were not too terribly worried about it, so neither should you.

The only reason the owners manual says to set the air pressure "as equally as possible" is because they know that is the way it should be ...ideally.


Having the dampening way off would be more noticable, and I think there is even a "warning" about that. But my experiance with the amount of difference in the shocks settings would kinda find that a leap.


KM
 

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Love My Baby
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Thanks KM, good write-up.
 

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Concert connoisseur
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okay, I used my cheapo inflator, it was like 10 bucks at walmart and is very slow. has a bicycle type end on it, the kind that flips and locks down. filled up nice and slow and when it got to where I wanted it I just unplugged it. then took the hose off the shock without so much as a hiss. worked for me.
 
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