nitrogen in doetsch tech shocks

dannyfab

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I have a set of doetsch tech shocks on my car that I am confused about. They take oil that provides the dampening but also nitrogen. Maybe an easy question but why do they need to be charged with nitrogen when the oil provides all the dampening?
 

Random Thoughts Racing

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The nitrogen provides some stabalization to the oil so that it will produce more consistant damping.
 

Moss2

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Oil is not compressible. If you really did fill it all the way up with oil and the shock extended it would not move any more. You need a little space for the oil that gets displaced by the shock shaft when it is compressed. Best thing to fill that little space with is a stable compressible gas like nitrogen.
 

1audiohack

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"Oil is not compressable." That is largely true if it is de-gassed. Oils can contain large amounts of compressable gasses dissolved into it like carbondioxide in soda. Also think power steering systems, you know, the ones that wont shut up until they sit overnight.

Oils like refrigereation and high speed CNC machine motion control oils are painstakingly de-gassed as part of their manufacturing process.

The Bilstien guys used to have a clear body monotube shock they used to carry around to shows with a Schrader valve in the regular place. With the shock collapsed and bled to atmospheric pressure you only had to stroke the shock three or four times to turn the oil completely into foam and you could feel the loss of dampening the larger the bubbles became. Then they would "charge" it up with a bicycle pump at less than five pounds. In two srtokes the oil would be completely tranparent again with the dampening restored. Now to be fair, with the shock bled at bump, the oil is under vacuum when extended and that will certainly help to aerate the oil but it makes the point. When the oil is under pressure the disolved gasses at least stay in solution with the oil.

The use of an inert gas also increases the life of the oil as oxidants in oil (shop air) with pressure and heat will break it down prematurely.

Hope that helps.

Best,
Barry.
 

dannyfab

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Thanks barry and all the dez people, I didn't think that the oil would foam but now it makes a lot of sence. I was going to test my car without charging my shocks but now I know that it would be pointless to even try to test my car without charging them.
 

Random Thoughts Racing

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"Oil is not compressable." That is largely true if it is de-gassed. Oils can contain large amounts of compressable gasses dissolved into it like carbondioxide in soda. Also think power steering systems, you know, the ones that wont shut up until they sit overnight.

Oils like refrigereation and high speed CNC machine motion control oils are painstakingly de-gassed as part of their manufacturing process.

The Bilstien guys used to have a clear body monotube shock they used to carry around to shows with a Schrader valve in the regular place. With the shock collapsed and bled to atmospheric pressure you only had to stroke the shock three or four times to turn the oil completely into foam and you could feel the loss of dampening the larger the bubbles became. Then they would "charge" it up with a bicycle pump at less than five pounds. In two srtokes the oil would be completely tranparent again with the dampening restored. Now to be fair, with the shock bled at bump, the oil is under vacuum when extended and that will certainly help to aerate the oil but it makes the point. When the oil is under pressure the disolved gasses at least stay in solution with the oil.

The use of an inert gas also increases the life of the oil as oxidants in oil (shop air) with pressure and heat will break it down prematurely.

Hope that helps.

Best,
Barry.
The clear tube is still in action at Bilstein, but not just a shows, if the plastic tube could take a high pressure the demo would get more than a little nitrogen.
 

Random Thoughts Racing

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Thanks barry and all the dez people, I didn't think that the oil would foam but now it makes a lot of sence. I was going to test my car without charging my shocks but now I know that it would be pointless to even try to test my car without charging them.
Perish the tought, it would foam instantly at zero pressure, but do contact the manufacturer to confirm the proper presure. Also, use an accurate pressure guage.
 

dannyfab

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Before I charge my shocks I want to make sure that they can hold the pressure. Is air dense enough to see if they will hold a charge or will the nitrogen hold a charge where regular air would leak out? I just don't wand to waste 5-10 dollars a shock to charge them when i could test them first.
 

Random Thoughts Racing

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Before I charge my shocks I want to make sure that they can hold the pressure. Is air dense enough to see if they will hold a charge or will the nitrogen hold a charge where regular air would leak out? I just don't wand to waste 5-10 dollars a shock to charge them when i could test them first.
Call them and ask, perhaps they will even charge them for you if you bring the truck over.

Toll Free: 1.800.8.SHOCKS

Doetsch Enterprises
515 Raleigh Avenue
El Cajon, CA. 92020
info@doetsch-shocks.com
Office: 619-442-7300
Fax: 619-442-7307
 

dannyfab

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I am tired of dealing with doetsch. Every time I call I get a lady that tells me she will call me back with the answer to my question HaHA what a joke.
 

Random Thoughts Racing

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Hitting them with a shot of air to check for leaks isn't unreasonable. Im sure a reputable shop in your neghborhood like Mirage can help you out with Nitrogen for a reasonable cost when you get to that point.
 

DSRacing

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If all you need is a shot of nitrogen, you can come by my house and you can charge them off my nitrogen tank. Shoot me a PM if your interested.
 

Kritter

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The clear tube is still in action at Bilstein, but not just a shows, if the plastic tube could take a high pressure the demo would get more than a little nitrogen.

roehrigs website has an awesome demo video of a clear shock and nitrogen deficiency. The demo is done using data collected from a nascar team on an actual course and simulated on the dyno.
 
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