Ski Boat Forum
General Category => General American Skier Discussions => Topic started by: Mike Harry on August 22, 2010, 06:57:01 PM
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Does anyone know what the balance tubes do for the speedometers? Just curious. Seems like they are a sort of shock absorber, but I don't know
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A Shock absorber would be a good description, it is also where (theroetically) where the water pushing up the hose converts to air pressure. The speedometer is an air pressure gauge, not water pressure. Any leaks in the hose between the ballast tube & speedo head will result in lower speed & irratic readings. If leaking near the head unit you run the risk of allowing water to enter the bellows in the speedo, which will really mess up the reading & then rupture if allowed to freeze over the winter.
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Good info! Thanks once again Ron
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Now, is there any way to get these apart so I can clean behind the glass? (the ones I just got from Brandon appear to be plastic)
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One of my speedometers works what appears to be perfectly. It responds quickly to the acceleration of the boat, but the other one responds much slower. They both equal out to the same speed in the end, but one takes about 10 more seconds to get there.
Any ideas? Its not a huge deal....... I just figured I would ask
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Mine does the same thing... weird. Left speedo rises along with the acceleration while the right speedo comes up much more graually. They both stop at relatively the same speed (within 1 or 2 mph) whether its 25, 35 or 43... Hopefully its a common problem with a commonly known fix... :)
Anyone...??? Anyone...??? Bueller...??? Bueller...??? ;D
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There is probably a small piece of something in the hose, balance tube, or pick-up restricting the rate the pressure can get to the speedo itself. If you clamped the hose with zip ties, you also could have a kink in the line restricting. Does it also take longer for it to slow back to 0 MPH? If you take the hose off at the speedo, you can try using air pressure to blow the lines out. Kind of a pain, but if you take the line off at every connection you can probably find which area the restriction is and solve the problem. They should rise and fall at a very similar rate and be within a few MPH of each other, most are calibrated at 36 MPH for slalom and should be the same at that speed.
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Not really concerned with a kink so much.... everything is new and nothing is zip tied, but I guess its possible there is some trash in the balance tube. Tube and pickups brand new. Not a huge deal I'm really using the GPS on my phone anyway, was just curious. So if I pull the hose from the back of the gauge and blow through the tube and pickup with a compressor there shouldn't be any problems with that right?
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You can pull the hose off at the speedo and try blowing back thru, but the debris will just swirl around in the balance tube if it ends up in that. This is why you should (if possible) disconnect the hose at all locations to get whatever blown out. Using an air compressor is fine, but keep the pressure below 35PSI. The speedo is only getting 33.8 PSI to get 50 MPH, I don't know what the hose will actually handle before you blow a hole in it. DEFINITLY DO NOT PUT ANY MORE THAN THE 33 PSI TO THE SPEEDO ITSELF!
Brandon
P.S.
The calibration using accurate air pressure is 17.0 PSI should be 35 MPH on a 0-50 MPH Airguide.
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Exchange the hoses at the speedo heads & see if the problem follows the hose, if so it's in the hose system, if not its in the speedo head.
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Alright. I did something stupid. I tried changing them while I was on the water.... I'm so stupid..... I know I got water in one of the gauges, am I screwed? Is it shot now? If not how do I get the water out?
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water can do 2 things, really screw up the accuarcy, and if allowed to freeze, destroy the diaphram which kills the speedo. Remove the speedo & place pitot inlet down & gently shake until nothing comes out, then I would leave in the sun on a dry day or two to evaporate anything left inside. Exercising the diaphram with nitrogen is another option but you nned to know what your doing.
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Good to know Ron thanks...... This is going to sound stupid, but the heat just isnt around right now like it usually is (in the high 90s or low 100s). Do you think I could put it in my powder coating oven at 90 or 100 and do the trick? Or do you think I should just stick with the sun method?
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Most home ovens have a hard time staying below120 if you have a comercial oven that can maintain 100 I would use it. The temperature isn't the key its the humidity, raising dry air expands it & becomes even drier accelerating the evaporation process. A high humidity warm oven doesn't work. Kind of like me & my computer, I just spent an hour typing in a new thread on how to install rubrails only to click post & it dissapeared I think it may have been too long???
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Oven is plus or minus 3 degrees .... I think ill be ok as far as that goes..... and dang it I needed to see how to install rubrail.... that's coming next.
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I'm going to write that one up in a word file & when done will email out as needed.