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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / July 2006Pneumatic Shocks for a Russian UAZ Simbir
Hi all, I own a Russian SUV, a consumer version based on their military jeep series. It has a ton of unsprung weight (solid axles front and back built pretty heavy). The Russian's use oil-based shocks on their cars for the most part, this vehicle included. The large amount of unsprung weight plus the use of oil based shocks seems to be causing excesive "jiggling" whenever we run across one of the many bumps here in Armenia. I've had the shocks re-worked recently (rubber seals replaced, oil replaced), and tried various levels of air pressure in the tires but am pretty much at a dead end there. I'm considering trying to get pneumatic shocks instead. They don't make them for this vehicle, so I'd have to either find a similar vehicle (not necessarily so hard since they tended to copy a lot from Toyota) or order some custom shocks. Questions: 1) Are pneumatic shocks better for a heavy vehicle, specifically one with significant unsprung weight? 2) How would I go about determining if a another vendor's shocks would work on my vehicle? 3) If I need to order custom shocks I ned some recommendations on vendors... Thanks all, B. Jetter - without the x's at: use3xnet@jetterxfamily.net > Hi all, My response is not an answer to your post, but a show of interest. Maybe someone with a lot more knowledge about this sort of situation can give you better help. I have earmarked this thread so I can follow it... Are you able to purchase a wide selection of shock absorbers in Armenia? If one could, and the cost were not exhorbitant, I might be tempted to cobble up some new brackets and adapt multiple shock installations where possible. (Although this would be an exercise in trial and error, and might not achieve anything at all.) >Are you able to purchase a wide selection of shock absorbers in Armenia? If >one could, and the [quoted text clipped - 3 lines] >trial and error, and might >not achieve anything at all.) I think this IS a good idea, but you need to be careful about the shocks that you pick. I think if you pick three different sets of shocks that are far enough apart, you might be able to figure out what basic range you want to be in. You might ALSO consider variable gas shocks, which would give you a lot of options to tweak things. --scott  Signature"C'est un Nagra. C'est suisse, et tres, tres precis." >I own a Russian SUV, a consumer version based on their military jeep >series. It has a ton of unsprung weight (solid axles front and back [quoted text clipped - 6 lines] >(rubber seals replaced, oil replaced), and tried various levels of air >pressure in the tires but am pretty much at a dead end there. The notion here is that the oil shocks are tuned to a particular frequency and the frame of the vehicle has a natural resonant frequency as well, and the two points need to be far apart from one another. >I'm considering trying to get pneumatic shocks instead. They don't >make them for this vehicle, so I'd have to either find a similar >vehicle (not necessarily so hard since they tended to copy a lot from >Toyota) or order some custom shocks. Or make some adaptors. But first, you probably want to find out what putting them on is going to do to the system resonance, and if your effective damping will be getting better or worse. First thing I'd do is try varying the viscosity of the oil in the oil shocks and see how the ride changes. That at least will tell you what direction you need to be going in. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." usenet@jetterfamily.net wrote in article <1153802090.241439.183120@75g2000cwc.googlegroups.com>... > Hi all, > [quoted text clipped - 17 lines] > 1) Are pneumatic shocks better for a heavy vehicle, specifically one > with significant unsprung weight? First of all, I suspect you do not understand shock absorber design. I believe you are referring to "Gas shocks" as "pneumatic." Fact of the matter is that "Gas shocks" are simply hydraulic shocks in which the fluid pressurized - usually by nitrogen. The concept is that the pressure will keep the fluid from foaming. Picture a bottle of Coca-Cola. Shake it just a little. As long as it is capped, it looks okay. Open the cap and release the pressure, and it foams up. > 2) How would I go about determining if a another vendor's shocks would > work on my vehicle? Most shock catalogs have size and mount information. You might luck out in choosing a shock from a heavier vehicle that is the same length and has the same mounts as your vehicle. You REALLY cannot tell much by "seat-of-the-pants" trial and error. There MAY be a professional race team in Armenia that owns a shock absorber dynamometer. THAT is the tool that gives you shock pressure comparison information. Without a dyno, it will be difficult - if not impossible - to "tune" your shocks. > 3) If I need to order custom shocks I ned some recommendations on > vendors... Probably best to go with one of the racing manufacturers such as Penske, Ohlins and others. Most of the major shock manufacturers are into Monster Truck shocks - which, I would guess, might be the best route for you to go - depending on your OEM shock size. Surf the web for Monster Truck Shocks, and get in touch with one-or-more of the manufacturers. Give them your weights and specs, and they SHOULD be able to design something that'll work for you. > You REALLY cannot tell much by "seat-of-the-pants" trial and error. > [quoted text clipped - 4 lines] > Without a dyno, it will be difficult - if not impossible - to "tune" your > shocks. Admittedly, all the bells and whistles equipment and software make this sort of project much much easier. To say that it is impossible to revamp one's shock system without it goes against the spirit of the hot rodder. Difficult and time consuming...that is more like it. Unfortunately, in many countries, there is a lack of almost every part, tool, and equipment except resourcefulness. One works with what one has. I have never been to Armenia, and have no idea what is available, but wish you the best in your project. > To say that it is impossible to revamp one's shock system without it goes > against the > spirit of the hot rodder. Difficult and time consuming...that is more like > it. Thanks for the encouragement. This is definitely a part of the world for trial and error. The current rear shocks come from the Soviet military jeep stock; the front shocks come from a Volga car - and that's standard from the factory. Somehow I doubt I can do much worse :-) > Unfortunately, in many countries, there is a lack of almost every part, > tool, and equipment [quoted text clipped - 3 lines] > you the best > in your project. > > To say that it is impossible to revamp one's shock system without it goes > > against the [quoted text clipped - 7 lines] > front shocks come from a Volga car - and that's standard from the > factory. Somehow I doubt I can do much worse :-) I have to ask if there's a communication barrier here. when you say this Russian Jeep-like vehicle uses "oil shocks" and then go on to say that they are rebuildable, does that mean that they are the older type, lever-arm shocks? and you are considering retrofitting what were called "aircraft-type" tubular shocks back when they were first introduced? I have to admit knowing nothing about any Russian vehicle except that they had a limo that looked scarily like a stretched version of a '56 Packard :) nate > I have to ask if there's a communication barrier here. when you say > this Russian Jeep-like vehicle uses "oil shocks" and then go on to say [quoted text clipped - 6 lines] > > nate Nate, The shocks are probably better discribed as "liquid" - some type of oil, but I've never seen the oil, so let's just say it's carbon based. By rebuilding, I mean the seals replaced, some type of valve inside adjusted for flow, and the "oil" flushed and refilled. Afraid I don't know the term "tubular shocks", although the picture at http://www.vanpeltsales.com/FH_web/FH_images/FH_chassis-pics/Flathead_Shocks_194 7-48_Tube.jpg looks almost exactly like my shocks. Thanks, Brian > > I have to ask if there's a communication barrier here. when you say > > this Russian Jeep-like vehicle uses "oil shocks" and then go on to say [quoted text clipped - 19 lines] > > Thanks, Brian OK, those are common modern-style tubular shocks... instead of trying to buy shocks for your application, perhaps (since you say you have the "correct" shocks now) measure the compressed and fully extended length of your shocks and try to buy some by spec instead of by application. However, I think the idea of using a more viscous oil is a good one, you might want to check with a motorcycle shop first (as motorcycles tend to use shocks built into the forks which therefore are by nature serviceable, as opposed to most tubular-style automotive style shocks which are sealed and are simply replaced when they're worn out) to see if you can get an assortment of fluids in various viscosities and try those and see if one of those makes you happy; if that does not work perhaps a good off-road shop could match up a heavier-duty shock to your application if you give them the specs of the shocks you have. I'm assuming that when you say "almost exactly" that the mounting method at the top and bottom is the same as well? (bolt through an eye, with rubber bushings) there are other options (bayonet mount etc.) but that one is fairly common. good luck, nate |
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