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Oil in Boge Front Struts
I am in process of rebuilding the front end on my '70 911 and pulled all the parts off to have them powder coated. When I pulled the strut inserts out of the Boge Struts, one side had a fair amount of oil in it. I was thinking maybe the strut insert leaked a bunch of oil and might be shot, but I also heard that maybe the strut inserts are supposed to be installed with oil in the bottom of the strut. The other strut on the car was dry inside. Anyway, can anyone clear up for me if maybe I have an issue with the strut insert, or if there is in fact supposed to be oil in there when the inserts are installed??
Thanks, Jeff |
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01-08-2009, 03:56 PM
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Join Date: May 2008
Posts: 726
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There are two types of inserts. Some factory strut inserts (shocks) are not sealed and the hydraulic oil is in the strut. When installing new sealed inserts you use either oil or coolant in the housing to cool the insert.
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01-08-2009, 04:14 PM
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So is there a definitive guide for strut installation within the housing?? When I put either new struts or reuse these struts back into the housings, do I definately put oil into the housing first? If so, what type of oil and how much?
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01-11-2009, 03:56 AM
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Registered
Join Date: Jan 2005
Location: cooperstown NY
Posts: 894
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my front struts had undiluted antifreeze in them.
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bob 1972 E pos correction: expensive pos someday.... "shut up and drive!" |
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01-11-2009, 07:13 AM
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Recreational User
Join Date: Mar 2004
Location: A Mile High
Posts: 4,159
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Mine had nothing in them, and still don't. I don't see the need.
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01-11-2009, 11:17 AM
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Registered
Join Date: Dec 2000
Location: philadelphia, pa
Posts: 594
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The purpose of putting antifreeze in the strut housing is to improve heat dissipation from the strut. Air is a very poor conductor, oil better, antifreeze better still. If the oil in the strut gets too hot and hence thin, the damping character and thus performance will suffer. For streey driving, this may not matter. Paul.
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01-11-2009, 11:22 AM
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AutoBahned
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Quote:
Thermal Conductivity [W/m K]: Propylene glycol 0.147 Engine Oil 0.145 Of course, there is much more to heat transfer in fluids than thermal conductivity, but I see no advantage to one liquid over the other. Either will be much better than air. |
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01-11-2009, 12:19 PM
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Registered
Join Date: Dec 2000
Location: philadelphia, pa
Posts: 594
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Randy,
I guess that's why we mix antifreeze with water in radiators. Water has conductivity of .58! Paul. |
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01-11-2009, 12:49 PM
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86 Carrera Coupe
Join Date: Apr 2008
Location: Holyoke, Massachusetts (western end of state)
Posts: 425
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I tried to find oil specific to use in the housing that encases the strut cartridge and just about every place I stopped looked at me like I was from another planet. Ended up using regular motor oil 5-15 weight as that was the lightest weight oil I could find on the shelf. I suppose motorcycle front fork oil would work well also. Yes it is used to transfer heat from the cartridge to the outside of the housing as that cartridge in there is constantly moving up and down. Mine were Boge struts but I don't think the Bilsteins use the oil in the housings. It takes very little oil to fill the void in the housing so don't put much in or you'll be cleaning it up like I was on the first one.
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01-11-2009, 02:07 PM
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Friend of Warren
Join Date: Oct 2000
Location: Lincoln, NE
Posts: 16,494
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The weight of the oil you put in is immaterial. Any oil will work.
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Kurt V No more Porsches, but a revolving number of motorcycles. |
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01-11-2009, 02:38 PM
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