Oil-Filled Front Shocks on SWB?

[mshaver51]

Friends,

I have removed the front suspension from my (Aug '67-build) 68 911. When i dis-assembled the front boge struts, I found the bottom half of the strut case was filled with oil.

I have begun to do the research about this feature, but I also wanted to ask the Registry members to add their intellectual capital, and perhaps offer research material/resources to assist my learning curve.

• were all SWB front struts filled with oil?
• what was the purpose of the oil?
• is it normal restoration protocol to replace the oil, and if so, which oil is proper?

This is my first 911 restoration, and although I have read pretty extensively, the oil was a surprise. Thanks for all of your input. All valid input is appreciated.

[72targa]

I have never dis-assembled a shock absorber...but I know that oil has been used as the hydraulic media to absorb the shock of the up and down motion of the shock absorber. I've been involved in the sale of said oil to an OEM and it's a very light viscosity grade. I'll be interested in other expert comment.

[frankc]

I assume that you are referring to the oil in the strut housing, not the strut insert. The light oil in the strut housing is used to transfer heat from the strut insert to the housing for the purpose of cooling. Approximately 50cc is used and will result in the fluid rising almost to the top of the housing once the insert is installed and displaces the fluid.

I have read various comments on whether or not the fluid is necessary for street applications, and also on the type of fluid (light oil, ATF, radiator coolant). The oil that I removed from my struts appeared to be in good condition, so I simply re-used it.

[edmayo]

Original strut shocks were open oil filled, thus the oil in the housing. That oil is what the piston moved to dampen the suspension movement. Replacement inserts have the oil contained within the insert, however it is normal to put some oil into the housing to aid in heat transfer from the 'sealed' insert to the strut housing. The oil in the housing of a 'sealed' insert has nothing to do with shock action, it is strictly heat transfer.

[ptrsbtrs]

Ed, does the oil also help to alleviate the "what the H*ll was that noise"? clunking sound from the front end ?

[edmayo]

Nope,,,,you've got something else going on.

[bfunke]

I replaced the junk KYBs with Bilsteins and I called the company to inquire about adding oil and Bilstein tech rep recommend adding no oil on their current inserts.

[Haasman]

I have always added oil to the struts to enhance heat transfer on applications with shock inserts.

[edmayo]

I replaced the junk KYBs with Bilsteins and I called the company to inquire about adding oil and Bilstein tech rep recommend adding no oil on their current inserts.

Sounds like you have your answer.

[Tim Morris]

The adding oil comments are correct! This learned from OLD SCHOOL German Tech's I apprenticed for in the 80's. Heat transfer, mild dampening effect and I've noticed corrosion protection. Put oil in the strut housings on the Bilsteins too, regardless of what they said... BTW, The Boge shocks should not be discounted and knee jerked to Koni upgrades. We put a set (Boge) on a 67S Targa, as they were the original type and they rode nicely and finally, were what the factory used for that particular build. Yes, an early S with Boge shocks and struts, confirmed.