Steering pipe to rack O-ring size

[Marc_986]

Has anyone figured out the size of the O-rings on the connection of the hydraulic lines into the rack?

Especially the return line has a single simple O-ring. This should cost cents, not $20. So I was hoping someone already looked at alternatives

[Gilles]

Mark, I just bought the samme two small o-rings for my Volvo V70 wagon and they charged me $18.70 each...!

BTW, these are metric (?) viton o-rings, but I didn't wanted to disasemble the car and then having to go searching for the right size..

[Marc_986]

Yeah, as I have a bit more time, I might as well give it a try. I studied O-ring sealing a bit today and that was quite informative. Seems the best way is to measure the groove (diameter and width) and bore diameter and calculate the right O-ring from there.

Tomorrow I will need to remeasure the steering rack connection diameter, as today, in the dark, I didn't get reasonable numbers

In my other thread I had shown a few available adapters. One of them with double O-ring. From what I have learned now, that is actually worse than the OEM setup which has a backup / support ring and the actual sealing O-ring. The function of the backup ring is to prevent the O-ring from deforming under pressure, being pushed into the space between steering rack and adapter.

Part of the selection is also on material used. Basically either Viton (as OEM) or NBR. In my application I see no reason that NBR is insufficient. Real strength of Viton seem at high temperature, but with the electric pump I should never get there (doesn't flow that much as the engine drive pump does at high RPM and no longer in the hot engine compartment).

To be continued.