| Author | Message | ||
     Brian Vogel Grand Master Username: guyslp Post Number: 2729 Registered: 6-2009 |
There have been cyclic posts asking about the compatibility of a given elastomer (e.g. EPDM, AFLAS, BUNA-N, etc.) with a given fluid (at least here). I don't think I ever posted this link before, but certainly meant to. The most exhaustive list I've ever seen comes from the Parker catalog (PDF Document): Parker Catalog, Section VII - Compatibility Tables for Gasses, Fluids, Solids The online reference from Marco Rubber (which is where I sourced my X-rings for rebuilding the Height Control Valves) is excellent as well: Rubber O-Ring Chemical Compatibility Chart - O-Ring Material Resistance Guide Brian | ||
| David Gore Moderator Username: david_gore Post Number: 3089 Registered: 4-2003 |
Thanks Brian, Two very useful references  | ||
| Larry Kavanagh Grand Master Username: shadow_11 Post Number: 307 Registered: 5-2016 |
Thanks Brian, Very interesting & essential information. | ||
| Alan Dibley Prolific User Username: alsdibley Post Number: 177 Registered: 10-2009 |
Informative, Brian. Thanks. It's interesting (and very comforting in view of the differences of opinion on the suitability of DOT5 for Shadows) that the Parker recommendations for silicone oils are an almost unbroken string of "1"s and Marco agrees with mostly green dots. Alan D. - SBH10630 with Oke DOT5 in the hydraulics. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2730 Registered: 6-2009 |
Alan, Unless I'm mistaken, I believe that "red rubber grease" (and plumbers grease) are composed of silicone. It's right up there with PTFE (teflon) in the non-reactive category. I've never had anything in particular against DOT5 fluid, but getting one's system suitably purged of the original DOT3 must have proved challenging. Heaven knows that liquid silicone has about as much "lubricity" as anyone could ever want. Brian, who congratulates you on having been willing to do your own experimenting with DOT5 and also willing to report about it - There actually exist "other ways" with these cars | ||
| Mark Aldridge Grand Master Username: mark_aldridge Post Number: 593 Registered: 10-2008 |
Brian, a friend of mine always uses silicone grease to assemble brake cylinders, callipers etc and never gets seized pistons ! I have tried this on my little used MG and no seized brakes.How recommendable this is ? any opinions anybody ? Mark | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2035 Registered: 9-2004 |
Seem to remember doing some tests with some old 363 seals and diaphragm submerged in dot5 with alarming results. IMO the best way to convert to DOT 5 is to totally rebuild the hydraulic system and then with the help of compatibility charts see if the correct parts are available. The one prob with dot5 is that the rat trap being in the low position and the common problem with water pooling in the lowest part of the system may cause great expense with the brake distribution valves. Have known dot5 to wax round brake pistons and cause sluggish operation when cold! I almost carried out a change years ago but chickened out. Well done to Alan. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2731 Registered: 6-2009 |
Mark, In looking up "red rubber grease" it appears to have a vegetable base but some formulations also contain silicone. As such, I'd see no problem in using silicone grease, particularly in your system which is using DOT5, though to tell you the truth I doubt you'd need it if you lube your seals with DOT5 when installing. It might, however, "stick better" to surfaces over time even if it's just the thinnest layer undetectable to the human finger. Who knows, but it makes sense as that's what regular grease does compared to oils. There is no reason that the correct seals for a RR/Bentley system, which are EPDM, should have any issue with silicone of any variety. Brian P.S.: I see I'm conflating posters here between Alan and Mark. That being said, the content is general enough that I'm going to leave it as is. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2042 Registered: 9-2004 |
I see this clashes with what is stated here. https://www.introcar.co.uk/blog/2018/09/improved-epdm-rubber-seals/ | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2734 Registered: 6-2009 |
Well, I don't doubt that the can be quality issues with any seals. The above, however, screams pure marketing. Seals are not individually tested. They're not even tested at the "single production run" level, given the number that get produced. Introcar puts out great replacement parts, but their "improved" seals, given the nature of mass manufacture of this kind of part, are no less prone to the occasional vagaries involved than all the rest of the world's are. I've had a single seal between the accumulator and accumulator control valve fail, and in very short order which I posted about here, including video. That appears, based on the way it failed, to have been a rogue seal of some other elastomer that got dropped in to a bag of EPDM seals. Otherwise, I've yet to have an EPDM seal fail, period, and haven't had a single person that got kits from me report such, either. Brian |
