Brake Rubber and Fluids

[Lange, Richard F]

Perhaps I've screwed up, but I have recently used plain old Dot3 type brake fluid in my TD brake system. I've used Lockheed Rubber in the master and slaves, and have been told I should have been using Girling.... So, to 'repair' this mistake, what are my alternatives? Are there brake seals made out of another material I can use, so I don't have to flush the lines and replace the fluid with Girling, or do I need to pull the master and slaves, replace the rubber, flush the line, and use girling? On very good authority - Mike Goodman - I should switch back to Giling Brake Fluid. On another car, I have used Silicone Brake Fluid, but I'd still have to flush and replace. Any good ideas? Dick Lange

> Boeing Commercial Airplane Group > DCAC-MRM PROJECT SUPPORT, BUILD TEAM > M/S 6M-HR Phone : (425 ) 965-6789 Pager: (206) 416-3663 > Cell Phone (425 ) 941-0386 Home Phone (425) 481-3063 > > > >

[brian bax]

Hello Richard, You haven't said whether the brakes are working correctly. I'm not aware of incompatability between recently manufactured seals and fluids but would be interested to learn more. Personally, I prefer silicone fluid but if the brakes feel ok I would leave things as they are. Regards Brian Bax TC3550.> -----Original Message-----

> From: Richard.Lange@PSS.Boeing.com (Lange, Richard F) > Sent: Sat Jun 09 16:16:17 BST 2001 > To: mg-tabc@yahoogroups.com ('mg-tabc@yahoogroups.com') > Subject: [mg-tabc] Brake Rubber and Fluids > > Perhaps I've screwed up, but I have recently used plain old Dot3 type brake fluid in my TD brake system. I've used Lockheed Rubber in the master and slaves, and have been told I should have been using Girling.... > > So, to 'repair' this mistake, what are my alternatives? Are there brake seals made out of another material I can use, so I don't have to flush the lines and replace the fluid with Girling, or do I need to pull the master and slaves, replace the rubber, flush the line, and use girling? > > On very good authority - Mike Goodman - I should switch back to Giling Brake Fluid. > > On another car, I have used Silicone Brake Fluid, but I'd still have to flush and replace. > > > Any good ideas? > Dick Lange > > Boeing Commercial Airplane Group > > DCAC-MRM PROJECT SUPPORT, BUILD TEAM > > M/S 6M-HR Phone : (425 ) 965-6789 Pager: (206) 416-3663 > > Cell Phone (425 ) 941-0386 Home Phone (425) 481-3063 > > > > > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > >

[Neil Nelson]

Hi Dick, Here is what I have been told about this problem. The rubber seals made in England were made of natural rubber. The seals US cars use are made of synthetic rubber. US Dot 3 brake fluid is mineral based and will damage the natural rubber seals. Girling brake fluid is vegetable based and is the proper one to use with the English made seals. I use silicone fluid in all my cars and have never had a bit of trouble. You are correct though, you do have to flush the system before changing over to it. Maybe someone else on the net can shed some more light on this subject. Chip, how about it? Neil Nelson TC0526 -----Original Message----- From: Lange, Richard F [mailto:Richard.Lange@PSS.Boeing.com] Sent: Saturday, June 09, 2001 11:16 AM To: 'mg-tabc@yahoogroups.com' Subject: [mg-tabc] Brake Rubber and Fluids Perhaps I've screwed up, but I have recently used plain old Dot3 type brake fluid in my TD brake system. I've used Lockheed Rubber in the master and slaves, and have been told I should have been using Girling.... So, to 'repair' this mistake, what are my alternatives? Are there brake seals made out of another material I can use, so I don't have to flush the lines and replace the fluid with Girling, or do I need to pull the master and slaves, replace the rubber, flush the line, and use girling? On very good authority - Mike Goodman - I should switch back to Giling Brake Fluid. On another car, I have used Silicone Brake Fluid, but I'd still have to flush and replace. Any good ideas? Dick Lange

> Boeing Commercial Airplane Group > DCAC-MRM PROJECT SUPPORT, BUILD TEAM > M/S 6M-HR Phone : (425 ) 965-6789 Pager: (206) 416-3663 > Cell Phone (425 ) 941-0386 Home Phone (425) 481-3063 > > > >

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[Chip Old]

On Sun, 10 Jun 2001, Neil Nelson wrote:

> Here is what I have been told about this problem. The rubber seals > made in England were made of natural rubber. The seals US cars use > are made of synthetic rubber. US Dot 3 brake fluid is mineral based > and will damage the natural rubber seals. Girling brake fluid is > vegetable based and is the proper one to use with the English made > seals. I use silicone fluid in all my cars and have never had a bit > of trouble. You are correct though, you do have to flush the system > before changing over to it. Maybe someone else on the net can shed > some more light on this subject. Chip, how about it? Neil Nelson > TC0526

I used DOT 3 fluid in Britcars for many years without any trouble, as well as in the Jackall system in a Y-Type I owned for several years, so I hold little credance in the conventional wisdom that DOT 3 eats british seals. However given the lower moisture activity of a DOT 4 like GT/LMA or a DOT 5 like silicon fluid, these days it makes little sense to use DOT 3. Chip

[Jetten]

I would like to throw in my knowledge and experience. I used to develop brakefluids for a major global chemical company from 1980 until 1985. Many major oil companies, brake component and car manufacturers used to be our customers. We sold this business in the meantime,but the technology hasn t really changed. DOT 3 and DOT 4 are both based on glycolethers, in fact DOT 3 fluids are straight glycolether based and DOT 4 fluids are typically based on borate esters of glycolethers. DOT 5 are silicon based fluids. This is globally valid. So none of the fluids are mineral oil or vegetable oil based. The only cars that use mineral based brake fluids typically have a central hydraulic system, like some Citroen models for instance. Filling brake systems that are designed for DOT 3 or DOT 4 with a mineral oil based hydraulic fluid will lead to catastrophic failure, due to extreme swelling of the rubber seals. DOT 3, DOT 4 and DOT 5 are supposedly interchangeable among eachother as far as their rubber compatibiliy is concerned. I.e. all 3 should be compatible with the rubber seal materials that are designed for conventional brake systems. In order to meet the DOT 3, DOT 4 or DOT 5 specs. these brakefluids are formulated such that the swelling of rubber components is within limits, that are clearly specified in the DOT 3,4 and 5 standards. Like wise rubber seals for conventional brake systems, should stand any of the DOT 3, DOT 4 or DOT 5 fluids. Where things can go wrong is when one mixes a DOT 3 or 4 fluid with a DOT 5 ( silicone based ) fluid. Let s assume initially a DOT 3 or 4 fluid had been filled into the brakesystem. The seals are saturated with DOT 3 or 4. Now a silicone fluid is filled. If the absorption of the silicone fluid is faster than de desorption of the DOT 3 or DOT 4 fluid, then excessive rubber swelling will occur. I.e. the solubilities and the rates of absorption/desorption can be different and that leads to the reported problems. In general it must be recommended to change rubber seals when canging over from DOT 3 or DOT 4 to DOT 5. A few words about preference for DOT 3 or DOT 4. DOT 4 fluids have a somewhat higher boiling point than DOT 3, when fresh. Also with the same amount of water absorption ( throgh the rubber brake hoses and seals as well as into the brake fluid reservoir), the DOT 4 fluids show a higher boiling point than DOT 3 fluids. However DOT 4 fluids are more hygroscopic and tend to absorb water faster than DOT 3 fluids. I.e. after a while they become equivalent in boiling point, and the DOT 4 fluid will have a higher water percentage at that point ( possibly more corrosive). For normal use and if brake fluids are regularly changed ( once every 2 years) then DOT 3 fluids are just as suitable as DOT 4 fluids. A DOT 4 fluid, which is not regularly changed is worse than a relatively fresh DOT fluid: more water absorption means lower boiling point and more corrosion. A few words about DOT 5. DOT 5 fluids have been developed for military applications, i.e. for vehicles that could stand in storage for years, without maintenance, yet had to perform immediately when required. They are superior in terms of boiling point retention and corrosion / conservation properties, since they don t absorb water. It may be better today, but one of the big drawbacks used to be their low air solubility leading to a spongy brake pedal feel. Other big advantage of course is that silicone fluids don t dissolve car paints, Summary: - DOT 3 and DOT 4 fluids are fine if they are changed regularly. - DOT 3 is certainly not inferior to DOT 4 for normal use. - DOT 4 can be inferior to DOT 3, if DOT 4 isn t changed regularly. - if changing from DOT 3 or DOT 4 to DOT 5 or vice versa, it is recommended to change all rubber seals. Best regards, Wim Jetten

----- Original Message ----- From: "Chip Old" fold@bcpl.net> To: "MG-TABC" mg-tabc@yahoogroups.com> Sent: Sunday, June 10, 2001 1:35 PM Subject: RE: [mg-tabc] Brake Rubber and Fluids > On Sun, 10 Jun 2001, Neil Nelson wrote: > > > Here is what I have been told about this problem. The rubber seals > > made in England were made of natural rubber. The seals US cars use > > are made of synthetic rubber. US Dot 3 brake fluid is mineral based > > and will damage the natural rubber seals. Girling brake fluid is > > vegetable based and is the proper one to use with the English made > > seals. I use silicone fluid in all my cars and have never had a bit > > of trouble. You are correct though, you do have to flush the system > > before changing over to it. Maybe someone else on the net can shed > > some more light on this subject. Chip, how about it? Neil Nelson > > TC0526 > > I used DOT 3 fluid in Britcars for many years without any trouble, as well > as in the Jackall system in a Y-Type I owned for several years, so I hold > little credance in the conventional wisdom that DOT 3 eats british seals. > However given the lower moisture activity of a DOT 4 like GT/LMA or a DOT > 5 like silicon fluid, these days it makes little sense to use DOT 3. > > Chip > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >

[LuckyFloridaLin@aol.com]

Wow; that one was a print-out for the my MG bible. Many Thanks. Tally Ho! Thom Collins

[Neil Nelson]

I knew someone had some answers to this. Do you suppose the story about this problem started many years ago and possibly there was, at one time, some difference between fluids or rubber parts? These stories have a habit of hanging on it seems. Thanks Chip and Wim I too am adding this to my collection of MG items saved on my Zip drive. But I still like the Dot 5. Neil Nelson TC 0526 -----Original Message----- From: Jetten [mailto:jetten@bluewin.ch] Sent: Sunday, June 10, 2001 3:38 PM To: MG-TABC Subject: Re: [mg-tabc] Brake Rubber and Fluids I would like to throw in my knowledge and experience. I used to develop brakefluids for a major global chemical company from 1980 until 1985. Many major oil companies, brake component and car manufacturers used to be our customers. We sold this business in the meantime,but the technology hasn t really changed. DOT 3 and DOT 4 are both based on glycolethers, in fact DOT 3 fluids are straight glycolether based and DOT 4 fluids are typically based on borate esters of glycolethers. DOT 5 are silicon based fluids. This is globally valid. So none of the fluids are mineral oil or vegetable oil based. The only cars that use mineral based brake fluids typically have a central hydraulic system, like some Citroen models for instance. Filling brake systems that are designed for DOT 3 or DOT 4 with a mineral oil based hydraulic fluid will lead to catastrophic failure, due to extreme swelling of the rubber seals. DOT 3, DOT 4 and DOT 5 are supposedly interchangeable among eachother as far as their rubber compatibiliy is concerned. I.e. all 3 should be compatible with the rubber seal materials that are designed for conventional brake systems. In order to meet the DOT 3, DOT 4 or DOT 5 specs. these brakefluids are formulated such that the swelling of rubber components is within limits, that are clearly specified in the DOT 3,4 and 5 standards. Like wise rubber seals for conventional brake systems, should stand any of the DOT 3, DOT 4 or DOT 5 fluids. Where things can go wrong is when one mixes a DOT 3 or 4 fluid with a DOT 5 ( silicone based ) fluid. Let s assume initially a DOT 3 or 4 fluid had been filled into the brakesystem. The seals are saturated with DOT 3 or 4. Now a silicone fluid is filled. If the absorption of the silicone fluid is faster than de desorption of the DOT 3 or DOT 4 fluid, then excessive rubber swelling will occur. I.e. the solubilities and the rates of absorption/desorption can be different and that leads to the reported problems. In general it must be recommended to change rubber seals when canging over from DOT 3 or DOT 4 to DOT 5. A few words about preference for DOT 3 or DOT 4. DOT 4 fluids have a somewhat higher boiling point than DOT 3, when fresh. Also with the same amount of water absorption ( throgh the rubber brake hoses and seals as well as into the brake fluid reservoir), the DOT 4 fluids show a higher boiling point than DOT 3 fluids. However DOT 4 fluids are more hygroscopic and tend to absorb water faster than DOT 3 fluids. I.e. after a while they become equivalent in boiling point, and the DOT 4 fluid will have a higher water percentage at that point ( possibly more corrosive). For normal use and if brake fluids are regularly changed ( once every 2 years) then DOT 3 fluids are just as suitable as DOT 4 fluids. A DOT 4 fluid, which is not regularly changed is worse than a relatively fresh DOT fluid: more water absorption means lower boiling point and more corrosion. A few words about DOT 5. DOT 5 fluids have been developed for military applications, i.e. for vehicles that could stand in storage for years, without maintenance, yet had to perform immediately when required. They are superior in terms of boiling point retention and corrosion / conservation properties, since they don t absorb water. It may be better today, but one of the big drawbacks used to be their low air solubility leading to a spongy brake pedal feel. Other big advantage of course is that silicone fluids don t dissolve car paints, Summary: - DOT 3 and DOT 4 fluids are fine if they are changed regularly. - DOT 3 is certainly not inferior to DOT 4 for normal use. - DOT 4 can be inferior to DOT 3, if DOT 4 isn t changed regularly. - if changing from DOT 3 or DOT 4 to DOT 5 or vice versa, it is recommended to change all rubber seals. Best regards, Wim Jetten

----- Original Message ----- From: "Chip Old" fold@bcpl.net> To: "MG-TABC" mg-tabc@yahoogroups.com> Sent: Sunday, June 10, 2001 1:35 PM Subject: RE: [mg-tabc] Brake Rubber and Fluids > On Sun, 10 Jun 2001, Neil Nelson wrote: > > > Here is what I have been told about this problem. The rubber seals > > made in England were made of natural rubber. The seals US cars use > > are made of synthetic rubber. US Dot 3 brake fluid is mineral based > > and will damage the natural rubber seals. Girling brake fluid is > > vegetable based and is the proper one to use with the English made > > seals. I use silicone fluid in all my cars and have never had a bit > > of trouble. You are correct though, you do have to flush the system > > before changing over to it. Maybe someone else on the net can shed > > some more light on this subject. Chip, how about it? Neil Nelson > > TC0526 > > I used DOT 3 fluid in Britcars for many years without any trouble, as well > as in the Jackall system in a Y-Type I owned for several years, so I hold > little credance in the conventional wisdom that DOT 3 eats british seals. > However given the lower moisture activity of a DOT 4 like GT/LMA or a DOT > 5 like silicon fluid, these days it makes little sense to use DOT 3. > > Chip > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[Chip Old]

On Mon, 11 Jun 2001, Neil Nelson wrote:

> Do you suppose the story about this problem started many years ago and > possibly there was, at one time, some difference between fluids or > rubber parts? These stories have a habit of hanging on it seems.

The story began back in the 1940s and 1950s when mineral-based "brake fluid" (really nothing more than normal hydraulic fluid or jack oil) was sometimes sold by unscrupulous types as brake fluid. You could often get by with it in an American car because post war American brake cups were almost always made of synthetic rubber (Neoprene or whatever). However if you used mineral-based fluid in a British car the result was disastrous because British brake cups were still made of real rubber. If you look at the TD/TF Workshop Manual (section M.16), it says "In cases of difficulty in obtaining Lockheed Genuine Brake Fluid use must be made of fluid conforming to S.A.E. specification 70.R2". If I remember correctly SAE 70.R2 is what is now known as DOT-3. Can someone confirm or correct me on this? You'll also notice in the manuals for slightly later British cars (MGA/B, TR2/3/4, etc) that they usually say to use genuine Lockheed or Girling fluid (depending on which brake systen is in the car), but if you can't find it, use genuine DOT-3 fluid. The warning was meant as a caution against using mineral-based hydraulic fluid, not as a caution against DOT-3. Chip