to silicon or not to silicon

[Charles_Shiplee@batesuk.com]

I rebuilt the brake system from scratch with new lines and replacement wheel and master cylinders. I still have a problem with a spongy pedal that slowly goes to the floor stopping about and inch above the firewall and a leak from the breather hole on the master cylinder. I have decided that the replacement master cylinder is at fault and have decided to rebuild my original ( "never throw anything TC away" ) and then refill the system with silicon fluid. I assume that the old fluid must be drained well from the system before the silicon goes in. Does any one have any experience of replacing DOT 4 with silicon. Would you recommend it or should I preserver with the DOT 4 Charles IMPORTANT NOTICE: This message is intended for the use of the person(s) or organisation (the Intended Recipient) to whom it is addressed. It may contain information which is privileged and confidential within the meaning of applicable law. Accordingly dissemination, distribution, copying or other use of this message or any of its contents by any person other than the Intended Recipient may constitute a breach of civil or criminal law and is strictly prohibited. If you are not the Intended Recipient please contact the sender as soon as possible. All information or opinions expressed in this message and/or any attachments are those of the author and are not necessarily those of The Group. All reasonable precautions have been taken to ensure no viruses are present in this E-mail. As The Group accepts no responsibility for loss or damage arising from the use of this E-mail or attachments we recommend that you subject these to your virus checking procedures prior to use.

[David and Joyce Edgar]

Charles, The silicone fluid will mix with the DOT 4 just fine but you don't get the full benefits of the silicone if you do. The DOT 4 will absorb water for one and if any is left in, will continue to do so. I would empty out as much of the old stuff as possible, but don't worry about making it 100% pure unless you are a perfectionist. When I converted over 20 years ago I pulled the cups out of the wheel cylinders and the master was off already. I then blew the lines clear and reassembled. David Edgar, TC 5108 La Mesa, California

>I rebuilt the brake system from scratch with new lines and replacement >wheel and master cylinders. >I still have a problem with a spongy pedal that slowly goes to the floor >stopping about and inch above the firewall and a leak from the breather >hole on the master cylinder. >I have decided that the replacement master cylinder is at fault and have >decided to rebuild my original ( "never throw anything TC away" ) and then >refill the system with silicon fluid. >I assume that the old fluid must be drained well from the system before the >silicon goes in. >Does any one have any experience of replacing DOT 4 with silicon. >Would you recommend it or should I preserver with the DOT 4 > > >Charles

[Chip Old]

On Thu, 22 Feb 2001, David and Joyce Edgar wrote to T-ABC list:

> The silicone fluid will mix with the DOT 4 just fine but you don't get > the full benefits of the silicone if you do. The DOT 4 will absorb > water for one and if any is left in, will continue to do so. I would > empty out as much of the old stuff as possible, but don't worry about > making it 100% pure unless you are a perfectionist. When I converted > over 20 years ago I pulled the cups out of the wheel cylinders and the > master was off already. I then blew the lines clear and reassembled.

According to the silicone brake fluid manufacturers, it can coexist with DOT3 and DOT4 fluid, but doesn't actually mix with it. If you drain the old fluid but don't clean the system thoroughly (or at least blow it out), you may end up with pockets or layers of old fluid still in the system. That doesn't impair the hydraulic capability of the system, but that old fluid will still absorb moisture. According to the manufacturers, if at all possible the brake cylinders, hoses, and pipes should be dismantled, cleaned with alcohol, dried thoroughly, and reassembled. If that's not possible, the system should be drained completely and blown out with air, then use silicone fluid to flush the system thoroughly. -- Chip Old 1948 M.G. TC TC6710 XPAG7430 NEMGTR #2271 Cub Hill, Maryland 1962 Triumph TR4 CT3154LO CT3479E fold@bcpl.net

[Ray McCrary]

I have always changed to the silicone being very careful to either rebuild the system first, or use 70% rubbing alcohol to clean the entire system. Failure to do so MAY leave with a drip......MAY not WILL or SHALL. The change also affords you an excuse to check the lines! Best, Ray McCrary "Speed is Life; of course Luck and Altitude are helpful, too."

----- Original Message ----- From: "Chip Old" fold@bcpl.net> To: "T-ABC list" mg-tabc@yahoogroups.com> Sent: Thursday, February 22, 2001 10:29 AM Subject: Re: [mg-tabc] to silicon or not to silicon > On Thu, 22 Feb 2001, David and Joyce Edgar wrote to T-ABC list: > > > The silicone fluid will mix with the DOT 4 just fine but you don't get > > the full benefits of the silicone if you do. The DOT 4 will absorb > > water for one and if any is left in, will continue to do so. I would > > empty out as much of the old stuff as possible, but don't worry about > > making it 100% pure unless you are a perfectionist. When I converted > > over 20 years ago I pulled the cups out of the wheel cylinders and the > > master was off already. I then blew the lines clear and reassembled. > > According to the silicone brake fluid manufacturers, it can coexist with > DOT3 and DOT4 fluid, but doesn't actually mix with it. If you drain the > old fluid but don't clean the system thoroughly (or at least blow it out), > you may end up with pockets or layers of old fluid still in the system. > That doesn't impair the hydraulic capability of the system, but that old > fluid will still absorb moisture. > > According to the manufacturers, if at all possible the brake cylinders, > hoses, and pipes should be dismantled, cleaned with alcohol, dried > thoroughly, and reassembled. If that's not possible, the system should be > drained completely and blown out with air, then use silicone fluid to > flush the system thoroughly. > > -- > Chip Old 1948 M.G. TC TC6710 XPAG7430 NEMGTR #2271 > Cub Hill, Maryland 1962 Triumph TR4 CT3154LO CT3479E > fold@bcpl.net > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > >

[avanparys@viperlink.net]

I had a rather unusual situation in that I started out with new lines, rebuilt wheel and master cylinders and began with silicon fluid because of all of the benefits it presents (no water absorbtion, doesn't eat paint, etc). Unfortunately, for some reason I was never able to keep the silicon fluid from seeping out over time. I would bleed the system, check for leaks and all would be fine. Then, in about two or three days of sitting, there would be small traces that would weep out of areas around both the wheel cylinders and master cylinder connections. After taking the system apart, replacing new lines with other new lines, using permatex on connections, etc., I gave up and on the eighth attempt, I went to the Castrol GTX. No leaks. While I've talked with others who have had similar experiences, most who use silicon fluid have no trouble at all. Anyway, where all this rambling is leading is that even after I flushed the silicon out, you can still see traces of it in the GTX when the system is bled. So, while DOT 4 and silicon fluid may be "compatible," they do not blend. BTW, don't forget that you might want to take .050" off the master cylinder piston if you go with the silicon. VR - Terry V.P. Charleston S.C.

--- In mg-tabc@y..., Charles_Shiplee@b... wrote: > > I rebuilt the brake system from scratch with new lines and replacement > wheel and master cylinders. > I still have a problem with a spongy pedal that slowly goes to the floor > stopping about and inch above the firewall and a leak from the breather > hole on the master cylinder. > I have decided that the replacement master cylinder is at fault and have > decided to rebuild my original ( "never throw anything TC away" ) and then > refill the system with silicon fluid. > I assume that the old fluid must be drained well from the system before the > silicon goes in. > Does any one have any experience of replacing DOT 4 with silicon. > Would you recommend it or should I preserver with the DOT 4 > > > Charles > > IMPORTANT NOTICE: > This message is intended for the use of the person(s) or organisation (the > Intended Recipient) to whom it is addressed. It may contain information > which is privileged and confidential within the meaning of applicable law. > Accordingly dissemination, distribution, copying or other use of this > message or any of its contents by any person other than the Intended > Recipient may constitute a breach of civil or criminal law and is strictly > prohibited. If you are not the Intended Recipient please contact the sender > as soon as possible. All information or opinions expressed in this message > and/or any attachments are those of the author and are not necessarily > those of The Group. All reasonable precautions have been taken to ensure no > viruses are present in this E-mail. As The Group accepts no responsibility > for loss or damage arising from the use of this E-mail or attachments we > recommend that you subject these to your virus checking procedures prior to > use.

[Chip Old]

On Thu, 22 Feb 2001, Ray McCrary wrote to T-ABC list and Chip Old:

> I have always changed to the silicone being very careful to either > rebuild the system first, or use 70% rubbing alcohol to clean the > entire system. Failure to do so MAY leave with a drip......MAY not > WILL or SHALL. The change also affords you an excuse to check the > lines!

Rubbing alcohol isn't the best type to use because it has additives that leave residue after the alcohol evaporates. I don't remember what the additives are, but they enhance the mixture's effectiveness as a rubdown. Use 90% or better alcohol. Having said that, I'll admit to using rubbing alcohol in a pinch, but I don't like to. -- Chip Old 1948 M.G. TC TC6710 XPAG7430 NEMGTR #2271 Cub Hill, Maryland 1962 Triumph TR4 CT3154LO CT3479E fold@bcpl.net

[Emgeeguy@aol.com]

I would use the Silicon with a new brake system, but I'm not sure about how you would be sure to have all of the dot 4 stuff out of the system before refilling with silicon, and i don't think you want the two to mix. Larry

[Dwyer]

Charles I put silicon fluid into our J2 about 15 years ago and I remain very happy. The conversion that had been done when the hydraulic brakes were fitted used Morris Minor type Lockheed brakes and I found that the rear cylinders in particular were very prone to sieze up due to moisture type corrosion with the old type fluid. Since fitting silicon fluid the system has functioned perfectly. Note that you are recomended to totally clean the system and preferably fit all new rubbers and flex hoses, as traces of old fluid may remain. I certainly won't change back and the TC will use silicon when I get to that stage. Regards Dave Dwyer

[C. Knight]

Charles_Shiplee@batesuk.com wrote:

> > Does any one have any experience of replacing DOT 4 with silicon. > Would you recommend it or should I preserver with the DOT 4

I rebuilt the TA with new lines, honed pistons and cylinders, new seals, and an overhauled master cylinder. (The replacement TA units supplied would have necessitated modifying the chassis mounting - but that is another story). I used Silicon fluid and found that I had to shorten the piston in the master cylinder and fit a slightly stiffer return spring to get the cylinder to replenish and the pedal to return. Bleeding the system was VERY difficult. It took many attempts using a pressurized brake bleeder. Foot pumping does not work with Silicon. That was nearly 3 years ago. We have done about 4000 miles since, mostly in the Welsh mountains where brakes get more use than the go pedal, and have had no trouble. When I came to rebuild one of my YAs last year I used DOT 4 and had no problems at all once I had tightened up a leaky connection. I felt that the only real advantage of silicon on a regularly used car is that it doesn't strip paint, and that isn't very important given the under floor location of the master cylinder on T-ABC and Y. If your car is to be little used then Silicon may be worth all the extra hassle to ensure that you do not get any corrosion problems in the pistons. Regards Cliff

[Roger Furneaux]

Hi Charles - the best way (in my experience) is to put silicone into a clean & dry brake system, and NOT to try pushing old mineral oil out with the new silicone. I used all new geniune Lockheed rubbers too - it seems that all rubbers are not equal, and that goes for many replacement bushes these days. even some synthetic rubbers can be degraded by oil. ocTagonally Roger

>I rebuilt the brake system from scratch with new lines and replacement >wheel and master cylinders. >I still have a problem with a spongy pedal that slowly goes to the floor >stopping about and inch above the firewall and a leak from the breather >hole on the master cylinder. >I have decided that the replacement master cylinder is at fault and have >decided to rebuild my original ( "never throw anything TC away" ) and then >refill the system with silicon fluid. >I assume that the old fluid must be drained well from the system before the >silicon goes in. >Does any one have any experience of replacing DOT 4 with silicon. >Would you recommend it or should I preserver with the DOT 4 > > >Charles > >IMPORTANT NOTICE: >This message is intended for the use of the person(s) or organisation (the >Intended Recipient) to whom it is addressed. It may contain information >which is privileged and confidential within the meaning of applicable law. >Accordingly dissemination, distribution, copying or other use of this >message or any of its contents by any person other than the Intended >Recipient may constitute a breach of civil or criminal law and is strictly >prohibited. If you are not the Intended Recipient please contact the sender >as soon as possible. All information or opinions expressed in this message >and/or any attachments are those of the author and are not necessarily >those of The Group. All reasonable precautions have been taken to ensure no >viruses are present in this E-mail. As The Group accepts no responsibility >for loss or damage arising from the use of this E-mail or attachments we >recommend that you subject these to your virus checking procedures prior to >use. > > > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >