Reproduction Master Cylinder... silicon DOT 5 ?

[Ray G.]

Hello;

Recently purchased a reproduction master cylinder for 1967. Original is beyond rebuilding.
Have read past threads/posts with pro & cons of DOT 5

GM licensed Reproduction Master cylinder comes with instructions reading "USE OF DOT5 FLUID VOIDS THE WARRANTY"

I have used DOT5 in the past and outside of bleeding the system being slower have not had any problems.

Interested in any comments on the above are appreciated.

Ray

[Bill C.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

I have used DOT 5 on the last three cars we restored.
Never had any issues with it - but never had to deal with a warranty issue either..
I gravity bleed all the cars, so it goes real slow when bleeding .. LOL

It is very nice not having to worry about old DOT3 fluid getting on paint and eating it away..

[Duke W.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

If you decide to go with DOT 5 I highly recommend disassembling the m/c, cleaning it with denatured alcohol, and assembling it with DOT 5. Same applies to the wheel cylinders/calipers, pipes, and hoses.

Some have reported problems with DOT 5, but many have used it successfully for decades In my experience problems can happen when the system is not completely purged of any DOT 3/4 fluid. There have been many threads over the years, including one recent within the last couple of weeks that reported DOT 5 degraded the elastomeric materials.

Silicone is a very unreactive chemical and should be compatible with both vintage and current replacement elastomeric parts.

Duke

[Larry M.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Buy the DOT 5 from one of the brake companies that still sell it. I use STAINLESS STEEL BRAKES Company........they started the Corvette SS brake rebuilding back in the 1970's.

DOT 5 formulation has apparently changed over the years from some suppliers, and has caused the warranty issues. So buy from a major company, not local auto parts stores.

FWIW.

Larry

[Ray G.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Thank You Gentlemen, your comments are much appreciated

[John F.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

I have never seen a car have a failure from DOT-5 as the reason for the failure.

[John D.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

DOT 5 in my 67 for over 25 years with no problems whatsoever. Didn't disassemble the system, just carefully flushed it with the new fluid. SAE paper 810804 supports there is no practical need for disassembly to convert as the tiny amounts of residual DOT 3 will not affect the elastomers or brake performance.

[Ray G.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Thank YOU everyone for your thoughtful answers.

[Terry M.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Thank YOU everyone for your thoughtful answers.

Ray
If you go with DOT 5, please let us know how it goes. An earlier thread on this subject ended with some question of recent changes to both the elastomeric materials and DOT 5. Resolving this question should help a lot of members.

[Tom L.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

When I changed my brakes lines and master (with a correct reproduction) I just flushed the calipers (these were not replaced) as best I could and that's it. The rest of the system was new anyway. It's been 7 or 8 years since then, no problems at all.

[Ray G.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Ray
If you go with DOT 5, please let us know how it goes. An earlier thread on this subject ended with some question of recent changes to both the elastomeric materials and DOT 5. Resolving this question should help a lot of members.

Hello;
Did use DOT5 with Dukes suggestion to clean any foreign material from the Master before proceeding. Firm solid pedal by gravity bleeding
at the master and calipers. Being careful not the introduce any air bubbles into the fluid.

Drove to the AZ Chapter meet 84 miles roundtrip last Saturday 10/21/17 and everything is functioning as designed by the General.

Pedal feel has not changed since completing the work on Saturday. Will post again if it does change.

Thank You all for the comments.

Ray

[Terry M.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Hello;
Did use DOT5 with Dukes suggestion to clean any foreign material from the Master before proceeding. Firm solid pedal by gravity bleeding
at the master and wheel cylinders. Being careful not the introduce any air bubbles into the fluid.

Drove to the AZ Chapter meet 84 miles roundtrip last Saturday 10/21/17 and everything is functioning as designed by the General.

Pedal feel has not changed since completing the work on Saturday. Will post again if it does change.

Thank You all for the comments.

Ray

Excellent Ray. I am glad to hear of your success.

[Patrick H.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

What brand of fluid did you buy, and from whom?

[Ray G.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Hello;
Used NAPA fluid on this Corvette. Have used other brands in Nomad and Chevelle.

I just pour a sample into a clean container to be sure it has the usually very light purple hue before using.

Thanks

[John L.]

Re: Reproduction Master Cylinder... silicon DOT 5 ?

Is there is need to change the brake fluid over a certain period of time when using Dot5 Fluid? I have been running Dot5 in my 66 for 10+ years with no problems, just wondering about need to change/flush system? thanks