One more thread about Silicone Brake Fluid

hudsonguy
hudsonguy Senior Contributor
edited November -1 in HUDSON
Okay, I know this has been discussed many times in the past, that is the old Dot 5 vs. Dot 3 or 4 argument, and I must admit I was adamant about believing in the Dot 5 silicone fluid I'd installed in my Hudson, but I've changed my opinion after reading more about the merits of each. To summarize what I've finally figured out;



-Dot 3, Dot 4 and Dot 5.1 are glycol based fluids.

-Dot 5 is silicone based fluid.

-even though silicone fluid does not absorb water, which I used to think was a benefit, it's actually a detriment, because the water that the system ultimately absorbs from humid air ends up 'pooling' in the lowest spots in the system, so silicone fluid can actually cause more rust issues (in the wheel cylinders) than it solves. So by absorbing the moisture into the Dot 3/4 fluid, and subsequent changing of fluid every so often seems to be the best situation.



But that's not the main reason I want to change back to glycol fluid. The problem I've experienced (and I remember people warning me about this on this forum), is the expansion and subsequent brake 'binding' that happens when doing frequent 'stop-and-go' driving, such as in the city or at big car shows and cruises, etc.



I've also heard advice that if you've converted to Dot 5 in the past, don't compound your error by trying to switch back, because removing every trace of silicone fluid is next to impossible.



I'm taking that last bit of advice as a challenge. Here's how I hope to do it;



1) remove (with suction pump) existing silicone fluid from master cylinder.

2) fill master cylinder with rubbing alcohol, and flush through the lines by pulling it through each wheel cylinder.

3) disconnect all lines at each wheel cylinder and master cylinder.

4) use compressed air to blow out the alcohol from the disconnected lines.

5) disassemble the master cylinder and wheel cylinders, and replace the rubber parts with new ones.

6) reassemble everything and fill with Dot 4 and bleed as normal.



Does anyone who has successfully done this procedure think I'm going about it the right way? I appreciate any help, or light you can shed on this issue.



Hudsonly,

Doug

Comments

  • Park_W
    Park_W Senior Contributor
    Doug, I would think that if the brake lines and cylinders were thoroughly flushed with the DOT 5 when changing over to that fluid, there wouldn't be any residual moisture to cause problems.
  • Unknown
    Unknown
    not sure, but with the availability of all of your brake parts, hoses, wheel cylinder rebuild kits, and master cylinder rebuild kit, right from Autozone, why not take it one step further, rebend new lines, rebuild your existing components, and start fresh that way? I bet doing it yourself, you might have $150 tops in all of the parts, and there is nothing that might come back and haunt you in the future.
  • hudsonguy
    hudsonguy Senior Contributor
    Park, that may very well be the case, but that doesn't address the binding problem I have experienced on several occasions.



    Hudsonkid, because three years (20K miles) ago I installed all new components in the brake system, including SS lines, so I'm not worried about those items.
  • Jon B
    Jon B Administrator
    Doug, I don't mean to argue with you, but I just want to say that I've been running my '37 on silicone fluid for 10-15 years and have had no problems! Heretofore, I thought the only problem with using it, was that it caused a problem with the hydraulic-type stoplight switches used in the StepDowns. My car uses a mechanical switch, so that was never an issue.



    Again, I'm sure you have good reasons. And indeed, there may be something about your year of Hudson that makes silicone impractical (as opposed to prehistoric Hudsons like I drive!). But I just wanted to present an alternate viewpoint to the discussion.
  • nick s
    nick s Senior Contributor
    Doug, your procedure sounds adequate. Be sure to give it a little extra bleed. As one who had problems (expansion and switches), I made the switch from 5-4 over 10 years ago with no I'll effects.
    good luck
  • 50C8DAN
    50C8DAN Senior Contributor
    I have been using DOT 5 in my Studebaker Hawk for over 10 years and now my 50C8 with never an issue of any kind as you note. I do believe there are some Urban Legends out there on some of these issues and I take them with a grain of salt, especially the one about water condensation.
  • [Deleted User]
    [Deleted User]
    Walt's Garage here; When I rebuilt my 53 Hudson Coupe, Finished in 1998 , I used al new lines, wheel cylinders, flex hoses and master cylinder. I filled the system with DOT 5, every 2 years I drain the master cyjinder, using a suction ball, refill with new dot 5. I have 104,000 miles so far on this system and never a problem. If your brakes drag after driving, it's because you do not have enough clearance in your brake pedal to master cylinder. Fluid will never build up to drag brakes. I drive across country every year, better that 500 miles a day and no brake build up. I use a Jeep brake switch with no problems.
  • hudsonguy
    hudsonguy Senior Contributor
    walt's garage-53 wrote:
    Walt's Garage here; When I rebuilt my 53 Hudson Coupe, Finished in 1998 , I used al new lines, wheel cylinders, flex hoses and master cylinder. I filled the system with DOT 5, every 2 years I drain the master cyjinder, using a suction ball, refill with new dot 5. I have 104,000 miles so far on this system and never a problem. If your brakes drag after driving, it's because you do not have enough clearance in your brake pedal to master cylinder. Fluid will never build up to drag brakes. I drive across country every year, better that 500 miles a day and no brake build up. I use a Jeep brake switch with no problems.



    I also used all new components 3 years ago during my brake rebuild when I installed the DOT 5. I have NOT changed the fluid since, so that's the first thing I'll try now. I do know that the two successful cross country trips I've made so far in my Hudson are a direct result of the inspiration, advice and help that Walt has given me. However, at no time during those trips was this an issue. The only time my brakes bind is when I'm driving slowly in town, contantly stopping and going, stopping and going. The latest incident is when we were looking for a particular house in a residential area and didn't know the address, so we just kept driving around for 1/2 hour of more from stop sign to stop sign, and the brakes slowly got tighter and tighter, and all pedal free play disappeared. After sitting for a while (to cool down?) the pedal free play returned and I was on my way. I've got the free play adjusted to be 1 to 1-1/2 inches. Could my master cylinder be acting up? I wouldn't think so, because it doesn't act like there's a residual buildup of fluid past the piston, which is what I'm used to experiencing with failing master cylinders.



    I haven't had any switch failures, although I already installed a second mechanical switch simply because the hydraulic switch was kind of 'late' to turn on. I like to be able to touch my pedal lightly for the brake lights to turn on.



    With several shows and trips planned in the next month, I was going to put off this 'fluid conversion' until early June anyway, but for now I think I'll simply change the DOT 5 and see what happens. Thanks to all for the help and opinions, I truly appreciate them.



    Hudsonly,

    Doug
  • PAULARGETYPE
    PAULARGETYPE Senior Contributor
    I Have Used Dot 5 In Both My 57 Hollywood And My 50 Pacemaker Cv The 57 Has Had It In For 15 Years And The 50 For About 7 So Far No Trouble Other Than The Brake Light Switch Going Bad
  • Unknown
    Unknown
    i always wanted to try that stuff i nmy dart, but its hard to find around here. now if only i could find wher to put it in my 31 essex i would use it in that, maybe ill have to keep a bottle under the seat or something. ha!
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