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Discussion Topic:
Dot 3 to Dot 5
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len47merc |
01-15-2017 @ 10:38 AM
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Senior
Posts: 1165
Joined: Oct 2013
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Does a simple and effective process exist for cleaning a brake/hydraulic system previously filled with Dot 3 to properly prepare it for conversion to Dot 5? If so, what is the process and what materials/solvents/cleaners are recommended? Or is this simply not worth the hassle excepting for installation in a completely new system (master, lines, & wheel cylinders)? A search of the Forum did not yield a solid, concrete yea or nae to this. Thanks -
Steve
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kubes40 |
01-15-2017 @ 10:54 AM
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Posts: 3407
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I think the question "Is it worth it"? is the one that needs to be answered by you first and foremost. There are pros and cons to each fluid. Dot5 does not attract moisture as does the Dot3. So, you won't find it necessary to flush the fluid every few years as you should do with Dot3. Dot5 will find leaks in places Dot3 will not. Dot5 will typically give you a softer pedal. Dot5 will destroy an authentic brake lamp switch rather rapidly. To change from Dot3, you simply need to cleanse the hydraulic system of the Dot3. This is not difficult if you have the proper tools. A power bleeder is in my opinion a necessity to do this flush thoroughly.
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CharlieStephens |
01-15-2017 @ 1:07 PM
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Senior
Posts: 893
Joined: Oct 2009
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If you are not a purist you can get a brake light switch designed to be used with dot 5 from Ron Francis Wire Works, https://www.ronfrancis.com, (800) 292-1940 Charlie Stephens
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oldford2 |
01-15-2017 @ 5:46 PM
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Member
Posts: 275
Joined: Oct 2009
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So many posts on this subject here and on Fordbarn. Kube40 pretty much sums it all up. I never understood why people are hung up on DOT3 absorbing moisture (which it does). When I put our 46 away for the winter (yes we have winter in MA) I change all the fluids and bleed the brakes. Now how much time to put fresh DOT3 in the system? Less than a half hour if you have a wife to pump- hold and top off the M/C. Plus, I installed speed bleeders so you can do it alone if your wife refuses. John
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len47merc |
01-15-2017 @ 6:20 PM
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Senior
Posts: 1165
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John/all, There is one VERY good reason for this being a serious consideration - that being the original floor mat in my '47 Merc. Carpet inserts still intact. Rouge Class multiple Award winner including Medallion. Every time you even breathe on this floor mat it cracks. Yes, I am NOW a purist, a Converted Preservationist, and I Now treasure all the original parts on this Merc and every other EFV8 I see and am blessed enough to see in person. If there is a way I do not have to touch or lift this floor mat again in my lifetime then I am all about it. For those of you that have seen the car in Charlotte or Gettysburg you can appreciate where I am coming from. Unfortunately this Dot 5 option, particularly based on Mike's and others' on this Forum quite valued inputs, appears not worthy of the effort required at this point. Yes, it may get quite a bit of airtime - but for those of you patient enough to continue to provide your experience and expertise with those of us not as seasoned I do thank you sincerely.
Steve
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TomO |
01-16-2017 @ 10:49 AM
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Posts: 7256
Joined: Oct 2009
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To flush the system of DOT 3 use denatured alcohol available in the paint department of most hardware stores. Mike summed up most of the drawbacks of DOT 5, but the softer pedal people get is due to the difficulty in bleeding air form the system. Both of my cars have DOT 5 in them. The 53 Lincoln is a breeze to bleed. I just fill a bottle with the DOT 5 and mount it on top of the master cylinder. At each wheel, I attach a bleeder hose with the end submerged in DOT 5. I open the bleeder screws and watch for bubbles. When the bubbles stop, I close the bleeder almost all the way and then leave it overnight. Gravity eliminates the air that is left in the system. I have tried this on my 40 Merc, and it does not work very well because the master cylinder is not above the wheel cylinders.
Tom
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len47merc |
01-16-2017 @ 11:13 AM
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Posts: 1165
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Thanks Tom - the DA is what I was looking for, that along with Mike's equipment recommendation. Also, I doubt the '47 will be much different than your '40 - bleeding the new system when it was being brought back to life 3 1/2 years ago was an education. After speaking here and off-line with you and other valued EFV8 colleagues I just cannot justify the conversion at this point and am looking at the least damaging process (again) for as carefully as possible lifting the original mat/insulation/liner, etc.. Haven't purged/flushed the system since my original DOT 3 install and with the salt (surprisingly) covering the roads now here in central NC the car will not be out of the garage for several weeks - thought I'd address it now. Steve
This message was edited by len47merc on 1-16-17 @ 11:17 AM
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shogun1940 |
01-16-2017 @ 1:16 PM
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Joined: Feb 2010
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I have had dot 3 in my 40 for 15 years,, with no problems, maybe i will change it this year . It sits in an unheated garage every winter.
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supereal |
01-16-2017 @ 2:41 PM
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Posts: 6819
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Replacing DOT3 with DOT5 by just running denatured alcohol thru the master cylinder, lines, and wheel cylinders usually won't flush out all traces of the DOT3. Disassembly or replacement of the cylinders will assure a lasting conversion. Bleeding the brake system, in any case, can be time consuming, and with the DOT5, expensive, as fluid collected while bleeding should not be returned to the system. At our shop we use a pressure bleeder to save time and fluid. DOT3 is inexpensive compared to DOT5. I replace the DOT3 every other year, and have had years of trouble free and safe braking.
This message was edited by supereal on 1-16-17 @ 2:43 PM
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len47merc |
01-16-2017 @ 3:05 PM
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Thanks Bob - great input. On my next full rebuild - likely not on this car but possibly the next project - I'll start fresh with the '5'. Standing pat with the 3 for now after all this very practical input. Appreciate your weighing in -
Steve
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