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Replacing Dot 3 Brake Fluid with Dot 5 #89140 07/15/08 08:16 PM 07/15/08 08:16 PM
Joined: Aug 2007 Posts: 601 Mass C charge70 OP mopar
charge70 OP mopar C Joined: Aug 2007 Posts: 601 Mass	I want to replace the Dot 3 brake fluid in my 69 Dart with Dot 5.I know I have to flush the lines as the two fluids aren't compatible.My question is this,what do I use to flush the system so it won't ruin any of the hoses or wheel cylinder rubber parts.The steel lines are fairly new,and I don't want to replace them.Thanks in advance, John. 1970 Dodge Charger R/T S.E. 1969 Dodge Dart GTS 440 M-Code 1970 Dodge Charger 500 383/4-speed w/A.C.

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: charge70] #89141 07/15/08 09:23 PM 07/15/08 09:23 PM
Joined: Jan 2003 Posts: 931 Windsor, ON L Lemon_Twist super stock
Lemon_Twist super stock L Joined: Jan 2003 Posts: 931 Windsor, ON	John I just had my third car converted from Dot 3 to Dot 5. Same process for all three. Open bleeder valve at one corner, pump brakes and keep addidng Dot 5 to master cyl, being careful not to let it run too dry so you get air in the system. Continue to bleed until new Dot 5 fluid only is coming out at the wheel cyl/caliper. Its a different color than Dot 3, so you will know. Repeat for other three wheels, top master cyl when completed, and then you are done. My 71 Cuda had discs up front as opposed to drums on the 69 Runner and 71 GTX so it required a little more fluid to flush out the calipers. I think my GTX went through just about 4 pints or so to get the job done. A disc car will require a little more. Rod

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: Lemon_Twist] #89142 07/15/08 10:15 PM 07/15/08 10:15 PM
Joined: Jan 2003 Posts: 5,788 Hamilton, Ontario Canada Magnum master
Magnum master Joined: Jan 2003 Posts: 5,788 Hamilton, Ontario Canada	If this helps I did the same as LemonTwist. Used the silicone fluid to push out the old Dot 3. It was about 6 years ago on an already "aged" braking system and is still working perfectly. 69 Super Bee, 93 Mustang LX, 04 Allure Super

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: Magnum] #89143 07/15/08 10:23 PM 07/15/08 10:23 PM
Joined: Feb 2003 Posts: 8,670 A Andrewh master
Andrewh master A Joined: Feb 2003 Posts: 8,670	well, you are supposed to use denatured alcohol to flush the system out.

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: charge70] #89144 07/16/08 03:36 AM 07/16/08 03:36 AM
Joined: Dec 2003 Posts: 22,695 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,695 Bitopia	What is the reason for going 5.1 when there are some pretty highly rated DOT 3's on the market? Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: jcc] #89145 07/16/08 05:44 AM 07/16/08 05:44 AM
Joined: Aug 2007 Posts: 601 Mass C charge70 OP mopar
charge70 OP mopar C Joined: Aug 2007 Posts: 601 Mass	Quote: What is the reason for going 5.1 when there are some pretty highly rated DOT 3's on the market? Jcc,the biggest reason for swapping fluids is that the master cylinder on my car weeped fluid at the rear,ruining the paint on the firewall.I'll be taking the engine out this fall and repainting,I know that the master cylinder is the problem,but I don't want to have to do this again. John. 1970 Dodge Charger R/T S.E. 1969 Dodge Dart GTS 440 M-Code 1970 Dodge Charger 500 383/4-speed w/A.C.

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: jcc] #89146 07/16/08 07:05 AM 07/16/08 07:05 AM
Joined: Jan 2003 Posts: 3,719 Space Station #5 471Magnum master
471Magnum master Joined: Jan 2003 Posts: 3,719 Space Station #5	Quote: What is the reason for going 5.1 when there are some pretty highly rated DOT 3's on the market? Unlike DOT 3, DOT5 is not hygroscopic (ie does not absorb water). Your brake system components won't rust over time making it good for cars driven infrequently (like collector cars). In the event of a spill, DOT 5 won't harm your paint like DOT 3 can (especially lacquer paint). Those are the pros. I'm sure someone will chime in with the cons here before too long. -Jim I can fix it... my old man is a television repairman. He's got the ultimate set of tools... I can fix it. Currently Mopar-less

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: 471Magnum] #89147 07/16/08 08:09 AM 07/16/08 08:09 AM
Joined: Feb 2003 Posts: 4,204 Fort Worth, TX Clair_Davis master
Clair_Davis master Joined: Feb 2003 Posts: 4,204 Fort Worth, TX	There are a bunch of other threads on brake fluids, and lots of good info in those threads as well. As for the high-rated DOT3 fluids, they must have low wet boiling points or they'd be DOT4's or DOT5.1's (assuming they're not silicone based). You CAN have very high dry boiling points in a fluid that only meets DOT3 specs because the wet boiling point is so low. Many of the highest dry boiling point fluids are SUPER hygroscopic - they suck moisture out of the air like it's giong out of style. Racers can feel the difference in their brake fluid from the start of the race to the end, and these fluids get changed out (or should) for every race. Clair 68 Sport Fury Vert (440/727) Getting a heart transplant... 69 Valiant 100 (340/833/EFI)

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: jcc] #89148 07/16/08 09:26 AM 07/16/08 09:26 AM
Joined: Jul 2003 Posts: 2,344 Cincinnati, OH 6 6T6Cuda top fuel
6T6Cuda top fuel 6 Joined: Jul 2003 Posts: 2,344 Cincinnati, OH	Quote: What is the reason for going 5.1 when there are some pretty highly rated DOT 3's on the market? Just to be clear 5.1 is not a silicone fluid like dot 5 is; dot 5.1 is "traditional" with a higher boiling point. 5.1 will suck moisture, and will damage paint!

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: 6T6Cuda] #89149 07/16/08 10:03 AM 07/16/08 10:03 AM
Joined: Jan 2003 Posts: 9,982 Ansonia, CT C CJK440 master
CJK440 master C Joined: Jan 2003 Posts: 9,982 Ansonia, CT	I use DOT 5 at the expense of a firm pedal. The DOT 5 is a little spongey no matter how much I bleed it. The fluid is expensive too but I have some master cylinder cover sealing issues and would have lost lots of paint had it been DOT3. 2017 Contusion Blue Challenger T/A 392 M6 "BLKNBLU"

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: CJK440] #89150 07/16/08 10:53 AM 07/16/08 10:53 AM
Joined: Jan 2003 Posts: 4,574 Upper Midwest Black_Sheep master
Black_Sheep master Joined: Jan 2003 Posts: 4,574 Upper Midwest	Quote: I use DOT 5 at the expense of a firm pedal. The DOT 5 is a little spongey no matter how much I bleed it. I've used DOT 5 in several cars and never experienced a spongy pedal. My '37 has had DOT 5 in it for 25 years with zero problems. IMHO using DOT 5 in an occasional use vehicle is a no brainer, especially when restoring a brake system using new wheel cylinders, master cylinder, etc... '69 Plymouth GTX See you on the street...

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: Black_Sheep] #89151 07/16/08 11:27 AM 07/16/08 11:27 AM
Joined: Jan 2003 Posts: 9,982 Ansonia, CT C CJK440 master
CJK440 master C Joined: Jan 2003 Posts: 9,982 Ansonia, CT	Both cars I ran it in were manual brake cars. I bled them every which way and always the same. 2017 Contusion Blue Challenger T/A 392 M6 "BLKNBLU"

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: 6T6Cuda] #89152 07/16/08 12:49 PM 07/16/08 12:49 PM
Joined: Jan 2003 Posts: 3,719 Space Station #5 471Magnum master
471Magnum master Joined: Jan 2003 Posts: 3,719 Space Station #5	Quote: Just to be clear 5.1 is not a silicone fluid like dot 5 is; dot 5.1 is "traditional" with a higher boiling point. 5.1 will suck moisture, and will damage paint! Do'oh! I should have known that "point 1" was there for a reason. So none of the reasons I listed are valid. Not sure why you would use DOT 5.1 in anything other than a race car. -Jim I can fix it... my old man is a television repairman. He's got the ultimate set of tools... I can fix it. Currently Mopar-less

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: 471Magnum] #89153 07/16/08 04:01 PM 07/16/08 04:01 PM
Joined: Nov 2007 Posts: 5,337 the house on the left. C cogen80 master
cogen80 master C Joined: Nov 2007 Posts: 5,337 the house on the left.	Quote: Unlike DOT 3, DOT5 is not hygroscopic (ie does not absorb water). Your brake system components won't rust over time making it good for cars driven infrequently (like collector cars). you will need tyo bleed the system from time to time because the moisture will gather at the ends of the system (calipers/wheel cylinders) since the fluid won't absorb it. no big deal though if you bleed them once a year or so.

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: 471Magnum] #89154 07/16/08 05:07 PM 07/16/08 05:07 PM
Joined: Nov 2004 Posts: 1,128 Tulsa, OK 7 73cudaproject super stock
73cudaproject super stock 7 Joined: Nov 2004 Posts: 1,128 Tulsa, OK	Quote: Quote: Just to be clear 5.1 is not a silicone fluid like dot 5 is; dot 5.1 is "traditional" with a higher boiling point. 5.1 will suck moisture, and will damage paint! Do'oh! I should have known that "point 1" was there for a reason. So none of the reasons I listed are valid. Not sure why you would use DOT 5.1 in anything other than a race car. Don't feel alone! Thankfully I learned something today and not the hard way...

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: 73cudaproject] #89155 07/16/08 07:16 PM 07/16/08 07:16 PM
Joined: Apr 2005 Posts: 4,914 new berlin wisconsin M Mr T2U master
Mr T2U master M Joined: Apr 2005 Posts: 4,914 new berlin wisconsin	some info ALL BRAKE FLUIDS ARE COMPATABLE with each other. silicone brake fluid retains AIR like standard brake fluid hold moisture. the best way around this is to place the black brake fluid bottle in the hot sun for about 1 to 2 hours, this is why it is delivered in black bottles. this will force the air out of the fluid. if you don't do this you will never get a hard brake petal no matter how much you bleed the system. also NEVER use silicone brake fluid in a anti-lock bracking system. perception is 90% of reality

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: Mr T2U] #89156 07/16/08 07:30 PM 07/16/08 07:30 PM
Joined: Dec 2003 Posts: 22,695 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,695 Bitopia	Quote: some info ALL BRAKE FLUIDS ARE COMPATABLE with each other. Maybe you should define "compatable". OK they are both liquid at room temp. But saying they are compatable goes against many schhols of thought. Seems my first reply reg "5.1" got by most readers. This is s critical safety issue and easy to lead the unknowing down a very dangerous path. I suggest everyone take all the above with a word of caution. Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: jcc] #89157 07/16/08 07:37 PM 07/16/08 07:37 PM
Joined: Apr 2005 Posts: 4,914 new berlin wisconsin M Mr T2U master
Mr T2U master M Joined: Apr 2005 Posts: 4,914 new berlin wisconsin	they will mix and not jell. you can put DOT 3, 4 & 5 together and your brakes will still work. you can just suck out the old brake fluid from your master. install new fluid to pump out the old stuff with no bad side effects. there is no need to flush your brake system with anything before changing fluids. Last edited by Mr T2U; 07/16/08 07:41 PM.

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: Mr T2U] #89158 07/16/08 07:41 PM 07/16/08 07:41 PM
Joined: Nov 2004 Posts: 1,128 Tulsa, OK 7 73cudaproject super stock
73cudaproject super stock 7 Joined: Nov 2004 Posts: 1,128 Tulsa, OK	Quote: some info ALL BRAKE FLUIDS ARE COMPATABLE with each other. silicone brake fluid retains AIR like standard brake fluid hold moisture. the best way around this is to place the black brake fluid bottle in the hot sun for about 1 to 2 hours, this is why it is delivered in black bottles. this will force the air out of the fluid. if you don't do this you will never get a hard brake petal no matter how much you bleed the system. also NEVER use silicone brake fluid in a anti-lock bracking system. This is interesting. I never heard about placing a bottle of brake fluid in the sun for a couple hours. My son flushed the brake fluid on our '01 Dakota at tech school. It has never been the same since. Brakes fine at highway and even lower speeds; however at very low speeds the front brakes seem to grab much harder than they should. My company truck is identical and it brakes totally different. I might be reaching for straws but maybe they used silicone fluid...

Re: Replacing Dot 3 Brake Fluid with Dot 5 [Re: 73cudaproject] #89159 07/16/08 11:21 PM 07/16/08 11:21 PM
Joined: Feb 2003 Posts: 4,204 Fort Worth, TX Clair_Davis master
Clair_Davis master Joined: Feb 2003 Posts: 4,204 Fort Worth, TX	I've never let the fluid sit in the sun to remove bubbles before, I just pour it slowly in to the MC and try to not create any excessive bubbles while bleeding. I've never really had a problem with a spongy pedal at all, either. That may have something to do with the 1-1/32" MC more than anything, but I did notice an improvement in pedal feel when I swapped the front hoses to braided stainless units. As for compatibility, I used to keep a plastic Coke bottle in my garage that was half full of a 50:50 mix of used DOT3 and DOT5 fluids. Periodically, I would shake up the bottle and see if anything would ever happen to the mix. The only thing that really happened was that the two fluids would be mixed up in to a frothy mix for a while, but within a couple minutes you could see a distinct layer between the two. After an hour or so, there were no visible bubbles in the silicone fluid, and both were nearly clear again. Never saw any trace of goo, sludge, crud, or corruption in the bottle. DOT regulations require that the brake fluids be compatible. The following is an excerpt from the 49th Code of Federal Regulations, Section 571, Federal Motor Vehicle Safety Standards, Subsection 6.10 Quote: S6.10 Compatibility. The compatibility of a brake fluid with other brake fluids shall be evaluated by running one test sample according to the following procedure. S6.10.1 Summary of the procedure. Brake fluid is mixed with an equal volume of SAE RM-66-04 Compatibility Fluid, then tested in the same way as for water tolerance (S6.9) except that the bubble flow time is not measured. This test is an indication of the compatibility of the test fluid with other motor vehicle brake fluids at both high and low temperatures. S6.10.2 Apparatus and materials. (a) Centrifuge tube. See S7.5.1(a). (b) Centrifuge. See S7.5.1(b). (c) Cold Chamber. See S6.7.2(b) (d) Oven. See S6.9.2(d) (e) SAE RM-66-04 Compatibility Fluid. As described in appendix B of SAE Standard J1703 JAN 1995 ``Motor Vehicle Brake Fluid.'' (SAE RM-66-03 Compatibility Fluid as described in appendix A of SAE Standard J1703 NOV83, ``Motor Vehicle Brake Fluid,'' November 1983, may be used in place of SAE RM-66-04 until January 1, 1995.) S6.10.3 Procedure. (a) At low temperature. Mix 50 [plusmn]0.5 mL of brake fluid with 50 [plusmn]0.5 mL of SAE RM-66-04 Compatibility Fluid. Pour this mixture into a centrifuge tube and stopper with a clean dry cork. Place tube in the cold chamber maintained at minus 40[deg] [plusmn]2 [deg]C. (minus 40[deg] [plusmn]4 [deg]F). After 24 [plusmn]2 hours, remove tube, quickly wipe with a clean lint-free cloth saturated with ethanol (isopropanol when testing DOT 5 fluids) or acetone. Examine the test specimen for evidence of slugging, sedimentation, or crystallization. Test fluids, except DOT 5 SBBF, shall be examined for stratification. Obviously, mixing fluids diminishes the benefit the higher-rated fluid. Clair 68 Sport Fury Vert (440/727) Getting a heart transplant... 69 Valiant 100 (340/833/EFI)

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