I would pick dot5 and just bleed till you get the fluid flushed.

 

Just Googled Dot 4 vs dot 5 and came across this...

"DOT3/DOT4 to DOT5 Brake Fluid Conversion
by Dave Barbieri


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Since I don't do 'conversions', I wanted to talk to some of our brake vendors (TX & CA) and get my facts straight. Here's the procedure recommended:


Use a turkey baster to suck all the old fluid out of the master cylinder reservoir. Fill the reservoir with rubbing alcohol. Get about 5 bottles; yer gonna need 'em. 8-P

Bleed the system, just like you would normally. Keep bleeding each wheel cylinder/caliper until only rubbing alcohol comes out. When all you see is only clean, clear rubbing alcohol, you're thru with the flushing.

Take all the brake lines loose at both ends. Use filtered, dry compressed air to blow out all alcohol. The lines must be free of all traces of alcohol.

Remove the master cylinder and wheel cylinders/calipers. Disassemble each component, clean thoroughly with either hot soapy water/hot water rinse or with a commercial non-filming brake cleaner. Dry each part and reassemble using DOT5 brake fluid as lubricant.

Components such as the combination valve will have alcohol in them from the flushing procedure. Blowing them out will be pretty touchy. Too much air and you 'blow out' the valve, too little and you don't get rid of the alcohol.

Re-install all the parts, fill the reservoir with DOT5 fluid, and bleed as normal.
There's not complete agreement on how DOT5 reacts with DOT3/4. Some tech reps said it forms a gummy residue that affects brake action. Two stated that the DOT5 would simply 'flush out' any traces of alcohol/DOT3/4 during the bleeding process. Since there's not 100% agreement, (and I'm both anal-retentive and paranoid when it comes to brakes), I listed the full procedure.

Do you really, reeeelly wanna do this? DOT5 is typically used in heavy eqyuipment, military vehicles, and (some) antique vehicles. All share the same characteristic of sitting for long periods of time. DOT5 gets rid of any concern about moisture absorption while sitting idle.

DOT5 is expensive and a PITA; I think you'll spend a lot of time and $$, only to be disappointed with the actual performance gains"
Hope it helps, no idea as to this guy's credibility.

 

He forgot to mention Dot 5 won't destroy a paint job if you spill some on it,whereas Dot 3/4 will destoy the paint job and will have problems with repainting. IMO Harley took a step bacwards goint to Dot 4.

To flush the Dot 4 from the system ,Do it the way RoadKing said.

 

When switching between the 2 brake fluids mentioned, unless you start with all new components, you really should remove and thoroughly clean all traces of the old brake fluid on the used brake components with denatured alcohol then reassemble the components and bleed them using the new brake fluid.

 

Jerry, thanks for the info, not that I want to but have to. I swapped the chrome calipers off my 04 RK and put them on my 06 Ultra. Didn't realize they were different fluids, fortunately I only bleed out one system and have introduced dot 4 into the calipers and master cylinder that had dot 5. I bought the rebuild kits as I am also anal about brakes and will flush the lines and rebuild and put the dot 4 back in the 06 Ultra because that is what is reccommended. Thanks for your input.
Frank

 

Hi.

DOT 5 is silicon based, and DOT 4 is water soluble oil based. The two are not compatible, nor can they be mixed. They will react, and swell all the rubber parts to the point they will lock it up solid.

GET THAT CALIPER OFF THE BIKE!!!!

You need to have it overhauled so you can use the DOT 4, because you can not get the fluid out of the seals, and they can swell and lock up the caliper.

I also recommend you replace the front brake lines(The rubber parts) now that they have been contaminated with the wrong fluid.

 

I think you got your fluids mixed up..

By not being observant, I used a used DOT 4 Master on DOT 5 system. It been this way for 7-8 months and the brakes work perfect. The issue with DOT 3 4 5 is that you need to flush out all of the fluid when changing mixing can cause the fluid to gel. Heck I've seen water in a DOT 5 system cause the fluid to gel some.. I suspect your seal swell come from the old mixing DOT 2 with DOT 3 back in the 60s. British cars used a funky rubber for piston seals that required DOT2, DOT3 would swell them and they'd start to leak. Bruce

 

yes definately replace.....what happens is all the rubber in your brake system will swell.especially your lines.squeeze the front brake and it could just lock up and stay there...ouch......

 

I thought 04's used DOT 5 fluid. At least that's what I thought the manual stated. Where I screwed up is I purchased a Master Cylinder Chrome Cover that stated DOT 4. After receiving my bike back after service I noticed that my brakes were very weak. What happened? They added DOT 4 to my DOT 5 system! They don't mix. I had to flush exactly as above.

 

I had an old ridgid shovel with a juice brake in the rear and a mech. front. the front didn't work. I changed over to dot 5 , did all the cleaning,blowing etc. rode to the store and on the way home blew right thru a busy azzed intersection literally standing up on one foot on the brake, When I got home, and directly after the prerequisite change of drawers, I opened the M/C and found my entire brake system was now filled with a clear silicon that had set up just like silicon caulking. If you not into death defying thrills I would say tear EVERYTHING that fluid touches down and change out lines,puck seals and even then I would be really cautious for a while. a whole new brake system won't cost as much as one trip to the E/R and the body shop (if your lucky enough to make the E/R)!!

 

They went to DOT 4 because of the ABS system. The DOT 5 is more paint friendly and has worked to replace DOT3 and 4 for me in the past, I just added DOT 5 and bled until there was no trace of the nasty fluid. I didn't have any problems. Those brakes will work with piss in them, and even with a small leak, they will be ok. I don't think that you would see a complete failure and any leak won't hurt your paint.

I know that there are better ways to do this, but what I did worked for me.

 

Old subject DOT 4 versus 5

I just had or going through a fiasco with my 05 RK. I rebuilt the front brake calipers using HD part number 44313-00. After a through cleaning, I follow their instructions to the tee. The instruction could not make it any clearer and it says to use DOT5. Not thinking and having an after market chrome reservoir I flush the system out not knowing what was in there instead of looking at the old cap which came with the bike when I bought it. Stupid on my part. So, the new chromed reservoir has a site glass in the side instead of on top. Well I did the rebuild about five month ago and low and behold due to some serious back pain I could not run the bike for about 6 weeks and when I went to take it out the other day I noticed fluid on my gas tank. If you guessed brake fluid you are correct. It ate the darn rubber around the glass sight glass. And to boot ruined the clear coat around that part of the tank. Now, I've seen so many post saying DOT5 will not ruin you paint job, that may be true but it eats right through the clear coat which is not incorporated in the paint as the newer paints are. Well I found my old cap and it says DOT4 So now, how screwed up is HD engineering that they can't keep track of what bike has what fluid. So now if you rebuild a caliper, you have to make sure your hoses, reservoir and seals all match up. If I can't get the tank re-clear coated again I'm looking at $500 plus, then a replacement reservoir for another $200. I don't know if my comp insurance will cover it or not. The part that got me so hot is, I just replaced that tank 16 months ago because I'm old OCD stick in the mud. Any and all comments welcome.

 

If it was me, I would have checked out all the parts and correct fluids before the change out.
Nothing worse than tearing things apart, then needing another trip to the store.

 

i used dot 5 syn as the book says(evo bagger) and was not working well(fronts/rear) went to dot 4 dino and have not had a problem for years, the syn would not come up and stay up...the dot 4 bled right away and holds...whats up with that?

 

i have DOT 5 in all three spots, front, rear and clutch and they work fine in my 2000 Road King. I like the not eating up paint part.
Tim