I need some help with this problem. I have a road king 2005 police bike. Unfortunately I purchased a dot 5 master cylinder in chrome for my bike did not realize that my bike uses dot 4 and it also is ABS brakes. I put some dot 5 fluid into the system and could not bleed properly and created problem for myself. I took the bike to HD and they want me to replace the entire braking system because I used the dot 5. They said that it will destroy all my seals but others have recommended flushing out the system and just using a new dot 4 master cylinder. I know that this was my mistake but now I have to resolve this issue. Question is can anyone recommend a realistic and safe course of action for me to take from this point????? I am planing to bleed the brakes front and back two times or more and then change the master cylinder to a dot 4.. Any good input would be great…….

 

Buying rebuild kits for the master cylinder and calipers that should include all the seals would be the thing. Then flush the lines and reinstall. Be sure to get the kits appropriate to your brake fluid.

 

To fix it you will need to rebuild the calipers and the master cylinder. You can flush (really flush) the brake lines if you want but if it was my bike I would be replacing the lines as well...

 

Thanks for the help and I am going to rebuild the master cylinder and the calipers. I really don't understand why so much damage may have been done. dot 4 is way more aggressive than dot 5. I would think that it would be a much bigger problem the other way around. Can anyone explain in a technical way why dot 5 creates such a problem and why it can not be simply flushed out and start again with dot 4 in the system?

 

Speaking from firsthand experience those two fluids are not compatible, do not mix and over time will cause corrosion and erosion inside your brake system, as well as generating a jello-like grey substance, that can clog up the internals. That has nothing to do with DOT4 being 'aggressive'! The 'rubber' seals for the two fluids are quite different, as already mentioned, and will react to the wrong fluid in ways that may cause brake failure. In addition, DOT5 is described as being incompatible with ABS systems, as it is said to froth or aerate in some conditions.

Frankly your dealer is over-reacting IMHO, however you have challenged them on their concern for your safety and for their own reputation plus risk of litigation! Follow the advice above. If you have stock rubber brake hoses chuck them and replace with braided, which will give you the bonus of better feeling brakes.

For future reference get yourself the correct factory service manual, use it and check you don't make similar mistakes again! I mixed fluids over the years on my Glide and it cost me an entirely new brake system, due to damage done. Be warned!

 

Next bike, look at the cover (if stock) or look at the service manual.
It tells you what to use.
DOT 4/DOT 5 mixed is very unsafe.
Possible to lock the brakes up while riding.
Dangerous!!

The dealership was covering their liabilities.
Safest thing is to replace the affected parts.

P.S
DOT 5 and DOT 5.1 are not cousins.
Do not mix the two!

 

This happens from time to time.
The dealer will look at liability and offer complete replacement as the only solution because of a liability concern.
Imagine for a moment that you slide on gravel and get hurt...imagine it had zero connection to brake fluid since you were not applying the brakes...then you get a lawyer to sue the dealer for your inability to control the bike do to incorrect brake service.
Consider this as opinion only and not fact.
Again this is opinion only and not directions.
This is going to take some time.
Not something you should rush.
DOT 4 will damage paint.
You need to replace the incorrectly labeled brake reservior cover.
Get the reservoir emptied out with shop rags or a MityVac or whatever.
Wipe it up with some Isopropyl alcohol 91%. Now that is clean.
Take the lines off at the caliper and drain the lines. Wrong stuff out.
See if you can push some Isopropyl alcohol 91 % through brake lines into a bucket.
Lines should be cleaner now.
If you are going to flush it out without pulling the calipers apart, then pull the calipers and open the bleeders.
Then push all the pistons back into the bores to expel as much of the DOT5 as possible.
Calipers a little better but still have residual.
Re-attach line and fill the system with 91% Isopropyl alcohol (walgreens/walmart) and run it through the calipers like you would with brake fluid.
This should mix and move into the system.
Then do the same thing again with the bleeder valves open.
This should move stuff out.
Repeat this cycle a few times.
Then pistons need to go all the way into the caliper again so do the removal and push of pistons again. They need to go into the caliper.
Repeat.
Drain everything.
Then go with DOT4.
Run it through the system as normal.
Maybe go around the block very slowly with a brake and release.
Drain, refill repeat.
You should see less and less of any mix.
Then consider addition of speed bleeders for final fill with DOT 4.
The brake lever will require up to a dozen squeezes to harden since the calipers need to move out.
If all feels good then change-out the DOT 4 after about 25-50 miles or a days ride near home.
Remember: The brake lever will require up to a dozen squeezes to harden since the calipers need to move out.
NEVER squeeze the brake lever unless it is on the bike and on the rotor or the piston will pop out.
Alternative is to place a piece of wood between brake pads but you risk misalignment of piston.
NEVER squeeze the brake lever unless it is on the bike with brake pads and on the rotor or the piston will pop out.
Remember DOT 4 will damage paint.
Protect all paint.
NEVER squeeze the brake lever unless it is on the bike and on the rotor or the piston will pop out.
Speed bleeders should make the job much easier for you...It takes a dozen or more squeezes before the lever hardens.
Never ride after brake service without making sure the lever is hard.
If this is beyond you ability consider taking the bike to an independent.
The DOT 5 should not damage DOT 4 rubber parts directly but the DOT 5 and DOT 4 mix do create a gel like glob that can cause clogs. That is why the system needs to be drained multiple times in my opinion.
Again this is opinion only and not directions.

 

I agree with im, completely drain the fluid, flush with alcohol and blow with some air. Fill with dot 4 and bleed. I would bleed the system again after some use.
Fwiw, Harley uses the same master cylinder and caliper repair kits from 2000- 2007. 2000-2004 used dot5 and 2005- 2007 uses dot4. The material used is compatible with all brake fluid.

 

im
thanks for taking the time and breaking it down for me. I am in the process of getting my bike up and running again. Your input is very helpful.

 

Dot 5 is a silicone based formula and Is totally incompatible with dot 4 . The dot 5 will eat every rubber component in the system, seals flex- hoses etc. a friend of mine put dot 5 in his hydraulic clutch and I had to replace all the rubber components in order to get it back to good. When in doubt--- read the lid and only put in what is called for