I stopped at a harley dealer one day because I needed primary oil and brake fluid. I did not know what type of brake fluid I needed so I asked the worker at the parts counter. She called someone for help, and after a short discussion she told me that I would need DOT4 brake fluid.

I blead the brakes using the DOT4 brake fluid and went on vaca for about 1 1/2 weeks. I took the bike out when I got home and my brakes locked up (the rear brakes, the rear was the system I used the fluid in). The brakes caught on fire, and upon closer inspection the seals were practicaly non-existent.

I brought the caliper to a different harley dealer, looking for a rebuild kit and to try and figure out what could have caused the problem, and they mentioned that the caliper smelled like DOT4 fluid. They asked if I had used DOT4 fluid and I told them that I had used the fluid the other dealer had given to me (at that time I wasnt sure if it was DOT4 that they had sold me). They said that under no circumstances should a harley dealer have given me DOT4 fluid for an 86' softail. The whole shop was quite surprised that they had sold me DOT4. They stated that I could attempt to THOUROUGHLY clean the system, but the best thing to do would be to replace the rear brake system.

The next day I went back to the dealership that sold me the DOT4, and I told the parts manager what had happened. He immediately aplogized and stated that they would replace all the parts necessary to ensure the bike is safe. He also apologized stating that they were happy that no one was injured. He wanted to order a new master cylinder, but I was not sure of the manufacturer on my bike (it was aftermarket). I told him I would return the next morning with the manufacturer. He then suggested that the dealer could come pick up my bike to ensure all the work was done properly. I took him up on his offer and arranged pick-up.

After they had my bike for about 24hrs the servoce manager called and stated that there was no way DOT4 brake fluid would cause a problem with my bike. I spoke to the store manager and he stated the same, that besides the fact that DOT4 and DOT5 seperate when combined together, it would not cause any serious problems.

One dealer is lying to me, and/or is very ignorant when it comes to brake fluid. Can anyone tell me who is correct? Is it OK to mix DOT4 and DOT5 brake fluid (as the dealer who sold me the DOT4 fluid told me)? Or, is putting DOT4 fluid in an 86' softail VERY dangerous, as the other dealer told me?

Lastly, will a thorough cleaning with a rebuild be sufficient or do I need to relpace the entire system?

Thanks for Reading
Tim

 

wow..i have no idea but that sux! hope you get it worked out. Keep us informed!

 

The dealer who said mixing the dot 4 and the dot 5 fluids caused the damage is right.

One thing you have to remember, when you are a do it yourselfer, it is your responsibilty to know your bike and your parts. If that dot 4 was handed to someone who knew what they were doing, they immediately would have handed the Dot 4 back to the parts person.

 

Anything I've dug up on brake fluids state 3&4 are compatible and dot5 will not mix. Dot5 can loosen crude in older systems and plug orfices and such but not damage to components. If a flush was done with mineral spirits it will swell the components and all these will need to be changed. The brake fluid alone is not the cause. Could be debri was dislodged during the bleeding as this causes rapid fluid movement that it normally don't see and plugged an orfice . Don't know what else to tell you other than the basic mixing of the two should not have caused any problem. Every web page I searched seem to say the same thing.
Ron

 

As far as I can find out, DOT 5 is a high temp version of DOT 3. DOT 4 was used by HD for several years because it is more 'paint friendly'. You can't mix 3 and 4 because it will turn to the consistency of week old jello. As you found out, the chemical reaction when you mix 4 and 5 is also really bad.

 

People who do not know what they are talking about should not post. This is a safety issue. The mix of 4 and 5 caused the damage period.

Dot 4 paint friendly? Are you kidding me? Go to your garage and pour it all over your tank and fenders.

Dot 4 is now being used due to some models having abs brakes, so they switched the whole line over to 4.

You people are playing with people's lives, it is no time to make guesses. Do that with your own life.

 

Dot 5 brake fluid is a synthetic silicone base and does not mix well with non silicone base such as dot 3, dot4 and dot 5.1.
Dot 3, Dot 4 and Dot 5.1 mix alright but you would have to figure your temp based on the lower heat range fluid.
I have never witnessed what you describe on your harley with the fluids being mixed or changed out. And I have dealt with a lot of brake systems with both and flushed back and forth with the occasional oops of mixing (not by me). What I have seen is generally bad performance (mooshy brake feel) and leaks. Mostly from the rubber seals etc not reacting well with the silicone base of Dot 5 fluid. Never witnessed or seen a brake system lock up a caliper, over heat fluid and cause a fire due to mixing or changing to from dot 5. Though I guess it could happen.
The dealer though legally has no liability. Liability lies with the person who worked on the brake system, which in this case happens to be you.

 

try it your self!!!! it is cheap, buy a brake seal rebuild kit and put it in pie tins.
mix the dot4&5 and then soak the rest in just 4 and just 5,

After your mixed parts are gew bring the test to the bonehead dealer and demand a free fix.

and yes a do it your self'er should be responsible but , everyone learns from others, even transplant doctors learn from others, my point is we all count on the knowledge from a professional or a book , nobody knows everything!!!
so when you consult with the people who should know and they stiff you they should fix it. after all it is your bike but there product.

 

The right thing to do would fix the bike, but they are not obligated to do so. When you work on your own bike, it is all on YOU. Why would you work on a bike, if you do not know what you are doing? If you had a Harley master cylinder it would have said what fluid to use.

Part of being a mechanic is knowing whether or not you have the right part. By installing the wrong part, you are proving to be incapable of the repair.

 

yes a do it your self'er should be responsible but , everyone learns from others

This is why they sell service manuals. If a mechanic asks another mechanic a question, gets the wrong answer and proceeds to do the job wrong, who is at fault?