BRAKE FLUID ISSUE....Please Read

taweste

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

Bud White

I can say dont Mix Brake Fluids as it causes seal problems .. In Cars we were always told to flush the system totally before switching brake fluid.. I cant offer if Dot 4 in the 86 softtail is Dangerous or not but bet Glider Can

__________________
"Tell me where I'm going, let my bones fall in the Dust, can't you hear that Ghost thats Calling as my Colt begins to Rust, in the Dust"

glider

Dot 4 and 5 should NEVER be mixed. It will turn into sludge in the system like BB's. A complete disassembly and rebuild of the entire system is in order using the proper fluid for the bike. Usually the cap will tell you what is on the system on the brake cylinders.

Here's some reading on the fluids.

Flushing Brake Systems - Harley Davidson Community

DOT Brake Fluids - Harley Davidson Community

Paying Attention To Brake Fluid - Harley Davidson Community

Mixing Brake Fluids - Harley Davidson Community

__________________
Psssst!
Please stop by the "self help section" for maintenance tips, diagnostic codes and much more.
click me!>>Self Help Information and Tips<< click me!

taweste

Thanks for the quick reply.

So mixing is bad, but if I asked you for the fluid for an 86 softail would you suggest DOT4?

The dealership which sold me the DOT4 is saying that it isnt a big deal to use DOT4 on an 86 softail?

I am going to read the links you provided, I am sure that will answer my questions.


Thanks

glider

I believe it may be 4 but not absolutely sure on an 86. Check the cap on the cylinder, it should tell you or the owners or factory manual will tell you also.

YES, mixing is VERY bad.

__________________
Psssst!
Please stop by the "self help section" for maintenance tips, diagnostic codes and much more.
click me!>>Self Help Information and Tips<< click me!

Apyle

In my 1987 fxrs it says right on the master cylinder caps DOT 5 only.

__________________
Money can't buy happiness, but it sure can rent it for a while!

SledDog

DOT 5 is standard for that year. Most, if not all, after market brake parts for that year are DOT 5. You said the bike was custom build. So we can assume (yea...I know...) that the brake fluid requirement was DOT 5.

As other have said, mixing is a no no. You can change to another form of fluid, but the seal must be able to handle it. And you must flush the system. DOT 5 does not destroy your paint job as DOT 3 would...

__________________
77 FXE "Shaker", 94 FLHR "Primitive Man", 96 FXD "Miss Low"
My Newest "Harley", MV Agusta F4 1000 S (05), 2009 Ducati Streetfighter S
Track Day Bike: 2000 Ducati 996 SPS

smitty901

From what I have been told DOT 5 was good Idea that went wrong.
I was supose to be better but it just did not work out in the real world.
So they went back to Dot 4

__________________
The Infantry leads the way

krikket

DOT 5 was originally introduced as a racing brake fluid due to its very high boiling point. However, DOT 5 is a silicon based fluid, which means its not practical for constant use because silicon does not absorb moisture. Any moisture will remain as water and corrode metal parts, and since no brake system is truly "sealed," the fluid requires more frequent changes.

DOT 4 is a glycol based fluid which is hygroscopic (water absorbing). As the fluid absorbs moisture, the fluid's boiling point drops significantly and can produce air bubbles in the system as the brakes heat up (from exhaust or just using them a lot).

What relevance does this info have? From what I've seen, seals made for one brake fluid cannot be mixed with others and will distort, deteriorate and crack. Harley's may have seals that can tolerate both type of fluids, but I doubt it. If the brake locked and caught on fire, they were so hot the seals wouldn't have survived anyways. So, for the dealer to say the brake fluid wasn't the cause is pretty far-fetched.

NEWHD74FAN

Krikket & Glider have it right exactly...DO NOT MIX SILICONE BASED DOT 5 with GLYCOL BASED DOT 4 EVER!!! DOT 4 is the highest temp rating for Glycol (old technology brake fluid) used primarily in Disc brake systems; DOT 3 was used in older Drum brake systems...think automotive technology here. Motorcycles are generally in a higher state of tune and much greater horsepower to weight density/ratios so you read your manual. DOT 4 contaminated his DOT 5 system, he must replace everything nitrile or rubber including hoses!