Got my new chrome front end stuff in. One of those items is the chrome brake reservoir. So I need to replace my brake system.

In '05, the MoCo went back to DOT 4 brake fluid. A few of the previous years were DOT 5.

My understanding is that DOT 5 has a higher heat tolerance than DOT 4, and DOT 4 higher than DOT 3.

Well, the new reservoir, and the stock reservoir both state, "DOT 4 only".

I head down to the Auto Parts store, and the closest thing they have is Valvoline synthetic, which states, "Exceeds Dot 3 and Dot 4". I asked the guy if they had any DOT 4, he pointed me to the Valvoline.

What difference does it make? I bought the Valvoline stuff, I'm headed to the garage to start this job, I'll check back. Should I head down to the HD shop and get their over-priced crap?

Mac

 

Mac

I would STRONGLY suggest a ride to the dealer for the proper fluid, check to see if the dot 4 is ALL 05 bikes or JUST the cop bikes, not sure here! Dot 5 is silicone, the others are not. The abs on cop bikes is why they went back to dot 4
There is a big problem with mixing fluids. Usually if this happens, even in small amounts, a complete disassemble , cleaning and replacement of the seals is in order. Don't go by the auto store guys on this one.The silicone and others DO NOT MIX without problems. A few $$ spent now will save you a world of grief later. JMHO

 

The world is leaving DOT 3 & 5 and going to the DOT 4. DOT 5 is silicone based and used to be touted for not being hygroscopic, or water absorbing. It had a high boiling point and that made it good. But it is incompatible with ABS components. DOT 3, the old standard, had a lower boiling point, and it was hygroscopic, which lowered the boiling point ever more as more water was absorbed into it over time. DOT 3 eats paint, while DOT 5 won't hurt paint. Don't know about DOT 4, though I suspect it'll be mean to paint.

The new DOT 4 has nearly as high a boiling point as the DOT 5, isn't s'posed to be as hygroscopic as DOT 3, is compatible with ABS components, and gives a firmer pedal feel than DOT 5.

Wal Mart carries DOT 4, and it's much less expensive than the re-branded HD stuff.

As TCSTD sed, don't mix the stuff. If it doesn't eat your seals, it will start globbing up and really make a mess of the brake system. Of course, you won't find it out 'til Ida Mae Fiddle-Withers pulls out in front of you and there's an 18 wheeler in the lane next to you.

 

They pretty well summed it up for you Pilot, follow their advice and you will be o-k. One other thing, if you ever use the dot 5 for anything, don't open it around any thing you are fixing to paint, the silicone will not let the paint stick properly.

John TN

 

Thanks for the help. I guess I'll head back to the auto store for a refund, and head to Wally World.

FWIW, I had no intention of mixing, I'm completely replacing the brake system, reservoir, braided lines...all of it. I guess the caliper is not being replaced.

I'll get the DOT 4...

Thanks for the help,

Mac

 

NAPA has Dot 4 as I just picked some up last week.

 

DOT 4 is a glycol-based fluid, while DOT 5 is silicone-based. They do not mix.
In '05, the MOCO started using DOT 4 in the FLHT family only.
The change to DOT 4 is reportedly due to requirements of the ABS, which may soon (?) be available on all FLHT's.

 

So technically, I could use the DOT 5...I don't have anti-lock brakes...I'll go with the DOT 4, but I just don't get it.

Mac

 

What is it you don't get. We will work thru this.

John TN

 

I guess I don't understand why they went backwards in technology...unless the DOT 5 doesn't work for anti lock brakes...TNW, I picked up the DOT 4 from Wally World today for $2.50.

Mac