Hi, Can anyone identify the vintage of the parts in these pics? I have this cheap build custom thats like 20 years old, EVO Engine, Dyna after market frame. The pics are my rear brake master cyl and it's caliper. Without thinking I replaced the fluid using Dot 3 (didn't think it was an HD part), but have been told I may be wrong and it needs Dot 5. Thanks

Rear master cyl


rear caliper


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More than likely it's dot 5. Showing the master and brake doesn't really matter in this case because they could have used any fluid when it was built. But judging by the age and type dot 5

And it is a Harley brake master cylinder. Just an older style

 

Standard for Evo era HDs is DOT 5.

There is a simple test to determine if the fluid you have is silicone based (DOT 5) or glycol based (the others). Take a syringe and pull the fluid from the MC. Put it in a glass. Add some water. Stir. Silicone won't mix. Glycol will.

But it's too late for you if you already added DOT 3. Nothing to do here but strip down the whole system (including full disassembly of the MC and the caliper), thoroughly clean it all out with denatured alcohol, then use DOT 5 on reassembly. You might consider replacing the brake line while your at it, just because its old and they don't last forever.

 

This is the way^

 

 

Factory used DOT5, If the system was completely new or had been flushed you could have used what ever you wanted.
BUT, that caliper is stock, and usually no one goes through the flushing process unless they've done
what you did, so you're probably screwed.

 

Thank you for the replies. Yes I pretty much figured I was screwed. Here in Canada denatured alcohol (ethanol) is quite difficult to obtain, few places have it. What other options are recommended for the flush, methyl hydrate (methanol)? I've read to use brake cleaner straight from a spray can, but isn't that hard on the rubber lines ?? Thanks

 

In Canada you should be able to get HEET water remover for gasoline its methyl alcohol and will work

 

Denatured alcohol should be available at a home improvement store in the paint section

 

Brake clean can be used but gets kinda expensive compared to denatured alcohol.
That and the lines really need to be completely filled while flushing, a little bit tougher to do using a spray can.

WP