On my front brake it says to use only DOT3 fluid and on the rear brake it says DOT 3 or 4. Doesn't DOT 4 just have a higher boiling point? So it should be fine to use DOT 4 or should I stick to using DOT 3 as recommended?
The recommendation on your brake is 25 years old remember .... like oil, tyres etc things have advanced If u have a Bursons there have a look for the blue dream ...... great for seeing where your at with a fluid change http://2fiftycc.com/index.php?threads/hey-mum-i-bought-a-hyo.2542/page-3#post-27715
Yeah that's why I'm thinking the rear brake has been replaced at some point. The DOT 4 I use for my mountain bike is blue from what I remember. Do you degas the fluid before using it? I'm used to drawing the fluid into a syringe, blocking the end and then drawing it back more to create a vacume and pull all the gas out. The brakes end up so much firmer.
Just don't use Dot 5 unless its from scratch ..... its a silicone based fluid ..... cant be mixed with the others.
I was under the impression that if the brake system wasn't designed to use dot 5 then it would ruin the seals .
I have some that I got many years ago for the Bonneville rear brakes ..... it was when it first come out from memory but I cant remember any of the dos and donts ..... apart from using it only after all traces of other fluid is gone. Sadly its still sitting on the shelf unopened Plenty of info on Google no doubt ..... I think it was originally invented for military vehicles ?
i flushed my brake lines and master cylinder with metho and had both calipers disassembled and put new seals in.as my system was clean should have no problems. but as i said i cannot feel any difference. will flush the rear brake system and do the same. hopefully will never? need to do again.
I would just stick to using one type anyway. Kinda defeats the purpose of using dot 4 if there is still dot 3 in there.
you can use DOT 4 brake fluid where DOT 3 is recommended, just don't go the other way... Brake Fluid is hygroscopic, it absorbs moisture from the air, always use from a sealed bottle, and change it every 2 years...
Well seeing as the bike has been sitting for quite a while I'll change it anyway just to be on the safe side.
Run dot 4, sintered pads and braided lines and you will have a very firm and grabby front brake......