EngineNoO9

dot 4 should've been in before I'd think and is what I wanna switch back to all around (I used dot 4 in all my lines, reason I say I think is the front brakes are new to me). in the fronts it hasn't been too long... 2-3 weeks tops? the clutch and rear brake longer (couple months now...) and those have the rubber hoses still - will those be affected by the alcohol?? so the fronts probably ok (though I was looking at MC rebuild kits and they aren't that bad...) but the rear and clutch prob needs work. also when you say flush them just do it like a brake bleed almost?? what I can I'll take apart but the calipers would require a rebuild if I took them all the way apart (but is possibly needed)

Hawkrider

No, if you tear them all the way down you won't need new seals. Just be careful putting them back in. I believe the edge of the caliper cylinders are tapered to allow for easy installation. I'd spray out the calipers and m/c and then use brake cleaner with the little plastic tube thingy on the nozzle to flush the lines.

Hawkrider

Oh, and I don't think the hoses will be affected much by the DOT5. I've just heard the seals are most affected.

EngineNoO9

really?? i was more concerned with the alcohol. I know my mity vac's hoses are ruined because of the dot 5. if you look at the hoses there's little dots all over the inside.... not exactly sure if that's from silicone build up or it degrading it. but then agian I bet it's a completely diff material then the brake lines. i can take a pic to show you. also denatured alcohol? i gotta dig up the article but i remember reading somewhere about people who used alcohol to clean their lines after putting dot 5 in and it caused brake failure... i guess though the denatured alcohol isn't supposed to affect the rubber right cause it's safe on seals?? oh and flush them like I do a brake bleed?? I guess though for the brakes and mc I should really try getting them nice and scrubbed clean...

EngineNoO9

"The single most common brake system failure caused by a contaminant is swelling of the rubber components (piston seals etc.) due to the introduction of petroleum based products (motor oil, power steering fluid, mineral oil etc.) A small amount is enough to do major damage. Flushing with mineral spirits is enough to cause a complete system failure in a short time. I suspect this is what has happened when some BMW owners changed to DOT 5 (and then assumed that silicone caused the problem). Flushing with alcohol also causes problems. BMW brake systems should be flushed only with DOT 3 or 4.

If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers."

EngineNoO9

that's what I've been basing things off of.... :-\

Hawkrider

Denatured alcohol is not mineral spirits. Like I said, if it were me, I would just use brake cleaner. I know that is safe for rubber. Just make sure and blow the parts dry with compressed air, if available.

superhawk22

Like I said before. :wink:

EngineNoO9

yeah. i'll probably throw my old front brake ss lines on (they're fine but the casing is ripped, granted my newer ones did the same thing somehow) as well as cleaning them out part by part... what should I do for the calipers and MC? just flush or try and take apart and scrub clean?

Hawkrider

Lemme guess, they're Galfers. Mine did the same thing. They are difficult to route. I ended up swapping the little brackets off the fender recently to get the right angles. Had to tweak one of them just so. Seems the Galfers could use an extra inch or so.

Hey! Didn't "she" say that. Hehehehe

EngineNoO9

actually these are russels and the others I have no clue... both have ripped in the same area...