soobie_newbie67 Posted June 20, 2011 Share Posted June 20, 2011 i want to change my brake fluid to DOT 5 cause the 3 and 4 cant take the heat that builds up when im decending hills. are there any kits out there (replacement seal and o-ring kit) for me to be able to change to DOT 5? some info on my current brakes: cross drilled and slotted rotors front and rear, ceramic brake pads front and rear, flushed brake system with new DOT 4 fluid. Quote Link to comment Share on other sites More sharing options...
skishop69 Posted June 20, 2011 Share Posted June 20, 2011 What makes you think DOT 4 'isn't taking the heat going down hills'? I lived there for 5 years and ran the hell out of my Brat in 100+ weather up and down Benton Hill with a trailer and motorcycle and never had a problem. Pedal fade? Boiling fluid? Riding the brakes too much? Need a more precise account of what's happening. And no, there aren't any kits available for use with DOT 5. You shouldn't need to change anything however, DOT 5 is NOT compatible with any of the other fluids and cannot be mixed. Not to be an a**, but an older Subaru doesn't have enough weight/power to warrant anything above DOT 4 even for racing. If you're boiling fluid, or having pedal fade, either you or the system is causing it, not the fluid. Quote Link to comment Share on other sites More sharing options...
davebugs Posted June 20, 2011 Share Posted June 20, 2011 I switched an antique VW (62 single cab) to DOT 5. Because I was redoing the brake system. Master cylinder, reservoir, wheel cylinders, brake hoses. Used my Motive pressure bleeder. First think I ever did DOT 5 in and it's been on jack stands the past few years waiting on the bumpers and wheels to be painted. Which reminds me I guess I outta call him! I went to it because this truck doesn't get many miles (or any recently) and it's supposed to basically be lifetime. Doesn't draw moisture much. Not at all for performance. Quote Link to comment Share on other sites More sharing options...
soobie_newbie67 Posted June 20, 2011 Author Share Posted June 20, 2011 What makes you think DOT 4 'isn't taking the heat going down hills'? I lived there for 5 years and ran the hell out of my Brat in 100+ weather up and down Benton Hill with a trailer and motorcycle and never had a problem. Pedal fade? Boiling fluid? Riding the brakes too much? Need a more precise account of what's happening. And no, there aren't any kits available for use with DOT 5. You shouldn't need to change anything however, DOT 5 is NOT compatible with any of the other fluids and cannot be mixed. Not to be an a**, but an older Subaru doesn't have enough weight/power to warrant anything above DOT 4 even for racing. If you're boiling fluid, or having pedal fade, either you or the system is causing it, not the fluid. well, it starts boiling the fluid then the pedal will start dropping to floor. i know its boiling it cause i just got it changed with a vacuum flush, and after doing the hill scene a couple times (with the pedal starting to go to floor about half way down the hill) i pulled my resivior cap and found my fluid was dirty with little floaties in it. btw, this hill exactly a mile long, almost facing straight down; its an off road hill and im going about 4mph the whole way down. and dont worry, you didnt sound like an a** at all. no offences taken either. Quote Link to comment Share on other sites More sharing options...
heartless Posted June 20, 2011 Share Posted June 20, 2011 are you downshifting at all??? if not, you should be - makes no difference if manual or auto, shift that puppy down to a lower gear - 1st would be good if the hill is that steep.. you should NOT be relying 100% on your brakes to control your speed - that is what causes the brake fade. use the engine and trans to help control speed using the brakes as needed, not constant. Quote Link to comment Share on other sites More sharing options...
soobie_newbie67 Posted June 20, 2011 Author Share Posted June 20, 2011 are you downshifting at all???if not, you should be - makes no difference if manual or auto, shift that puppy down to a lower gear - 1st would be good if the hill is that steep.. you should NOT be relying 100% on your brakes to control your speed - that is what causes the brake fade. use the engine and trans to help control speed using the brakes as needed, not constant. ok, 2 problems with that. 1. my subaru is a EA82 turbo which = to 7.7to1 compression so not much engine braking at all. the hills i go down are so steep that if i use shift down to try and slow down, the car will just keep speeding up bringing up the engine rpm. plus, the trails i take are pretty treacherous, so im not able to go down them fast, which also makes gearing down a problem. if i had the dual range 4 low and first gear would do the trick, but i dont have D/R. also i wanted to leave a little note i wasnt thinking about. when the brakes start getting squishy, i can use the e-brake (which only works the front i know) and it feels normal like my brakes arent hot at all. i know my problem is that the brake fluid cant take the heat. its awesome cause when i do this at night, when i get to the bottom of the hill, i can actually see my rotors glowing. oh, and its a 5 speed full time 4 wheel drive. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 20, 2011 Share Posted June 20, 2011 does that fluid heating coming from hydraulic action in the master cylinder or caliper operation? what vehicle? sounds like you're pushing it hard - but lots of folks offroad, carry enormous loads, auto-crossing, racing.....and not going to DOT 5. seems to suggest you might be able to help your situation some other ways as well. now for anecdotal nonsense: i climbed up and down an offroad mountain access road elk hunting in colorado for miles without any brake issues in my XT6....and i was pulling like 1,500 pounds of trailer, 4 wheeler, tent, wood stove, camping gear, fire wood.....yours should hold up to a fraction of the weight that XT6 was handling. Quote Link to comment Share on other sites More sharing options...
Ricearu Posted June 20, 2011 Share Posted June 20, 2011 switch to organic pads. your rotors will last alot longer too. Quote Link to comment Share on other sites More sharing options...
brumby420 Posted June 21, 2011 Share Posted June 21, 2011 Ive been told not to use dot 5 because it wont absord ANY water and if and water at all gets into it it will run through the brakes and cause brake failure. Quote Link to comment Share on other sites More sharing options...
ferox Posted June 21, 2011 Share Posted June 21, 2011 its awesome cause when i do this at night, when i get to the bottom of the hill, i can actually see my rotors glowing. It kind of sounds like your caliper pistons weren't backed off enough when brakes were switched creating too much contact all the time...in effect pre-heating your system before you get to the hill. It could also be that your pads were not properly broken in after install, but I don't know much about ceramic pads and whether they can glaze over. Those may not be your problem(s), but they are common reasons for over-heating of the brake system after new components are installed. Of course you may just have the wrong subaru for what you are doing. If your rotors are glowing at the bottom of the hill, then as people have already mentioned-DOT 5 isn't the solution. Quote Link to comment Share on other sites More sharing options...
Flowmastered87GL Posted June 21, 2011 Share Posted June 21, 2011 Ya, I think something else needs to be done other than brake fluid. Maybe change pad materials, or better yet swap in a dual range tranny. They can be had for like $50 bucks if you keep your eyes open. You would have to change to a 3:90 rear diff to match too. Quote Link to comment Share on other sites More sharing options...
soobie_newbie67 Posted June 21, 2011 Author Share Posted June 21, 2011 It kind of sounds like your caliper pistons weren't backed off enough when brakes were switched creating too much contact all the time...in effect pre-heating your system before you get to the hill. It could also be that your pads were not properly broken in after install, but I don't know much about ceramic pads and whether they can glaze over. Those may not be your problem(s), but they are common reasons for over-heating of the brake system after new components are installed. Of course you may just have the wrong subaru for what you are doing. If your rotors are glowing at the bottom of the hill, then as people have already mentioned-DOT 5 isn't the solution. ever notice that the brakes on race cars can get so hot that they glow bright even in the daylight? a little bit of glow from riding the brakes (so little i only see it at night if i do the hill) would be normal. im using ceramic brake pads, which im noticing dont smell as bad or small for as long as some other pads i have used on other vehicle's. i think it might just be my master cylinder or something. with the brakes properly bled and flushed, i took notice that my pedal still feels soft, and i can never get my brakes to lock up on a dry surface. i got more searching to do. jumped the gun. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 21, 2011 Share Posted June 21, 2011 subaru master cylinders don't fail very often but i guess it's possible it's leaking internally? Quote Link to comment Share on other sites More sharing options...
Ricearu Posted June 21, 2011 Share Posted June 21, 2011 yeah, my gl with rear disk conversion, has 195/60-16's, with raybestos rotors up front, turned OEM rears, and all 4 corners have raybestos organic pads. It will straight lock all 4 up on a good panic stop:) I like brakes... Quote Link to comment Share on other sites More sharing options...
soobie_newbie67 Posted June 21, 2011 Author Share Posted June 21, 2011 subaru master cylinders don't fail very often but i guess it's possible it's leaking internally? yeah, thats kinda what i was thinking. i have seen it happen with some other vehicles my family owns, so im not really ruling it out on my car. its not that big a deal to replace the master cylinder anyway. Quote Link to comment Share on other sites More sharing options...
skishop69 Posted June 21, 2011 Share Posted June 21, 2011 Ok, the problem you have isn't boiling fluid. The floaties you see are just crap knocked loose from the flush and general wear/old age on components. If the fluid were boiling, you wouldn't be able to remove the cap without getting third degree burns. You have a couple things that could be going on. First is your master cylinder, the most likely cause. It's internally bypassing and will only get worse. Second, are brake hoses. The may look good, but if they are degrading, the will bulge/expand when heated up. This is hard to catch without getting them toasty, standing on the brakes and having someone check for bulges. The fluid is most definitely not your problem. As for not using DOT5, it's primary use is vehicles that don't see a lot of driving and don't get regular service. Water is going to get into the brake system one way or another, it's inevitable. DOT5 won't chew up your paint and plastics and it has a slightly higher boiling point. Not really a 'performance enhancer'. Quote Link to comment Share on other sites More sharing options...
soobie_newbie67 Posted June 21, 2011 Author Share Posted June 21, 2011 yeah, thats kinda what i was thinking. i have seen it happen with some other vehicles my family owns, so im not really ruling it out on my car. its not that big a deal to replace the master cylinder anyway. actually, i wanted to add to this. i remember having the same problem and feeling in a different rig right before the brake booster went out. i wonder if that might be a problem.... Quote Link to comment Share on other sites More sharing options...
soobie_newbie67 Posted June 21, 2011 Author Share Posted June 21, 2011 Ok, the problem you have isn't boiling fluid. The floaties you see are just crap knocked loose from the flush and general wear/old age on components. If the fluid were boiling, you wouldn't be able to remove the cap without getting third degree burns. You have a couple things that could be going on. First is your master cylinder, the most likely cause. It's internally bypassing and will only get worse. Second, are brake hoses. The may look good, but if they are degrading, the will bulge/expand when heated up. This is hard to catch without getting them toasty, standing on the brakes and having someone check for bulges. The fluid is most definitely not your problem. As for not using DOT5, it's primary use is vehicles that don't see a lot of driving and don't get regular service. Water is going to get into the brake system one way or another, it's inevitable. DOT5 won't chew up your paint and plastics and it has a slightly higher boiling point. Not really a 'performance enhancer'. ok ^^this^^ is most likely my problem. i'll check all those areas you mentioned. thank you. Quote Link to comment Share on other sites More sharing options...
Techtac Posted June 29, 2011 Share Posted June 29, 2011 Some brake fluids have a very high dry boiling point. That may also help if you are working them hard, but I aggree that you should do the master cylinder first... http://www.amsperformance.com/cart/Castrol-SRF-Racing-Brake-Fluid-(1-liter).html Quote Link to comment Share on other sites More sharing options...
czny Posted June 30, 2011 Share Posted June 30, 2011 Master cylinders will wear a bell shape in the area of highest pressure as the piston moves over time. More so with an aluminum m/c than cast iron m/c. This allows fluid to bleed around the piston diminishing the hydraulic advantage so that it becomes harder to stop. Never rebuild an aluminum m/c, always replace it. Brake hoses skive(pare thin layers) from fluid eroding the rubber lining & weakening the hose over time. Your floaties in the brake fluid are likely bits of rubber, plus worn metal/piston cups from the m/c . Like others have said this allows the hoses to expand reducing the effective braking force. Change all your brake hoses & replace the m/c if it's the original. Overhaul your calipers & wheel cylinders. You need a good seal to get maximum force. Check your rotors & drums for hard, discolored spots too since they've been so hot - glazed surfaces on the linings too. I've been doing auto repair since '72. What good is going fast if you can't stop:eek: Quote Link to comment Share on other sites More sharing options...
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