DOT 5, I gone and done it....

Discussion in '1st & 2nd Generation 1983-1989' started by 74ullc, Oct 19, 2014.

  1. 74ullc

    74ullc New Member

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    I went ahead and put DOT 5 in my front brake system. The front brakes were dragging on me so I figured while I had the entire system apart I'm going to switch over to DOT 5. I took both calipers and the master cylinder all the way down and cleaned everything with alcohol.

    Calipers were actually very clean inside, a little crud was trapped in the little plugged hole on the bottom, the hole created during machining. The piston cups had some buildup on them so hopefully that was the only cause of the dragging. The little pressure relief hole in the master cylinder was not clogged at all.

    I flushed the lines with alcohol and blew them out with air, gave them plenty of time to dry. So every nook and cranny in the system was cleaned and flushed with alcohol. Should be no DOT 4 left in there.

    I reverse filled them, bottom up. Took minimal bleeding and lever is solid again. Wow...DOT 5 is purple!

    About to head out for a quick test run, so if you never hear from me again I guess the bike exploded due to DOT 5 contamination. I will say, working with a brake fluid that I didn't have to handle like nuclear waste was very nice. There is no way to not get some on the calipers during bleeding, even with a bleeder hose some leaks out around the bleed screw threads while it's loose. Not having to worry about a little drip here and there was nice. I still cleaned everything both during and after but it does add some peace of mine for sure!

    If if ends up working well in the brakes I'm going to switch the clutch over next. I get a small drop at the weep hole about every 5-6 rides on the clutch slave cylinder. Not enough to even run down the sprocket cover, but enough that if I stick my finger against the weep hole there will be a drop there. I want to repaint the sprocket cover and it would be pointless with DOT 4 in there. The leak is so minor that I'm not worried about it yet, but something I'm keeping my eye on.

    But even with zero leaks, I still think the benefit of not having a paint eating monster in three separate systems on the bike is a great feeling. Even if I do have to drain and refill every year.
     
  2. FJ12rydertoo

    FJ12rydertoo Member

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    Is DOT 5 also silicone based? I put silicone based fluid in the clutch of my FJ because they are notoriously prone to leakage at the slave cylinder, and I got tired of repainting. Had no issues.
     
  3. f3racer

    f3racer New Member

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  4. Mark919

    Mark919 New Member

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    To the best of my knowledge, DOT 5 should only be used in brake systems designed for silicone fluids. The issue is compatibility with seals, o-rings, and hoses.
    IIRC, the US military started using DOT 5 to avoid having to properly handle DOT 4. It was a disaster for them. Brakes failed all over the world and they had a massive retrofit activity.
     
  5. thx1138

    thx1138 New Member

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    I have heard this before and can't comment on the experience of the U.S. millitary. My experience is having put dot 5 in my cb750 in about 85 and never had an issue since. I did change the seals though.
     
  6. FJ12rydertoo

    FJ12rydertoo Member

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    I changed seals, just OEM, in the clutch slave cylinder before I changed to silicone fluid and have never had any issues. And no leaks either, and the regular fluid leaked like clockwork after about 4 years.
     
  7. thx1138

    thx1138 New Member

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    Whenever this topic comes up I am reminded of that song;
    "it's the end of the world as we know it, but I feel fine"
     
  8. 74ullc

    74ullc New Member

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    6 replies in 5 hours....hot topic for the gen 1 subforum.

    Before I switched over I read and read and then read some more about it, good bad and ugly. In the end I never came across any examples of anyone having any problems with it first hand other than the occasional complaint of soft pedal feel. It was all just a bunch of people giving examples of the bad they think/guess would happen. I take that back....apparently some MG's from the 60's had natural rubber seals in the brake system and those seals would fail after switching over. However there is debate in the MG circle that the problem was caused by flushing the system with mineral spirits before the switch over. I guess mineral spirits was considered the ideal fluid to flush with, now alcohol is considered ideal. Just info I read on a few forums, I'm no MG expert.

    I did find many examples of people putting it in their bikes decades ago and never having any issues. Just like thx1138 and his cb750 in 1985, and no problem. Many users of DOT 5 for decades describe the system as "frozen in time" when they take them apart. Zero corrosion, zero leaks, no water in the system and fluid that looks just as clean and clear as the day they put it in. We all know what DOT 3/4 looks like after just a few years. It starts turning dark almost right away, that's supposedly from moisture and corrosion.

    About the military problems with DOT 5. I searched and found that they switched to DOT 5 in the 1980's, but I cannot find anything about them switching back to DOT 3/4. If anyone can find any info on a switch back away from DOT 5, I would like to read it.

    The stuff I did find about the military using it comes from military vehicle owners forums, people who have surplus Jeeps, trucks, that sorta thing. ***This is just info I picked from a few forums so who knows how accurate it is, just like anything else, grain of salt.*** The military switched to DOT 5 in the 1980's to avoid the problems they were having with brake systems on vehicles that spent a lot of time sitting. DOT 3/4 absorbs moisture very quickly and thus was creating all sorts of corrosion problems in the brake systems. We have all seen the white crusty crud that bursts out from around seals on a vehicle that has been sitting for any period of time. When moisture is absorbed in DOT 3/4 it mixes in and that's what causes it to darken and also causes corrosion problems in the entire system. According to military members from that time, when vehicles were switched they used a pressure bleeder. They did not take the system all apart and clean/empty everything. So there is still a puddle of DOT 3/4 sitting at the bottom of the system now filled with DOT 5. ***again, this is just stuff I've read on forums*** They also used DOT 5 to top off vehicles that still had DOT 3/4 in them until that vehicle had the full swap to 5 done.

    The only problems/complaints I found from actual users of DOT 5 were soft pedal in some vehicles, fine in others, and problems bleeding supposedly because DOT 5 is bad about aeration. Meaning if you shake the bottle or throw it around and then add it to the brake system it will have air bubbles in it. Let it sit and be careful while adding it to the master cylinder and it should be fine. But still, the aeration part does worry me. If the fluid gets full of little bubbles from normal vibration/agitation while riding that cannot be good at all. Fluid full of bubbles will compress considerably more than bubble free fluid. Then again, HD uses DOT 5 and nothing vibes like one of those. I figure a few test rides will tell me if its going to be a problem in my bike. I still have DOT 4 in the rear brake so I will have brakes even if I completely loose the fronts, which I REALLY doubt will happen or else I would have NEVER made the switch. Still I will be easy, take it slow and be super cautious for the first few rides to be sure.

    For me the selling point is that DOT 5 doesn't eat paint, on a 30+ yr old bike some brake fluid leakage is going to happen at some point. However, that single benefit does not out weight problems that could effect braking performance and safety! Only living with DOT 5 for some miles in my bike will answer this for me. The fact that DOT 5 will last for years and years without changing is nice I guess, but I will still be changing the fluid every 1-2 yrs max. If changed every two years like most manufacturers recommend then the moisture/corrosion problems with DOT 3/4 will never be a problem either. So this feature of DOT 5 may be a huge benefit for something like a show car that only needs brakes when backing off a trailer and the owner doesn't really want to change the fluid out every 2 yrs. Honestly how many people change the brake fluid every two years, so this may be a huge advantage for regular cagers if, again, braking performance does not suffer.

    We'll see.....if it works it works, if not I'll switch it back out. I'm going to order a complete set of spare seals for the front/rear brakes and clutch to have ready just in case.

    A friend I ride with regularly put DOT 5 in his 1978 KZ650 last summer and has had zero problems with it. I've ridden his bike recently and the front brakes felt good to me. That's the only actual for real example I had to go on and it's a positive one.
     
  9. 74ullc

    74ullc New Member

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    Went for a quick test ride and the front brake was definitely not all there. So was thinking, either need another bleed or this DOT 5 just ain't gonna work. Got home and there is quite a bit of brake fluid leaking out from around the threads on the bleed screw threads on the left caliper. That would be the problem I bet.

    That sucker is tight so I'm not sure yet why its leaking. I'm going to pull the bleed screw and hope it's just got some crud in there causing the leak. I hope I didn't over tighten it! I worry that I'm tightening stuff too far sometimes, but with that tiny 8mm wrench?

    Bleed screws are still available so will add a few of those to the list of parts for the next order.
     
  10. 74ullc

    74ullc New Member

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    Should add....the bike didn't even explode or anything during the test ride. So that's good.

    Plus just after I started the bike for the warm up in the driveway a Bald Eagle flew directly overhead at treetop level, not more than 30 feet from me. He came at me directly head on from over the neighbors house across the street and then right over my head. As he passed he was looking at me with that big right eye of his, head tilted for a better look.....I think he liked the VF700F red white and blue paint scheme.

    My first Bald Eagle sighting ever other than on a trip to Maine over a decade ago, but that doesn't count because that was on a boat trip specifically to see bald eagles. This one flew right over my head in my own driveway! They are not exactly common around here.....very rare actually. Pretty awesome!
     
  11. rjgti

    rjgti New Member

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    do not use dot dot 5 in a dot 3/4 system. not a good compatibility issue
     
  12. 74ullc

    74ullc New Member

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    I think I did enough homework on the compatibility issue. As long as the system is taken apart and cleaned/flushed there is no issue. In fact lots of people just drain the old 3/4 and add 5 right on top of it and have no problems. Some do have problems....but many don't. I completely broke down the entire front brake system and cleaned it with alcohol. I'm not worried about compatibility at all. A few other features of DOT 5 do have me on alert until it proves itself to be ok in my bike, but not compatibility.
     
  13. Dukiedook

    Dukiedook New Member

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    The problem with DOT5 is people along with the military thought it would mean less maintenance but they found out the maintenance levels were the same as 3/4 sans paint issues.
    If you are careful around DOT3/4 and replace at normal intervals works just fine.
     
  14. 74ullc

    74ullc New Member

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    When I decided to do the swap I thought 5 would be more maintenance, shorter change intervals and such. But there are many many users of 5 for years who say they never have to change it, compared to 3/4 which starts sucking up moisture the second you break the foil seal on the bottle.

    I'm still going to change it every year, and the first change I'm going to dissemble the calipers to see if there is any water pooled up in the bottom of the system. That seems to be the only concern, water will not be absorbed into it and will sink to the bottom of the system and sit. But lots of users claim there is zero water in the system when they dissemble.

    One of the arguments against DOT 3/4 is that it absorbs moisture readily so there is moisture and thus corrosion throughout the entire system. (if the fluid is not changed regularly, should not be an issue with us enthusiast but your average cager???) On the other hand DOT 5 will not absorb moisture, but the trade off is that if water is in the system it will pool at the lowest point and create corrosion in that pocket, wherever that may be. On my calipers that looks to be the plugged hole that was created during machining.

    This is from wiki.....I don't really like to quote from wiki but this sums it up and seems to be in agreement with what users of 5 say....

    Most automotive professionals agree that glycol-based brake fluid, (DOT 3, DOT 4, DOT 5.1) should be flushed, or changed, every 1–2 years under non-racing conditions.[2] Many manufacturers also require periodic fluid changes to ensure reliability and safety. Once installed, moisture diffuses into the fluid through brake hoses and rubber seals and, eventually, the fluid will have to be replaced when the water content becomes too high. Electronic testers and test strips are commercially available to measure moisture content, however moisture test strips were taken off the market because they absorb moisture in the air before they can be used. The corrosion inhibitors also degrade over time. Degraded inhibitors cause corrosion in the braking system. The first metal to corrode is copper. You can determine when it is time to replace brake fluid when copper ions hit 200ppm.[3] New fluid should always be stored in a sealed container to avoid moisture intrusion.

    DOT 5 is silicone fluid and the above does not apply. Ideally, silicone fluid should be used only to fill non-ABS systems that have not been previously filled with glycol based fluid. Any system that has used glycol based fluid will contain moisture; glycol fluid disperses the moisture throughout the system and contains corrosion inhibitors. Silicone fluid does not allow moisture to enter the system, but does not disperse any that is already there, either. A system filled from dry with silicone fluid does not require the fluid to be changed at intervals, only when the system has been disturbed for a component repair or renewal. The United States armed forces have standardised on silicone brake fluid since the 1990s. Silicone fluid is used extensively in cold climate, particularly in Russia and Finland.
     
  15. thx1138

    thx1138 New Member

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    I agree wth this completely. You should replace the silicon fluid at least every 10-15 years without fail.
     
  16. thx1138

    thx1138 New Member

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    I did strip my 750 front brake system down after 15-20 years because of all the water pooling stories.
    What I found was shocking. The entire front brake system was totally and utterly free from water and corrosion. No gunge built up around the piston seals at all.
    Maybe it was because I never left the master cylinder cap off while the bike sat in the rain?
    I reassembled it all with the same seals and it is still refusing to leak or fail to this very day.
    If you want to be super cautious then change it after a year but then try to avoid wasting time on it for the next 10 or 15 years.
    Spend all that extra time riding.
     
  17. ridervfr

    ridervfr Member

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    I stayed with dot 4 on my bikes when I over hauled the brake systems. Regarding your weepy clutch bleeder, maybe its a machining problem? I bought two brand new Honda oem slaves that weeped around the threads of the bleed nipple. Seems that that the conicle shape in the slave that mates up to the bleeder valve may be a little off (might be able to tune it up with some valve lapping compound and a golf-t?) I tried some teflon tape but was not happy, in the end I used a liquid teflon from Locktite, works like a charm, that is until I have to bleed the clutch again.

    If your afraid of screwing up your paint or someone elses, just have a water spritz bottle handy when your working with the stuff, you could go as far as misting the area your working on too. Thats a little too anal for me though, I use some towels and have the water bottle handy. Fluids get changed two years or sooner, clutch gets sucked oot as they get dirty faster than the brakes. Cheers.
     
  18. 74ullc

    74ullc New Member

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    Good to hear from an actual user of DOT 5 for 30 yrs. Your description of what you found when you finally did get back into it seems very common from people who have actually used it. I read stuff like that over and over again while researching it.
     
  19. 74ullc

    74ullc New Member

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    ridervfr, on the clutch its actually the slave cylinder itself leaking, not the bleed screw. There is a tiny weep hole on the bottom of the slave cylinder against the sprocket cover. So it's leaking from the backside of the cylinder and then running out onto the sprocket cover. But it's a tiny tiny amount and doesn't seem to be regular. In fact it seems to have stopped, it hasn't leaked the last 100 miles at all. I took it all apart when I first got the bike running so maybe it just needed time for the seal to reseat.

    It is the bleed screw on the left brake caliper that's leaking. I just haven't had a chance to mess with it yet. I have read of people fixing them with compound like you describe. But by using an extra bleed screw and turning the threads off it so you can use it instead of a golf T. It wasn't leaking before I took the caliper all apart so hopefully it will seal up by just pulling the screw back out and cleaning it up. Fingers crossed.

    I have had good luck getting float valves in carbs to seal by using a q-tip with compound on it. Chuck half a q-tip in a drill and polish that sucker up. I could also try that but that would mean taking the caliper all back apart, sure don't want compound getting in the brake system!
     
  20. 74ullc

    74ullc New Member

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    Need to update this with results now that its done. I got the bleed screw to stop weeping by taking it out and cleaning the tip. I chucked the screw in a drill and held a paper towel in my hand with some polishing compound, cleaned it up, just had some black crud in the end. Sealed up fine after that and brakes now feel solid.

    So results for now are that the brakes feel really good, better than before. I'm sure they feel better because of the rebuild, not the DOT5 vs DOT4 but seems like no bad effects of the DOT5 yet. Time will tell for sure.
     
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