Member Contributer tomk1960 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Has anyone here used DOT5 brake fluid in the hydraulic clutch system for their first gen VF? I use DOT5 in brake systems that I've completely rebuilt (lines replaced or thoroughly cleaned out) and have had excellent results. Is there any reason why I shouldn't have similar results using it for my hydraulic clutch? I could be opening a can of worms asking, since I know that there are proponents and opponents of DOT5. But for me, the facts right in front of me - the brake systems in my SOHC 750 (dual front disc upgrade.single piston) and CB1100F are by far the best and are now silicone DOT5 based. Thanks. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 if your using new lines and seals you should be fine. harley used dot 5 for god knows how long on both brakes and clutch Link to comment Share on other sites More sharing options...
TNRabbit Posted April 28, 2014 Share Posted April 28, 2014 Provided the seals & lines are compatible with silicone fluid. If not, it will deteriorate them. Link to comment Share on other sites More sharing options...
Member Contributer vfr350 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Hydro clutch on a harley? That must be new. I thought one of the main differences in brake fluid was boiling point, dot 5 being the only synthetic. Link to comment Share on other sites More sharing options...
Member Contributer MadScientist Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 DOT 2 was the last non-synthetic brake fluid, it is no longer even mentioned in FMVSS 116. DOT 3, 4, and 5.1 are all synthetic, simply meaning the glycol ether/borate ester components are not naturally occurring substances and must be manufactured (thus synthetic). The same applies to DOT 5, only it is silicone based. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Hydro clutch on a harley? That must be new. I thought one of the main differences in brake fluid was boiling point, dot 5 being the only synthetic. aftermarket hydro for hd has been around for 50 years Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted April 28, 2014 Share Posted April 28, 2014 Being silicone based, DOT 5 brake fluid is hydrophobic. Since it does not absorb moisture, any moisture that finds its way into the brake system will precipitate out at the lowest point of the system, the calipers. Unless flushed regularly, this will cause corrosion in the calipers. What you want is DOT 5.1 which is polyglycol based and therefore hygroscopic. 5.1 has a higher boiling point than 4.0 having said all that, if you are braking hard enough on the street to boil DOT 4.0, then Marc Marquez needs a new teammate, you. IOW, DOT 4.0 will be fine. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Ha Ha ^^^^^ Link to comment Share on other sites More sharing options...
thx113 Posted April 28, 2014 Share Posted April 28, 2014 I put silicone in my CB750FB brakes in about 1985, never bled or otherwise did anything to them from that day forward. In about 2005 to 2007, after reading the dire warnings on the use of Dot 5 and the pooling of water in the low points of the system I got worried and stripped the brakes down. After 20 or so years the brakes were spotless inside as they had been when assembled 20 years previously. No water, jelly, or corrosion to be seen. Maybe I was lucky and got some sort of super fluid or maybe my system was perfectly sealed. Dow Corning silicone brake fluid was what I used both times and I don't know if it is any better or worse than others. The brakes did (and still do) work perfectly without a soft lever, they were good enough to lock the front wheel on a 250kg motorcycle with good tyres on dry road, so I was always happy with them. I did use new calliper seals and master cylinder kits but settled for flushing the brake lines as I didn't have the money to replace them. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Don't use DOT5 in DOT4 systems, they are not better because they have a higher number the system, seals & general performance was designed to use DOT4 so use that & save the money. DOT5 has NO performance benefits in a DOT4 system. If you do persue this, then you should use all new seals & preferably a complete new clean system ! Link to comment Share on other sites More sharing options...
Member Contributer tomk1960 Posted April 28, 2014 Author Member Contributer Share Posted April 28, 2014 I've been using DOT5 fluid in the brake systems for my CB1100F and SOHC 750 for at least 4 years and the brakes are phenomenal on both bikes. (the SOHC has the dual front disk upgrade) The brake systems for both bikes were completely rebuilt with new K&L kits in the master cylinders and calipers. New lines went on the SOHC and the lines on the 1100F were thoroughly flushed out and cleaned. The main reason I switched to DOT5 was to eliminate the possibility of causing paint damage. (The bodywork on the SOHC is pristine and I had just restored the 1100F.) In the case of the 1100F, DOT5 saved my tank because my master cylinder had a "weeping" cover that dripped on the tank during an extended ride. After numerous attempts to fix the leak, I ended up replacing it with another restored MC and no more leaks. The brand new paint on the tank would have been ruined if I hadn't made the switch to DOT5. The brakes on that bike are the best of all 6 of my bikes and there have been no ill effects. Flushing the fluid every couple of years is no problem and the extra expense for DOT5 is worth it IMO. The DOT3/4 vs DOT5 discussion always causes a spirited debate with people pro and con DOT5. My experience with DOT5 has been very positive and successful and I have no reason not to continue down this path with future restorations. I understand the concerns, but my experience speaks volumes. Since the clutch master and slave cylinders are completely rebuilt and the lines are now completely flushed out and clean, I plan to switch to DOT5. I'll let you all know how it goes and if I notice any difference with DOT5 since the system had DOT4 in it up until now. The bike should be ready to ride by this weekend since I'm almost done with my "mild" restoration. Thanks for all the inputs. Link to comment Share on other sites More sharing options...
Member Contributer VFRDYLAN Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Hydro clutch on a harley? That must be new. I thought one of the main differences in brake fluid was boiling point, dot 5 being the only synthetic. aftermarket hydro for hd has been around for 50 years It is also stock on the Vrod line and has been since 2002. Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Tomk, could it be that since you are installing all new lines, seals and doing a complete rebuild, this is actually where the performance gain is coming from? Forgive my ignorance, but what particular properties of DOT5 could actually make it better than the others? Yes there is the safe on paint, hydrophobic properties and low boiling point but what specific property of DOT5 would actually make it that much better from the get go? Link to comment Share on other sites More sharing options...
Member Contributer tomk1960 Posted April 28, 2014 Author Member Contributer Share Posted April 28, 2014 Tomk, could it be that since you are installing all new lines, seals and doing a complete rebuild, this is actually where the performance gain is coming from? Forgive my ignorance, but what particular properties of DOT5 could actually make it better than the others? Yes there is the safe on paint, hydrophobic properties and low boiling point but what specific property of DOT5 would actually make it that much better from the get go? I have no personal experience in seeing improved performance swithing to DOT5 - I'm doing it mainly for paint friendliness. Some say that it's got a mushier feel than DOT3, but that's contrary to my experience with it. One of the 1100F forum members from New Zealand races regularly and swears by DOT5. I've restored at least 100 dual piston calipers and dozens of master cylinders have seen some pretty disgusting crud built up from DOT3. It will be interesting to see what the insides of my brakes look like in a few more years. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 Being paint friendly is great & recommended use is for racing, so that matches the New Zealanders findings. Using with all new or thoroughly cleaned system with new seals is doable. But as stated there is no performance benefit, other than its lack of water attracting properties, which leads to gunged up pistons, if maintenance is not kept up with DOT3/4 systems. Most people with poor brakes, suspension etc is usually down to poor maintenance or pure laziness on the part of the owners. Link to comment Share on other sites More sharing options...
Member Contributer FJ12Ryder Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 I guess I'll weigh in here with regard to DOT 5 silicone fluid. I use it for the clutch and brakes on my FJ for the same reason Tomk does: kindness to paint. The FJ1200 has a problem with brake fluid leaking past the slave cylinder seals and running down the countershaft cover, resulting in ruined paint. That happened twice on mine and I got tired of repainting, so I changed to silicone fluid, and no more ruined paint. Also no more leaks. I'm not sure of the reason for that but I didn't change the seals before putting in the silicone fluid. Everything works okay. I also don't notice any sponginess in the lines due to the silicone fluid. I do run stainless lines if that makes any difference. Unless you're worried about paint damage I don't see any reason to go to all the hassle of changing over to silicone fluid. That's my thoughts anyway. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 so ,like everyone with fancy paint has said.. it saves your paint.. thats why HD uses it. it has a higher boiling point.. thats why racers use it. it DOESN'T corrode or screw up your system !!! thats a myth started by retards who didnt use new seals + lines and ended up with weird braking. just like " DONT put your batteries on the ground !! it will discharge!!"" :mellow2: if someone says that to you, slap them so hard their mother feels it. Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted April 28, 2014 Share Posted April 28, 2014 The ability to absorb moisture is a BENEFIT of DOT 3/4/5.1 You WANT the moisture to be absorbed into the fluid. Therefore it can be changed for fresh fluid and the moisture does not attack the system components. Unless left too long, of course. It needs to be renewed like everything else. DOT 5 does not have these properties, and therefore needs to be renewed more often, so that any moisture does not settle out at the lowest point and begin to corrode the brake pistons and cylinder bores. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 The ability to absorb moisture is a BENEFIT of DOT 3/4/5.1 You WANT the moisture to be absorbed into the fluid. Therefore it can be changed for fresh fluid and the moisture does not attack the system components. Unless left too long, of course. It needs to be renewed like everything else. DOT 5 does not have these properties, and therefore needs to be renewed more often, so that any moisture does not settle out at the lowest point and begin to corrode the brake pistons and cylinder bores. you mean like the brakes i rebuild all the the time on HDS? the ones that sat from the 70s till now and have perfect, but dirty parts? and yeah.. they are parked right by the chesapeake bay ... lost of moisture in the air. so , a new flush every year vs every other year .. sounds about right.. Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 "Protecting the paint" sounds like a bizarre reason to switch brake fluids. The only time I've ever damaged anything with brake fluid was when I tried to blow out some caliper pistons with compressed air--never tried that again! Ciao, Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 "Protecting the paint" sounds like a bizarre reason to switch brake fluids. The only time I've ever damaged anything with brake fluid was when I tried to blow out some caliper pistons with compressed air--never tried that again! Ciao, you never had a $20,000 paint job and dot 3 or 4 will leave stains and eventually destroy the area it keeps dripping on.. as the poster says his bike weeps it.. Link to comment Share on other sites More sharing options...
Member Contributer tomk1960 Posted April 28, 2014 Author Member Contributer Share Posted April 28, 2014 "Protecting the paint" sounds like a bizarre reason to switch brake fluids. The only time I've ever damaged anything with brake fluid was when I tried to blow out some caliper pistons with compressed air--never tried that again! Ciao, you never had a $20,000 paint job and dot 3 or 4 will leave stains and eventually destroy the area it keeps dripping on.. as the poster says his bike weeps it.. Correction - my 1100F master cylinder wept, but it cries no more. I replaced it with another that I had and never had the issue again. But until I did, the little drip that formed as it slowly wept out would blow off and splatter all over my freshly painted tank as I rode. DOT3 or 4 would have trashed the paint without a doubt. I see nothing bizarre about protecting my investment. And since my brakes work great, why not? I rebuilt the entire system anyway, so it was going to get new fluids. Link to comment Share on other sites More sharing options...
Member Contributer FJ12Ryder Posted April 28, 2014 Member Contributer Share Posted April 28, 2014 It will also cause plastic to deteriorate over time until it is pretty much toast. Link to comment Share on other sites More sharing options...
Member Contributer MarkDetroit Posted April 29, 2014 Member Contributer Share Posted April 29, 2014 Don't use DOT5. The seal and o-ring materials in the brake or clutch system were not selected to handle silicone. And even if you buy all new seals and o-rings those new parts will not have the proper materials either. The seals will swell and fail early. No question. The use of silicone was just done so that the jugs of fluid could stay exposed to air w/o deteriorating. It was a boner move that the military tried. The experiment failed and the military switched back. Lots of seal kits were sold for the move back. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted April 29, 2014 Member Contributer Share Posted April 29, 2014 Don't use DOT5. The seal and o-ring materials in the brake or clutch system were not selected to handle silicone. And even if you buy all new seals and o-rings those new parts will not have the proper materials either. The seals will swell and fail early. No question. The use of silicone was just done so that the jugs of fluid could stay exposed to air w/o deteriorating. It was a boner move that the military tried. The experiment failed and the military switched back. Lots of seal kits were sold for the move back. thats the military.. using the cheapest possible dealer. Link to comment Share on other sites More sharing options...
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