Topic: cb750 master with dot5??????????

[mario medeiros]

If you were to rebuild your master and the caliper with all new gaskets and seals could you then run dot5 fuild in your brakes?Very nice paint jog that I do not want fuild on.Thanks

[MattFreeman]

I believe brake fluid is backwards compatible. That being said I would and do run dot 4.

[ekpent]

Dot 4 has a higher boiling point that Dot 3 and the Dot 5 is a different animal altogether being silicone based.

[KiefRichards]

Bot 5 is NOT compatible with 3 or 4, meaning you can't mix them.
If they mix they can gel up into a masty mess.
If system is totally cleaned of all dot 3/4, I don't see why you can't use 5.
Some may argue that the seal can be damaged...meh i dunno.

If you do use it, flush often and don't mix!

[Garage_guy_chris]

There is a DOT 5.1 which is Glycol based like DOT 3, 4 this should be ok to use as it just has a higher boiling point. The DOT 5 is indeed silicon based and cannot be mixed. DOT 5 i would think would work better but the risk is that plastic and rubber parts may not agree with it.

Typically with the bike i would run a good quality DOT 4 and forget about it. just change it every couple years.

[Muckinfuss]

Like everything else on the interweb, there are opposing statements regarding just about everything.  One of those is the 'goo' factor.  Some say that even one drop of 3 or 4 hidden in the system will react with the 5 and create a goo.  Some say that's not true.  What is it you think DOT5 would do for you that 4 won't? because without a guarantee of no 'goo', no swelling of seals and everything else negative being said about the stuff, I'd be reluctant to be the lab experiment for the truth.

DOT 5.1 is used almost exclusively in systems that require glycol based fluids of lower viscosity for ABS functioning because it's non-silicone, just like 3 and 4.  DOT 5 is, however, silicone based and foams like a rabid dog in ABS pumps.  DOT4 is the primary fluid used on just about every race circuit that I know of.  DOT5 is (let the Europe guys chime in here) generally not available in Europe and those bikes that have DOT5 on the reservoir, are specifying DOT5.1 due to ABS.  Since 2006, Harley has dropped using DOT5 in production motorcycles.  They were the only motorcycle manufacturer to use 5 in production.

There are arguments that DOT5 doesn't absorb moisture from the air, which is true.  However, unless you are using Teflon core brake lines, moisture will migrate into the system, no matter what type of fluid you use.  DOT3 and 4 can be tested for moisture using cheap test strips from any automotive supply.  Or, just bleed every two years to be safe.  DOT5 will just float on the moisture as it accumulates in the caliper.  It doesn't bleed out like the other types and the caliper has to be inverted so the bleeder screw is the low point of the system.  Failure to maintain, just like any other brake fluid, will result in corrosion that can cripple the system when needed to perform.  Most recommendations are to bleed once a year...just to be safe. 

The price gets to me...$16 for Bel-Ray DOT 5 12 oz vs $6 for a quart DOT 3 or 4 at Walmart that also works just fine in my cars.

One final thing, DOT5 is more compressible than the glycol based 3 and 4.  You will feel the difference......like there's one little tiny air bubble that you can't bleed out.

[Stoli]

I think Dot 5 is the only fluid that won't eat your paint. 4 and 5.1 both eat paint. I use 5 in one of my 750s and am glad I do since I can't seem to bleed my brakes without getting at least a drop somewhere. Works fine so far. Maybe I got no air bubbles because I can't tell the difference.

[dusterdude]

As to the question as asked,yes

[Jerry Rxman Griffin aka MuthaF'er]

If you were to rebuild your master and the caliper with all new gaskets and seals could you then run dot5 fuild in your brakes?Very nice paint jog that I do not want fuild on.Thanks

Sure, no reason you can not. Mine work just fine. Started with just the front. No problems. Now back also. No problems. No claims other than it works just fine.

[Don R]

 I used Dot5  in my 40 chevy, the master cylinder is under the floor. When it was cold I always had a soft pedal. If I let it warm up (idle) for a while the pedal would come right back. I eventually went back to dot 3, I didn't have a problem with it gelling or anything.

[Mr Freeze]

I use DOT 5 in my bike and it works great. Since it's silicone based it keeps the rubber and seals happy. Get yourself a speed or vacuum bleeder kit and you'll be golden.

[krusty]

I have Dot 5 in my 750F1 since I upgraded to dual discs, everything was renewed. I then used it in my 350F after a thorough cleaning of all parts in the system. Both working just fine, no problem.

[bjbuchanan]

I have never understood the apparent advantage, the main one being no damage to paint. Just how long do you guys leave brake fluid on your paint? It isn't like it touches and instantly bubbles, you gotta leave it there like a slob for brake fluid to have any effect. Maybe I am just lucky with ALL of my vehicles, cars and motorcycles.

Use 3 or 4, 4 has the higher boiling point. Change intervals are almost irrelevant because we are mindful owners eh? Besides, 2 years is a hell of a long time for it to sit with a bike anyway. Chances are by then that you have tinkered in some way or maintained the bike. Even if you haven't that is just a recommended maintenance interval, it isn't like your brakes will not function at all in any way. They will just not function to their fullest due to water buildup.

 DOT5 is just not worth it, price or performance, in any way in my opinion. It is exaggerated just like the unbelievable uses of Seafoam.

[goldarrow]

I often find big tall bottle of dot 3/4 sealed unopened at garage sales for $2-3.  I'm sticking with that. 

[Jerry Rxman Griffin aka MuthaF'er]

BJ,

It's that leaky seal that does the real sneaky damage. Then there's the guy that is filling his master that spills on his tank. You know, the unobservant or lazy guy. I now use DOT5 

[PeWe]

Cover the bike when changing, refilling the brake fluid.  Old bed sheet or paper around the master cylinder

[alacrity]

I replaced all the components of my cb550 front brake system except the OEM switch, and I cleaned that out with acetone etc.  I have custom paint on my bike... And chose to run dot5 because I am a sloppy pourer.  ;-).  A $40 mityvac bleeder makes that process a cinch.  Been running the dot5 for over a year with no probs at all.  However with my hoped up engine, that single disc wasn't enough even though it's new and all steel lines (especially when riding Two-up).   I just did the Distinguished Gentlemens Ride with my wife on back... And at one steep downhill at a fast-changing yellow, I decided the bike needed more (and smoother) stopping power with less finger effort.  So I did a dual disc conversion this week and of course stayed with dot5.  I have plenty of lever feel, which helps me have a nice ramp for modulation just before the front wheel locks up for emergency stops (you all DO practice emergency stops, Right?)


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[Lostboy Steve]

I use galfer dot5 in my 550 master after rebuilding it.

[JohnG]

I have two 750s: an SOHC  '75  F   and a DOHC  '79 F. 

I have been using Dot 5 in the '79 since 1983 and no problems.

I changed the SOHC over to DOT 5 about 7 years ago, also adding a second front disk at the time. 

No problems except for one thing.  The DOT 5 can trash the hydraulic sending unit to turn the brake light on.  They last me about a year to a year and a half.  I think the internals swell up and cease flexing.

I found out that Harley uses DOT 5 from the factory so I got a Harley sending unit and adapted it.  End of problem.  (Now I am probably the only guy in America with a Harley part on a Honda!)

I have an old car  ('58 Ford) that I use DOT 5 in.  Same problem.  The sending units were cheap so I bought a box for $3 @ and just toss them when they fail  (same deal  . . . . every year and a half or so)

Remarkably, the '79 went over 20 years at one point with no brake work and it was all working fine at that time.  The rear disk had been left with DOT 3 and the whole thing had turned to junk long before.

(the dual disks on the '76 F are the best mod I ever made to it, and I made
damned near everything in the 38 years I have had it).

[tomk1960]

When I rebuilt the dual disk brake system on my '74 750, I switched to DOT5.  I cleaned and rebuilt the calipers and master cylinder and blew out the brake lines with Brakleen followed by lots of compressed air to remove all traces of the old DOT3.  My brakes are phenomenal and the hydraulic brake light switch is fine after 4 years.  4 of my other bikes have DOT5 as well.  I'll never go back to DOT3 or DOT.