Topic: Dual caliper conversion(brake fluid)

[tgascon]

I'm getting ready to start a conversion on my 75 CB550K.
I'm probably going to use a M/C from a modern bike.
Does it matter what type of brake fluid I use? Should it match the M/C (Suzuki, Kawi ect..) or just use the stuff Honda recommends as I'm using the stock Calipers?

Thanks

[eldar]

You will get many answers on this. It is almost as bad as an oil thread. The simple answer is this: Use either dot 3 OR synthetic. NOT BOTH. Dot 3 is the standard. it works however it attracts water which causes corrosion in the master and caliper. It also eats paint.

Synthetic works well too. It does not attract water so it does not cause corrosion. It also does not eat paint.

Many here use DOT 3 and Many use Synth. Both groups have good results. The dot 3 camp though will say it is not as good. I have used both. Both have worked great for me. I have had the corrosion happen and the paint removal so I decided to go with the synth.

I recommend getting a braided line for your brakes, it WILL make a difference, no matter what fluid you go with. I do nudge toward the synth though.

[JohnG]

I am a DOT 5 person but not without costs as my front brake sending unit ('76 750F) died a couple of times. My reasons are mostly desire of lack of corrosion. (I finally converted to a Harley sending unit)

There is an article in one of the current car restoration magazines  by an engineer.  It talks about how DOT 3 (and 4) absorb water over time (which most people knew) but additionally that 2 yearsis a good point to flush it out and put new in.

I built a road race bike in 1984 based on a 1979 750F.  I put stainless lines on it and DOT 5.  Raced it for 3 seasons and then made it back into a street bike, selling it  in 1994.  The new owner used it for several years but then it ended up outdoors in Maine for two winters.  I got it back two years ago; it was a mess as you can well imagine. However, after all this, the front brakes worked flawlessly and the fluid looked clean. Meanwhile the rear brake, which was still DOT 3 based, was total junk, not even being rebuildable.

My 76 CB 750F and 1958 Ford Thunderbird are both DOT 5 based with the only problem being the aforementioned sending units, since solved.

Knowing more now about DOT 3 now, it would not bother me to use it as I would change it, especially with the help of those neat bleed screws with the check valves in them.

          John

[Jerry Rxman Griffin aka MuthaF'er]

DOT5 (silicone) and Speed Bleeders for me. DOT3 works. DOT5 works. There are advantages using DOT5. Don't believe DOT5 was available when our bikes were made so there is no way it could have been recommended then. That's as far as I'm going with a controversial topic.

[CrisPDuk]

Don't know whether this would apply to our bikes or not, but when we upgraded my friend's rally car from DOT4 to DOT5 in an effort to lessen the car's chronic brake fade problems, we were advised by several reputable people in the motorsport industry to change all the seals in the sytem for silicon ones because apparently DOT5 brake fluid had a tendency to disolve the factory fit ones

We were also advised to flush the lines through to remove any traces of the DOT4.


Ironically after doing all the work, we never got to find out whether the fluid reduced the brake fade problems or not

Because on it's very first event after we'd done the work, my mate spun on a corner and stuck it backwards into a tree at  :omph

[Terry in Australia]

I wouldn't worry about using dot 5 fluid in our bikes, it's not gonna do much to improve the braking performance, the best thing you can do is use braided steel lines and a good MC, (a CB750F2/F3 item is ideal) new caliper seals and new pads, and drill your discs, and you should be able to do "stoppies".

I did this conversion on my K1 in January, and couldn't believe the difference, it's incredible, I've converted a few over the years, but haven't used braided lines before, they're definately worth the added expense! Cheers, Terry.  

[JohnG]

Terry, I agree with you... DOT 5 will not change brake performance.  I use it 'cuz I live in New England and everything rusts here so I hate rust...

However my real reason for this post is to find out from you what master cylinder you used.  I have a cb750F and have thought about dual disks but the question is what components to use?   GL 1000 parts from 75-76 come to mind.

        thanks!
        John

[Terry in Australia]

G'Day John, no worries mate, what calipers are you using? Regardless, the F2/F3 MC is about the best you can use and still retain that OEM look.

I did have a late model Suzuki GSXR1000 item on it when I was sorting the conversion out, it was a tad better than the F2 MC, but not worth the added expense unless you just like the look of the remote reservoir etc. Cheers, Terry.

[CrisPDuk]

I wouldn't worry about using dot 5 fluid in our bikes, it's not gonna do much to improve the braking performance, the best thing you can do is use braided steel lines and a good MC, (a CB750F2/F3 item is ideal) new caliper seals and new pads, and drill your discs, and you should be able to do "stoppies".

I did this conversion on my K1 in January, and couldn't believe the difference, it's incredible, I've converted a few over the years, but haven't used braided lines before, they're definately worth the added expense! Cheers, Terry.  

I'd agree with Terry on this one
 
I've classed braided lines as an essential fit on all my vehicle rebuilds, even the wife's runaround has them

Not only do they not flex under pressure, thus giving you noticeably more line pressure at the caliper where you actually need it, they are also virtually indestructible even when subjected to extreme levels of abus which rubber (and to an extent copper) lines most definitely are not

[tgascon]

Thanks to all who replied!
My M/C is on the way thanks to Ebay and the only thing left to get are a set of braided lines.
Can't wait to feel the difference!

Thanks again
T