Hi All, I have an '07 VFR, and an '84 VF. About 1 yr. after I got my '84, the clutch slave cyl. seal went out. I replaced it and also used Dot 5 Silicone fluid instead of Dot 4. Now I know that Dot 4 is preferred for brakes and that's what I use there. I figured if the Dot 5 caused probs with the clutch, that would not be near as bad as probs with the brakes :^). Well, 40K+ miles later, the '84 clutch is fine &, probably not the best practice, the clutch fluid has never been replaced again. So, I'm considering the idea of preemptively replacing my '07 Dot 4 clutch fluid with Dot 5 Sil. Anyone know of probs this might cause with the more modern clutch system? TIA, Anders
Ok before you read this - geek alert! Dot 5 Sil was developed for racing. It has a higher boiling point and is more stable over time. The gotcha is it absorbs water faster than the gycol based and any moisture will congregate at the lowest point in the calipers or slave cylinders. Brakes thats not good, if the water boils, you have no brakes. Thats why its typically changed after every race. Slave cylinder? Hadnt thought about that one, the clutch slave doesnt get as hot as a caliper, but still the moisture factor is still there. 40K on you old '84? I bet if you inspected the slave you would have rust on the lower side of the piston. Switch on a new bike to Dot 5 Sil? Hmmmm, what would you gain? 2 cents - if your looking for an upgrade in fluid - go with Valvoline synth Dot 4 thats out there. Its a higher quality product and more stable over a longer time vs the standard gycol Dot3 or 4, much like the upgrade in oil from dino to synth. I use it in everything I own and it helps avoid caliper or slave issues. MD
I think Mello Dude is right, but here's another option: use DOT 4, and just change it out every couple of years. It's easy to flush the clutch system - just one bleed valve. You would maintain maximum performance, and stay clear of moisture issues. I'll bet the problem with your '84 was just age, wear, or moisture from not being changed, rather than the type of fluid used.
I learned what Mello stated years ago. DOT5 is not for the street unless you have stainless steel sleeves in the braking/clutch cylinders. The only advantage of 5 is the higher boiling point. The disadvantage is the water/moisture separated in the system which cause rust. This is one of those times just because it's better for racing doesn't mean it's better for the street.
