Clutch Drag

[go_hercules]

After battling some clutch noise, I changed clutch oil and buttoned everything up. Well, to my surprise, the clutch started dragging a lot when in gear and clutch disengaged. Took the clutch back apart, everything okay. After some head scratching, I realized that the only thing it might be was that I changed the type of oil I had been using. I was running Honda HP transmission gear oil 80W/85W. I switched to Honda GN4 10W30 engine oil which is approved for 2 stroke transmissions and clutches. Since the bike originally called for 30W, I figured 10W30 would be fine. Well, I drained it out and put the 80W/85W trans oil back in, and the clutch drag went away. The viscosity of the two seems about the same. On the Bel Ray site, they say that 80W/85W is equivalent to 20W50, so it seems like the 10W30 would be thinner. But I found the opposite to be the case.

Has anyone else ever experienced clutch dragging after changing oils? As a test, I put the bike on a center stand and started it. Put it in gear with the clutch pulled in. The back wheel takes off and starts spinning. With the 10W30, I could hit the back brake and stall the engine. With the 80w/85W I could hit the back brake and stop the wheel but the motor still idled. I might even try some 75W transmission oil or even some ATF to see what happens.

[Bullfrog]

Yet another interesting test. Lots of folks already use ATF for their Hodie transmission/clutches - and have for years.
Ed

[go_hercules]

Hey Ed. Anything special I need to know before trying the ATF? Like what kind? I know there are about a dozen types of ATF nowadays.

[Bullfrog]

Sorry, I haven't run ATF in my scoots, so I haven't memorized which type of ATF is "correct" for use in a Hodie. But I'm sure someone with experience on the topic will post soon.
Ed

[go_hercules]

Another question just occurred to me that I meant to ask. How tight should the fiber clutch disks fit onto the center rotor gear? Mine slide on the rotor, but are a very snug, sliding fit. Should they fit the rotor looser, sort of like the steel plates fit the cage? If they are too snug, wondering if that can cause the clutch to drag because it might not let the disks fully separate? Thanks.

[olddogs]

Yes, the fiber plates fit the center rotor gear very snugly.

Choosing a transmission oil can be as personal as finding a favorite pre mix combo. I used type F transmission fluid for many years, but switched to 80/85 gear oil when I started running the bikes under extreme conditions of vintage motocross. I noticed the clutch pinion bushing wearing faster with transmission fluid and got a longer life out of the bushing when using the Bel Ray gear saver oil. This was on highly modified Hodaka racing engines, but the transmission fluid may work fine for stock bikes leading normal lives.

[go_hercules]

I tried some Type F ATF today. The clutch drag is about the same, was hoping it would be less. The clutch did not have this much drag before I took it apart. I had it apart to check it while working on the throwout bearing. No clutch parts were changed. However, I did mix the friction disks and steels up so they are in a different place than they were before. Don't see how that would matter but who knows. The friction disks measure about 0.077" thick. Worn but usable I think. If I measure a friction disk in several places the thickness varies by about 0.003" - wondering if this could cause drag somehow? Kind of at a loss here. By the way, the clutch bushing is perfectly smooth, no drag there.