Topic: Performance clutches.

[Don R]

  Per has been coaching me on using the F2 clutch/ transmission in my K5 turbo motor. For now, I used the stock F2 clutch with the gl disc in the middle. I've noticed the slanted corks and wide tabs on the outside disc of some. The performance engines I bought have extra (7?) thinner clutch plates with red friction and copper coated steels.
  I see Cycle x has a 6 spring clutch kit possibly based on goldwing parts and a cb clutch with fewer discs also. Their lockup clutch looks inspiring but may be beyond my current budget.
  Does anyone have a favorite clutch setup they would like to share?

  The PO of this bike thinks our clutches are just too small in diameter to get good results but he is running a Hayabusa with an aftermarket clutch in it.

[Old Scrambler]

I have had good fortune at Bonneville with stock Honda units in combo with RED Barnett springs............ I shift at 10,000 rpm but take it real easy on the downshift. You may need a lock-up unit depending on your dial-up and when it comes on.....

[slikwilli420]

I'm using cycle x coated steels and ebc frictions in both race bikes right now. I like the feel of them and they handle the rigors of racing. I'm using the late baskets with the riveted steel since the later basket is designed to disengage the clutch better.

[Don R]

 I really doubt this bike is going to be a weekly bracket warrior but having my best parts all in one motor is a goal I've had for a while. One of the carb'd 836's will be the one that get's thrashed if I get hooked on the racing end.
 In the meantime, I'm soaking up information like a sponge.
  It's much appreciated since I normally just run whatever is the best stuff out of my extensive junk collection.

[dragracer]

My "go-to" set up is the F2/3 clutch assembly with all stock steels and fibers. In my F3,  I have stock Honda clutch springs with shims added. Bike has had high 1.30/ low 1.40 short times and lasted me several seasons of hard racing with no measurable failures.  In the F1, I use 2 stock springs and 2 of there medium springs. I've had low 1.30 sixty foot times with a best ET of 10.29@124mph. Personally I would probably have left all 4 medium springs in the bike but my brother didn't like the degree of lever pull so I mixed stock with medium. I think the bike would benefit from more clutch spring pressure but it's working fair "all horsepower " but it'll be suspect under a full nitrous load. I'll find out in the next 60 days or so how it's going to behave.

[Don R]

  Thanks, I ordered stock Honda F2 frictions just to have, I had already used a DA sander on the steels. They were pretty gunked up from sitting for years.

[Don R]

    If you use the late model deep clutch basket and F2 center but don't have the double riveted steel, do you make up the thickness difference with another friction or steel?  I did print out the measured thickness from the cycle X clutch page, it shows both thicknesses I just wasn't sure how to get there. 

[Jerry Rxman Griffin aka MuthaF'er]

Don, that double steel is from a 75 - 79 GL. Don't you have one in your garage? Don't forget to use a late model clutch cover too. 

[Don R]

   I have one and used it in my current project but as I learn more about it, I see that I have a couple of the late type clutches but no more of the double riveted plates. They are going for $80 on ebay. I did buy another deep center and a NOS big tab/slant cork fiber disc.
   To be honest, I just enjoy learning about this stuff.

[corky]

Would it be useful to know what oil everyone is using with their clutch combos?  I am not trying to suggest an oil discussion thread so much as, I use this clutch with this oil, and it holds great!  :-)

It sounds promising that factory clutches aren't too bad.

Thanks,
Daniel

[PeWe]

My K6 with F2 clutch felt more rigid after the upgrade from K6 clutch. Not only less rattle.
(Setup then 1005 cc, 93whp later 101 whp and more torque)

I read somewhere that the double, riveted plate make it as two clutches in one.

The K6 clutch had washers under the springs to stiffen it further. Those washers came with a clutch kit in the early 80's.

The clutches with Barnett 66 lbs springs (black).

No washers needed in the F2 clutch that has higher stack but still same part with towers for springs compressing it together until towers bottomed. 

I use same EBC CK-1145 clutch fibers as in with K6 clutch

(I tested if I could replace the double plate with a std plate + extra fiber that needed another metal plate. Stack height too high.)

No slip due to oil. Had a few slips before due to not enough play of the clutch arm adj screw.
Red Line 20W-50 motorcycle oil is very fine.

I have noticed that thicker Red Line motorcycle oil could make the starter gear to slip when I mixed more 20W-60 during hot summer days. No clutch slip.

I had a few clutch slips last autumn when engine was not really warm.
Thats why I let the nearby shop to glass bead them plus 2 another sets.

I used Eurol HD oil mineral followed by
Spectro HD 20W-50 mineral New pistons, bores.

I had done some assemblies with different cams before so engine might have got some doses of assembly  lube. 4 cam installations......
3 different cams and 2 setups of cylinders w pistons, heads on same oil not much used.

Too much assembly lube might be slippery. (Red Line in a bottle)
Need to change oil again for my fresh glass beaded plates, except the double one.

I'll make sure to not throttle too much the first 20 minutes.
I had clutch slip when riding to the last dyno. Not on dyno run when engine was warmer,  104whp.

Lots of work and adjustments to get the power. When that is reached, clutch worries. 

[Don R]

 Look for JASO-MA on the oil bottle label.
 
  I watched a hot rod garage show recently on TV and they discussed breaking in dry clutches. It turned out the rear of the block was leaking oil onto the new clutch.

  I noticed I'm missing the bevel washer for my collection of parts for one more.

[Jerry Rxman Griffin aka MuthaF'er]

You may be able to buy a complete GL clutch pack on EBay for less than $80?

[Don R]

You may be able to buy a complete GL clutch pack on EBay for less than $80?

  And,,,, I did. Thanks. Under $35 shipped. It has the nut and washer and the riveted center. 3 things I can use even if nothing else works. If it has some good frictions and steels so much the better.

[desertrefugee]

Glued to this thread. I'm not putting together a strip warrior, but there's never been a motorcycle in my stable of any size or manufacturer that didn't get flogged severely on the street from time to time. This is good stuff!

EDIT: Let me just say that my CBX and my VMAX(s) ate clutches until I made serious, concerted changes.

[Don R]

 I have the NOS wide tab slant cork friction, a goldwing clutch pack and F2 center are in transit. I'll post some pics when I get it together. 

[Don R]

 One of the clutches I have came with an F2 transmission but it didn't include the 40mm snap ring that holds the basket on the shaft. I'm not sure how bad I need one but they seem to be unobtanium.
 It isn't an inner with the hole tabs in, or an outer with the hole tabs out. The snap ring pliers go into the notches on the ends of the ring. An outie may work with some shaving, I'll have to give one a try or search the odd Honda hardware pan again.
 
 I assembled an F2 clutch using two plates where the riveted one goes. All appears good. My gl1000 clutch pack is due for delivery next week. I'll post a pic. when I have it all.

https://www.partzilla.com/catalog/honda/motorcycle/1977/cb750f-a-750-super-sport/clutch

[slikwilli420]

One of the clutches I have came with an F2 transmission but it didn't include the 40mm snap ring that holds the basket on the shaft. I'm not sure how bad I need one but they seem to be unobtanium.
 It isn't an inner with the hole tabs in, or an outer with the hole tabs out. The snap ring pliers go into the notches on the ends of the ring. An outie may work with some shaving, I'll have to give one a try or search the odd Honda hardware pan again.
 
 I assembled an F2 clutch using two plates where the riveted one goes. All appears good. My gl1000 clutch pack is due for delivery next week. I'll post a pic. when I have it all.

https://www.partzilla.com/catalog/honda/motorcycle/1977/cb750f-a-750-super-sport/clutch

Kenny at Cycle X had a bunch of those snap rings made up. Give him a shout.

[Shtonecb500]

i love this forum.

[Don R]

 I need to call Kenny anyway, thanks. I've been putting it off because I know what it's going to cost. L0L!

 On the left K3 clutch middle F2 with the double spacer and right is a K2 with the red race clutches and copper coated plates. (there are probably too many in there)
  Note the late basket has a welded band and is square on the ends. Cycle X offers this drilled for weight reduction.

[Don R]

 I saw a late clutch basket on facebook being drilled for weight reduction. The jig was simple, just flat stock inserted between the gaps sitting on spacers. The post mentioned more lubrication for the discs where the tabs wear on the basket and center.
 Someone also mentioned Hondaman and CycleX's tip on drilling more oil holes in the center hub.

[Ellz10]

I saw a late clutch basket on facebook being drilled for weight reduction. The jig was simple, just flat stock inserted between the gaps sitting on spacers. The post mentioned more lubrication for the discs where the tabs wear on the basket and center.
 Someone also mentioned Hondaman and CycleX's tip on drilling more oil holes in the center hub.

I was curious about this as well. Trying to find out a little more info so I can do this myself.

[Don R]

 I got the gl1000 clutch today, hub, center, lifter, discs and plates. The slanted cork frictions show some wear, the plates look new as does the double plate in the middle. 
  The hub has fine splines so it can't drop into a 750 and bring along it's 6 springs. CycleX has done their homework to make this swap fit. I'm guessing the gl1000 transmission shaft is involved.
  All of it was about half the price of a NOS double plate. $34.42 shipped. Thanks for the heads up, Jerry. I also got a nut bevel washer and lock tab. I noticed the same guy has the gl1000 trans dirt cheap, should have bought it all and saved shipping.
  Anybody need a 76 wing clutch hub, lifter and center? 

[Don R]

 I noticed the gl1000 clutch hub has more oil holes drilled than the 750F, they are all in the top of the tooth and near a support rib.