Topic: 1975 Honda CB750F Clutch Discs

[RodSOHC750]

I'm installing new clutch discs and plates.  One of the friction plates has a wider tab.  Can someone tell me where this disc goes in the assembly?  Nothing in the Shop Manual indicates this.

[RodSOHC750]

According to the slip that came with the new discs, I should be using the 7 friction discs for my 1975 model.  However, the discs removed had 6 friction discs with 1 friction disc with the wider tab. 

[HondaMan]

According to the slip that came with the new discs, I should be using the 7 friction discs for my 1975 model.  However, the discs removed had 6 friction discs with 1 friction disc with the wider tab. 

The bikes by that time had 6 plates with one thicker steel plate (usually a double-steel plate with springs in between the plates) and the top plate was a "slipper" plate. This upper plate has (if OEM) slanted cork blocks and wider tabs to fit the wider slots at the outer end of the clutch basket. It was intended to let the shock of a too-harsh clutch dump dissipate somewhat, to protect the tranny and drive chain, and it worked well, until this one plate wore out. In most of these clutches, this is the normal failure mode: this plate wears a lot more than the others, until it slips. PartsNmore sells ones that have square-cut blocks with the wider fingers, and I use them as the replacement.

Some riders complained that the clutch "rattled" at idle, so Honda issued a bulletin to switch the double-sprung plates with one thicker baseplate from the GL1000 bike, instead. Yours might have that, if the bike was modded.

The bikes made between 2/72 and about 6/75 (K models) all had 7 cork clutch plates. The earlier and later ones have just six, with the later ones as described above, and the early ones had a thick steel plate as the first plate, held in place with some thin wire retainer rings over its 'teeth' and the next steel one in the stack.

[madmtnmotors]

Including the friction disk with the wider tabs you should indeed have seven friction disks total. The friction disk with the wider tabs goes in last. It should be the outermost position. That is the only place it will fit. The clutch basket has wider gaps at the outer edge.

[RodSOHC750]

Thanks for the info.

I installed seven friction discs total.  The seventh and final disc in the stack has a wider tab.  I noticed this friction disc will not drop down in the basket to nest with the disc stack. In the picture, there is a gap about the thickness of a friction disc at the stack bottom. This is due to the wider tabs on the seventh disc.  Is this ok?    If not, the kit has a seventh disc with normal width tabs. 

[HondaMan]

If you have the 6 normal plates and a wide-tab slipper plate, and the top fingers fit within the basket's edges (not sitting above the basket), then it will work. You probably then have the thinner plates (0.136" thick) that we are seeing today. The top plate, if not a slipper plate, will be similar in thickness to the others. I just bought a collection of such plates from PartsNmore and installed them in a late-model K6, which has the same clutch as yours: I replaced the top slipper plate with a normal plate and the total stack came out to be 0.38" less than with the original plates (minus the slipper plate), so it will work out OK.

Honda's plates (like 22201-371-000) used to be a little over 0.142" thick and their slipper plate (22202-391-000) was almost 0.157" thick. When combined with the dual-sprung plate, there was only room for a total of 6 plates. After the dual-sprung plates were replaced (as most are) with a simple steel plate, it becomes a 7-plate clutch again, like the K2 post 2/72 thru K6 bikes, with the non-reinforced center hub (injection-molded cast body).

These variances cause LOTS of confusion in these bikes today! So much so that I ended up with my CB350F as 'payment' from a finally-happy, but [formerly] very frustrated Vet who had been ripped off by 3 shops in a row, each one changing his clutch plates (even though the last one just did), even changing his basket, hub center, and finally the clutch cover (outside), all to still have no clutch, or barely enough to make the bike run up to 25 MPH in any given gear, that was all it would do. I found 7 friction plates in the end, all slant-cut type of 0.157" thickness, a much-modified hub (ground out to fit the clutch plate fingers), and the plates installed backward, so the oil would never leave the plates. And, the clutch cover was from a K4 bike, so the spacing to the lifter was too tight and could not be adjusted far enough to let the clutch fully close. All it needed was 6 plates and the Gold Wing thicker one, or 7 plates with the top one properly oriented (slipper type), and an "F"clutch cover. Poor guy...

[madmtnmotors]

Is this ok?

Yes.

[Jerry Rxman Griffin aka MuthaF'er]

Thanks for the info.

I installed seven friction discs total.  The seventh and final disc in the stack has a wider tab.  I noticed this friction disc will not drop down in the basket to nest with the disc stack. In the picture, there is a gap about the thickness of a friction disc at the stack bottom. This is due to the wider tabs on the seventh disc.  Is this ok?    If not, the kit has a seventh disc with normal width tabs.

That may be a 77/78 basket which is longer.

[MRieck]

 I think the real problem at this time is people missing up early/later style basket, covers, lifter plates, steels etc expecting it to work. You have to know what you. A simple....emphasis on simple....chart with measurements would be a good thing if unsure of part origins. People don't need to know where the ore used to make the aluminum originated or what county in Ireland the cork came from.

[madmtnmotors]

People don't need to know what county in Ireland the cork came from.

Of course, everyone knows the best cork comes from the Ireland County of Cork, while the County of Limerick produces a more whimsical version of cork...