Author Topic: Clutch basket dampers (Read 1459 times)

rddcw · « **on:** July 19, 2025, 06:33:14 PM »

It’s been sometime since I’ve been on the forum as personal things got in the way and had to put away my 74’ CB 750 K for a while. But now, I’m back and started the ole Gal up again 😊. Went thru all the mechanicals and tune. Cleaned the carbs and benched synched them. But know they eventually need to be vacuum synched. Has that dread clutch rattle sound but quiets down when you engage the clutch. Pulled the clutch cover off and grabbing hold of the outer clutch basket, there really isn’t hardly any play. Just minute. I purchase a set a clutch dampers and looks pretty self explanatory to complete the job.
Question to all you tech guys, has anyone done this modification to their bike ? And does the clutch basket just slide out easily with the guts inside after you remove the clutch springs ?

Ozzybud · « **Reply #1 on:** July 19, 2025, 06:58:47 PM »

I have done 2 bikes. You have to drill out the rivets and tap the holes for screws.
They are not a user serviceable item.
You may be hearing a primary chain rattle as the noise does not change when engaging or disengaging the clutch.

rddcw · « **Reply #2 on:** July 19, 2025, 07:55:39 PM »

Well it definitely changes or quiets down when you pull in the clutch lever 🤔
And yes, I have the instructions that came with the dampers, so well aware of the modification.
Glad to see you’ve done this procedure and had success 👍

scottly · « **Reply #3 on:** July 19, 2025, 08:04:19 PM »

Are you talking about the primary drive dampers? These can only be replaced with the engine cases split. There are no "clutch basket dampers" on a 750 as far as I know??

rddcw · « **Reply #4 on:** July 19, 2025, 08:12:37 PM »

Trying to posts you a picture of the instructions

rddcw · « **Reply #5 on:** July 19, 2025, 08:15:50 PM »

And here is the source I purchased the dampers from. Hopefully they work 😊

scottly · « **Reply #6 on:** July 19, 2025, 08:17:29 PM »

That is not an SOHC 750 clutch..

rddcw · « **Reply #7 on:** July 19, 2025, 08:21:03 PM »

I don’t know. I’m just trying to educate myself. That’s why I ask the experts. Seems like one of your members did make this mod so I don’t know 🤷‍♂️

scottly · « **Reply #8 on:** July 19, 2025, 08:28:13 PM »

No, Ozzy was talking about something else.

Before you take anything apart, complete the fine tuning process, including the vacuum sync, as most of the so called "clutch rattle" is caused by an uneven/too low idle.

rddcw · « **Reply #9 on:** July 19, 2025, 08:34:59 PM »

Yes, I plan to vacuum synch the carbs first but the damper mod makes sense to me. Apparently somebody is having success with this mod so I don’t know 🤷‍♂️

rddcw · « **Reply #10 on:** July 19, 2025, 08:39:09 PM »

Not all that great vacuum synching carbs but I’ll give it heck of a shot especially if I can get rid of that clutch rattle. But the carbs as far as the mechanical adjustments, are spot on including bench synched 👍

scottly · « **Reply #11 on:** July 19, 2025, 08:45:33 PM »

Quote from: rddcw on July 19, 2025, 08:34:59 PM

Yes, I plan to vacuum synch the carbs first but the damper mod makes sense to me. Apparently somebody is having success with this mod so I don’t know 🤷‍♂️

That mod and those parts are NOT for an SOHC 750 clutch!

rddcw · « **Reply #12 on:** July 19, 2025, 08:55:51 PM »

Wonder what they are for then 🤔. Dampers were pretty inexpensive. I can always return them

newday777 · « **Reply #13 on:** July 19, 2025, 08:59:33 PM »

Quote from: rddcw on July 19, 2025, 08:15:50 PM

And here is the source I purchased the dampers from. Hopefully they work 😊

Like Scott said, that is not for your 74 750K4

scottly · « **Reply #14 on:** July 19, 2025, 08:59:57 PM »

Quote from: rddcw on July 19, 2025, 08:55:51 PM

Wonder what they are for then 🤔.

I was wondering the same thing! Please let me know what you find.

rddcw · « **Reply #15 on:** July 19, 2025, 09:13:47 PM »

If I was in Phoenix right now, I ride out to your area and show them to you

scottly · « **Reply #16 on:** July 19, 2025, 09:18:56 PM »

Search the web site of the place you bought them from for the part # or SKU, and see what they fit.

Ozzybud · « **Reply #17 on:** July 19, 2025, 10:13:15 PM »

Quote from: rddcw on July 19, 2025, 08:15:50 PM

And here is the source I purchased the dampers from. Hopefully they work 😊

Those rubber dampers are for a 1979-82 cb750F/K
I believe our sohc 750's still used the springs for dampening.
Both of my mods were CB400F

rddcw · « **Reply #18 on:** July 19, 2025, 10:21:05 PM »

Interesting. I’ve never seen the backside of the outer clutch basket so I don’t know 🤷‍♂️

rddcw · « **Reply #19 on:** July 19, 2025, 10:36:56 PM »

This apparently is the earlier outer clutch basket for the CB’s

Flyin900 · « **Reply #20 on:** July 20, 2025, 06:08:50 AM »

That mod was developed by a fellow in Netherlands years ago. I have done a few for the CB900/CB1000 DOHC models which it was designed for specifically.

The rattle can be reduced somewhat by the suggestions in tuning and syncing. Having specialized in the DOHC Series of motors and bikes for many years, I believe on that motor then these are the causes. The rubber dampers in the internal main shaft drive (6) pcs and the normal stretch of the main Hyvo Drive chain off the crankshaft is the source of what your hearing. Dampers are now hard from age and heat and the chain has stretched, or the rubber slipper for the chain has worn too.

I am not familiar with a SOHC CB750 motor and if they use any of these parts. Your main drive off the crankshaft is a regular drive chain style X 2 pieces I believe.

cooldrum · « **Reply #21 on:** July 20, 2025, 07:56:44 AM »

I also ride a K4 and I've found to minimize the clutch rattle a vacuum sync improves things with a complete tune up and also do a cam chain adjustment too. I also run my idle at around 1300 rpm and it's smoother when i come to a stop. It's those small things that make a difference. 35K miles and still rolling

. The damper mod looks to be for the dohc models. Keep on riding your sohc and things will smooth out

fizzlebottom · « **Reply #22 on:** July 20, 2025, 08:25:59 AM »

I replaced the clutch dampers on my CB650 last year. My clutch basket has more in common with the DOHC Hondas of the time than previous SOHC models though. I got mine form KM Carburetor. I had to order the CBX dampers and trim them down to length, as the CBX dampers are the exact same shape as the CB650 but with added length.

The original dampers were ROCK hard and there was some play in the clutch, therefore dampening absolutely nothing. Drilled the rivet heads, punched out the rest, tapped new threads for the new low profile bolts, and installed all the new stuff. I used loctite and torqued the bolts either to whatever instructions provided or what the FSM says to do for that bolt size. Can't remember.

Either way, it made some difference. At the very least I know my dampers are good for another 30 years.

The trickiest part of the whole operation is making sure you're keeping on center when either drilling or punching out the rivet. Everything else is just time and patience.

rddcw · « **Reply #23 on:** July 20, 2025, 09:44:42 AM »

This has been quite an education for me and I appreciate all the responses. The early outer clutch baskets like mine are totally different than the later ones as I have found out and these rubber cushions or dampers obviously would not work. I’m not even sure if these early baskets even had them 🤷‍♂️

Jerry Rxman Griffin aka MuthaF'er · « **Reply #24 on:** July 20, 2025, 11:43:29 AM »

No clutch dampers in SOHC 750's. Inside the basket you will find only plates.

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Author Topic: Clutch basket dampers (Read 1459 times)