Topic: Need some help identifiying a clutch that came in my '69 cb750

[Thunder]

So, a while back i assembled the engine on my Cb750k, it all went together pretty OK, and i utilized most of the engine components that were in her.
Like an idiot i didnt think to double check everything going in, other than tolerances.... I shouldhave been more careful as i think the guy stuck whatever he could onto it, to have a rolling chassis for sale.

 (basically i had to change everything except engine and frame)

Started her up about a year ago and there was knocking and various other noises, but i left  diagnosis until i had done tappets/timing/carb synch.

These have now been done, along with new exhausts and she is alot quieter, but the clutch was making a huge noise, better when pulled in, but still a racket, as well as a distinctive knock/tapping... location unknown but seems to come from the engine front.

Carb synch was completed so i thought to pull the clutch (i have a GL1000 double plate i am hoping to use)

Pulled clutch and this is the hub i have , but on looking in the interwebs it seems to be wrong???
Looking on the internet is very confusing, i have Mark's book and he mentions the steel band running on the splines for k0-k1 engines?
Was the 72 and up clutches without the steel band surrounding the spline, or was the steel band still there?

Any help identifying what clutch hub i actually have.








I pulled 3 other clutch baskets out the shed and they all have the steel band around them, one is complete, so i will be dissasembling and taking a close look at that.

I am just trying to figure out if the knocking noise i heard might have been this clutch knocking on the clutch case (something i read on this forum) , if so where?
Then there is the spline teeth length... any ideas as to lengths for different years?

Any help or advice/observations/things to look out for would be really helpful


Thanks so much
Thor

[Henning]

That's the same as mine - no steel band - on an early 750 K1. But the PO's been in there so who knows if it's correct. I know he's been in because he used a screwdriver to beat off the retaining nut, and used the same implement to beat it back on again. 

[Thunder]

Yip, PO's making life fun . The internet is great but image search can only do so much as when i type in CB750k0 clutch hub i get people offering ones like ours, but i am pretty convinced they are supposed to have steel bands around them and squared off splines...

(not to mention the ebay DOHC ones that pop up as well 


This is why i am trying to identify the origin of this hub, as it might account for the knocking noise, as i read on here that the later hubs are wider and can knock on the earlier outside clutch casings.

If anyone has definitive pictures of a K0, K1 or even K2 hub i would appreciate it, as i can use that to make something up/identify stuff

Here is what i believe my hub should look like (websearch)





Thor

[madmtnmotors]

Looks like your inner and outer aluminum components are keyed 90 degrees out. The inner aluminum hub should sit flush on the outer friction disk. The inner and outer will only mesh properly in two of the four possible orientations. If not oriented properly the teeth on the two aluminum pieces do not mesh as they should, unless you are only showing pictures of the clutch for reference. 

[69cb750]

22100-300-020 CB750E-1056080 Sep 1970 band added

[Thunder]

Looks like your inner and outer aluminum components are keyed 90 degrees out. The inner aluminum hub should sit flush on the outer friction disk. The inner and outer will only mesh properly in two of the four possible orientations. If not oriented properly the teeth on the two aluminum pieces do not mesh as they should, unless you are only showing pictures of the clutch for reference. 

Yip reference only

[Thunder]

22100-300-020 CB750E-1056080 Sep 1970 band added

So are you saying my hub is correct without the band?
what about the squared off splines/fingers?
Mine has none

CMSNL has this as the 69 clutch hub?


And this as a 72? I think this is the same as mine


Thanks for the help so far guys!

Thanks
Thor

[69cb750]

So are you saying my hub is correct without the band?

The band was added at engine CB750E-1056080 cause hot rodders bent some fingers.
Early basket - https://www.cb-four.com/cgi-bin/shop/__Clutch-hub-Honda-CB750Four-K1-K2-is-used__15-2160-09_07.07.html

[Thunder]

Fantastic!!!!

Thank you so much!!!

(Here is the photo from the above link in case it dissapears and someone else is running down this road)


Its a mixed blessing tho... if i have the correct clutch it will not account for the knock or it being so out of whack after i tuned the carbs.
It is possible i assembled it incorrectly, but will take a look.
I might stick in one of the complete assemblies (with a band) i have lying around and just check if that runs quiet.


Would i then be correct in assuming the squared off spline/finger ones is from a later model?


Good to know it is correct as it eliminates one question

...back to the shed

[Terry in Australia]

Looks like your inner and outer aluminum components are keyed 90 degrees out. The inner aluminum hub should sit flush on the outer friction disk. The inner and outer will only mesh properly in two of the four possible orientations. If not oriented properly the teeth on the two aluminum pieces do not mesh as they should, unless you are only showing pictures of the clutch for reference. 

Wilbur's on the money Thor, more than one "expert" has been caught out with clutch issues due to the inner and outer components not meshing properly. I became one old guys hero a few years ago when I fixed his problem in 5 minutes after he'd been scratching his head for weeks wondering what was up with his clutch. (I left before he could ask me any tricky questions for fear of eventually looking like a dick that just got lucky, which of course I am.....)

The noise you are describing is a worry though, I had a close encounter of the pants sh1tting kind last week when my gearbox locked up my back wheel @ 40 MPH, just moments after leaving the freeway when I was doing 70 MPH. Pulling the clutch made no difference at all, I just rode it out until the skidding stopped. Had I been riding on a wet road, or cranking it into a corner, it may well have been my last ride.

I was told that the engine has never been apart, so it could well be a little known issue that appeared in the thread below. I'm busy working on my Kawasaki Z1000 "Mad Max" bike so I haven't pulled it apart yet, but this thread is definitely worth reading, as the noises you describe are similar to mine, and that could mean that if ignored, catastrophic failure will be visited upon you, it seems to have happened with later models than yours, but if someone's been in there and have put the c clips in the wrong way, it could happen to you. Check it out.

http://forums.sohc4.net/index.php/topic,86429.msg2092390.html#msg2092390 


New Years Eve Bitsa disaster 2019 by Terry Prendergast, on Flickr

New Years Eve Bitsa disaster 2019 3 by Terry Prendergast, on Flickr

[PeWe]

Sudden "clonk" sound not good. I agree with Terry that has experience of a recent Terryfying ride with a sudden black line behind bike without WOT involved.

The primary drive hub on that photo is a later model.
I guess from K6 (maybe F-1975 too) since it has the circlip holding the clutch steel basket and the more narrow washer entered next.
The earlier had no circlip and the washer next much wider.
You have to open cases to replace that one if you want all internals to match the year.

If everything is mixed inside, possible that the transmission is later as F, K7 etc which had other final gear.  That can be used in K too if taking that gear and place it on a K shaft if I have understood everything right. 
(I'll do that for a coming build using F trans in a K engine. need to move the gear to K final shaft with bearings)
The K final gear look different than the later F, K7.

I have such transmission I'll use in a K2-K6 case, final gear to be moved to an K shaft.

Here link to see difference between the early and late primary hub cush drive. Post about replacing the rubbers inside.
The upper has a groove for circlip the earlier I posted has no grooves.
I have found that the splines must match too, not too big clearance having a clutch basked with play on that shaft. My basket had to be removed by a puller, tough to install the other basket. My old clutch however had a play on its old splined shaft.

http://forums.sohc4.net/index.php/topic,151616.msg1732303.html#msg1732303

Below  K final gear LEFT (without bearings). Later F  RIGHT. Gear not same. It must match with used trans gears.


See my later clutch with circlip and narrow spline washer.