Author Topic: Cb400f clutch help needed (Read 1837 times)

soonerbillz · « **on:** July 15, 2025, 02:57:46 PM »

Need some help here.
Replacement of the clutch discs.
I took the clutch apart a couple of months ago to see why my clutch was slipping. I had done all the adjustments as per the manual but it still slipped on hard acceleration.
I found the discs worn and ordered a set of new springs as well.
But as I said it's been a while.
Today I started to reassemble it all and to be honest I can't for the life of me remember the order of the stack.
Specifically how that special metal plate that is cone shape goes as well as the friction that has the bigger inside diameter.
I have the factory manual and a Clymer but on this note it's pretty ambiguous.
I've searched the web to no good and I'm hoping you all can help me pull my head out of my ass.
Thanks

I did get folks trying to help me I'm still confused.
So here I'm back still kind of confused 😕
I followed advice given on the placement but came onto a problem.
1st
Here is my inner hub
As you can see the snap ring and the 2 special plates are on as I never did take them off the inner hub

soonerbillz · « **Reply #1 on:** July 15, 2025, 03:00:19 PM »

I bench trial assembled following manual and the given advice.
I end up with 1 too many friction discs at the pressure plate end. ??

soonerbillz · « **Reply #2 on:** July 15, 2025, 03:02:13 PM »

From the advice and manual description I was thinking the snap ring was to be holding the curved plate onto the inner hub.
But the snap ring groove is nowhere wide enough for the 2 special plates with the curved plate and the snap ring.

soonerbillz · « **Reply #3 on:** July 15, 2025, 03:06:40 PM »

If I stack with the large inner diameter friction 1st then the curved plate and follow up the rest as normal I end up using all the discs.
But that can't be correct.

What I missing here?

soonerbillz · « **Reply #4 on:** July 16, 2025, 07:21:55 AM »

Still hoping for someone to advise
Thanks.

Mark1976 · « **Reply #5 on:** July 16, 2025, 09:40:03 AM »

I just did this last summer installing a Barnett clutch pak, but I'll be damned (if I'll open up one of the 2 bikes I currently have) if I can remember this being an issue. The cms diagram (from the inner hub) shows steel plate, snap ring, then fibre and steel alternating with the remainder.

soonerbillz · « **Reply #6 on:** July 16, 2025, 01:16:26 PM »

Can you direct me to this "cms" image?

Mark1976 · « **Reply #7 on:** July 16, 2025, 01:32:57 PM »

Cmsnl.com

soonerbillz · « **Reply #8 on:** July 16, 2025, 02:49:12 PM »

I went there and the blow up and install description are the same as the factory and aftermarket manuals.
It does not show an image as you described.

HondaMan · « **Reply #9 on:** July 16, 2025, 08:41:37 PM »

Maybe this will help?
The first 2 full steel rings go on, then the "Plate B" (aka Pressure Plate), then the spring clip, then alternate cork-steel-cork for the stack.

soonerbillz · « **Reply #10 on:** July 17, 2025, 11:45:42 AM »

To be honest I don't even understand what the reason for the curved bell plate is for.
Wouldn't just a regular flat plate work as well?

soonerbillz · « **Reply #11 on:** July 17, 2025, 11:46:49 AM »

I assembled it like this.
It's the only way it could go.

soonerbillz · « **Reply #12 on:** July 17, 2025, 01:46:09 PM »

Somebody must have had this issue/question at some time but I can't believe how few helpful responses my post has gotten.

Tim2005 · « **Reply #13 on:** July 17, 2025, 02:34:03 PM »

Your latest photos explain it. That plate should not be bell shaped like that. It should be flat.

Actually that is pretty incredible. I've known them to distort in that way that by a half a millimetre or so, never seen one distort as much as that though despite years of riding & abusing 400s.

soonerbillz · « **Reply #14 on:** July 17, 2025, 03:02:51 PM »

Thanks Tim for responding.
Also, thanks for throwing a handg grenade into my brain.
If this is true what am I supposed to do will all the parts book that calls that plate a "Bellville spring " ?

soonerbillz · « **Reply #15 on:** July 17, 2025, 03:04:12 PM »

I am beyond fubar now
So much for my awaited vintage ride Saturday.

jonda500 · « **Reply #16 on:** July 17, 2025, 06:38:55 PM »

that curved plate will need to be replaced - it is not a spring and I've never seen a 400-4 use that type of clutch spring
John

bryanj · « **Reply #17 on:** July 17, 2025, 08:29:50 PM »

The only beveled washer i know of goes under the castellated clutch nut

Tim2005 · « **Reply #18 on:** July 18, 2025, 09:28:58 AM »

Quote from: soonerbillz on July 17, 2025, 03:04:12 PM

I am beyond fubar now
So much for my awaited vintage ride Saturday.

Your vintage ride- is it like the ones around here, a gentle group ride at the speed of the slowest? Will you be keeping under 5-6000rpm? If so, as a temporary measure put the clutch back together without that distorted plate- just have 2 friction plates together at that point. See if you can get it to adjust to a normal lever within the range of the adjusters, and give it a try. 400F clutches will take a fair bit of extra power so I suspect that the slight loss of clutch friction from having one plate too few won't matter as long as you ride it gently. That way you can still go on the vintage ride then fix it properly afterwards. I'd welcome others' thoughts on this too

soonerbillz · « **Reply #19 on:** July 18, 2025, 10:25:12 AM »

Yeah it's a 55mph and less group ride.
But it's 200 miles round trip.
I've already signed off as a no show so bummed I am.
I just ordered all new steels, 6 of them to replace what I have.

HondaMan · « **Reply #20 on:** July 18, 2025, 10:50:14 AM »

I haven't seen a "Belleville spring" plate like that one before in a CB400F clutch. I've seen them in 300 HP dragracing bike clutches, where they serve a specific function, but it takes a lot of torque to make them work.

soonerbillz · « **Reply #21 on:** August 13, 2025, 09:57:45 AM »

So a big thanks to who helped solve this issue.
It did turn out that the bell curved steel plate was the culprit. I ordered a new flat standard steel to replace and it all worked out fine. Lesson learned.
Thanks folks.
Now though I have a new issue.
When get the bike in neutral and start the engine it drops into 1st as proper. I'll take off and shift up through the gears. When coming to slow down it will shift down 6th,5th, 4th and 3rd fine.
After that it will not shift down any further. I can't get into 2nd, neutral or 1st.
If I shut off the engine it still won't shift down but after rocking and fighting the shifter it will finally find neutral or 1st though the neutral light will not come on.
Then I can start the engine put it in 1st and it shifts again up through the gears but it does it again.
After I did the clutch I put a new oil filter on and filled the engine with 10-40 standard oil that was marked for 4 stroke motorcycles.
Any ideas what could be happening?

Mark1976 · « **Reply #22 on:** August 13, 2025, 04:08:13 PM »

Quote from: soonerbillz on August 13, 2025, 09:57:45 AM

So a big thanks to who helped solve this issue.
It did turn out that the bell curved steel plate was the culprit. I ordered a new flat standard steel to replace and it all worked out fine. Lesson learned.
Thanks folks.
Now though I have a new issue.
When get the bike in neutral and start the engine it drops into 1st as proper. I'll take off and shift up through the gears. When coming to slow down it will shift down 6th,5th, 4th and 3rd fine.
After that it will not shift down any further. I can't get into 2nd, neutral or 1st.
If I shut off the engine it still won't shift down but after rocking and fighting the shifter it will finally find neutral or 1st though the neutral light will not come on.
Then I can start the engine put it in 1st and it shifts again up through the gears but it does it again.
After I did the clutch I put a new oil filter on and filled the engine with 10-40 standard oil that was marked for 4 stroke motorcycles.
Any ideas what could be happening?

So, first things first, see if ya have a bad neutral indicator bulb, pull the left side cover and ground out the wire coming from the sending unit, its either a bad bulb and or a bad sending unit (personally never seen a bad unit but it can happen).
Then (and you're not going to like it) pull the right side cover, then the clutch basket and inspect the shifting linkage between the shifter shaft and the shift drum. There's a tanged fork that rotates the shift drum, (a couple of summers ago I had a very similar issue, I did a post on it, damned if I can find it) sometimes one or both of the tanges can get bent from hammering the shifter on downshifts (thats how I did it). It can be straightened if its not too bent up to badly, then inspect the indexing pins on the shift drum, they could be damaged as well and make sure the retaining bolt is tight. But if that doesn't remedy the issue, it's very likely you've got a bent shift fork, which necessitates splitting the lower halves to repair. Even then you may end up replacing a shift fork and if the linkage if its bent up bad enough, which is not as bad as it seems. It's a good 2 day project though, I've done before.

soonerbillz · « **Reply #23 on:** August 13, 2025, 07:10:36 PM »

Thanks for the reply.
I know the neutral light is operating properly as it lights up when I finally get it in neutral.
Appreciate your take on the possible shifter parts behind the clutch. I'll take a look and see if that's the issue. Hoping so.

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Author Topic: Cb400f clutch help needed (Read 1837 times)