Author Topic: Cb750k6 clutch disc query  (Read 2543 times)

Offline Paulreade

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Cb750k6 clutch disc query
« on: December 21, 2018, 08:55:18 AM »
Hi guys, I'm after a bit of advice. I have just stripped the clutch down and have 7 friction plates  ( existing) 6 of which have perpendicular grooves and the outer disc with the wider tabs has grooves or swirls running out at approx 45 deg. The replacement plates (7 no) all have grooves running out at 45 deg. When looking  at the basket from the right hand side of the bike does the basket / clutch spin clockwise ?. If so do the discs fit as per sketch B ?- this would mean the discs would be facing you as shown when inserted into the basket.  I assume this is the case as this would allow oil to be thrown away from the plates more easily ?. It's the first clutch I have ever stripped so just want to ensure its put back correctly.d The manuals simply do not show this level of detail that I can see.
Look forward to any pointers / advice / decent YouTube links etc.
Paul
Ps the picture C indicates the pattern of the grooves on the 6 discs removed. The 7th outer disc is similar to B.
« Last Edit: December 21, 2018, 08:57:11 AM by Paulreade »
Current bikes:
Suzuki GSX 1250 FA
Triumph t100 bonneville
Honda cb750 k6

Offline Nurse Julie

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Re: Cb750k6 clutch disc query
« Reply #1 on: December 21, 2018, 09:43:02 AM »
They go in as your picture A Paul
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

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Offline Trigger

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Re: Cb750k6 clutch disc query
« Reply #2 on: December 21, 2018, 09:51:22 AM »
K6 clutches can be a little complex, first you must make sure it is a K6 basket as, some have been swapped about. The first plate in is a metal plate with the flat side facing in. There should also be a double metal plate  ;)

Offline Paulreade

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Re: Cb750k6 clutch disc query
« Reply #3 on: December 21, 2018, 06:06:36 PM »
Crikey pic A ? - surprised at that !. Does the basket spin clockwise ( looking at bike from right side ). The outer (7th) plate on the clutch I removed was I'm pretty sure as pic B so a bit confused now ?.
Can you elaborate on the whys and where fores as to why they should go in a particular direction and what are the pitfalls of placing the 'wrong way'.
There is a YouTube ( the only one I found) by an Aussie guy and he I'm sure placed the discs as pic B , I will however watch again.
In the interim I'd be interested to know the 'tech ' stuff though as I'm on a steep learning curve on this bike.
Kind regards
Paul
Current bikes:
Suzuki GSX 1250 FA
Triumph t100 bonneville
Honda cb750 k6

Offline Paulreade

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Re: Cb750k6 clutch disc query
« Reply #4 on: December 21, 2018, 06:10:14 PM »
Hi trigger, you mention a double plate , was this the plate to make the clutch quieter that I have heard of, I don't think there is a double plate in mine but I will double check before putting back together. I won't rush this as yet as I'm a tad confused on the disc issue at present. I may photo the existing for comment ?
Current bikes:
Suzuki GSX 1250 FA
Triumph t100 bonneville
Honda cb750 k6

Offline Nurse Julie

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Re: Cb750k6 clutch disc query
« Reply #5 on: December 21, 2018, 06:49:44 PM »
Paul. I can't explain anything technical as I go by pictures
Here is the pic and instruction from the Workshop Manual. What I can say is that Trig is rebuilding a CB750 K6 at present, which has an original K6 clutch in it and when he put the plates in, they were as in this picture. Hope this helps a little.

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LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
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Offline Trigger

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Re: Cb750k6 clutch disc query
« Reply #6 on: December 21, 2018, 07:04:31 PM »
There were a few different clutches used on the K6, some had the K4/K5 set up and some had the F1 set up.
If you do not have the double plate then, the first plate is a friction pate and build up. All the steel plates have a bevelled edge and make sure the bevel faces out. If one of the steel plates are in the wrong way then, you will get clutch judder  ;)

Offline Paulreade

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Re: Cb750k6 clutch disc query
« Reply #7 on: December 21, 2018, 08:42:11 PM »
How interesting. Really appreciate that. I shall try and find out why the grooves are situated as they are and hopefully add a post.
Thanks for your input on this.
Regards
Paul
Current bikes:
Suzuki GSX 1250 FA
Triumph t100 bonneville
Honda cb750 k6

Offline Paulreade

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Re: Cb750k6 clutch disc query
« Reply #8 on: December 30, 2018, 08:43:14 AM »
Hi trig, nurse Julie.
I think prior to Xmas you asked me to clarify near side or offside. I confirmed offside looking into the basket, which is what the extract you showed on the photo seems to indicate. If that is the case then the friction discs go in as pic A - agreed ?.
I asked the same question on the USA site but no one has replied at all which was surprising, nor has David silvers come back which again is a little disappointing.
Which manual do you use as the ' haynes' manual is far from adequate and quite a disappointment.

If you can just confirm the above I'll get on rebuild. Appreciate your assistance on this.
Regards
Paul
Current bikes:
Suzuki GSX 1250 FA
Triumph t100 bonneville
Honda cb750 k6

Offline Trigger

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Re: Cb750k6 clutch disc query
« Reply #9 on: December 30, 2018, 09:08:33 AM »
I can't understand why you asked a question and i gave you the answer and, then you still question my answer  :o
In the past month i have built 2, K6 engines and 2, 500 fours which all have the directional plates and lost count of how many over the years. The picture is from the Honda CB500 Four workshop manual, which all plates are directional.

The K6 never really had its own manual but, originally only the last outside plate was directional  ;) 

Offline Paulreade

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Re: Cb750k6 clutch disc query
« Reply #10 on: December 30, 2018, 05:02:53 PM »
I received a post back from the us site today stating the complete opposite - they referred to a tech bulletin which I have asked for a copy.
It's a lack of confidence issue I guess trig, plus a habit of a working lifetime of clarifying everything with all and sundry before work proceeds. Its  all a bit confusing to someone who has never delved into a motorcycle engine before and wants to ensure the bike is preserved for years to come.
  :-\
Cheers
Paul

Current bikes:
Suzuki GSX 1250 FA
Triumph t100 bonneville
Honda cb750 k6

Online K2-K6

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Re: Cb750k6 clutch disc query
« Reply #11 on: December 30, 2018, 05:57:29 PM »
I think there's information that leads to conflicting opinion on this.

The Honda manual I have for 750 F2 is very specific in stating that the angled slot plate should be fitted as picture B in your early post.  it also has the double plate fitted to centre clutch pack.

As far as I'm aware the angle is there to manage oil dissipation as the clutch is released and so will affect the bite "feel" and how smooth the initial drive takeup is. It doesn't look like it will cause a problem as such when fitted either way, but it should change the operation in a small way but only for pulling away from a standstill.

If you look at how the clutch operates,  engine running,  clutch open, in first gear.  Then the metal places are stationary with the fibre plates rotating with the crank, and oil between each interlayer.
As you bring the clutch toward closing then it has to squeegee the oil out of the layers to gain traction and start to rotate the metal plates. This is then driving torque through the gearbox.

As the plate with the angle slots is approached by the flat plates either side of it, the oil has to be wiped into the slot for its exit route out of the clutch pack. If the slots face forward (as in A) then it has the effect of working against centrifuge, which keeps the oil in play longer, which gives a softer clutch bite. 
In the B plate scenario,  the oil is less retained against centrifuge,  so should give a quicker bite transition,  and potentially more difficult to modulate torque takeup.

They both don't seem technically wrong but should give subtly different initial affects.

I doubt that the affect is aimed at moving geachanges as all of the clutch pack is moving together after initial pull away. 

If you don't like the effect when installed, then it's easy to flip the plate.  It's more fine tuning by designers than any technical disaster if it's fitted backward.

Offline Trigger

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Re: Cb750k6 clutch disc query
« Reply #12 on: December 30, 2018, 06:14:40 PM »
I have always fitted them by the Honda manual, which is in the picture with the 500 four clutch and states " NOTE, Fig 118 "  ;)

Offline Paulreade

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Re: Cb750k6 clutch disc query
« Reply #13 on: December 30, 2018, 06:20:33 PM »
Good answer to the question. I will fit as fig A. Keeps everyone happy and makes sense.
Really appreciate the input.
Many thanks
Paul :)
Current bikes:
Suzuki GSX 1250 FA
Triumph t100 bonneville
Honda cb750 k6

Offline Trigger

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Re: Cb750k6 clutch disc query
« Reply #14 on: December 30, 2018, 06:30:32 PM »
The other concern is 6 of your plates should be "C" vertical so, it will be interesting to see what the result are as, i have only fitted 6 vertical and 1 angled to a K6  ;) 

 

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