Clutch re-assembly - the correct schematic

I have attached a photo of my stacking sequence ready to be re-assembled - but what about the random washer? It came off with the other simialr-sized washer at the rear of the assembly (far right in the photo). Help! anyone any ideas before I put it together?

Anlaf


ha ha I had one of those left over in my box too !:laugh:

I seem to remember that it is exactly the same size as the washers that fit under the valve springs but I still had one washer too many :confused:
 
Well, 5twins, I hadn't spotted that one. I ordered replacement plates for a 79 and seven plates arrived. I did count six steel plates including the one I thought was left in place, which turns out to be the base plate. So now I know the base plate is fixed in there the other five steel plates match up with a six friction plate clutch alright.

There is no discernible difference in dimensions between the seven friction plates I took out and the new ones (except the ones I took out are worn to 2mm oblivion), so I am probably okay to use six of the seven.

THE MEASUREMENTS - I did a quick check just now and came up with the following measurements - bear in mind it is dark here, the lighting in the smallest workshop in the world is not that good, and my glasses are covered in oily fingerprints. Ill get accurate measurements tomorrow, but it looks like...

Base plate 1.4mm, steel plates (4 of the 5) 1mm, and the remaining plate 0.8mm.

There's is no evidence of significant wear, but there is the bevelling to adjust for - I noticed quite a bevel/drop-off on the rims where I measured, so the numbers are likely to be bigger when I can see clearly (and yes, it is raining here).

Anlaf
 
Hmmm ...... that clutch pack sounds like it's really been used, or more likely abused, lol. The only worn Yamaha friction clutch plates I ever found were from one that was drag raced, and although worn a few thousandths, they were still within the wear limit. All the friction plates I've checked from normally used street bikes measured like new, right at about 3mm. Like I said, I never checked steels, but it is something I'm going to start doing.
 
on my 78 the 7x friction plates measure 2.95-2.97 and the 6 steel plates all measure 1.4mm All 6 steel plates are loose .They have done approx 18k miles

1mm sounds very worn to me too thats 2.5mm lost in the steel plates alone.?
 
Yes, they do. Measure them again tomorrow in the daylight ..... and use your good eye, lol.
 
Yes, I'll polish the glass eye first, but 2mm friction plates and 1mm sounds like excessive use (abuse, more like), but they are likely to be 1.4mm if I hold my mouth right.

By the way, Peanut, this is a picture of the bearing from my donor engine clutch - it had no washer letter e (as per some earlier manuals). Poor light for detailed photography, but you can get the idea - I can image trouble finding neutral on that bike (and 1st to 5th probably).

Anlaf
 

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yes it looks about as good as the bearing I've just taken out of my clutch.
Even though it probably only had 5k miles on it I could see clearly where the washers either side of the bearing had rubbed on the bearing due to compression forces.

The new bearing I bought from Yambits has probably 5x as many needle bearings and should be a big improvement in clutch operation hopefully.
 
When I was working on my 75 clutch, I used 100 or 120 grit sand paper to clean any discoloration on the plates, this coarse paper roughed them up a bit. I also used the same paper to break the sharp edge of the steels.
With out breaking this sharp edge I think it would be better to have the sharp edge out, not in. This will let the plates slide easier as the pressure plate pushes them in. This lets the pressure plate push and hold better, less likely to slip.
Removing the sharp edge makes the plates slide well both ways, in and out.
On the new bearing I didn't find it helped much. My bearing wasn't worn enough to notice any excessive wobble I could blame them for over the replacement bear from Mike's. If your bearing feels tight with little basket wobble I wouldn't replace it.
Leo
 
Yes, I replaced mine as well and saw no improvement. Apparently my original was still OK. And don't believe for a minute the claim you'll be finding neutral any easier. That one is total BS.
 
Oh yeah, I have to agree with 5twins, the story that "finding neutral" will be a lot easier with the new style thrust bearing, is complete fiction...............retailers call it "marketing"...............in politics they call it "spin".

The real problem with finding neutral, is due to the fact that the design simply does not create enough plate separation. I drilled a second hole in my wormgear operating arm, which gives a larger plate separation, and that makes finding neutral no problem.
 
PLATE MEASUREMENTS - they all look to me as if they are: Base Plate 1.4mm and the other five are not more than 1.2mm.

STEEL CLUTCH PLATES - THE SHARP SIDE - I wonder why Mr Yamaha designed the steel plates with a bevelled and a flat (sharp) side. I have no experience in metal production but I understand the plates would have been pressed and come out raw with both sides sharp, and the bevelled-edge must have been added. They could have done both sides (expense?) or it was a specific design feature that has become lost in translation.

I am sure we will work it out. I can understand the theories for the flat (or sharp) side facing in or facing out, but I can't quite see how the sharp teeth might diminish the clutch action - as I look at the friction plates, the raised sections are the parts that have all the contact, is that correct?

Anlaf
 
Oh yeah, I have to agree with 5twins, the story that "finding neutral" will be a lot easier with the new style thrust bearing, is complete fiction...............retailers call it "marketing"...............in politics they call it "spin".

The real problem with finding neutral, is due to the fact that the design simply does not create enough plate separation. I drilled a second hole in my wormgear operating arm, which gives a larger plate separation, and that makes finding neutral no problem.

Do you have a pic of your wormgear arm, I'd be very interested in seeing that little adjustment! :D

BTW, what size socket will I need for the clutch hub nut removal?
 
The early years spec of a 3.5 mm new with a wear limit of 3 mm. These were the clutches with the rubber O-rings between the fiber plates. I think they quit using the in 73.
The newer spec is 3 mm new with 2.7 mm as minimum.
So if your bike is newer than 73 the 2.7 is minimum. I have pulled apart a few clutches and measured the plates. Very few are worn much below the 3 mm.
If you are having clutch trouble I would upgrade the spring first.
If you look at your steel plate you will see that they are a stamped part. Any stamped part will have a beveled or rounded edge on one edge and a sharp edge on the other. As the die pushes into the sheet steel it rounds the edge. On the exit side it stretches the edge, this is what makes one edge sharp. They could invest man man hours on removing this sharp edge but the cost of the steel plates would at least triple if not increase even more.
If you use 150 grit sand paper you can remove this sharp edge. While you are sanding you can remove any discoloration on the steels.
On the clutch basket you will see that this sharp edge has worn the edges of the basket slightly. If very worn you can sand these ridges a bit too. Don't take much off, this can lead to excessive clearance and clutch shudder as it engages.
If these ridges are to big then replace the basket. There are usually many on Ebay. Just be sure to ask about broken springs in the back side and a good return policy if you find any broken.
Om my 75 I did this and increased the spring strength by about 50 percent. This stopped the slipping but I can still pull the clutch with two fingers. Not easy but with two fingers.
Leo
 
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Brilliant thread, brilliant diagrams. Most especially the one at the beginning there. The side view totally cleared up my clutch issue.
Thing was. Clymer gave me the order of parts but the drawing in the book made washer 'a' look like it was the same OD as the thrust washers. Didn't make sense to me as this put pressure on the outer bearing case. But I did it anyway , being trusting and I spose a bit naive.
When I went to do up the clutch boss nut I got the basket binding. I couldn't do much more than hand tighten.
So, I looked around and found the clutch torque to be way in excess of what it take. Much head scratching..
Thanks to this post, and the side diagram I could see for the first time that washer 'a' is smaller OD than the thrust. Thus putting pressure on the inner bearing case.

Wicked. Sorted. Now I can move on.

Getting me barrels honed on Thursday. Onward and upward.

Thanks again to all you tireless enthusiasts, and the head scratchers for askin in the first place.
 
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