Clutch Conundrum & Questions

[Anonymous]

I took the clutch out of my '83 GS750ES this evening in order to investigate the source of the rattling noise at idle (when the clutch is not engaged). I thought that the noise might be in the clutch basket: either worn rivets or lazy damping springs. However, the rivets looked OK, and only the 3 thick, course springs (i.e. not the 3 thinner, finer springs) showed a little bit of movement in their slots. I couldn't turn the backing plate relative to the body of the clutch basket. There were some slight "flattenings/dimplings" on the basket where the tabs of the drive plates engage but nothing that merited the term "grooves". I suppose that the rivets/damping springs and clutch basket marks could be related to the rattling but I am not convinced at this point.

What was interesting was that the clutch basket nut wasn't on tight?.certainly not up to the 36 ? 50.5 lb.ft of torque specified, even though the lock washer was bent over correctly against one of the nut's edges. I could just about undo the nut by hand. Does any body think that this could be related to the rattling sound? Also, when I retorque the nut, are there any special tricks or techniques for bending up the lock washer to engage the nut tightly? I can already imagine myself wasting 30 minutes trying to get hold of the edge of the washer so I can bend it. Since I don't have a spare lock washer, is it OK to reuse it and just bend up a different part of the washer's perimeter? (Hap, I promise to get some new lock washers when/if I order some parts from Ron Ayers!)

Three other questions:

1) Am I correct in thinking the clutch plates with the friction material are the "drive" plates?........if I order some I want to make sure I get the right plates.
2) How does one measure the drive plate thickness accurately without an expensive micrometer? The friction material on the plates is about the thickness of about 3 or 4 sheets of paper on each side of the metal part of the plate (after 34,000 miles)??.is this too thin?
3) Some of the front faces (not edges) of some of the tabs on the perimeter of the drive plates have irregular, vertical (i.e. sort of radial) scratches that look fresh. I cannot see where these faces would contact anything else and get scratched. I suppose they could have been made prior to installation but that would have been over 20 years ago. Anybody seen this sort of thing before, or got any ideas as to the cause?

As always, many thanks in anticipation of your advice.

Simon Waters

[1100ED]

Ill b the first to mis lead you Simon. You can re use the washer and bend it over in a different location. the nut almost coming off by hand sounds like it may very well be the culprit. The clutch fiber plates((guessing again) why not just re assemble the unit and see what happens. unless your clutch was slipping already. I am used to the two different types of clutch plates being refereed to as the steel plates and the fiber plates. Most fiber plates that i have seen are designed with groves in the fiber portion that could be described as being lines of radius of they were extended inward toward the center of the individual disk. If yours are smooth then my conclusion would be that they are completely worn. HOWEVER It may be that some brands of clutch fibers are made without the little groves in them.
ThATS MY BEST SIMON

[Hap Call]

Re: Clutch Conundrum & Questions

What was interesting was that the clutch basket nut wasn't on tight?.certainly not up to the 36 ? 50.5 lb.ft of torque specified, even though the lock washer was bent over correctly against one of the nut's edges. I could just about undo the nut by hand. Does any body think that this could be related to the rattling sound? Also, when I retorque the nut, are there any special tricks or techniques for bending up the lock washer to engage the nut tightly? I can already imagine myself wasting 30 minutes trying to get hold of the edge of the washer so I can bend it. Since I don't have a spare lock washer, is it OK to reuse it and just bend up a different part of the washer's perimeter? (Hap, I promise to get some new lock washers when/if I order some parts from Ron Ayers!)

That nut being loose can certainly be the source of the rattling (I would almost bet on it). I advise you to get a new clutch hub nut from APE. You can purchase them from Murdoch Racing for about 10 to 12 dollars. You can reuse the washer but I would change it if it is too beaten up from prior use. I use a big honking screwdriver to lever up the edge of the washer then tap it into place.

Three other questions:

1) Am I correct in thinking the clutch plates with the friction material are the "drive" plates?........if I order some I want to make sure I get the right plates.

The plates with the friction material are called friction plates and the metal plates are called drive plates...at least that is the way I have always referred to them.

2) How does one measure the drive plate thickness accurately without an expensive micrometer? The friction material on the plates is about the thickness of about 3 or 4 sheets of paper on each side of the metal part of the plate (after 34,000 miles)??.is this too thin?

I have always replaced them only if they were slipping...never measured them. You should be able to see some shallow "slots" that radiate outward on the friction plates. The metal plates should have a bunch of tiny indentions that you can just feel with your fingernail. The metal plates should not have any signs of overheating such as bluing of the surface or warping.

3) Some of the front faces (not edges) of some of the tabs on the perimeter of the drive plates have irregular, vertical (i.e. sort of radial) scratches that look fresh. I cannot see where these faces would contact anything else and get scratched. I suppose they could have been made prior to installation but that would have been over 20 years ago. Anybody seen this sort of thing before, or got any ideas as to the cause?

Could you take some photos and post them?

Hap

[Anonymous]

Re: Clutch Conundrum & Questions

The plates with the friction material are called friction plates and the metal plates are called drive plates...at least that is the way I have always referred to them.

I don't want to belabour the naming question, because I think probably the "metal" and "fiber" naming convention will be misunderstood least often. My understanding was that the fiber plates are called drive plates, and the metal plates are driven plates -- because the metal plates are driven by the fiber plates.

2) How does one measure the drive plate thickness accurately without an expensive micrometer?

I went shopping for measuring tools when I was pulled my engine apart, and found that for most purposes a caliper will do the trick just fine. I imagine (someone correct me if I'm wrong here) that even a vernier caliper, which can be got pretty cheap, will give you enough to compare with Suzuki's specs in this case.

Michael

[Anonymous]

Thank you, gentlemen, for your replies.

One more question related to Hap's recommendation: What is different about the APE clutch hub nut vs. the standard Suzuki nut? Also, is the standard lock washer used with the APE nut, and do you apply the same tightening torque?

Mmmmmmm.......that was three questions. :?

Simon

[Hap Call]

Thank you, gentlemen, for your replies.

One more question related to Hap's recommendation: What is different about the APE clutch hub nut vs. the standard Suzuki nut? Also, is the standard lock washer used with the APE nut, and do you apply the same tightening torque?

Mmmmmmm.......that was three questions. :?

Simon

My understanding is that the APE nut is machined to closer tolerances. They (that is APE) says that the new nut will stop the loosening that you and I saw on our bikes. I used the standard lock washer when I did mine. I also applied the stock torque standards to mine. The guys at Murdoch Racing can give you specifics.

Michael is right...call 'em metal or fiber and no one gets confused!

Hap

[silverhorse47]

Simon if the fiber disk is over 2.5 mm you are ok. The further over it is the better. You should be able to get a good eyeball idea of this with just a good stainless ruler.

My clutch had the 'spring type rattle' and it was definitely the lighter springs that were the culprits. I could spin the heavier springs in their holders, but not move them endo. The light springs definitely moved endo, and I could move the backing plate very slightly in rotation. It does this when it engages, anyway, but it should be hard to do...

I spread my springs with a 45 degree cold chisel. All is well now and has been for some time...(purists need not reply). If there is no end play in any of your springs I think the source of the rattle must be the loose nut. Check to make sure there is no wear on the splines of the basket from it being loose. If there is wear and you don't want to replace it right now......(purists stop reading here), 'bearing fit locktite' will keep you going for a long time.

I reuse this type of washer all the time unless there is a smashed circle part on it from the nut digging into it. If it was properly torqued there will not likely be this depression, but if there is one the washer is likely weak exactly where the new edge will crimp the nut. As far as turning it up...can use big honking screwdriver as suggested, or put a little something under the lip as you tighten the nut so it turns up as you snug it down, then use water pump pliers to press it up against the nut after it is torqued. I usually also take a blunt chisel and tap it flat against the nut, but I doubt if this is really necessary.

S.

[Anonymous]

Re: Clutch Conundrum & Questions

I thought that the noise might be in the clutch basket: either worn rivets or lazy damping springs. However, the rivets looked OK, and only the 3 thick, course springs (i.e. not the 3 thinner, finer springs) showed a little bit of movement in their slots. I couldn't turn the backing plate relative to the body of the clutch basket.

Right, forgot I wanted to comment on this point. Even with the weak damping springs in my clutch basket, I was unable to turn the gear relative to the basket. Three of my springs were rattling (can't recall which) and the other three seemed to have been shimmed at some point, as there were washers at one end. If I gave the basket a shake, I could hear the loose springs rattle -- and that was the clearest indicator for me. Replacing the clutch basket has fixed the problem.

I would certainly start by tightening the hub nut, if it seems to be loose -- cheapest solutions first, right? But if the damper spring are loose enough to rattle when you shake the basket, I would also keep them in mind.

Michael

[1100ED]

A tip given to me by Steve Johnson in Birmingham Alabama was that if you use the billet replacement nut it could be a little rough some times and a little rubbing compound in the threads ans some lapping wouldn't hurt. just clean it off afterwords. The nut that i received from Murdoch happened to be just fine and i didn't need to do anything. I also think that you can purchase a high quality lock washer yo go with that nut but i dint remember any more --it has been a couple of years since i did a HD clutch and hub mod.

[Anonymous]

Again, many thanks for the replies.

Following the advice, I shall try reinstalling the clutch with the hub nut torqued to spec (when the cover gaskets arrive). I have ordered an APE nut from Murdoch Racing (talked to Jay, Dom, and I even said some nice things about you :roll: ) for $10.75 + $5.79 shipping. Jay at Murdoch said that the big advantage of the special nut was that you could torque it up higher than the OE nut without running the same risk of stripping threads. He also said a touch of Loctite Blue could be used, as well as the lock washer. BTW, I had already double-checked that the Suzuki part number for the '83 GS750ES clutch hub nut was the same as for the '82/'83 GS1100's, so the APE nut will fit.

Silverhorse47, I squinted fiercely at the fiber plate thickness measured against a mm ruler.......came out at about 2.6 mms vs. 2.7 - 2.9 manual spec, and 2.6 mm thickness limit (also as per manual). While I have them out, I will take the basket and plates down to the m/c store where I know the folks fairly well and ask their opinion. I am pretty sure the fiber plates are at the end of their life but I would also like their opinion on the scratches on the plate tabs and the basket condition. For the life of me, I cannot imagine what could contact those surfaces and produce these marks. Hap, unfortunately, I don't have the equipment to take and post pictures but I will pass on anything I learn from the local experts.

One last thing: there is usually one unforeseen thing on a job that can "get" you. On this clutch removal, it would have been having a metric socket big enough for the clutch hub nut.........ironically, the nut was loose enough to only require the slightest twist from the "jaws" of an adjustable wrench engaged at right angles to the nut. Hap or Scotty, do you know if the APE nut requires the same size metric socket as the OE nut?

[Hap Call]

It was the same sized nut. I had a socket but not a 1/2" drive torque wrench that would go that high, I weighed my middle daughter, measured out on the breaker bar the distance I needed (torque=force*lever arm) and had her stand on it... :?

Hap

[silverhorse47]

Simon yes the standard for the clutch thickness is 2.7 to 2.9...but the limit is 2.4. So I would agree that your plates are getting close to the end.
S.

[1100ED]

It was the same sized nut. I had a socket but not a 1/2" drive torque wrench that would go that high, I weighed my middle daughter, measured out on the breaker bar the distance I needed (torque=force*lever arm) and had her stand on it... :?

Hap

ENGINEERS 8O

[silverhorse47]

" 2.6 mm thickness limit"

Sorry Simon...I was reading the specs on the 700 rather than the 750... 2.6 is correct for the 750.

S.

[Anonymous]

came out at about 2.6 mms vs. 2.7 - 2.9 manual spec

If in doubt, I would replace the friction plates, while your at it.

the nut was loose enough to only require the slightest twist from the "jaws" of an adjustable wrench engaged at right angles to the nut.

Like Hap, I bet that's where the rattling sound came from.

the m/c store where I know the folks fairly well

Perhaps they are willing to lend you a (32 mm ??) socket and maybe even a torque wrench over the weekend :roll:

I did re-use the old washer.
Try to get a big screwdriver behind it and bend it.