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Clutch Spring Fatigue Is REAL! (And other scary bedtime clutch system stories...)

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    Clutch Spring Fatigue Is REAL! (And other scary bedtime clutch system stories...)

    Springs: I just did the clutch job on my GS1100GL last night, and measured free length of the old vs. new clutch springs using a dial caliper. Old springs were 1.540". New springs were 1.624". That's .084" in free length! A note about springs: I know that some have shimmed their springs to regain spring pressure, but I don't think that is a good idea; the old springs have lost spring rate and length over time, and shimming only compensates for length. The springs are cheap. Buy them.

    Discs: My clutch discs are in spec for thickness, albeit at the bottom of spec (.015", with spec being .014-.020",) so the springs alone likely would have resolved my slipping problem. But I LOATHE rework, so I bought all new discs. I will save the original discs for possible future need.

    Plates (steels): Slipping, however, was not the only problem I had; the clutch was grabbing enough to tug the bike forward in gear with the clutch disengaged, but not so much that I couldn't easily restrain the bike with my feet. When I removed the clutch three weeks ago to inspect it in order to order new parts, I found uneven discoloration on three of the plates. Uneven discoloration means the possibility of distortion. Right or wrong, I associated the discoloration with the grabbing, and replaced the plates with all new.

    "The Piano Wire" (Scary bedtime story number 1): If you are taking off the innermost plate, SPEND THE $4 AND BUY THIS THING. I did not know that it was a one-use part, so I didn't buy it. Not only do the bent legs at the ends of the wire deform when removed from the drum, but also the whole length of the wire gets kinked a little when it is removed from the teeth in the drum. And for those who haven't been that far into a clutch job before, I will say that there is a spring washer behind that innermost plate which must be compressed in order for the wire to fit. I would be keen to see the tool Suzuki used to install this wire at the factory. Not having a special tool, I carefully and conservatively used a pair of welder's Vise Grips (big C jaw) to compress the spring washer just enough to press the wire into a few teeth, then repositioned the drum and pressed the wire into a few more teeth. Once I got all the way around, I found that the wire needed to be clocked a bit in order for the second bent leg to fit into the hole. So the wire came off and I started the process again. Having done this once, I could probably make a fresh attempt with a new wire in less than half an hour, but the whole process of discovery took about two hours from start to finish--FOR THE WIRE ALONE.

    Cover and pinion gear (Scary bedtime story number 2): With the clutch assembled and torqued, I reinstalled the cover with a new OEM gasket. I spun down all the bolts, then snugged them, then tightened them. When I went to reinstall the actuator arm, I found that the pinion shaft no longer moved effortlessly through is freeplay. I could easily push the arm through its range of play with only my index finger, but it was restrained. So I called my local GS whisperer and asked what gives. He had never heard of such a problem. I removed the cover and laid it on the flattest surface I have, which is a milled top for a table saw. I found no lack of flatness to be concerned about, reading .008" as the worst possible scenario. I inspected both mating surfaces and dowel holes for debris or any matter that could cause a bind, but found nothing. I put the cover back on and went around the bolts very gradually tightening each one and checking for movement on the pinion shaft before moving to the next. The shaft moved smoothly. The last two were the top two bolts on either side of the pinion shaft. When I gave those their last tighten, it was only then that the shaft's movement became tight. Having investigated and eliminated every other possible cause for the shaft to be difficult to turn, I decided to send it. I tightened those bolts and installed the actuator arm in the correct orientation. After running the engine and cycling the clutch a few times, I found the arm's movement to be more free. Time for a shrug...

    So, I have a working, not slipping, not Bidenishly grabbing at an inopportune time clutch and am ready to take a ride and find the next failure that puts the bike back on the center stand while I wait two weeks for parts to come in...
    1982 GS1100GL: hand built stainless 4-1 exhaust, pods, jetting.

    #2
    I bought new clutch springs, I am not sure why. Should I just replace them when they arrive? Only complaint of the clutch is that it grabs with the handle too far out (my fingers are too short it feels to get accurate slow moving from start).
    GS1000G 1981

    Comment


      #3
      Originally posted by Noreg View Post
      I bought new clutch springs, I am not sure why. Should I just replace them when they arrive? Only complaint of the clutch is that it grabs with the handle too far out (my fingers are too short it feels to get accurate slow moving from start).
      If your clutch is not slipping, you can change the engagement point simply by using the adjusters. It's completely straightforward.

      I don't know if your bike has an adjuster in the middle of the cable, but down on the engine case, you can loosen the locknut a bit, then "tighten" the adjuster barrel a turn or so, re-tighten the locknut and see how you like it. You can also make fine adjustments using the adjuster on the clutch lever perch.
      1983 GS850G, Cosmos Blue.
      2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
      2015 Yamaha FJ-09, Magma Red Power Corrupts...
      Eat more venison.

      Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

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      Comment


        #4
        Originally posted by Noreg View Post
        I bought new clutch springs, I am not sure why. Should I just replace them when they arrive? Only complaint of the clutch is that it grabs with the handle too far out (my fingers are too short it feels to get accurate slow moving from start).
        As bwringer said, the springs will not make a difference for engagement. Engagement point is all in cable adjustment. I don't know what the manual says on the subject, but my practice with clutch cables is to adjust a small amount of slack such that 1/16-1/8" of lever travel takes up the slack. This is to ensure that when the clutch is engaged, nothing holds it back.
        1982 GS1100GL: hand built stainless 4-1 exhaust, pods, jetting.

        Comment


          #5
          Originally posted by Longitudinal View Post
          Springs: I just did the clutch job on my GS1100GL last night, and measured free length of the old vs. new clutch springs using a dial caliper. Old springs were 1.540". New springs were 1.624". That's .084" in free length! A note about springs: I know that some have shimmed their springs to regain spring pressure, but I don't think that is a good idea; the old springs have lost spring rate and length over time, and shimming only compensates for length. The springs are cheap. Buy them.

          Discs: My clutch discs are in spec for thickness, albeit at the bottom of spec (.015", with spec being .014-.020",) so the springs alone likely would have resolved my slipping problem. But I LOATHE rework, so I bought all new discs. I will save the original discs for possible future need.

          Plates (steels): Slipping, however, was not the only problem I had; the clutch was grabbing enough to tug the bike forward in gear with the clutch disengaged, but not so much that I couldn't easily restrain the bike with my feet. When I removed the clutch three weeks ago to inspect it in order to order new parts, I found uneven discoloration on three of the plates. Uneven discoloration means the possibility of distortion. Right or wrong, I associated the discoloration with the grabbing, and replaced the plates with all new.

          "The Piano Wire" (Scary bedtime story number 1): If you are taking off the innermost plate, SPEND THE $4 AND BUY THIS THING. I did not know that it was a one-use part, so I didn't buy it. Not only do the bent legs at the ends of the wire deform when removed from the drum, but also the whole length of the wire gets kinked a little when it is removed from the teeth in the drum. And for those who haven't been that far into a clutch job before, I will say that there is a spring washer behind that innermost plate which must be compressed in order for the wire to fit. I would be keen to see the tool Suzuki used to install this wire at the factory. Not having a special tool, I carefully and conservatively used a pair of welder's Vise Grips (big C jaw) to compress the spring washer just enough to press the wire into a few teeth, then repositioned the drum and pressed the wire into a few more teeth. Once I got all the way around, I found that the wire needed to be clocked a bit in order for the second bent leg to fit into the hole. So the wire came off and I started the process again. Having done this once, I could probably make a fresh attempt with a new wire in less than half an hour, but the whole process of discovery took about two hours from start to finish--FOR THE WIRE ALONE.

          Cover and pinion gear (Scary bedtime story number 2): With the clutch assembled and torqued, I reinstalled the cover with a new OEM gasket. I spun down all the bolts, then snugged them, then tightened them. When I went to reinstall the actuator arm, I found that the pinion shaft no longer moved effortlessly through is freeplay. I could easily push the arm through its range of play with only my index finger, but it was restrained. So I called my local GS whisperer and asked what gives. He had never heard of such a problem. I removed the cover and laid it on the flattest surface I have, which is a milled top for a table saw. I found no lack of flatness to be concerned about, reading .008" as the worst possible scenario. I inspected both mating surfaces and dowel holes for debris or any matter that could cause a bind, but found nothing. I put the cover back on and went around the bolts very gradually tightening each one and checking for movement on the pinion shaft before moving to the next. The shaft moved smoothly. The last two were the top two bolts on either side of the pinion shaft. When I gave those their last tighten, it was only then that the shaft's movement became tight. Having investigated and eliminated every other possible cause for the shaft to be difficult to turn, I decided to send it. I tightened those bolts and installed the actuator arm in the correct orientation. After running the engine and cycling the clutch a few times, I found the arm's movement to be more free. Time for a shrug...

          So, I have a working, not slipping, not Bidenishly grabbing at an inopportune time clutch and am ready to take a ride and find the next failure that puts the bike back on the center stand while I wait two weeks for parts to come in...
          Sounds good to me...I check the length of springs but have never had them out of spec.

          the cover: This reminds me of those places the gasket need be the right thickness because a mechanism in a cover mates with something on the engine.(another example is on some valve covers where the tach gear drive on the cover mates with cam worm gear ie:GSX400)..Too thin can cause the gear to bind. Too thick can cause the teeth to mesh loosely. It's Something to look at.

          Comment


            #6
            Originally posted by Gorminrider View Post
            Sounds good to me...I check the length of springs but have never had them out of spec.

            the cover: This reminds me of those places the gasket need be the right thickness because a mechanism in a cover mates with something on the engine.(another example is on some valve covers where the tach gear drive on the cover mates with cam worm gear ie:GSX400)..Too thin can cause the gear to bind. Too thick can cause the teeth to mesh loosely. It's Something to look at.
            It's a Suzuki gasket, and its thickness isn't pushing the rack and pinion toward or away from each other.
            1982 GS1100GL: hand built stainless 4-1 exhaust, pods, jetting.

            Comment


              #7
              But I do know what you're talking about. In my FIAT days, we used to stack two cam box gaskets if we needed a tiny bit more range for valve lash adjustment.
              1982 GS1100GL: hand built stainless 4-1 exhaust, pods, jetting.

              Comment


                #8
                I've yet to open up a Suzuki motor & have the clutch spring IN SPEC. For those that are really tight... by the EBC +15% spring set for $8 and use three of them. It works and also seems to compensate for worn plates better than new stock (assuming that anyone who wants to save on springs is not going to want to drop $80 on new plates....

                If I remember correctly, if you don't replace the steels then you don't have to mess with that piano wire. I agree it's a pain to fit but I don't remember it being a two hour job...

                I've had that "stiff release" problem before. I think it's that it gets turned further than it would during normal use and goes stiff (perhaps the bearing is stiff or maybe something gets slightly ovalized or you disturb some crud on the top seal or something). As you say if you activate it a few times in my experience it settles in back to normal.
                Last edited by salty_monk; 08-21-2020, 02:44 PM.
                1980 GS1000G - Sold
                1978 GS1000E - Finished!
                1980 GS550E - Fixed & given to a friend
                1983 GS750ES Special - Sold
                2009 KLR 650 - Sold - gone to TX!
                1982 GS1100G - Rebuilt and finished. - Sold
                2009 TE610 - Dual Sporting around dreaming of Dakar..... - FOR SALE!

                www.parasiticsanalytics.com

                TWINPOT BRAKE UPGRADE LINKY: http://www.thegsresources.com/_forum...e-on-78-Skunk/

                Comment


                  #9
                  Originally posted by Longitudinal View Post
                  But I do know what you're talking about. In my FIAT days, we used to stack two cam box gaskets if we needed a tiny bit more range for valve lash adjustment.
                  It's also a technique for lowering or raising fuel pump pressure on some cars
                  1980 GS1000G - Sold
                  1978 GS1000E - Finished!
                  1980 GS550E - Fixed & given to a friend
                  1983 GS750ES Special - Sold
                  2009 KLR 650 - Sold - gone to TX!
                  1982 GS1100G - Rebuilt and finished. - Sold
                  2009 TE610 - Dual Sporting around dreaming of Dakar..... - FOR SALE!

                  www.parasiticsanalytics.com

                  TWINPOT BRAKE UPGRADE LINKY: http://www.thegsresources.com/_forum...e-on-78-Skunk/

                  Comment


                    #10
                    Originally posted by salty_monk View Post
                    If I remember correctly, if you don't replace the steels then you don't have to mess with that piano wire. I agree it's a pain to fit but I don't remember it being a two hour job...
                    Right. I was tempted not to replace that innermost/bottom-in-the-stack plate, but I hate to do a job 90% instead of 100%. There was no evidence that the bottom steel was distorted, but what if... It certainly wouldn't be a two hour job now that I know to order a new one and developed a technique for installing it. But that first run and the follow-up run after I found that the wire needed to be a clocked a couple of degrees so the second bent leg could go into the hole made for a miserable night.
                    1982 GS1100GL: hand built stainless 4-1 exhaust, pods, jetting.

                    Comment

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