Striped bolt on clutch slave cylinder?

Discussion in 'Mechanics Garage' started by sac, Mar 14, 2010.

  1. sac

    sac New Member

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    Hi, I'm new to the vfr world. Just bought a 1999 model three days ago. Bike runs great with 39,000 onthe clock. Yesterday I discovered that the lower, long 5mm bolt that holds the clutch slave cylinder to the right side of the case seems to be stripped. Slides in and out without resistance as though it has been that way a while. The clutch seems to work fine, but I'd like that bolt to be tight. Can I tap it to 6mm? Is there room for that? Anyone run into this? Will I need to take the right crank case off (I'd really rather not) or can I do it with a long tap? Or should I just ride it since it seems to works fine?
    Thanks a lot in advance for any advice.
     
  2. vfrcapn

    vfrcapn Member

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    You should be able to take the clutch slave off with just the other two bolts and then I'd try tapping the bad one to 6mm. No need to disconnect the clutch line. Mine's not off right now but I don't see why this wouldn't work, you may need to drill out the clutch slave mounting hole to 6mm. I think the clutch slave screws right in to the 'left' side of the motor anyway?
     
  3. dizzy

    dizzy New Member

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    Gauge the depthness of the hole with a caliiper. See if there is room to put in a 'teeny' bit longer bolt which might tighten down.
     
  4. donald branscom

    donald branscom New Member

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    You need to do it the right way. It is very important before it gets worse.
    The clutch slave cylinder can exert thousands of pounds of pressure.
    It can cause the case to crack or the clutch push rod to get bent.

    Remove the clutch slave cylinder WITHOUT removing the hydraulic line.
    Put a small clamp gently on the slave cylinder and piston to keep them from
    coming apart but do not apply any pressure on the clamp.

    Now you will be able to see the hole and figure out how much material
    is left and if you can tap the hole to the next larger size.
    Remember the next larger size might be american SAE size.
    You want to remove the least material possible.

    If you do not know how to do this right ask for help.
    Do not use the TAP on a drill motor,turn it by hand.
    If you do this right you will save the case and your clutch and be able to ride all summer.

    It is good that you noticed this problem. Before it gets real expensive.
    Don't forget that the hole in the slave cylinder may have to be made just slightly larger for the next size bolt or screw.
    Look online for DRILL TAP CHART and figure out if the next size up will be metric or american.
    Like I say ...increase the bolt size by the smallest amount possible. Use lubricant on the tap.
     
    TonyD likes this.
  5. sac

    sac New Member

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    @ vfrcpn - Yes, it is the left side (my other right). I should have said crank case cover. I thought there might be something in the way since the bolt is so long.
    @ donald - thanks for the clamp suggestion.

    I'll give it a try.

    Thanks!
     
  6. sac

    sac New Member

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    As it turns out, the stripped bolt hole was 6mm. The bolt was 90mm long. I was able to tap it to1/4-20 by welding a 1/4" bolt to my tap inorder to get the extra length. It seems to be fixed.

    Thanks again.
     
  7. squirrelman

    squirrelman Member

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    Like this ??

    Here's how i fixed this customer's bike: since there was no material left to rethread, i got a long screw from hardware store as large as would fit into the hole and with a countersunk-type screwhead that would sit flat against the surface and a nut that fit.

    Inserted screw from back, tightened nut on top of slave cylinder, firmly attaching slave and transferring loads from the broken mounting point to ALL other cover mounts.

    This fix is simple, elegant , cheap, and eliminates rethreading or possible popping of any attempted hole repair
     

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    Last edited: Mar 16, 2010
  8. sac

    sac New Member

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    I left the slave cylinder in place. If you remove it an extra long tap wouldn't be needed, would it?
     
  9. donald branscom

    donald branscom New Member

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    I like the idea of taking it apart to really see what is going on and to get the shavings and chips out.
    A stud is a good idea because then you are not unthreading it often and that lessens the damage that can occur.
    I wish the manufacturers would get their sh^@ together and make the clutch slave cylinders more universal and adjustable so that you can adjust them in or out with shims to get more throw at the lever.

    And get the transmissions so they can be removed WITHOUT splitting the cases!!!
    Damn how many years will it take??? Husqvqrna did it. H-D does it. Several bikes have that option.
    Taking the entire engine apart just to replace a shifting fork is crazy people!!!
    I have been waiting since 1969!!!! Oh and while they are at - it GET RID of shifting forks and just use ball bearings that drop into holes like HODAKA did.
     
  10. sac

    sac New Member

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    Squirrelman, I didn't see your explanation yesterday.

    "Inserted screw from back, tightened nut on top of slave cylinder, firmly attaching slave and transferring loads from the broken mounting point to ALL other cover mounts."

    I guess since i did not disassemble anything I don't understand what is going on here. Your pictures seem to show the stock bolts. The stripped hole on my bike was the lower long bolt which holds cylinder onto case. It is a blind hole into the case. Does your solution just secure slave cylinder to drive sprocket cover and rely on one less bolt to hold cover to case?

    I'm sure you know what you are doing. I'm not a mechanic and am just trying to learn a little bit.

    Thanks
     
  11. Alaskan

    Alaskan Member

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    Would a Helicoil work in that situation?

    If we're complaining about design, how stupid is it to require splitting the case to replace the clutch pushrod seal? Grrrrr!

    Threadjack Alert: Donald, did you have a Hodaka? One of my first bikes was a Super Rat. What a blast!
     
  12. squirrelman

    squirrelman Member

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    <<<<<>>>>>


    Yes, it secures slave to sprocket cover.

    SAC, you'll need to remove the sprocket cover to fix the problem and be VERY careful not to over-tighten the bolts !!!!

    NO muss, no fuss.

    Typically, the mounting point is damaged too much to thread or helicoil.

    Your damage is probably very similar.

    There is only one cause of this problem: an uneducated mechanic !!

    There is a very specific low torque for these small bolts, and an exact sequence for tightening them ( see service manual).

    In the photo here the long bolt has the ruined mounting point and is held in place barely by only 2 threads, not repairable since too much material has been pulled away.
     

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  13. sac

    sac New Member

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    The shop guide that I have doesn't include torque spec for the drive sprocket cover bolts, including the two long ones at slave cylinder. Can anyone provide the number for those?

    Thanks.
     
  14. squirrelman

    squirrelman Member

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    Hard to get a realistic torque reading on very low torque bolts.

    Instead, it's a matter of an educated hand: feel initial tightening, then give it a LITTLE bit more. Just that little , and no more. Comes with experience........
     
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