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Thread: 78 r80/7 drive shaft bolts wrench

  1. #16
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    Clarify -- the new bolts will go on the drive shaft to transmission , inside of the rubber boot. The gasket is where the rear drive bolts to the swing arm.
    Brian

    86 k100rt, 78 r80/7

  2. #17
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    Quote Originally Posted by yankeeone View Post
    Clarify -- the new bolts will go on the drive shaft to transmission , inside of the rubber boot. The gasket is where the rear drive bolts to the swing arm.
    Ok! Gotcha. I did't know that you had removed the rear drive to do this.

    I may get some flak for this, but I would use a very thin film of silicon seal on the swingarm-to-rear drive gasket as well. I have seen that stuff seal water pumps in cars with NO gaskets. It was especially developed for metal to metal seal with no gaskets to take up space. When properly installed, the silicon material will work wonders!
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

  3. #18
    Rally Rat
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    Arlington, TX
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    Rear drive gasket

    There is no requirement for sealant on this gasket and I can understand why. The rear drive has to be connected to the swing arm so that, when the axle is inserted, it slides in with a minimum amount of friction.
    The correct way to align everything is to bolt up the rear drive without tightening the nuts. Then you insert the axle. This aligns the drive unit so that the axle slides in smoothly. Then you tighten the nuts. So if you add sealant then you're pushing the drive unit towards the rear, thus screwing up the alignment on a different plane. Believe me when I say that I've seen some shade tree mechanics put globs of silicon seal on the gasket to the point that you have to drive out the axle with a hammer! This leads me to the rule of thumb, that if you ever work on a bike that has red, high temp silicon seal oozing out of every mating surface, then you know that someone who doesn't know squat about mechanics has been working on the bike.
    Boxerbruce

  4. #19
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    Quote Originally Posted by 1074 View Post
    There is no requirement for sealant on this gasket and I can understand why. The rear drive has to be connected to the swing arm so that, when the axle is inserted, it slides in with a minimum amount of friction.
    The correct way to align everything is to bolt up the rear drive without tightening the nuts. Then you insert the axle. This aligns the drive unit so that the axle slides in smoothly. Then you tighten the nuts. So if you add sealant then you're pushing the drive unit towards the rear, thus screwing up the alignment on a different plane. Believe me when I say that I've seen some shade tree mechanics put globs of silicon seal on the gasket to the point that you have to drive out the axle with a hammer! This leads me to the rule of thumb, that if you ever work on a bike that has red, high temp silicon seal oozing out of every mating surface, then you know that someone who doesn't know squat about mechanics has been working on the bike.
    The whole purpose of a gasket to begin with is to compensate for two mating surfaces that are not perfectly matched, due to machining imperfections. Also, over the 35+ years, I am sure that the gasket material hasn't been perfect either, and had a "tolerance" as to its thickness and compressabiity.

    When properly used, the silicon sealer would at most add a thickness of .0005 (probably not even that as it would fill gaps, and squeeze out everywhere else which wouldn't affect alignment at all. I am sure the "tolerances" on the swingarm and on the rear drive machining wasn't that close. Add in the gasket material, and the tolerance "stack" becomes more. Silicon will not affect this at all. When used properly, there would be very little squeezed out, and that would be nearly imperceptible, if at all.

    Also, considering the fact that the other side of the swingarm is a squeeze bolt I can guarantee that if you ever had a problem inserting an axle, it wasn't because of .0005 thick of silicon.
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

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