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Thread: R80 Clutch Actuator Bearing Question

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  1. #1
    Registered User dwyandell's Avatar
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    R80 Clutch Actuator Bearing Question

    I have my '84 R80ST apart to lube the transmission input shaft splines and replace a leaking neutral switch, but I need some guidance from the gurus on the actuator linkage and throwout bearing. . . the parts fiche is a little unclear on this.

    After removing the arm and pulling everything out, the boot was crunchy and clearly had leaked a bit. The old cupped bearing looked a bit dodgy . . .so I ordered a new 'old style' bearing (07 11 9 984 020) from the fiche. What I received has 3 pieces--the bearings in a plastic cage, and two grooved raceway bushings.

    At first, this didnt look like what came out of the hole. The bearing cage I removed is metal and cupped, and neither raceway bushing came free when I took it apart. I dug around in the piston and found that one of the raceways was stuck there, and pulled it out. The other raceway seems firmly affixed to the end of the pushrod.

    My gut feeling, since the boot was leaking and the old parts have some rust, is that this inner raceway is just rusted onto the pushrod and a good twist with the needlenose pliers will pop it off the rod. Then, I'd have 3 pieces more or less the same as what I received. But before I use brute force. . . ..were some of these made with that inner raceway bushing pressed onto, or built into, the end of the push rod? The fiche has none of this. And if my gut is wrong and I go with the brute force approach, chances are I'm gonna be replacing the rod, which means pulling the tranny, etc. etc. Plus these parts are expensive.

    It looks like the parts were changed in '88 to a piston with an integral bearing . . .

    Here's the piston, old cupped bearing and one raceway. . . alongside the new bearing.
    R80STThrowoutBearing-7067small.jpg
    Dave in Vermont
    '84 R80ST
    '81 R100 hack

  2. #2
    Registered User dwyandell's Avatar
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    And heres a picture of the other raceway, stuck fast on the end of the rod. You can see in the mirror the groove. . . .
    So which way do I go with this??


    R80STThrowoutBearing-7073small.jpg
    Dave in Vermont
    '84 R80ST
    '81 R100 hack

  3. #3
    Administrator 20774's Avatar
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    My gut tells me that the bearing is a stack, that third piece is just stuck good. You might work with some good penetrant to soak that inner race. From the picture, it looks like the clutch pushrod has some rust on the surface...that's quite unusual...it should be fairly clean.

    One thing that you should be careful of is the rod to which the one piece is likely stuck has a felt ring surrounding it, about 2-3 inches inboard of the end of the rod. If the rod is pulled too far aft, the felt becomes exposed and it is a devil to get it back in. Typically, the only way to get the clutch pushrod and felt back in is to pull the transmission and shove everything in from the front where you can easily guide the felt into the shaft hole and then push the rod home.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
    Registered User dwyandell's Avatar
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    Yes the last inch or so, at the 'arm end' of the pushrod, is rusty and dirty--likewise the old bearing, the piston, etc. I think the boot had been leaking for awhile. But what does that arm end of the older-style pushrod normally look like? Is it flanged, with a nipple in the middle to center the thrust bearing? I think the parts fiche I saw must be for the new style, which looks like the bearing and piston are mated; looking at the fiche, the newer clutch rod looks like it doesnt have a flanged end .. .
    Dave in Vermont
    '84 R80ST
    '81 R100 hack

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    Administrator 20774's Avatar
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    Anton has a good description of the '81-on pushrod here:

    http://www.largiader.com/articles/throwout/

    In it he says "Bearing races remained at 23.5mm OD but now were 11mm ID to fit around the new adapter that is pressed onto the end of the pushrod." So, it would appear that in your case, that item is indeed pressed on. If that's the case, the only recourse is to remove the rod and deal with it outside the box. That means removing the tranny. He mentions that the individual item assembly has been superceded by the single unit. Interesting...you got individual items as a replacement...left over stock on the shelf?
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  6. #6
    Registered User dwyandell's Avatar
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    I just found the same thing Kurt. Thanks. There's a good photo here .. . .

    The original bearing, and what is on my bike (and what I was sent) are all the old style which has 3 separate parts - an inner cage holding ball bearings flanked by two grooved outer races. These are stacked. The pushrod has a step at the end, and a flanged bushing sits on the step so that the bearing assembly rests against the flange.

    I think the flange itself is pressed on. IN my case, the inner bearing race is rusted onto the shaft and the flange. In the picture, coming from the transmission side, you can see the rusted pushrod, then the flange, then the rusted bearing race, then the nipple of the flange sticking out at the end.

    So this answers my question -- I'll need to be *persuasive* to get that inner bearing race off the shaft, I think. May well need to take out the gearbox.

    BTW if you look at the linked photo of Anton's you can see the newer style as well. The piston and bearing are integral, and there is no flange on the end of the clutch rod. So if one is using a new style integral piston/bearing on the OLD style rod (e.g. if I were to upgrade), it's necessary to remove the pressed-on flange at the end of the rod. Or you can just buy a new style rod.

    No MaxBMW did not send me the wrong thing, or old stock. They sent what I requested. Simply replacing the old bearing, but re-using the original rod and original piston, costs $28 for the replacement bearing; if you upgrade to the new piston/bearing/rod, it costs about $110 in parts.
    Dave in Vermont
    '84 R80ST
    '81 R100 hack

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