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Another Tach Gear Housing Oil Seal Replacement!!!

Discussion in 'XJ DIY How-To Instructions' started by Nuch, Mar 26, 2018.

  1. Nuch

    Nuch Well-Known Member

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    I was moved to put this thread together because we lost the images (at least for the time being) from Big Fitz’s thread that can be found here:

    http://xjbikes.com/forums/threads/tach-gear-housing-oil-seal-replacement-w-pics.19538/

    His words are still Gold. If I were you, I’d read through (and follow) his process first. Below is what I did just this afternoon in the driveway… honestly it didn’t take very long. Maybe a half hour from start to cleanup.

    Just a few weeks ago, I brought a “new” RJ home. The seller stated that it had a head leak and had intentions of getting it fixed, but just never got around to it. He even gave me the brand new OEM head gasket still sealed in plastic.

    After giving her a thorough scrub down, it appeared that the majority of the oil mess was coming from the tachometer drive gear. The lower end of the motor is a bit oily as well, but I have a sneaking suspicion that it’s a cheap-o oil filter cover gasket that is the offender.

    Here it is after the initial scrub… Not bad!
    a-tacho_01.jpg



    First unscrew the outer collar. I had to “break” it with a pair of pliers, but once free, she came right off by hand.
    a-tacho_02.jpg



    Pull your tach cable out and swing it out of the way for the time being.
    a-tacho_03.jpg



    At this point I removed the threaded adapter that had the giant flat head slot across it. I used a thin spackle knife to break it free and then it unscrewed pretty easy.
    a-tacho_04.jpg



    Remove the “stopper” (Yes, that’s it’s name) with a H5 Hex Key.
    a-tacho_05.jpg
     
    Last edited: Mar 28, 2018
  2. Nuch

    Nuch Well-Known Member

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    Using a pair of pliers, Gently grab hold of the housing and do a “twisty, wiggly, uppy, downy” type of movement while you also pull away from the engine. Did I say be gentle? Yeah, be gentler than that.
    a-tacho_06.jpg



    You’ll start to see the o-ring first as it makes it’s way out, At some point you’ll be able to complete the pull without the pliers.
    a-tacho_07.jpg



    Here it is in all it’s glory.
    a-tacho_08.jpg



    Now the gear drive can be removed from the housing. Now is a good time to clean it up real good and buff the heck out of the shaft because… why not?
    a-tacho_09.jpg



    Once the gear drive is out, pull the oil seal. I used a bent pick. Make sure not to scratch the bore. Also at this point, notice the position of the groove on the oil seal. The groove faces towards the engine.
    a-tacho_10.jpg
     
    Last edited: Mar 28, 2018
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  3. Nuch

    Nuch Well-Known Member

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    Now liberate the O-Ring from the outside of the housing.
    a-tacho_11.jpg



    Old vs. New! Look at how chunky our new seal is. Reminds me of a chocolate donut. No wonder we were getting oil on our jeans at speed.
    a-tacho_12.jpg



    After you give the housing a good scrub, slather some silicone grease on the seal, send it home into the housing, remember, the seal has the groove TOWARDS the engine.
    a-tacho_13.jpg
    As a side note, I checked in with Len regarding the amount of grease that should be used... he said, and I quote... "Silicone grease cannot be over-used in any situation!"

    Let's assume he's just talking about rubber gaskets and o-rings. :eek:



    I used a 1/4” extension to make sure the seal made a good seat!
    a-tacho_14.jpg



    Now grease up the o-ring.
    a-tacho_15.jpg
     
    Last edited: Mar 28, 2018
  4. Nuch

    Nuch Well-Known Member

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    Seat the o-ring in the groove on the outside of the housing.
    a-tacho_16.jpg


    Replace the drive gear.
    a-tacho_17.jpg


    Gently screw the threaded adapter back into place. You can tighten it later
    a-tacho_18.jpg


    Putting the housing back in was probably the most difficult thing about this project. It took a bit of wiggling, but eventually she went home. Go easy… the gears should find their way. Then replace the “stopper" and hex bolt. I used that spackle knife to give the adapter a good tightening after the stopper was in place.
    a-tacho_19.jpg

    Now replace your tach cable. You’re done!
    a-tacho_20.jpg
     
    Last edited: Mar 28, 2018
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  5. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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  6. Nuch

    Nuch Well-Known Member

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    Here you have the two new parts that were used. Remember the groove on the seal when you replace it... Groove TOWARDS the engine! Where did I get them? Where else but from Len @ XJ 4 Ever. Click the top right hand corner of every page to get them (if you’re not already in the know of course!) or anything else you might need for your XJ.
    a-tacho_parts.jpg
    Much thanks to Len for the parts and advice. A shout out to Hogfiddles for the help and advice as well. I heard he had the unique opportunity today to travel by both a XJ and snow mobile in the same hour. What’s better than that?
     
    Last edited: Mar 28, 2018
  7. cgutz

    cgutz Well-Known Member

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    Nice write up. My old seal didn't come out as nicely as yours, had to do some "digging" and gentle scraping with the pick, carefully so as not to gouge housing.
     
  8. Nuch

    Nuch Well-Known Member

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    Yeah, It did come out pretty easy, which made me think it didn't need replacing... But when I compared the old to the new, It was clear that the new seal from Len was BETTER. I have a few more things to sort out before I can give her a good run to determine the results of my handiwork...
     
  9. Chitwood

    Chitwood Well-Known Member

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    Thanks to this magnificent write up I decided I would tackle this task on the gf's bike since it is weeping a little bit from the tach drive. However, I cannot for the life of me get the threaded adapter to come loose. I have a new plan of attack to try this evening and we will see from there. Any chance a 550 tach drive is the same as the 650? I know where there is one and for a fact the threaded adapter is loose on that one if my efforts fail/I destroy something.
     
  10. Nuch

    Nuch Well-Known Member

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    Since the write up...
    After connecting the tach cable and riding a bit, I noticed that the tach gauge response was very sluggish. I lubed the cable and put things back together but still had the same problem. I've read that the internal cable could get bound up when you reinstall the connections (I believe it was k-moe that posted it?) So I made sure that didn't happen... still no good. Then I loosened the nut on each end of the cable and only "finger tightened" it... Boom! there's my bouncy needle!

    Unfortunately, now it's weeping again... :mad: Haven't had the chance to re address the problem. I'm happy to report that the RJ is registered and insured (and titled I might add... thank you NYS! CT doesn't issue anymore over 20 years is it?) Perhaps I need to go tighter with adapter... Maybe someone can chime in here on this one???

    Yamaha is listing the same part number on that adapter (256-17848-00-00) for both the 1982 XJ550RJ and the 1982XJ650RJ.
     
  11. Chitwood

    Chitwood Well-Known Member

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    I did manage to free the threaded adapter from the aluminum housing and got the seal and o ring replaced. It has not been ridden since so hopefully everything works out for the best.
     
  12. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    I have recently discovered a terrible secret in regard to tach drive housings and am working on the write-up. Essentially, at some point during their evolution Yamaha changed the part from machined aluminum to cast/molded POT METAL which will distort over time and bind the gear shaft.
    As long as your housing is obviously aluminum, it will not have the issue.

    Stay tuned.
     
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  13. Door dude

    Door dude Active Member Premium Member

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    Might try some teflon tape or heat resistant plumbing tape ? I have seen where, that the cable nut as i call it can get out of round and become oval shaped. and a possible leak.
     
    Last edited: Aug 25, 2020
  14. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    The cable retaining collar is not an oil seal; if oil gets that far something else is amiss.

    As long as the housing is for sure aluminum we can pretty much rule out an issue with the housing itself.

    There are two ways for the unit to seep oil: past the oil seal/shaft; or past the body where it plugs into the head. If it is leaking past the oil seal on the shaft, either the seal was installed backward, the threaded collar was over tightened distorting the seal, or the shaft is worn, bent or pitted.

    If it is leaking around where the body plugs into the head, then the special "D" profile o-ring on the body needs to be replaced. This is not a normal o-ring, it has a flat inner surface, in section, it is only half-round.

    One other thing worth mentioning: if it WAS leaking appreciably before, it may have pumped a bunch of oil up into the cable which is now draining back out making you think the unit is still seeping...
     
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