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Tach Gear Housing Oil Seal replacement w/pics

Discussion in 'XJ DIY How-To Instructions' started by bigfitz52, Jul 12, 2009.

  1. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    AS REQUESTED:

    Here's a common problem on XJs with mechanical tachometers:

    [​IMG]


    We need to get it apart and replace seal #4 as well as the (#2) o-ring:

    [​IMG]

    First, disconnect the tachometer cable and push it out of the way, or remove it altogether if you plan to do anything to it.

    Remove the one retaining bolt and the little yoke, and pull the unit out of the front of the motor.
    I had the best results grabbing it with a big pair of pliers lined with cardboard and twist/wiggling it out.

    Unscrew the "adapter" (#5 in the diagram) from the housing body. It may require Kroil, or heat from a propane torch, or both, or nothing at all. I just did TWO; one needed Kroil AND heat, one unscrewed by hand.

    [​IMG]


    The old seal; With the adapter out, we can now get to the old seal. you'll need to dig it out. Don't tear up the housing in the process.
    Note: It's a "real" oil seal, with a metal "frame" just like bigger ones; I use a spring hook myself.

    [​IMG]

    Success!

    [​IMG]

    Discard the o-ring and the old seal.

    [​IMG]

    Now is a good time to clean everything. Use a small chunk of Scotchbrite if necessary to get the inside of the housing where the seal goes CLEAN.

    *tip* drop the retaining yoke and its screw into white vinegar to soak for a while, it will come out looking new.


    NOTE the new seal: It has two different sides, the "lips" go down, or toward the motor.

    [​IMG]


    Install the new seal Apply a light smear of silicone grease to the outside of the seal, ensure it is positioned correctly ("lips" down or toward the motor) and press into place. I used a 9mm deepwell socket.

    [​IMG]

    The new seal in place:

    [​IMG]


    Fit a new o-ring IMPORTANT NOTE ABOUT THIS PART: Beware of shoddy aftermarket parts. The o-ring is NOT a "conventional" o-ring, but is in fact, "D-shaped" in cross section, the portion that fits against the housing body is flat. Our buddy chacal carries the correct o-ring as does Yamaha themselves; others may offer a conventional o-ring. That is incorrect for this application.

    A smear of silicone grease helps...

    [​IMG]

    REASSEMBLE. Be sure to thouroughly lube the gear shaft with clean motor oil, and be sure the housing is well lubed, put a few drops down the bore before you plug in the gear.


    Reinstall on the bike. Smear the housing with oil and plug it into place; the square "locating block" should be in the 8:eek:'clock position; reinstall the yoke. Torque the retaining screw to 7.2ft/lbs.

    [​IMG]

    ALL BETTER!

    Clean up, lube or otherwise service your tach cable and reconnect.
     
    Andrew Nichols likes this.
  2. bill

    bill Active Member

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    Another great how to Fitz Thanks!
     
  3. ASHMan

    ASHMan New Member

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    Fitz, it's like you just knew my bike was leaking from there!
     
  4. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    It's the odds... BOTH of mine were, I got to do it twice yesterday.

    That poor little oil seal has a pretty hard life; it doesn't get "pressure fed" or anything even close so it's not cooled by fresh oil all the time; and it gets pretty blasted hot right above the exhaust ports there. Once it's baked hard, it's doomed. I've put about 4K on my '81 since I resurrected it, and it just started leaking big time.
     
  5. ASHMan

    ASHMan New Member

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    I only can have one right now, so sayith the wife. But there is this cb I have my eyes on...
     
    Andrew Nichols likes this.
  6. OnTheStorm

    OnTheStorm Member

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    Mine had another rubber seal between the #5 on your diagram, and the housing on the cable. the screw on the cable end also did not screw all the way in. Is this necessary? either end of the tach cable is not screwed in all the way...another screw-up by the P.O.?

    any chance you could give me the part numbers from chacal for those replacement parts as well? I can't seem to find them in the catalog.
     
  7. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Yep. I encountered the same on my '83. I suspect the PO bought the parts, and couldn't figure out where the seal went (since it's hiding) so he just jammed it in between the cable and the housing.

    It's supposed to be the way I show it.

    From Page 5 of Len's catalog:

    HCP3539 OEM tachometer cable drive gear (on cylinder head) OIL SEAL. If you're leaking oil where the tach cable attaches to the drive housing on the drive adapter housing, it's because this oil seal (and/or the drive gear O-ring) is bad and need to be replaced. Fits all XJ550 models, 1980-81 XJ650 Maxim and Midnight Maxim models, and 1982 XJ650 Seca model.
    $ 5.95


    HCP3537 OEM tachometer cable drive gear O-RING. If you're leaking oil where the tach cable attaches to the drive housing on the drive adapter housing, it's because this o-ring (and/or the housing oil seal) is bad and need to be replaced. Fits all XJ550 models, 1980-81 XJ650 Maxim and Midnight Maxim models, and 1982 XJ650 Seca model.
    $ 4.95
     
  8. Polock

    Polock Well-Known Member

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    is that the first time you used that vise? sure is pretty :)
     
  9. OnTheStorm

    OnTheStorm Member

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    cable housing still wont screw in all the way. there is a rubber gasket on the inside of the housing (on the cable). this supposed to be there? It looks like a thick washer, but it is rubber?
     
  10. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Sorry just noticed your post. No, it's not. No rubber washer inside cable ferrule, like I said suspect a PO who bought a new seal couldn't figure out where it went and jammed it in.
     
  11. Rebel51

    Rebel51 New Member

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    Many thanks to bigfitz52 for the instructions, and to chacal for having the parts! I bought my '81 Maxim 650 and the PO said the tach wasn't working, "...and I don't know why." Didn't take long to find the tach cable dangling in the wiring harness, and a bolt where the tach gear should be. The bolt wasn't even screwed in, it was held in place by a rubber grommet. Long story short, XJ4Ever had the parts, and bigfitz52 had the instructions. Worked like a charm, so, again, thanks to all!
     
  12. AutoAndy7

    AutoAndy7 New Member

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    LOVE IT! Extremely helpful, great pics! :twisted:
     
  13. schmuckaholic

    schmuckaholic Well-Known Member

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    Here, gimme a little bit and I'll package that up for you nice and pretty like...
     
  14. pbthoe

    pbthoe Member

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    Nice write up fitz. Cheap,easy, quick fix for a messy problem. Now I can tell the difference from where I park the XJ vs. the Harley. It's amazing what a mess a teaspoonful of oil can make at 60 or 70 mph.
     
  15. bluemiata

    bluemiata New Member

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    I have an '82 XJ650RJ that I'm replacing the tach cable on, since the tach was operating erratically - when rev's got up around 5k, the needle would drop back around 4k, even though the engine revs were increasing. I removed the knurled nut at the gear housing, but the cable doesn't want to come out. Is this typical?Thanks!
     
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  16. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    No, it's not. Somebody has probably jammed it in there. The stock cable has a flared ferrule that meets up with the gear housing and is held by the knurled nut.

    Your problem may turn out to be the instrument itself. That's covered here: http://xjbikes.com/Forums/viewtopic/t=15303.html however, in your case, some "surgery" will be required to gain access.
     
  17. extremo

    extremo New Member

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    I just found this thread.

    While my '81 559 Maxim is not leaking oil here, the tach cable knurled nut (plastic?!) keeps working loose with vibration. Sometimes during a ride, the tach will just drop to zero. I pull over and stop reattach it by hand. When I get home, no matter how much I tighten it, it seems to work loose in a week or two.

    What's next? Locktight?, teflon tape?
     
  18. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    If the tach cable knurled nut at either end is plastic then it's a cheapo aftermarket piece. Collar/nuts at both ends should be alloy.

    The reason the cable nuts (and this applies to the speedo cable too) come loose:

    There are "flats" on the ferrule part of the cable. When tightening the knurled collar/nut, you need to hold the cable sheath from turning with a small wrench when you tighten the nut.

    If you don't hold the cable, what happens is as you tighten the nut, you can end up "winding up" the cable sheath. In other words, you inadvertently apply a rotational "preload" to the cable so that as it tries to straighten itself back out, it applies "unscrewing" force to the nut which then works loose.

    I should probably shoot a couple of additional pics and add that little 'tip' to the article, eh?
     
  19. broberg

    broberg Member

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    Sorry to bump this thread, but I'm removing my tachometer from the 550.
    Is there any ready-made plug that fits this contraption, and when removing the cable should I leave the rod in or remove it. I'm guessing nothing is reliant on the rod being in place for everything else to function properly?
     
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  20. seca550RK

    seca550RK Member

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    I recently bought my bike, and when I got it home i noticed the tach bolt had almost completely unscrewed. I tightened it up but I notice the tach seems to jump or stall when I get over 4000 rpm. any ideas what could be going on? Thanks!
     

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