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Doing the 750 Seca's Forks.. (Rebuild.. now a HOW TO!)

Discussion in 'XJ Technical Chat' started by Chorca, Jun 11, 2009.

  1. ManBot13

    ManBot13 Well-Known Member Premium Member

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    I could see the damper rod spinning through the middle oil lock valve hole, but didn't see the damper rod hole line up.
     
  2. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    The oil lock valve was too far "down" (or up) to allow the holes to line up.......
     
  3. diverpete1

    diverpete1 New Member

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    Great breakdown and photos. Thanks!
     
  4. vegasrett

    vegasrett New Member

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    need to do mine but im a 600 and clear up in 1998. this write up seems rocking but anyone know any major changes i should prepare for?
     
  5. ManBot13

    ManBot13 Well-Known Member Premium Member

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    The 750 seca forks are unique, even compared to other '80s xj forks due to the anti dive. I'd look for other guides specific to seca II or at least the more standard xj forks.

    A manual will help. The most important differences are the top caps and the oil control valves at the bottom and a manual can give you those specifics.
     
  6. vegasrett

    vegasrett New Member

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    ive bounced through the manual and everything looks pretty straightforward. its just been my experience with the other bike that for each job the manual excludes some key piece of information. im a little dense and just looking to go in as well armed as possible.
     
  7. ManBot13

    ManBot13 Well-Known Member Premium Member

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    But that's what I'm trying to tell you. This write up IS awesome (I used it myself for my 750 seca forks, Chorca did a very good job). However, the "key" pieces of information that are covered within are not of use to someone who doesn't have the 750 seca fork (and other bikes don't because the design isn't actually very good).

    I assume this thread came about because there are so many differences between the 750 seca forks and other XJ forks, and the other excellent How-To's on this site didn't cover those differences. But the evolution of the motorcycle fork hits a dead end with the 750 seca fork and it's anit-dive, so it's not going to be applicable to your Seca II fork.
     
  8. vegasrett

    vegasrett New Member

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    thanks, ive been running through old threads looking for a good write up for my forks. havent found one and was just wondering how similar things are. i'll keep searching.
     
  9. apato632

    apato632 Member

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    This is a great writeup. Thanks Chorca!
     
  10. joejr2

    joejr2 Active Member Premium Member

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    Great instructions and photos unfortunately I completed everything on my 81 seca 750 front end rebuild before I saw your old post.
    Did you have any difficulty bleeding the brakes ? I haven't been able to get the air out of the lines no matter what I do. The spring in
    the master cylinder does not want to return the piston so there is no way to pump the fluid from the reservoir to the calipers. I tried
    pumping fluid from the anti dive bleeder towards the top. I couldn't get the fluid to go through the master cylinder to the reservoir,but I
    was able to trace the fluid to the top of the metal tube where it screws into the master cylinder. Some where the fluid is being blocked
    inside the master cylinder, Let me know if you had an easier time. I have rebuilt the MC twice and have polished the bore so it's mirror smooth
    and used parts i got from chacal. I also rebuilt the whole anti dive unit on bothe ssides with Len's parts it's a real head scratcher.
     
  11. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    For everybody's sake, I made this a sticky, so it's always right up top.

    Dave Fox
     
  12. xjmat

    xjmat New Member

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    Hi,

    I am trying this job, but have run in to a problem with this step:

    The next step is to get the dampening rod's bolt off. This is at the bottom end of the fork.

    I am using a hex-key on a long wrench, but the little bolt of joy is not moving. So I have 2 questions:

    1. is the hex key for this 6mm? (That is what I am using, but there is some wiggle-room that terrifies me, and the last thing I want to do is round out that hole)
    2. Who has hints for how to loosen this thing?

    Right now, the well is full of WD40 and every so often, I go out there, and tap the nut with a hammer. And then every few hours I try to remove it without rounding out the nut hole...

    the fear..
     
  13. ManBot13

    ManBot13 Well-Known Member Premium Member

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    Is the bolt turning but not loosening? or just not turning at all?

    A hex bit on a socket is usually best, so you can get a lot of torque on it. Also, install the springs and spacers which should hold the damper rod in place. An impact gun will also help.
     
  14. Dadoseven

    Dadoseven Active Member

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    From your avatar, it looks like you have a 750 SECA, is this correct? Are the forks out of the triple tree? Are the anti-dive actuators still attached? Have you already removed the cap at the top? The 750 Seca's forks
    are different than most other XJ's. More information can help us guide you.
     
  15. k-moe

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

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    Remove the anti-dive unit from the fork body. In the lower anti-dive hole you will see a chunk of aluminum with holes in it. Stick an Allen key into the hole. That will hold the oil lock in place and keep the bolt from spinning.
     
  16. xjmat

    xjmat New Member

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    Hey!
    Awesome, and thanks for the replies! Yes, a 1981 seca (Australia model). I have the forks off the bike, I have the fork cap off, the spring out, the oil drained, the anti-dive actuator off. I have a 6mm socket on a torque wrench (long, lots of leverage), and the fork in a bench-vice, and the bolts just aren't turning. If I didn't know better, I'd say they're seized. The have been marinating over night in wd40, so I'll give them another go now, and see what happens. The only thing I don't have is an impact driver. If they don't come off soon, I'll think about taking them to the mechanic.. it's like admitting defeat though :/

    Holy hell. It came out (1 so far) eventually. The WD40 had soaked down overnight, I suppose all along the threads, and allowed me to get it out. Man. I am not certain they need to be that tight.

    Also: should I put thread lube on it before it goes back in? My feeling is yes.
     
    Last edited: Sep 12, 2017
  17. k-moe

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

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    The damper rod bolts are held in place with thread-locking compound. Using thread lube on them is ill-advised and may result in you being badly hurt when the damper rod bolts back out.
    Use a mediium strength thread locking compound on clean threads.
     
  18. xjmat

    xjmat New Member

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    very good point. Threadlocker it is.
     
  19. xjmat

    xjmat New Member

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    Well, I followed the instructions, but I have a conundrum. One fork is now longer than the other. The short fork bounces back quite quickly to its extent. The long one bounces back quickly, to the length (approx, I suppose) of the short one, then extends slowly. Now I am not certain whether they were different lengths when I took them off the bike. And so now... What, I ask?

    The short one took almost a week for me to get the fork seal out, so the other is all nicely put together and filled with oil, but I recall that the insert was longer in the long one when I was tapping the oil seal down - I used a tube of PVC to push the seal down, and it aligned with the top of the "long" fork, but was a good 2cm clear of the short one. Anyone know anything about this?
     

    Attached Files:

  20. ManBot13

    ManBot13 Well-Known Member Premium Member

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    that looks to be the length of one of the inner bushings. You didn't accidently put both on one side, or forget to remove the old one did you?
     
    k-moe likes this.

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