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  1. #1

    Default Transmission Rebuild 1976 XLCH Ironhead Sportster

    What started as a quick fix has become me tearing the whole motor apart. I'm learning the vocabulary from the service manual, but some stuff just doesn't quite click.

    The original problem: I bought the bike with "no first gear" - I had a feeling the dogs were worn, but one day I tricked her into first. I can get first gear if i do this:

    If i'm rolling at like 20 mph in 2nd, pull the clutch in, and down shift, I can 'tap' it down into first probably 10% of the time but I have to blip the throttle and even then it's very rare. I can never shift into to first at idle, or directly into first. I always have to skip Neutral.

    I'm in the process of inspecting all of the gears, clearances, play, etc. Can someone please help me better understand the tech specs sheet from the manual.

    Click image for larger version. 

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    What does the clearance between clutch faces mean? Is that with the trans in Neutral? I couldn't find a robust, comprehensive description of how/where to measure.

    I have a feeling the problem comes from the forks being mis-adjusted. The MS Fork is standard, and the CS fork is +2. I've ordered new fork roller bushings, a new shift shaft, the shift shaft seal that is on the outside of the case, and a new case bushing. I think this will help with the play I was having considering the amount of moving parts in the left side shift linkage there was. I'm gonna look in to the other links as well.

    I have some questions about the gear teeth as well. Here's a video for the main shaft and counter shaft.

    Counter Shaft https://www.youtube.com/watch?v=NyXK03nEggs

    Mainshaft https://www.youtube.com/watch?v=ZiEeXdAICug

    Here's another concern - I'm not sure if the CLUTCH GEAR (37448-71) is too worn. The angular teeth are a bit chewed up, but I'm not sure what the threshold is for wear on this gear due to it's shape.

    Click image for larger version. 

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    This photo is really small for some reason, sorry for that.

    I just got the gears cleaned up and I'm going to try and get a video up of the trans as it was put together when I pulled it out.

    HELP!

  2. #2
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    First off calm down a little lol. This is a detailed job but the FACTORY manual will talk you thru it. On your mainshaft drive gear, the one in the small pic, the 4 parts stickin up are commonly known as clutch dogs. If the corners are chipped or rounded off it's junk. If the pockets on the gear it mates too are in the same shape ditto. These "clutchs" are what keeps the gears engaged, NOT the shifting forks. When they are worn the gears try to disengage under power and the fork gets an undue pressure put on it. Don't cheap out on your tranny. ANDREWS is the only name you need for gears and shafts. Fuck tedds junk.You will need a micrometer and a telescoping gage to check your needle roller clearance on the right side of the main. The 23 loose rollers. As far as the side clearance read and reread your OEM FACTORY manual. These clearances will be adjusted in various ways. A bench vise with soft jaws is a real need here. Follow your manual! If you have gotten this far you should be ok. If your gears look shoddy best bet would be a whole set from ANDREWS and be done with it. Yes they are expensive but they are worth every penny.

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    Check your messages.

  4. #4

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    Hubbard's advice above is spot on. Here are a couple of things to consider:

    If you have trouble engaging first gear at a stop, or finding neutral, a dragging clutch is usually the issue, not the transmission.

    Used HD gears can look pretty bad and still function. If the transmission is jumping out of any gear under load, that mating gear pair need to be replaced before further damage ensues. If it's not jumping out of any gear, consider the full gear set useable.

    Set-up of an XL four speed consists of two parts, the spacing of the gears by selecting shims and shift forks, and setting the end play of the shafts. The first part is done with the transmission assembled onto the trap door, and preferably the trap door held in soft jaws in a vise. The second part is done with the transmission assembled into the motor case, and you need a dial indicator for setting shaft end play. There is no way to do it properly without the gauge.

    Jim

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    This thread is enlightening for XL trannys.

    https://www.jockeyjournal.com/forum/...ironhead+build

    (Don't pay much mind to what DR says, that Boy is full of shit as a Christmas Turkey).

  6. #6

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    Quote Originally Posted by Hubbard View Post
    First off calm down a little lol. This is a detailed job but the FACTORY manual will talk you thru it. On your mainshaft drive gear, the one in the small pic, the 4 parts stickin up are commonly known as clutch dogs. If the corners are chipped or rounded off it's junk. If the pockets on the gear it mates too are in the same shape ditto. These "clutchs" are what keeps the gears engaged, NOT the shifting forks. When they are worn the gears try to disengage under power and the fork gets an undue pressure put on it. Don't cheap out on your tranny. ANDREWS is the only name you need for gears and shafts. Fuck tedds junk.You will need a micrometer and a telescoping gage to check your needle roller clearance on the right side of the main. The 23 loose rollers. As far as the side clearance read and reread your OEM FACTORY manual. These clearances will be adjusted in various ways. A bench vise with soft jaws is a real need here. Follow your manual! If you have gotten this far you should be ok. If your gears look shoddy best bet would be a whole set from ANDREWS and be done with it. Yes they are expensive but they are worth every penny.
    Thanks Hubbard, I've got a lot of good info and i understand what to inspect. My concern in reading the manual is the way it is worded. Again, I'm still in the process of verifying the play, the clearances, and whats worn. I'm working on getting some images uploaded of all the parts that I'm concerned with, i'm just dealing with some shoddy internet connection currently. I have the OEM FSM and the Parts manual. If I have to start replacing anything, I plan on sticking with OEM if I can, just because Andrews is not in the budget right now. Worth it, I know - once I get this gist of everything I plan on really Getting this thing in tip top shape, she's just been limping with no first gear and I'm trying to get one good season before I rebuild her from the bottom up the way i want and not fixing the PO's "fixes".

    I've also got a video uploaded here with the trans assembled. VIDEO

  7. #7

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    Quote Originally Posted by JBinNC View Post
    Hubbard's advice above is spot on. Here are a couple of things to consider:

    If you have trouble engaging first gear at a stop, or finding neutral, a dragging clutch is usually the issue, not the transmission.

    Used HD gears can look pretty bad and still function. If the transmission is jumping out of any gear under load, that mating gear pair need to be replaced before further damage ensues. If it's not jumping out of any gear, consider the full gear set useable.

    Set-up of an XL four speed consists of two parts, the spacing of the gears by selecting shims and shift forks, and setting the end play of the shafts. The first part is done with the transmission assembled onto the trap door, and preferably the trap door held in soft jaws in a vise. The second part is done with the transmission assembled into the motor case, and you need a dial indicator for setting shaft end play. There is no way to do it properly without the gauge.

    Jim
    Thanks Jim! I've uploaded a video of the whole trans assembled out of the case HERE.

    You can hear the gear teeth hitting the forks when there is no load on the CS - I'm hoping this is normal or my freeplay in the trap door bearing is outta spec. I haven't had time to put her back in the case since I changed the forks around. I've also order some new fork roller bushings to some of the play out of the Cam Plate bc it was pretty sloppy.

  8. #8

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    Quote Originally Posted by Dragstews View Post
    This thread is enlightening for XL trannys.

    https://www.jockeyjournal.com/forum/...ironhead+build

    (Don't pay much mind to what DR says, that Boy is full of shit as a Christmas Turkey).
    Thanks Drag! I saw your posts on the other Ironhead with the Fuzzy seat and I was hoping I'd hear from you. I've got some heads that are in bad shape -I'm thinking full valve job considering how bad they are out of the seats. I'll try to get more photo up and some better documentation - I'm trying to really get detailed so that other ironhead guys can get good, details, reliable info. My other full build thread is HERE

  9. #9

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    P,
    If the gears are hitting the shift forks, grind the forks for clearance. That is common with some brands of aftermarket shift forks. Use your old fork for reference.

    Jim

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    i have not built a sporty tranny since the 80's so its been a while for me
    from your video your gears seem fine. i would rebearing it, just cause im in there and properly shim it. forks are cheap get a set from ANDREWS and your rollers, make sure nothing is worn in pawl and your plate the rollers sit in, this is where I think your problem lies....

  11. #11
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    Aaaaaaaaa .... Errrrrrrrrr .... Gee Wiz, Dave

    AP doesn't make any forks ... But they kick butt making gears and shafts ...
    http://www.andrewsproducts.com/sites.../page_29_0.pdf

    In the Vid, what I think I saw was a lot of slop in first gear.... Looks like a shifter cam might be needed due to the gates having worn ??
    Also not a lot of dog engagement ... Gear spacing would take care of that problem....

    Back in da day Ron Trock made shift forks .... But that's been 40 years ago....
    You can still get some .... As Art.. !!!
    Last edited by Dragstews; 02-20-2019 at 7:58 AM.

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