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Subject: New Yoke has wrong threads - which is correct?

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Kimberly    Posted 04-19-2019 at 12:48:25 [URL] [DELETE]        [Reply] [Email]  
  • New Yoke has wrong threads - which is correct?
  • I went to install the new yoke on the tractor and it would start and then bind. So I examined the threads and they looked good. Then I noticed the threads are coarse; the threads on the draft control plunger on the tractor are fine. The person stated that the yoke was for an 8N. I will have to return the yoke; and it is in better shape than when I received it, cleaned up and painted. Were two different plungers/yoke used on 8N or did this part come from a different Ford? Or, did someone replace the draft plunger rod on my tractor with one not from an 8N? Do I need to replace the plunger; part #541? Or do I have the correct plunger and not the correct yoke? This project just isn't going well.

    Tim Daley(MI)    Posted 04-20-2019 at 04:48:37 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • There are two very important facts to remember when buying parts today. First, with the new/aftermarket or used OEM ones sold, especially on fleabay, there are less than a handful of sellers who actually know what the parts are and will list them as such. The rest have no clue and most will always list them as, “Fits 9N, 2N, 8N FORD TRACTOR” so their item gets maximum exposure. The part may or may not work for all models but may also require other parts to be changed as well in order to make them work. Often times they also will list the wrong part number as well. It’s honorable that you wish to keep your tractor as original as possible; however, since you are not doing a complete rebuild/restoration, what JMOR said is advice to be seriously heeded. You’ve already chosen to use the later NAA hydraulic piston so that negates adhering to an original 8N design anyway. I advise too -make the parts you have work. Nobody is going to chastise you for using the wrong yoke and plunger. Tractor folks don’t judge at shows, none I’ve ever attended anyway. Who’s going to pull your top cover off and inspect the piston??? Pull the yoke??? The second point to follow is the MPC’s list by year the parts and if a change was made, will usually have a letter suffix to designate that. That is where details come into play. Sometimes the MPC’s will detail what the change is in the part description, more often than not they don’t. That’s when further research is needed which usually requires original blueprint drawings that have the EI listings. Not an easy task since very few sets of the original 9N Blueprints exist. The Benson Ford Research Center in Dearborn, Michigan at The Henry Ford/Greenfield Village does have at least one set of prints and you can get copies of any part you wish by going online and requesting them via a form they provide. Be forewarned that copies are not cheap and you must designate what drawing you want as the kids working there are not going to be of any help. The yokes and plungers all have special fine thread pitches. The 1949 MPC shows the yoke as p/n 9N-546-C, and listed in all subsequent MPC’s as well. The plunger, 9N-541-C, shows it was changed to p/n 8N-541 in 1950. What exactly the ‘A’ and ‘B’ suffixed parts were would have to be investigated further by the EI sheet number as listed on the drawing. That means the EI sheet(s) would need to be accessed in order to further determine the changes. Like I said, that could get expensive. You’d have to first have the original drawing. Depending on what revision you have, the change may or may not be documented on it. If not, then the EI sheets would be need to be looked at. As my good friend Marvin Baumann once told me, “…there will never be a complete comprehensive book on Ford Tractors because so may changes were made, never documented, and/or many drawings were destroyed.”

    Tim Daley(MI)

    JMOR    Posted 04-19-2019 at 17:59:07 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • All you ever wanted to know about draft plungers, but were afraid to ask.....not really! :)

    Kimberly    Posted 04-19-2019 at 18:42:23 [URL] [DELETE]        [Reply] [Email]  
  • I am confused
  • I read through the entire forum post you linked to. What is suppose to be on my tractor; it is a 49 8N. Was it changed out at some point or is it what is suppose to be on it?

    JMOR    Posted 04-19-2019 at 22:30:31 [URL] [DELETE]        [Reply] [No Email]  
  • Re: I am confused
  • I gave you the facts. You decide what to do with them. Any will be just fine as long as the two parts thread together.

    Kimberly    Posted 04-19-2019 at 23:11:53 [URL] [DELETE]        [Reply] [Email]  
  • Re: I am confused
  • After reading that, I have no idea what Ford did concerning the draft plunger. Did they mix and match over the years, some tractors in the same years having 18 and some having 24 or did they switch at some year. Reading that forum I did not understand why there are different ones. Yes, I realise that many of these old tractors may have parts on them from different years but I would like to keep it as close as to what it was new; silly maybe but that is just the way I am. I have no great knowledge of these tractors. I am trying to learn though.

    To sum up, after reading that forum I have no idea if someone switched the plunger on my tractor with another or if it has the correct one for the year. That is my confusion.

    Ed Gooding (VA)    Posted 04-20-2019 at 07:22:40 [URL] [DELETE]        [Reply] [Email]  
  • Re: I am confused
  • Kimberly, what is your end goal for your 8N? Are you desiring a factory-correct restoration, or do you just want to refurbish a reliable working 8n? If restoration, I would suggest downloading the '49 dealer parts book from our Manuals library here. It will show the parts needed for a factory-correct restoration. If you just want a worker, find matching draft control components, install and use her!

    deanostoybox    Posted 04-20-2019 at 00:22:04 [URL] [DELETE]        [Reply] [No Email]  
  • Re: I am confused
  • All 8Ns should have 5/8-24 thread. Your plunger is right. The yoke which seems to be 5/8-18 from your picture with a ruler may well have come off of a 52 8N, but if so it would have been replaced at some time. Had a 41 9N here a while back for some minor work, it had the 5/8-18 thread on it, still belonged to the original owner.

    Hope this helps.

    Kimberly    Posted 04-19-2019 at 18:29:47 [URL] [DELETE]        [Reply] [Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • The threads on my plunger are 24. So what does this mean exactly? My tractor is a 1949 8N. The seller said he removed the yoke from a 52 8N. Finer threads give you more control over the play in the draft spring since the yoke has to be horizontal. Should I replace the plunger to match the yoke or try to get a yoke to match my plunger? Or, I could just put the old yoke back on even though it is almost worn through; it actually looks as if it could break. If I had a welder, I would just beef it up with the welder and let it add to the history of the tractor.

    TheOldHokie    Posted 04-20-2019 at 10:23:08 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • I'd say the seller was full of it. Don't compound his error and confuse a future owner. Return the incorrect yoke and get the correct one with 24 pitch threads.


    Dean    Posted 04-20-2019 at 07:28:34 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • They are all fine thread.

    Sounds like someone has sold you a pig in a poke or yet another improperly made Chinese part.


    Kimberly    Posted 04-19-2019 at 18:09:15 [URL] [DELETE]        [Reply] [Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • So I need to pull out my gauge and see what I have on the plunger and yoke that came off the tractor.

    Kimberly    Posted 04-19-2019 at 17:31:59 [URL] [DELETE]        [Reply] [Email]  
  • Update on the Yoke
  • The seller stated that the Yoke is from a 1952 Ford 8N tractor. I have a 1949 8N and I would say from the condition of the draft control plunger; with the amount of pitting it had and the amount of wear on the Yoke; worn completely through and almost half gone, that both are original. It appears that changes were made. Hopefully some others will come in and comment.

    Kimberly    Posted 04-19-2019 at 17:23:16 [URL] [DELETE]        [Reply] [Email]  
  • Quick and Dirty Gauge
  • I have a thread pitch gauge to check the threads; little harder to do in a bore where you can't see but just have to go by feel. I might try pulling out the gauge and see what I can find out. The quick and dirty though when put against the plunger shows why it starts to bind after engaging the second thread or so. The pitch is different. So the Yoke is useless to me and I will return it. The question is what tractor was it on? The listing said 8N 2N 9N Yoke. While not maybe coarse threads, the pitch is different.

    deanostoybox    Posted 04-19-2019 at 13:24:30 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • The yoke and plunger on my 51 8N are fine thread.

    JMOR    Posted 04-20-2019 at 10:42:55 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • How fine is "fine"? 18, 24, 32?

    TheOldHokie    Posted 04-20-2019 at 20:07:29 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New Yoke has wrong threads - which is correct?
  • Well if we want to talk industrial standards ANSI/ASME classification would be:

    5/8-18 = unified fine series (UNF)
    5/8-24 = unified extra fine series (UNEF)
    5/8-32 = umified special series (UNS)

    So the 8N variants are all extra fine threads 😐


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