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Subject: 8n hydraulic cover/seat mount location

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Doug    Posted 01-29-2020 at 15:26:36 [URL] [DELETE]        [Reply] [Email]  
  • 8n hydraulic cover/seat mount location
  • I've got a broken bolt stem in the hydraulic cover/seat spring mounting location and before I start to attempt to back out the remaining portion of the bolt, I'm curious as to how thick the casting is at the location where the seat spring bolts into the hydraulic cover. Unfortunately, someone that owned the tractor previously had attempted to remove the bolt and really messed up the upper portion of the hydraulic cover's female tapped area. Depending on how much thread I have left in the hydraulic cover once the bolt stem is removed, I suspect that I may end up having to drill out and tap a new mounting hole in the cast cover and drill a new hole in the seat spring. Any advice or suggestions would be appreciated.

    Tim Daley(MI)    Posted 01-30-2020 at 06:49:14 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8n hydraulic cover/seat mount location
  • HiYa Doug-
    The OEM Ford 8N seat spring, p/n 9N-400-C, is fastened using two 7/16" studs (#883836-S8), 2 lockwashers (351436-S8), and 2 hex nuts, 7/16-20 (#33792-S8), not bolts, however a previous owner may have swapped them out for hex bolts. You may or may not know that studs are engineered with the same major size but each end has a different thread pitch, one coarse and one fine. Cast iron requires thread sizes to be coarse -it's the nature of the beast. The end that accepts the hex nut fastener is always the fine thread. The stud used is 7/16"-14 and 7/16"-20 x 1-3/8" L. It would depend on how much of the broken stud or bolt you are working with. Have you tried an Easy-Out? I, too, do not think you should try and drill out the hole unless you have the proper tools. You arenít going to get it using a hand drill. If the drill walks, it will cause the broken stud to encroach into the base thread and you could end up with more of a mess. A good magnetic base drill unit would be best and a carbide drill bit and an experienced machine shop would be a good place to have that done if you need it drilled out. Worse case is to have it repaired at a professional shop and if need be insert a Heli-Coil. If you get the broken stud out, donít drill it out Ėonly chase a tap to clean up the 7/16-14 threads. Look first to see if it is a blind hole. You donít want to bottom out the tap and break it.

    FORD N-SERIES TRACTOR HYDRAULIC LIFT TOP COVER:

    Tim Daley(MI)

    Doug    Posted 01-30-2020 at 09:19:01 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8n hydraulic cover/seat mount location
  • Tim,
    Thank you for the detailed response and information/instructions. Fortunately, I do have the proper tools with the exception of the magnetic drill. I have a set of ez-outs in straight and spiraled flues along with left spiral cobalt bits. I feel pretty good about centering the initial pilot hole with a punch to begin the process even without a magnetic drill. My biggest concern, as with most "issues" that seem to plague our 70 year old tractor, is how far (correct repair or not) did the previous owner(s) go with their attempted repairs. With the damage that I see to the mounting face, it would appear that the tractor saw one or more unsuccessful attempts to repair. The other spring mounting stud has been replaced with a bolt so I'll remove it and replace it as well now knowing the proper hardware for the spring mounting. Having read dozens and dozens of forum topics, it never ceases to amaze me how our tractors have been "franken-tractored" over the years and I suspect ours is no different. I appreciate that our previous generations used what they had on hand to make repairs, and it is a testament to the original design that these tractors are still working for so many. I'll keep you posted as I get into the project and let you know how it goes. I'll take some pics for y'all as well so that you can see what transpired. Thanks!

    Tim Daley(MI)    Posted 01-30-2020 at 11:01:35 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8n hydraulic cover/seat mount location
  • A stud is a stronger, more efficient fastener than a bolt. FORD engineered them in certain applications. Heads were used with studs until the mid-1950's. Many fellas go to bolts when they pull their engines and/or heads and replace the studs with bolts. You can use bolts, probably with no consequences. Here's a link to 7/16 studs, Grade 8 Zinc, 10 for $10. Length is 3/8 longer but holes are not blind so simply grind down the ends 3/16" each. They also have 7/16 x 1-5" L in Black Oxide, 10 for $42 -yikes! Good luck whatever you do and report back with end results.

    Tim Daley(MI)

    Doug    Posted 01-30-2020 at 11:21:31 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8n hydraulic cover/seat mount location
  • Just went and did some more investigating of the broken bolt/stud. I was able to clean out the grit and dirt in the area and it is now obvious that the previous "attempt" left a broken tap in the hole- yipee. Now I have the fun task of trying to remove this and see what's left with respect to thread integrity, etc. Worse case scenario,should the tap removal and whatever is left of the threads be unusable, what do you suggest?

    Tim Daley(MI)    Posted 01-30-2020 at 13:48:38 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8n hydraulic cover/seat mount location
  • A good machine shop will have a tap burner. Since you don't want to muck with any shop so options are severely limited. You won't get a broken tap out with any drill, trust me. Carbide is the best cutting tool, titanium coated, and cobalt is just a tougher steel coating for HSS but neither is going to cut a broken tap. Carbide is brittle. A carbide tool must be solid and the workpiece as well. One slop and the carbide will chip. A broken tap almost always needs to be burned out with an electric arc machine. You asked for my opinion so I suggest if you want to save your OEM top cover, ask around local machine shops; you might be surprised to find prices. Option #2 is to bite the bullet and buy an ebay special top cover. that may require a new piston and cylinder so weigh options.

    Tim Daley(MI)

    Doug    Posted 01-30-2020 at 13:58:02 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8n hydraulic cover/seat mount location
  • Thank you, Tim, for the options that I must consider. None of these sound too exciting, but it's reality. I really appreciate the advice that you and others provided. I'll let y'all know what I end up doing.

    John in Mich    Posted 01-29-2020 at 16:15:37 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8n hydraulic cover/seat mount location
  • Look at the other seat bracket bolt. Measure it. Drill out the broken one and no deeper, install a helicoil and install your seat. I would not try to drill a new hole in the casting.

    JMOR    Posted 01-29-2020 at 17:59:14 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8n hydraulic cover/seat mount location
  • As John says, measure the good one. On drilling, be aware that those holes go all the way through and will make a nice path for contaminants to fall into the hydraulic compartment.

    David D. Smith    Posted 01-29-2020 at 19:11:56 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8n hydraulic cover/seat mount location
  • Use a reverse turning drill bit. Sometimes doing that removes the stub itself.
    Dave <*)))><

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