Grease Fitting Repair

In an earlier thread on grease fitting repair Dunner WI suggested that a stripped 1/4 inch fitting could be replaced by using a 7mm zerk, which is just slightly larger. I assume I would need to drill out the old hole with a 6mm bit and tap with a 7mm tap. I finally did find a source for both 7mm zerks and M7 taps at G. L. Hewett, but I'm nut sure which tap I should use. The zerks I found are described as "Straight, M7 x 1 Taper Thread." The three taps are referred to as Taper Thread, Bottom Thread, and Plug Thread.

The stripped fittings are on my Woods 1020 loader, and I can get the joints apart, so that I can get access all the way through. But the steel is very hard. (We had tried to drill one out for a 1/8 zerk, and had problems). The guy helping me is concerned that the steel might be so hard that we would have a problem getting it tapped.

I would appreciate advice on whether this is likely to work before I order the zerks and tap.
Source for 7MM M7 Taps
 
If you don't want to go metric a Harley-Davidson grease fitting is 5/16-24. Then you won't need to get the metrics.Part numbver is 9851 .Letter dril I is the tap drill.
 
Charles, if your material is that hard, I would consider a "drive-in" fitting. It has skirts on it and installs with a driver and a few hammer taps, not ideal/not cheap but may avoid grief on broken off tap removal (see McMaster-Carr grease zerk types). BTW, the three tap classifications you reference indicate how near the end of the tap a full thread will be formed. See link for full explanation.
Untitled URL Link
 
Zerks that steeply taper similar to an ease-out are commonly available at auto part houses. I install them with a box end wrench so inward pressure can be applied while screwing it in.
 
Another idea I have used with success (assuming you have room) is to weld a 1/4" NF nut over the hole and screw in a new grease fitting. I have done this with old and new projects and it works well. Mike
 
I highly recommed the drive fittings. Go on flea bay and find them. Do not come in a kit so you need to order as per size. They look as if they have threads till you look real close; they are like a barb hose fitting but little. The sizes I have are 3/16 -1/4- 5/16 and 3/8. Very easy to work with. CAREFULLY drill a STRAIGHT TIGHT hole in the size you are going to use. Blow out any trash and steel your nerves. Set it straight in the hole and give a little tap. Look it over and make sure it is still straight. Tap again a little harder and check again. If you did it corectly the next time you should be able to go WHAM. That drive should seat it down to the stop collar ring. You must hit them square!!!!!!! If you did everything to the letter they will not come out. I needed to get one out and had to used vice grips. ONLY use them on solid areas. Loader arms ,axle heads, loader pins Etc. Thin stuff still needs regular screw in zerks. I have a box of regular fittings from harbor freight and have expanded it to include these drive fittings and larger special fitings for like old hit and miss engines. Also store the number drill and tap sets for like 1/4 28 fittings etc. Flea bay listings.
3//16 141401264328
1/4 161366231608
5/16 121420570029
3/8 110575753803
That should get you started. My international 300 has the little ones on the fast hitch arms. They still work almost 60 years latter.
 
(quoted from post at 19:09:38 09/16/14) Another idea I have used with success (assuming you have room) is to weld a 1/4" NF nut over the hole and screw in a new grease fitting. I have done this with old and new projects and it works well. Mike
My welder/general tractor repair guy came up with a similar solution the other day. He said that if I just had an old 1/8" pipe coupler, he could do a work-around. I rummaged around in my old plumbing parts box and found a strange conglomeration of pipe fittings that were all connected together for some purpose of which I can't imagine. But it just happened to include an 1/8" elbow. I gave it to him, he cut off the female end, welded it over the zerk opening, and got me back in business uprooting the hated privet. But the best part of the story was the chance it gave me to lecture my wife on why my habit of never ever throwing anything away does occasionally pay off. :)
 
(quoted from post at 22:57:09 09/16/14) What parts store? I definately need to get some.
I'm not sure if you were asking me. If so, I just found an old 1/8" galvanized street elbow in my old parts box, and he cut off the female end to make the connector for the zerk. I don't know if you can still get them at local home center stores, but you can order them. A coupler might be cheaper, plus you could get two connectors from it. http://www.grainger.com/product/Coupling-5P916
 
I was looking for Zerks that are steeply taper. I
think my zerks are mostly a 1/4 inch x 28. When I
have a bad zerk, it seems that some replacement
zerks are slightly larger than a 1/4" or my fingers
and eyes don't work as well as they should.

So either I do loads of work so I can re tap the
threads or try to figure a way to cut the threads
down on the zerk.
 
Fantastic discussion. Everything from a sturdy field repair with materials at hand to a very educational explanation of terms. Smaller crawler, that was a great link. I have nothing to add, just saying thanks to all.
 
(quoted from post at 02:31:19 09/17/14) I was looking for Zerks that are steeply taper.
.... That's funny, On another thread in this forum some folks have been talking about Google, so I decided to try to do you a favor by Googling "Steeply tapered grease zerks." And wouldn't you just know that the first hit directed me right back to your post asking the question? But another post sent me to the Alemite site that indicates there indeed are two different 1/4" zerks: a 1627-B (Straight) and a 1629-B (67.5°).
http://www.alemite.com/catalog/details.aspx?identifier=fittings_1-4ptf
Another link refers to the 1629-B as "thread-forming." And another referred me to Amazon and other sites to order them.

I hope da.bees will chime in again and let us know if that's what he meant, and give us some details. If I understand correctly, it might be a lot better solution than trying to drill and tap hardened steel--not to mention having to spend a fair amount of money with a minimum order for a rare sized fitting and tap.
 
(quoted from post at 14:46:23 09/17/14) Fantastic discussion. Everything from a sturdy field repair with materials at hand to a very educational explanation of terms. Smaller crawler, that was a great link. I have nothing to add, just saying thanks to all.
Absolutely! I have two 1970's vintage JD utility tractors, and spend a fair amount of time on the forum asking stupid questions. It always amazes me that smart people, some of them actual John Deere mechanics, are willing to spend their time to help novices like me. Unfortunately I rarely have any useful knowledge myself to contribute much to the discussions.
 
Victor Machinery Exchange, a machine shop supply
house, at www.victornet.com has 7mm metric taps
in .50, .75, 1,25, and 1,0 pitches. They also
have a real nice catalog, and will send one free if you order something.
 

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