46 Plymouth P15 help with grease zerks on front spindle

[3046moparcoupe]

Thinking I would replace the old grease zerks on the front spindle/upper control arm area of the 46 Plymouth. At 1st I thought all these original type zerks were bad because you couldn't see a check ball in the hole opening of the zerk - but now after messing with them a bit, I'm guessing that they were just made differently back then - In that they must have another internal way of holding the grease in once the grease gun is removed from the zerk. If this is true - it still would seem like a modern zerk would be better as it would keep all contaminants from entering the zerk and then being pumped on inside when you do add grease......

 

In respect to the above, I have ordered multiple packages of 1/8 - 27 grease zerks and the threads seem to be a bit different from these old original zerks. (They don't just thread into the hole like the old zerks do).

 

My 46 Plymouth Parts Book lists the zerks as : 1/8 taper thread...

 

Granted, I have been moving really slow on this to avoid experiencing one of those "poopie ca ca" moments....that said, when I start threading the modern 1/8 - 27 grease zerks into the hole by hand, the new ones will only go in about a single turn,...where the old zerks will screw in about 4 full turns and seat themselves nicely in the hole.

 

These old zerks look to be made of stainless steel, and when I do a stare and compare of the threads to the new zerks,...they look to be a match (comparing the tips of the threads to each other). The new zerk threads do however seem to be more pronounced, (like the threads are cut and not rolled and they extend out to sharp points),...while the threads on the old zerks look more like rounded rolled type threads without the sharp points out on the tip of the threads.

 

Figured I better reach out to my forum members before I just grab a 7/16 box end and try wrenching these new zerks in.

 

All reply's welcome, I appreciate your time and help.

 

Steve

 

[Don Coatney]

Grease zerks are not a "wear" item. Only reason I have ever had to replace one is if they plug up and even then a bit of heat from a torch will normally get the flow going. Why fix what is not broken?

[Plymouthy Adams]

Mary Hartman Mary Hartman...yellow waxy build-up

[3046moparcoupe]

Don, have you replaced any zerks on your 48 P15 ? If so - what did you use, thanks...S.

[Don Coatney]

I added a zerk to the top of my steering box. I used a zerk I have had in my tool box for about 50 years.

 

[knuckleharley]

Guys,maybe I am wrong,but "1/8th tapered thread" sounds like a standard pipe thread fitting to me.

 

The new ones should be a direct replacement unless they have "Chinese threads". I have noticed in the past that the Chinese generally seem to do a horrible job of converting US measurements into Metric.

 

Or maybe it's just Chinese Metric,and the rest of the world has the same problems with their crap that we have?

[austinsailor]

Similar problem - I once went to Long Island Sound to sail a boat back to Texas. In getting it ready I found the oil sender of the jap diesel was bad. Got a new one, it appeard to be the same thread. After an hour or two of trying unsuccessfully to get it started in the hole I came to the conclusion that it was the same tapered thread, just not tapped as deep. Bought a tap, 1/8" pipe as I recall and a handle, ran the tap in a couple more turns and everything fit just right.  Like mentioned, chinese threads and american threads, not always the same.  Same thread, just a bit different as to how far they went in. 

 

I have replaced a number of old zerts on mopars of that era and have never run ito that, though. I'm guessing it's the cheap chinese zerts that are different.

[Plymouthy Adams]

the zerk fitting come in various thread size and angles....be sure what you buy is what you need

[Dave72dt]

Try a 5/16 fine thread nut on one of the original zerks or try a fine thread bolt where the zerk fits.  That size was used back in that era and uncommon  in use today.  It's about the same size as the 1/8 pipe thread and may be what you have for thread size---  or not.

[Merle Coggins]

Similar problem - I once went to Long Island Sound to sail a boat back to Texas. In getting it ready I found the oil sender of the jap diesel was bad. Got a new one, it appeard to be the same thread. After an hour or two of trying unsuccessfully to get it started in the hole I came to the conclusion that it was the same tapered thread, just not tapped as deep. Bought a tap, 1/8" pipe as I recall and a handle, ran the tap in a couple more turns and everything fit just right.  Like mentioned, chinese threads and american threads, not always the same.  Same thread, just a bit different as to how far they went in. 

 

I have replaced a number of old zerts on mopars of that era and have never run ito that, though. I'm guessing it's the cheap chinese zerts that are different.

 

I used to work on Komatsu equipment. They would use 1/8" tapered pipe plugs in test ports. I would run into this same thing and I found that their 1/8" taper pipe is 1 thread different. NPT 1/8" pipe is 27 TPI. I believe the Japanese 1/8" pipe was 28 TPI. We could usually run a tap into it a bit and our NPT fittings would work fine.

 

Merle

[OnkelUdo]

Any chance they are running BSPT instead of NPT?  We run into this in solar pump and brewing equipment lot. 95% of the time you can get it to thread and if not super high pressures, you you can get it to seal but minor weepage is not unheard of.

 

Edit: Just looked it up again and the difference is 27 TPI 60 degree for NPT and 28 TPI 55 degrees for BSPT for 1/8" pipe.

Edited June 4, 2016 by OnkelUdo

[3046moparcoupe]

Thanks AS/KH and Don - I appreciate your help and sharing your experience with me,..

I did purchase these zerks off of ebay - so chances are they are Chinese made....I'll see if I can find some USA made,....and see if that's a fit....

I appreciate the option also to look at the 5/16th dimension as well, and I will do so,...the parts book does list this zerk as being 1/8 tapered thread, but still who's to say there isn't something else in there,...easy enough to prove or disprove as you stated - thanks Dave

I believe there's enough room inside the hole to run a tap, so I would think running a 1/8 - 27 npt tap carefully through the threads might also fix this small issue, ( if the usa made zerk doesn't )...that would produce a bit of metal grit inside the hole - but it's right at the hole opening, and there are only 2 rows of female threads inside the zerk hole....so I guess it would be more accessible than most situations like this ( as far as trying to clean all the metal fragments out of the hole... )

I'm hoping USA made might fix this....

Before messaging the forum this morning, I did contact a zerk company that I found on the computer - thinking they might be able to help me with this, question being ( are all 1/8 tapered thread fittings supposed to be the same ? ) They said they had documentation that went back to 1949, and as I understood them - that was when the NPT classification came about, also from what I've read about the pipe thread fit, there's one style that is supposed to be an interference type fit, between the male and female threads - which could also explain why these new zerk threads also are fitting so tight into the old zerk hole...

Last thing I wanna do is make a mountain out of a mole hill - I just don't wanna strip out my threads or damage things in any way - in respect to that - it helps more than you can know, when you guys with experience in this are good enough to share positive information with me.

Thanks

Steve

[3046moparcoupe]

Thanks Merle and Onkeludo,....

What I have purchased that is producing this tight fit situation is all labeled as 1/8 - 27.....but again I bet for sure they are Chinese made....and as mentioned above that might be whats happening.

I'll be the 1st to admit for sure - I have stood back sorta afraid of this. With only two rows of threads, I sure didn't want to mess the hole up. You get to where you can feel what a bolts doing when your wrenching it, there might be resistance - but if it's smooth and even, your ok, so I did my smallest 7/16 hand wrench and turn the zerk inwards a slight bit...and it didn't seem to start binding up,...but this situation is more delicate than most so I stopped, figured I better not proceed - until I learned more, so I backed it on out, all the threads looked fine,..and I thought don't experiment. Lean on the forum again about this and gain their insight and experience, rather than experimenting..

Thanks again for all your input.

Steve

[3046moparcoupe]

Found some Lincoln brand 1/8 " pipe thread grease zerks at Oreilley's Auto Parts, they had to order them out of Oklahoma City which only takes 2 days, so they'll be here Saturday...sales counter said they were USA made, so we'll see,...I'll let folks know how this turns out.

Thanks

Steve

[3046moparcoupe]

well the Lincoln brand 1/8 pipe thread grease zerk's wasn't the answer,....these Lincoln zerks fit tighter in the threaded hole bore than any I've tried,...these basically will only start and turn maybe a 1/4 turn by hand before they tighten up and stop...starting to think I just need to slowly run a 1/8-27 tap into the existing hole threads, in effort of trying to deepen my existing threads to accept the normal 1/8-27 zerks.

While I did have the old original zerks out, I took my calipers and did some measure comparison between the old zerks and the new stuff I've been buying,...I measured at the 1st thread, inside the thread valley,..and the new 1/8-27 zerks are 7-8 thousands larger than the old zerks....even the old zerks did not thread all the way in, they left about 2ea of the 5ea total threads showing,....I wonder if whomever at the Plymouth plant, that installed the zerks on this P15, may have been on their first day on the job ..

I sure do and did appreciate all the responses back with this,...nothing better than folks willing to try and help..

Steve