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PostPosted: January 15, 2015, 1:27 am 
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The voice of reason
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I could post a picture but the worn part looks exactly like it did when new, with its typical import narrow housing.


Kurt, I think this is a valuable discussion and I'm glad you took the effort to start it. I think the "typical import" phrase is maybe causing an issue. I know someplaces China bashing is very popular. It's possible the only reason it's typical is that the cheapest units are no longer made in the stares. Those imports may be copies of "typical american" industrial grade parts from 30 years ago.

I have seen the ones with narrow housings used and wondered about them. I don't even remember where or when.

If you could I would still like to see a picture, not because the flaw will be obvious but it helps to recognize them.

There's another inexpensive style I've been wondering about that has wider bands of teflon or plastic visible on the sides. I think they are the injection molded ones and the Aurora folks seem to call them out as inadequate in their literature I pointed to above. Those have full size bodies. After looking at the picture I think they might be particularly bad on axial loads because it looks like the race doesn't really go 360 degrees around the ball. I haven't seen one in person yet though.

You mentioned the ones that failed were loose to start with. Is there a chance the teflon part was missing? I suppose that would be rattle loose. Still if it was loose, maybe enough dust and grit get in there to cause problems quickly. Can you twist the ball around 90 degrees and look inside?

Good rod ends last a long time. I've replaced rod ends on a formula car when I bought it, but don't recollect replacing them afterwards even with years of use.

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PostPosted: January 15, 2015, 4:24 am 
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The more I think about the few descriptive comments so far, the more convinced i am that these were probably just plain old 2-piece rod ends, as shown in robbovius' last picture, which are NOT by any means an "imported" specific style of rod end. ALL rod end manufacturers make these, and make them cheaply...Even the "US made" brands. If the rod ends in question were actually PTFE lined, the reason for the excessive play is probably because (much like Elvis) the PTFE liner has left the housing. This is by no means necessarily a reflection on the bearing manufacturer, let alone country of origin, nearly as much as it is the end user for selecting the wrong STYLE of rod end for the application.

Since FK seems to be the pedestal mounted "US made" manufacturer of choice, note that FK also makes cheap 2-piece style rod ends that are equally unsuitable for our applications as well. They may be expected to cost much more than an "import" brand like Midwest Control too, but FK is competing for business in a global marketplace just like everybody else. The cheapest 1/2" 2-piece metal-metal FK's can be had for <$4 each. I also see the PTFE lined 2-piece FK's for just over $11 each purchased individually, or just over $7 each in batches of 10. By comparison Midwest Control currently sells their equivalent PTFE lined 2-piece rod ends for a similar price purchased individually, and only about $1 less each at the quantity of 10 pricing. I won't argue that the FK 2-piece rod ends could potentially be a bit nicer than the Midwest Control 2-piece rod ends of the same exact style, and the PTFE liner may even be a bit more durable in the FK's, but I doubt if it would make a dramatic difference to the end result in this situation. The biggest difference would be from going to a different style, more like the "US made" ones that are doing just fine on the other joints, even if it's just that equivalent "imported" rod end.

There are quality rod ends available, manufactured both domestically and abroad, available in more suitable styles for our application.

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PostPosted: January 15, 2015, 7:37 am 
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I bought pn 4483T601 from Mcmaster for $18 each. They are actually QA1.

Description:
"With PTFE/Kevlar Insert—A heat-treated, chrome-plated bearing steel ball glides on a durable, self-lubricating, self-sealing PTFE/Kevlar insert. Housing is heat-treated chrome molybdenum steel."

1/2-20, Static radial load capacity, 16,238 lbs.

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PostPosted: January 15, 2015, 12:32 pm 
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FK supplies both domestic and import versions of their 2 piece low carbon steel rod ends. They both have identical load ratings but only the domestic ones have a teflon version available. ultimate radial load 1/2" bore =

The above units have what I think KB58 is referring to as a narrow housing, but I am not completely sure. These housings have a step in their outer diameter so the full thickness is only in a center band around the housing. The catalog says these all have about a 20 degree misalignment spec, which is a lot more than some of the 3 piece fancy ones. That may be the underlying reason they have that shape, but I'm not sure yet.

Continuing thru the catalog the next series of rod ends with heat treated bodies and

Notes:
Tolerances vary on these units. It looks like when they mention "performance" or "precision" the bore diameter tolerance is +.0015", -.0005", the other joints are +.0025", -.0005". All the 2 piece joints are the lower tolerance. All the imports are the lower tolerance.

It looks like all the 2 piece housings have that step in the outer diameter, that is probably from the race forming process. The lower strength 2 piece housings are narrower in width.

Quality is partly what your needs are. For example if you need 15 degrees of angularity, the precision 3 piece units simply will not work. It's worth checking your angularity needs when spec'ing your bearings.


http://www.fkrodends.com/Downloads/2013%20FK%20Automotive%20Catalog%20low-res.pdf

Code:
1/2" bore rodends from FK:

Series    ultimate radial load      angularity     housing width     comment (domestic unless noted)
CM        8386 / 7200 (PTFE)       20                 .453"                 2 piece low carbon housing
ECM      8386                                                  .453"                 economy (import) 2 piece low carbon housing
CMX      25,000/21,400 (PTFE)   24                 .593"                 2 piece heat treated steel housing
SCM      4700                             20                 .453"                 2 piece stainless steel PTFE

JM         6700                             12                 .500"                 3 piece precision wear resistant low carbon housing
JMX       16,242                          12                 .500"                 3 piece precision heat treated alloy steel housing
SJM       19,520                          11                 .515"                 3 piece precision stainless steel housing PTFE

RSM       12,843                         10                 .500"                 3 piece extra strength low carbon housing 5/8" shank
RSMX     31,420                         10                 .500"                 3 piece extra strength heat treated housing 5/8" shank
ALRSM   14,880                         10                 .500"                 3 piece extra strength aluminum housing 5/8" shank
                                                                                                (available in red or black!)

KMX       12,696                         12                 .500"                 import 3 piece heat treated alloy housing nylon race

PMX       23,314                           9                 .515"                 3 piece stainless steel wear resistant PTFE


edit: so much for the Code BBCode modifier not adjusting your formatting...

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PostPosted: January 16, 2015, 4:12 am 
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KB58 wrote:
If I recall, the Midwest Control Product parts at the time I ordered them (2010 timeframe) were about $3.50 each.


Could you post the part number of the specific Midwest Control rod-end you bought and is having the issue with.
I'm considering to buy a bunch of rod ends from Midwest Control.
Would want to see if I'm looking at the same or not.


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PostPosted: January 20, 2015, 6:42 pm 
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horizenjob wrote:
There are specs for these things even if Midwest control isn't giving them. Rod ends is a pretty big subject.
Kinetic's are import, imported by the aptly named Rod End Supply in Olathe, KS, and I didn't have any trouble getting the specs. Here's a link to our rod end page, with pics and radial loads:

http://www.kineticvehicles.com/rodends.html

I'm pretty open about my sources, and in many cases (such as this one) Kinetic just serves as a bulk purchasing and info/testing center (a la The Dallas Buyers Club except I'm a nicer guy). I have another business that buys lots of rod ends so we can pass the savings on to you, blah blah blah and thus endeth the advert, and here beginneth the info.

--I have over a hundred thousand miles on my Locost. It rides on 1/2" RES mid-range LX series, (to quote my own page) "A self-lubricating, self sealing NylaFiber* race, and C1045 mild steel body for 6,660 pounds ultimate static radial load, which should be sufficient unless you hit a fire hydrant at speed." I haven't seen any play in them yet. Mind you, I'm not a hard charger, and Locost control arm end loads may not be as high as at-the-spindle loads on a Midlana, but the wear resistance of the RES LX tie rods suits me fine, despite their asian heritage. Kinetic sells them for $10 and $8.65 in lots of 16.

--RES (and Kinetic) also has cheapass two piece rod ends for $3.50, and in my opinion they are suitable for test fixtures and Grassroots Motorsports $2015 Challenge cars, but that's it. See the page I linked for more info, but it seems to me that it's more of a quality vs cost issue than a continent of origin issue.

--At the other end of the RES scale is the X series, which are $4 more expensive than the LX, and are (here I go quoting myself again) "Exactly like the LX except with a heat treated 4130 chromoly steel body, good for16,238 pounds ultimate static radial load, which means if you hit a fire hydrant, you still won’t be driving home, but your rod ends should be in pretty good shape after they’ve been extracted from the wreckage."

So in summary, rod ends come in different qualities for different prices, from a variety of sources.

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PostPosted: January 20, 2015, 7:20 pm 
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JackMcCornack wrote:
...--RES (and Kinetic) also has cheapass two piece rod ends for $3.50, and in my opinion they are suitable for test fixtures and Grassroots Motorsports $2015 Challenge cars, but that's it... So in summary, rod ends come in different qualities for different prices, from a variety of sources.

This. In hindsight I shouldn't have said "import", that's my bigoted Amarican coming out, implying Chinese-made, but than again, I'm sure they have good ones as well. The point being, if we won't pay more than $3.50 for a rod end, we get what we deserve.

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PostPosted: January 20, 2015, 8:12 pm 
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Jack, something I am interested in is axial load ratings for these Nylon injection molded bearings like the LX you sell. From the picture it looks like there is an area on the side with extra Nylon where I am guessing they inject the material. That concerns me and I am wondering if that particular model or type of bearing is less suitable for an axial load than other of the Rod End Supply bearings like the PX.

Actually in their catalog I only see one bearing with an axial load rating and that is the wide series spherical bearings.

There also appears to be a typo in these tables that is identical to one in the FK bearing catalog. In one place they give the bore tolerance of the ball as +0.000 and I think they mean +0.015. I'm not sure If I have the energy to track that down, but it makes you wonder... :rofl:

I ask about this because the rod ends are oriented vertically on Car9 and so there are some axial loads. Not a major issue perhaps, but I just can't help wondering about these things...

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PostPosted: January 23, 2015, 6:51 pm 
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horizenjob wrote:
From the picture it looks like there is an area on the side with extra Nylon where I am guessing they inject the material.
The area (areas, actually; there's two of them--I'll take a pic later and edit it in to this post) is where the ball is inserted. Unlike the cheapo rod ends, where the body is formed around the ball (by stamping, it appears) these have the race ground into body and then there are access slots added so the ball can be inserted. I'm guessing that's where they inject the material too, but that's not why the slots are there. They're there so they can get the ball in without messing with the body afterward.
horizenjob wrote:
There also appears to be a typo in these tables that is identical to one in the FK bearing catalog. In one place they give the bore tolerance of the ball as +0.000 and I think they mean +0.015. I'm not sure If I have the energy to track that down, but it makes you wonder... :rofl:
I'll bet it's a tighter tolerance than +0.015...I'd wager you can move the decimal point over by one. An AN8 bolt* is pretty snug, and feels similarly snug from rod end to rod end. Also, the ball-to-body tolerance might well be +0.000 (that is, less than half a thousandth, though not actually zero in the pure math sense) since the bearing material is injected and from the look of it, it's only about as thick as a powdercoat of paint. So they probably have spectacular control of the fit 'twixt ball and body

*BTW, diameter tolerance on an AN8 is 0.495 to 0.499, which is a range of 0.004, and they're made by conventional stamp-the-head-and-roll-the-thread bolt fab techniques.

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PostPosted: January 23, 2015, 7:30 pm 
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The area (areas, actually; there's two of them--I'll take a pic later and edit it in to this post) is where the ball is inserted. Unlike the cheapo rod ends, where the body is formed around the ball (by stamping, it appears) these have the race ground into body and then there are access slots added so the ball can be inserted. I'm guessing that's where they inject the material too, but that's not why the slots are there. They're there so they can get the ball in without messing with the body afterward.


That reminded me of the crane rail tie that I had sitting on my desk, Gantrex makes them in a similar fashion, albeit with a much larger tolerance:

Image


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PostPosted: January 24, 2015, 12:50 am 
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Hi Jack, you're right on the tolerance, add a zero. I really should be wearing reading glasses all the time now when I type. The tolerance was for the bore hole in the ball.

I see what you mean about inserting the ball, that's clever.

I'm impressed with the mileage you've obtained with those rod ends. I feel better about putting them on my car with that data point.

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PostPosted: January 25, 2015, 1:50 pm 
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KB58 wrote:
The point being, I wouldn't pay more than $3.50 for a rod end, and I got what I deserved.


Who's, 'We', dude? Fixed that for you.

:-)

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PostPosted: January 25, 2015, 7:33 pm 
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A recent doc on the tube was talking about the economic miracle in China and how good they are at making counterfeits. It led me to thinking about high mark up items and the security of supply chains. On the bright side the really big mark ups are for medicines. Or not :ack:


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