tripple gear bushings

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philip
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tripple gear bushings

Post by philip » Mon Sep 09, 2019 9:53 am

i am in need of new pins and triple gear bushings. the vendor has cheap ones and the z bronze at 21.00 ea.
i have read the whole story about clearance z bronze and gears locking up. i would like to hear from people using both and your
results. philip


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Re: tripple gear bushings

Post by Les Schubert » Mon Sep 09, 2019 10:35 am

I question that you actually NEED bushings. Pins, definitely yes. I have not replaced the bushings in years. Always the pins


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Re: tripple gear bushings

Post by philip » Mon Sep 09, 2019 10:50 am

they measure .684 is that runable? philip

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Re: tripple gear bushings

Post by DanTreace » Mon Sep 09, 2019 12:25 pm

Philip

Here are Ford's service tolerances, 1st column is factory new, 2nd column is allowed service tolerance, when over/under tolerance, repair or replace.
190933 - Copy.jpg
If the gears are very nice, and bushings have proper service dimensions on the pins, one can reuse.

Have mostly found the bushing face is worn, and risk of running gear against the flywheel is high, other times the bushing is loose in the gear or bushing is too worn in the i.d.

Gears that have excellent teeth..hardly any wear, normally have nice bushings, showing lack of high milage and good care.
The best way is always the simplest. The attics of the world are cluttered up with complicated failures. Henry Ford
Don’t find fault, find a remedy; anybody can complain. Henry Ford


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Re: tripple gear bushings

Post by Les Schubert » Mon Sep 09, 2019 1:40 pm

I just measured some new pins at .675”. So if your existing bushings are worn fairly “linearly”,
And the flanges keep the gear from rubbing on the flywheel, then I would just run them.
Consider that originally they used low a LOT more than we do today (plowing mud and snow etc). I doubt I drive in low for more than 100 yards in a day of T driving (I have a Ruckstell).
Your plans maybe different though, so just my thoughts.
All the best


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Re: tripple gear bushings

Post by Adam » Mon Sep 09, 2019 5:02 pm

Dan, Where did that chart come from?

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Re: tripple gear bushings

Post by AdminJeff » Mon Sep 09, 2019 9:56 pm

Les Schubert wrote:
Mon Sep 09, 2019 1:40 pm
I just measured some new pins at .675”. So if your existing bushings are worn fairly “linearly”,
And the flanges keep the gear from rubbing on the flywheel, then I would just run them.
Consider that originally they used low a LOT more than we do today (plowing mud and snow etc). I doubt I drive in low for more than 100 yards in a day of T driving (I have a Ruckstell).
Your plans maybe different though, so just my thoughts.
All the best
I wish it was 100 yards.... more like 1/2 mile a day on my hill each way. Coupled with questionable bearing material from way back who knows when and you get this. Warning, viewing nor suitable for some...

I'm going to get the needle bearing setup from Dan M. I never want to deal with this ever again.
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Re: tripple gear bushings

Post by Les Schubert » Mon Sep 09, 2019 10:18 pm

Jeff
It would appear that the bushings seized to the pins. This seems to be a all to common problem when people fit new bushings too tight to new pins. I have never seen this happen when original Ford bushings are run on new pins.
In regards to the needle roller system I have those in service on a high performance T engine and am quite satisfied

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Re: tripple gear bushings

Post by Matt in California » Mon Sep 09, 2019 10:53 pm

Jeff,
I would like to get the bearing material tested. I might be able to at the local university materials lab. Let me know if you are game for sending me a sample. If so I will check to see if it is possible.

Thanks,

Matt


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Re: tripple gear bushings

Post by Scott_Conger » Mon Sep 09, 2019 11:07 pm

I've never seen a bushing wear so thin as the one that has left only the thrust remainder on the flywheel, nor have I seen a spun gear wear out the bushing quite like it did. Often times, even silent transmissions have a bushing welded onto the pin and spinning happily within the gear. This looks like a lubrication problem to me. Chicken or the egg...who knows?

It also looks like the drum assembly was not stable within the triple gears and wonder if the front bushing on the brake drum destructed first and oscillated within the triple gears. Oh, to be there for the teardown...
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Re: tripple gear bushings

Post by Tlman » Tue Sep 10, 2019 1:06 am

Scott, I would also like to see the rest of the story.

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Re: tripple gear bushings

Post by AdminJeff » Tue Sep 10, 2019 1:12 am

Les Schubert wrote:
Mon Sep 09, 2019 10:18 pm
Jeff
It would appear that the bushings seized to the pins. This seems to be a all to common problem when people fit new bushings too tight to new pins. I have never seen this happen when original Ford bushings are run on new pins.
In regards to the needle roller system I have those in service on a high performance T engine and am quite satisfied
Nope. 2 of them spin freely on the pins and all three wore basically the same - look closely at the gear wear pattern in the flywheel that shouldn't be there. Funny how so many folk "know" exactly what happened. As a trained engineer, what I know is that is all speculation at best. I am up for testing the metal though... not that it will ultimately lead to anything conclusive.
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Re: tripple gear bushings

Post by AdminJeff » Tue Sep 10, 2019 1:19 am

Matt in California wrote:
Mon Sep 09, 2019 10:53 pm
Jeff,
I would like to get the bearing material tested. I might be able to at the local university materials lab. Let me know if you are game for sending me a sample. If so I will check to see if it is possible.
Thanks,
Matt
That would be fun. My engineering mind accepts the offer if it's doable. There would need to be a control with another known good, original bearing. perhaps even a new one as well. Metallurgy is complex and would need specialized, precisely calibrated equipment to get any kind of useful results. Then an educated and expert interpretation of the results. I'm game tho.

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Re: tripple gear bushings

Post by Scott_Conger » Tue Sep 10, 2019 9:57 am

There is speculation, and there is knowing. As an engineer also, I know I would have stopped driving that thing long before it ended up looking like this. And yes, what I and others have posted prior to this has been speculation. There are two kinds of speculation: Speculation based on experience, and speculation that is simply a Wild A$$ Guess. Fortunately, this isn't the First Model T, and determining cause of failure isn't necessary to improve the design, or save the company itself from ruin. I also know that there isn't a single moving part and very few non-moving parts on that transmission that I would reuse. I'd repair it (by replacing the whole mess) and move on. Now you know that Model T's should not typically knock, crack, or bang, despite what anyone tells you. Best of luck to you on getting back on the road.
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Re: tripple gear bushings

Post by Walter Higgins » Tue Sep 10, 2019 10:47 am

Just to throw it into the mix, I think what is often overlooked is what process people are using to size their bushings after installation in the gear. Without "leading the witness", so to speak, I would like to hear how others are accomplishing this -- both those who have and have not suffered a failure.


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Re: tripple gear bushings

Post by Les Schubert » Tue Sep 10, 2019 10:55 am

I am also a trained engineer and I spent my career as a rotating equipment specialist and inventor. Model T builder and driver for 45 years. My fastest T powered T speedster does 100 mph. I have put many thousands of miles on the cars I have built


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Re: tripple gear bushings

Post by Original Smith » Tue Sep 10, 2019 10:58 am

Bob Bergstadt spent a lot of money a few years back having the Z bronze bushings made. I would buy them from him.


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Re: tripple gear bushings

Post by Scott_Conger » Tue Sep 10, 2019 11:09 am

Jeff

just got off the phone with Hank on a different subject. Your name came up regarding forum and I think it might be wise to take him up on his offer. He has a lot of stuff and knows what he's doing.

Les

I spent many hours balancing gas bearings on Schenke-Trebble balance equipment. My guess is your stuff was larger, but we probably were dealing with exact same physics on different scales

Philip

to try to bring this back to your question, the advice to buy Bob's material for the premium $$ will be money saved in the long run.

all the best to you all
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Re: tripple gear bushings

Post by TonyB » Wed Sep 11, 2019 12:27 am

That broken triple gear is the first tooth problem I have ever seen on a triple gear. I agree that most restorers make the triple gears too tight on the pins causing all kinds of problems. I have seen many with the bearing loose in the gear and many where the face has worn such that the gear touches the flywheel.
But that’s the first bad tooth😎😊
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Re: tripple gear bushings

Post by Altair » Wed Sep 11, 2019 12:50 am

I would kike to discuss the correct process to fit the bushings, honing by hand with a small hone using oil versus honing in a vertical jig. Also reaming by hand or in a vertical jig. I have honed the bushings to fit by hand, however I cannot confirm they are perfectly straight, they look and fit good, but?


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Re: tripple gear bushings

Post by art32mor » Wed Sep 11, 2019 1:18 am

What hasnt been said or TALKED about is the rest of the bushings drums center shaft 4th main PAN
how was the crand and trans shaft coupled was it true
NOPE NARRY A WORD HERE
if theres wear throught the hole trans will coz the trans sagg and cause wear
To find root cause one must look at each piece in its relationship to the problem child and GO


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Re: tripple gear bushings

Post by Scott_Conger » Wed Sep 11, 2019 9:22 am

Bob

Sept 9, 9:07
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Re: tripple gear bushings

Post by Kohnke Rebabbitting » Wed Sep 11, 2019 10:49 pm

Clearance for the triple gear bushing should be .003, that is what Ford reamed them at by, Micing New Old Stock, drums, and triple gears.

Also, K. R. Wilson Reamers make a .680 hole for the pins. I have got one good used set of transmission Wilson reamers, and 2 sets of N.O.S., they all cut the same size hole, for what ever Bushings. The O. D. of the pin should measure from .676-50, to .677-00.

The new repro pins, some are all over in size. There two companys making them. One is good, other isn't worth the postage.

The good company, still has to be checked for size, they will very. If the pins need to be brought into Spec's, Emery strips, and a lathe, will do it.

Always Mic the old pin, where it pushes into the flywheel, your new pin should be .003 larger. If smaller, it may not stay, if larger, it may bust your flywheel.

If the brake drum bushing is not reamed in a Jig, chances are it is not as true as it could be, also the tail shaft. Tail shaft bushings can not be cut in a lathe, and have them align with each other, unless you have excess clearance. The picture of the triple gears, what broke them, they tried to run over the Driven Gear, to much slop, and or out of alignment.

If you don't get the brake drum bushing " WE HAVE ALWAYS USED JUST ONE " driving plate, in perfect alignment, you will get a heck of a vibration,
and it doesn't take much, misalignment.

Herm.
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Re: tripple gear bushings

Post by George Mills » Thu Sep 12, 2019 1:26 pm

I need to post a comment here and do please forgive me in advance but it bears saying before the subject takes on legs. Those who wish to pursue the material science or the manufacturing art behind how the triple pin and bush ‘worked’ for Ford have fun and go for it. I do encourage such thinking. Yet for this topic, the last time folks started to re-engineer and re-think the idea behind bushes and pins the result was that at least half of the tranny’s rebuilt from ideas wound up swallowing themselves in the first 200 miles during that year and the year after! That’s a tall order where the risks surely exceed the rewards.

The sum and substance of the conclusions of the time was that guys like Herm and those others who had the tooling, the process, and have matured their own ‘art’ 100 times over with success could in fact use stock modern bushing material, stock pins from a vendor, and have 100% expectation of success in achieving a so-called 0.0035” clearance with proper surface finishes. Fine for them, they earned it! Buy a rebuild from them and rest assured.

For the rest of the world, you can not simply say ‘I creep up with a brake cylinder hone’ or the like and shoot for 0.003” in order to net out at 0.0035”. You ‘might get lucky, then again might implies 50%. Use good tools, shoot for 0.004” to 0.005”, and the odds for success improve 10 fold.

Trying to do it with a bandsaw, a file, and timesaver? You are indeed wasting your time and effort. Sure there will be the guy that says his grand-daddy burnished pins buy burying them in the sand and turning them ever day…but that was HIS granddaddy, using GRAND-DADDY sand, and granddaddy knew the days needed to turn…if you get my drift.

Think and be wise…that’s all. Most of the above pending questions and offers have been asked and answered a decade or so ago…use the search engine, go back, find what to do and even if you use stock off the shelf bushings your tranny will work fine with little noise.

Remember, as an analogy…all of the so-called Chinese metal that was considered crap ALWAYS passed the chemical properties test…

If someone, especially the newbies wishes to explore more in depth back-and-forth of the how’s and why’s, shoot me a PM I’d be happy to discourse.


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Re: tripple gear bushings

Post by philip » Thu Sep 12, 2019 2:35 pm

i am going to replace the pins only and let it roll. philip


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Re: tripple gear bushings

Post by Chaffins » Thu Sep 12, 2019 9:15 pm

RUNNING FIT

Note: In the Ford Service Manual, page79, Par 292 Ford uses different terminology to describe clearance. For the transmission triple gears he says 0.002 running fit. For all other bearings in the Model T Ford he uses the term clearance. On page 80 , Par 295 he says that if the clearance between the transmission bushings and shafts exceed 0.005 clearance they should be replaced. Obviously running fit is different than clearance.

Clearance means the total distance between a shaft and the bushing as measured with a feeler gauge. In this case the shaft would be against one side of the bushing leaving a gap to the other side of the of the shaft. This would be the clearance.

Running fit means that the shaft is on center of the bushing leaving a gap or clearance to each side. We believe that Running fit, 0.002 in. means clearance on all sides of the shaft or 0.004 In total clearance. This is particularly important with the triple gear bushings as they are under the most stress in use.

This point is highly disputed by many who claim that all the bushings should be reamed for 0.002 clearance. If that were so why didn’t Ford just say that instead of saying 0.002 running fit for the triple gear bushings?

Everyone I know of who set their transmissions up with 0.002 clearance have had their triple gear bushings seize on the pins. The drum bushings only survive because the drums turn at a much lower speed and for a shorter period of time.
Experience has proven that the bushings need 0.004 In. clearance to survive. Herman Kohnke says that his KR Wilson reamers ream the bushings to 0.003 in. I believe that Wilson screwed up on this. The bushings may survive at 0.003 but you are taking a risk. We all know that they fail at 0.002.


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Re: tripple gear bushings

Post by Kohnke Rebabbitting » Fri Sep 13, 2019 12:40 am

Well Glen, my new old stock tripple gears that came from Ford, already reamed, measure exactly, .680. The Wilson reamers are, an exact fit in the Ford reamed Tripple gear bushings. If Wilson screwed up, then Ford made the same mistake.

Yes I agree .002 thousandths, is to small.

Like ball caps, Ford cut all I.D.'s to 9/16's, or .562-50. At that size they will work fine, if cut at .002, they will some times smear, because when bolted to an irregular surface, they will twist, causing a bind.

We have probably rebuilt around 400 transmissions, all .003 clearance on the gears, never a failure, the same with 55 years rebuilding, babbitt bearings, knock on wood.

Herm.


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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 1:05 pm

Herman, I also have a reamer that cuts to 0.003 clearance. I agree 0.003 is probably ok but not 0.002. But that still doesn't explain why Ford plainly said 0.002 running fit. Ford never uses this term anywhere else and None of the other Ford repair manuals even address this issue, only the Ford Service Shop Manual. No where can I find a plain definition of running fit, but I think my definition is logical. There are many who disagree but offer no evidence for their disagreement. Good hearing from you. Glen


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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 1:29 pm

I would imagine that those words then, have become what we know today as ANSI Tolerance RC7
https://www.amesweb.info/FitTolerance/F ... erial.aspx
With respect to putting parts into service today, and given the parts that are presently available today, I am in the camp that looser end of the spec is safer than tighter. The quietest, sweetest performing transmissions are those which are "shot" by modern tolerancing and machine practice. And I am certain that "correct" fitting of parts has been the ruination of many a T transmission. I am always glad to hear from folks like Glen and Herm...two people with the experience to back their opinions, even if their opinions (.003 vs. .004) have their own tolerance range. Ignore these guys at your peril. :D
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Re: tripple gear bushings

Post by Walter Higgins » Fri Sep 13, 2019 1:48 pm

My mics read in tenths -- let's just make it 0.0035 and call it a day! :lol:


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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 2:00 pm

Walter

you and I both!
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Re: tripple gear bushings

Post by Walter Higgins » Fri Sep 13, 2019 2:12 pm

Scott found online what I was trying to find in my 17th. Ed. Machinery's Handbook, which is the oldest that I have at 1966 and I agree with the classification of RC7. Since I don't see a definition on the link, I will add what's in my book, P. 1,350:

"RC7 Free running fits are intended for use where accuracy is not essential, or where large temperature variations are likely to be encountered, or under both these conditions."

The definitions of running fits fall within RC3 to RC9 with them being more strict the lower the number. Lower numbers are "light journal pressures" and "not suitable where appreciable temperature differences are likely to be encountered" and start getting more liberal as you move your way up the scale. RC7 definitely fits the bill for our transmissions.


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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 2:18 pm

There are several descriptions on the internet for running fit including yours but none of them say how to make the measurement. This is so basic it stinks and they all ignore it. A lot of words and space wasted. No help at all.

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Re: tripple gear bushings

Post by Walter Higgins » Fri Sep 13, 2019 2:21 pm

If Scott's link doesn't do it for you (though it should if you input the parameters), buy a Machinery's Handbook. There are tables that offer a visual representation.


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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 2:45 pm

Walter, Then why doesn't someone post the data here?

FORD SPECS AND TOLERANCES
The Model T Ford was an amazing machine. After 100 years we still cannot fully understand why Ford did what he did. And after checking dimensions of parts produced by Ford it is obvious that his machinist didn’t always meet his specs. In most cases the dimensions and tolerances of parts I have checked are bigger than specified on the drawings. And even today we find NOS parts that are oversized and will not work. But be that as it may Ford was extremely successful in production and no one has matched his ingenuity, not even Volkswagen. It took them twice as long to produce 12 million Beatles.

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Re: tripple gear bushings

Post by Walter Higgins » Fri Sep 13, 2019 3:18 pm

It's a good bit to post, I don't have a practical way to scan it from the book, and I'm not certain that I can for copyright reasons. Even my "new" 25th Edition from 1996 has the exact same information in it. With all the stuff that you make, I'm surprised that you don't have a Machinery's Handbook at your fingertips.


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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 3:29 pm

Walter, I have never need one. I have always gone by fords drawings and common sense. While producing over 300 new parts and never having any problems I think we have been successful. But on this one Ford threw us a twist by choosing to not just stay with a tolerance or clearance instead of saying running fit. Thanks Henry. Rest in peace.

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Re: tripple gear bushings

Post by Walter Higgins » Fri Sep 13, 2019 3:40 pm

Once I heard an old parable something about a horse and it's drinking habits that might apply here....

Nothing in the Handbook is contrary to Ford's print in this matter. In this case it provides a definition and guidelines for a term that seemed to be in dispute in this thread. Separate from that, how one can never need something when they apparently do not know what is in it is a mystery to me.

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Re: tripple gear bushings

Post by DanTreace » Fri Sep 13, 2019 3:44 pm

The Ford Service does mention the tolerance of the reamed triple gear bushings as a 'Running Fit' to the shaft of the triple gear pin.

That 'running fit' is one of the classes of tolerance for fits.

The Ford blueprints call out the tolerances of the pin and the reamed bushing

Pin shaft tolerance: .6770 -.6775' O.D.
Reamed bushing tolerance : .6785-.6790 I.D

So the tolerance or fit between these parts ranges from .0015 -.0020. That leads to a 'clearance' of .003" to .004".

These are the numbers that are successful for Glen and Herm and others, when done right with the good workmanship of aligning the drums and gears for reaming.

Murray Fahnstock with his Ford Power Plant chart of service ( I posted above earlier) listed .005" as "serviceable" but I can attest that .005" makes for a more noisy set of triple gears , as I had my last engine set for 'safe' clearance, but..oh boy. ;)


Found this info in The Automobile , 1916, to describe the classes of fits, you can see that a "Running Fit" is in the middle of the pack of precision fits.

The upper end of the chart is for shafts, the lower end of the chart is for bores, or the reamed bushing. The # on the left of the chart are tolerance units, if you look at "Running Fit" and look down on the lower chart you can decipher the range of about .0015" to .0035" or so, that is what Ford stated as the .002" running fit , it makes it on this chart in the middle of the grade for a running fit.
IMG_0468.jpg
And listed definitions:
Fit in general denotes the physical correlation of two parts joined tog-ether, and is characterized by the clearance or interference.
Clearance is the free space between bore and shaft.
Interference is the amount by which the diameter of the shaft to be inserted exceeds the bore.
Allowance is 'the difference between shaft diameter and bore; it is positive when the shaft diameter is greater than the bore and negative when the shaft diameter is smaller than the bore. Positive allowance is interference; negative allowance is clearance.
The best way is always the simplest. The attics of the world are cluttered up with complicated failures. Henry Ford
Don’t find fault, find a remedy; anybody can complain. Henry Ford


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Re: tripple gear bushings

Post by Kohnke Rebabbitting » Fri Sep 13, 2019 3:59 pm

Chaffins wrote:
Fri Sep 13, 2019 1:05 pm
Herman, I also have a reamer that cuts to 0.003 clearance. I agree 0.003 is probably ok but not 0.002. But that still doesn't explain why Ford plainly said 0.002 running fit. Ford never uses this term anywhere else and None of the other Ford repair manuals even address this issue, only the Ford Service Shop Manual. No where can I find a plain definition of running fit, but I think my definition is logical. There are many who disagree but offer no evidence for their disagreement. Good hearing from you. Glen
Here, when we fit a Ball, roller, ect. bearing to a shaft, what ever the application may be, we call that a fit.

If the application is for movement, as a shaft turning in a bearing, that we have always referred to as running fit.

It just does not seem, ( Spock Logical ) That Ford, and K. R . Wilson reamed at .680 hole, with .003 clearance, and I do know from much personal experience, it does work.

The Guy that wrote the book, may not have even been a mechanic, and as we both Agree .002 will stick them tight.

No body that I know, refers to a fit in any kind of bearing, as .002 on each side, as being .004, or .002 clearance, with .001 on each side, that would be ( Spock Illogical ) , and very confusing to a simple Guy, like me. I take shaft size, and subtract, from the hole size, and wallah!

Are you still working Glen? I want to again thank you for all the Babbitt business over the years. I also still have about a 1000 cam bearings you sent me, very handy.

I was very lucky to take out a retirement plan when I was 19! It is called, work till the day you die !

Thanks,

Herm.


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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 5:04 pm

Dan

with due respect, I do not have the drawings, but have seen them (and I recall the pins are as you state) but the Ford drawings give maximum and minimum material conditions. They do not give tolerances, though one can derive a nominal dimension and tolerances around that nominal condition from the values given. So a discussion of tolerances can be a confusing rabbit hole here. If you will re-review the information you included in your post, placing a smallest hole to a largest pin, and vice-versa, you will come up with different numbers than you did (which will further confound what we know to be true regarding fitting these parts too closely). The chart which Dan posted can be found on Page 1280 on this link:https://books.google.com/books?id=hAlaA ... &q&f=false

It is interesting to see the genisis of later/modern (for us) specs. Geometric Tolerancing and Dimensioning is a whole 'nother kettle of fish.

Additionally, and not unimportantly, both Stevens and KRW were in the business of providing servicemen with tools that would produce SUCCESS. I believe that Herm's reamers represent the logical and successful formula to a repair "back in the day". Reading their literature can teach a modern mechanic volumes, with regard to practical and successful analysis and repair of what was "state of the art" when published. There are times when those firms varied from FORD practice and I do not believe it was to the detriment of their customers, but to their betterment.

And again for those too lazy, stubborn, or simply not inclined to check (no offense intended), the ANSI spec provides a clear set of tolerances (around a nominal value) which fit perfectly with what Herm and Glen espouse. If either of them wish to argue with me for agreeing with them, then that is what makes life interesting!

Through the years, I have found that more success is to be had in properly applying a specification to a given machining job than trying to guess what the confusing language was on a very old technology/drawing. If you doubt that, try applying old Trade Formulas used in watchmaking: One particular one I was interested in stated in part, you use Dragon's Blood as one part of a concoction for making a durable Lacquer for Brass. Even with the internet and 40 year's experience as a professional and now hobbiest, I still don't know what that is!

I have always found the language around FORD's description to be both precise and confounding. It is indeed a running fit, and knowing the operational parameters, we can easily and properly apply a modern specification which perfectly aligns with Glen/Herm. If you wish to focus on the confounding part, that being the "number" given, well, use it at your own risk.
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Re: tripple gear bushings

Post by Walter Higgins » Fri Sep 13, 2019 5:34 pm

Another point to be made is with respect to the reaming operation and all this back-and-forth of whether it was 0.003 or 0.004 -- in the past Mr. Mills has mentioned that it is highly likely that at the factory the bushings were finished to size with a sizing ball. That is a completely different operation from reaming and other considerations with respect to surface hardness and how it affects the material were mentioned.

What I have not seen mentioned are some of the many variables as they relate to reaming. If anything, a reamer can make a hole larger than it's stated size depending on feed, speed, its fit in the pilot, how sharp the cutter is, etc. While the KR Wilson fixture is neat and no doubt practical, it is not a very high class affair. It probably wouldn't be difficult to ream a hole and have these variables cause the end product to come out at least 0.6803. If the surface finish is a bit rough, you have lots of high ridges as compared to something finished with a sizing ball. Now throw them in an engine, go run it up a hill, take it back apart, and measure and I'll bet you could see another 0.0003 once they burnish in. When you're talking about all these different processes for finishing the hole, all these other factors need to be discussed. For much of this stuff there is more than just a number on a mic. You have to take into considerations the dynamics of the hole sizing process and what that bushing is going to see immediately after it is put into service.


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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 6:16 pm

This is all mumbo jumbo. Why can't anyone just tell us what 0.002 running fit is in clearance? I think I know but no one agrees.


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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 6:22 pm

Dan, Your chart says tolerance units not clearance. What does that mean? Glen


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Re: tripple gear bushings

Post by Les Schubert » Fri Sep 13, 2019 6:25 pm

This has all been “entertaining “!
I will continue with my policy of reusing original T bushings in conjunction with new pins (unless they are excessively worn) I’m Ok with clearances in the.008” range. My freshly rebuilt engines are quieter than most of the ones I hear


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Re: tripple gear bushings

Post by kerry » Fri Sep 13, 2019 6:40 pm

I'm with you on that Les.
Some claim to never have had a failure at a set clearance but in reality one would not really know until it's pulled down again, a locked bush on a pin can spin in the gear for many years without any telltale signs.


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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 7:10 pm

Glen

If we knew if FORD was using BORE BASIS, SHAFT BASIS, or BILATERAL BASIS, we would have a better grasp of what ".002" meant. However, with research in 1920's documentation, I think we can figure out EXACTLY what ".002 tolerance" meant.

Regarding the Chart that Dan provided, the upper left portion is tolerance for Hole Basis, while the larger portion of the chart is for Shaft Basis tolerancing and it represents the GERMAN basis for fits. This chart is difficult to use and was not fully incorporated for use in USA at the time.

Industry in Europe, UK, and United States were conflicted regarding tolerancing and class of fit, regarding types and how to break down those classes. In the United States, for awhile, the American Engineering Standards Committee, sponsored the American Society of Mechanical Engineers to issued a questionare to industry to quiery them regarding the MEANING of their IN HOUSE tolerancing regimes. Society of Automotive Engineers (SAE) settled on a system where tolerances were set at "plus" for bores, and "plus" for shafts, where the low limit was the "nominal" size called out, which was found to be very hard on gauges when establishing appropriate fits of parts. In Germany, just the opposite was the case, where "nominal" was the high limit. In 1921, America was still struggling with standards; which to use, how to apply, how to verify. It was a disaster and allowed for line/line fits on parts meant to rotate...BAD

In 1921 standards had STILL not been settled upon, but progress was being made. Finally, as they worked toward standardization of what "tolerance" meant, they conclude with: "It is the opinion of the Bureau that in general the minimum hole should be of basic size and that the tolerances on the hole should be plus, and that the maximum shaft should be of such a size as to give the quality of fit desired, all tolerances on the shaft being minus." This, however was STILL not the final word, thus, the one FORD drawing with a "tolerance" cannot at ALL be interpreted by today's standards with CERTANTY. Period.

And yet, with FORD being a leader in manufacturing, it is absolutely to their benefit to adopt what was recommended, so, If, on the other hand, FORD was going by RECOMMENDATIONS, then there you have it, in 1921 language for NEW manufacturing, the RECOMMENDED standard is: The standard is nominal "hole" plus .002 and nominal "shaft" minus .002. So, how about that? FORD drawing recommends ".002" tolerance. Just as recommended. Which is NOT necessary the TOTAL clearance, nor a mandate to have .002" "on both sides". It is the TOLERANCE, and now you know how to apply that .002" in the drawing.

This would explain why you find .004 (max) clearance to be a good, serviceable and reliable bearing for new Triple gear bushings, and why an "average" fit of .003 reamed by Stevens/KRW was chosen.

Class Dismissed.
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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 7:39 pm

And not that anyone gives a d#$n, but I just found out what "Dragon's Blood" is. If you have not read the whole thread, this is meaningless to you, so just ignore.

And to stay on topic: Les, I'm with you...loose=good, tight=bad
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Re: tripple gear bushings

Post by AdminJeff » Fri Sep 13, 2019 7:48 pm

Wow. ok so everyone has some input here. This is one for the forum history books. how to beat a topic to death and then keep on beating it.

I say it's probably time to take a breather on this topic guys....

You guys all got me hot and bothered so I had to go take apart the '27 motor/trans I got in the barn find this afternoon just to see what I have to work with. Looks like I got incredibly lucky. Everything in the trans looked great - obviously lots to check w/ mag/etc but visually sound.

But I do have a question about the triple gears in this "new" trans....

Yup, amazingly something that hasn't been discussed. When i pulled the gears out, I pushed 2 of the bushings out of the gears with my fingers. They were snug but they came right out. They each measured about 4-5 thou in terms of pin to bushing clearance (inside bushing minus pin). Aren't the bushings supposed to not come out of the gears? No abnormal wear patterns anywhere.

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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 7:55 pm

Mon Sep 09, 2019 9:07 pm

sometimes they spin. Sometimes for years. There is all level of mechanics out there.

You will find the gear is likely now oversize in the bore. New bushings (Bob's) will be slightly oversize and should press in fine, anyway.
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Re: tripple gear bushings

Post by AdminJeff » Fri Sep 13, 2019 8:00 pm

what's with the time stamp posts? I delete those each time I see them as they mean nothing to me which means they mean nothing to 99.9% of everyone else who reads these forums.

My plan is to send this set of gears to Dan M. to get the needle bearing setup. I'm assuming they'll work ok for that mod. Andy Clary recently came over and experienced my "hill" for the first time. He now knows why I want to go this route.

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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 8:08 pm

When I have done it, twice now, it refers to a day/date/time a specific question was answered already. On the same topic thread. I will refrain from now on. And as far as "beat to death" I have NEVER seen anyone publish the specific reasoning or documentation as I have, as to why Fords drawing is as cryptic as it is, or what it actually means, based on long-gone, long-lost historical documentation. You may have gotten nothing from it, but I'll bet there are folks who have had their eyes opened just a tiny bit.

Thanks for your work on the Forum.
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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 9:08 pm

This subject and I get beat to death every couple of years. My only concern is for the idiots that think 0.002 running fit means clearance. And believe me, there are a lot of them out there. They are the ones that you will se sitting along side the road with seized triple gear bushings. Do what works for you as long as it works. Good night. Glen


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Re: tripple gear bushings

Post by philip » Fri Sep 13, 2019 9:24 pm

I didnt mean to get all of this going again I only wanted an opinion on the
Clearance I have On the old bushings I think I will use the old ones with new pins. Philip


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Re: tripple gear bushings

Post by Scott_Conger » Fri Sep 13, 2019 9:32 pm

Glen

I fail to see how every post on this lengthy thread agreeing with you that .002 clearance is too small, is a sign of your getting beaten up. There have been detractors in the past, but they are not showing up now, and if they did, they would be arguing against what I believe to be very compelling evidence supporting your position. I have watched your posts through the years and have learned from them. Thank you.
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Re: tripple gear bushings

Post by AdminJeff » Fri Sep 13, 2019 10:04 pm

Chaffins wrote:
Fri Sep 13, 2019 9:08 pm
This subject and I get beat to death every couple of years. My only concern is for the idiots that think 0.002 running fit means clearance. And believe me, there are a lot of them out there. They are the ones that you will se sitting along side the road with seized triple gear bushings. Do what works for you as long as it works. Good night. Glen
That is certainly my takeaway and the only thing I'll remember after beating this topic to death.

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Re: tripple gear bushings

Post by Chaffins » Fri Sep 13, 2019 10:08 pm

Thanks Jeff, Glen


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Re: tripple gear bushings

Post by Kohnke Rebabbitting » Sat Sep 14, 2019 6:02 pm

Through the years, I have found that more success is to be had in properly applying a specification to a given machining job than trying to guess what the confusing language was on a very old technology/drawing. If you doubt that, try applying old Trade Formulas used in watchmaking: One particular one I was interested in stated in part, you use Dragon's Blood as one part of a concoction for making a durable Lacquer for Brass. Even with the internet and 40 year's experience as a professional and now hobbiest, I still don't know what that is! " END QUOTE "

Scott, I am not completely sure, but if you were wondering what Dragon's Blood is, it is a Pigment, Blood Red, used in violin Varnish.

I used it mixed with shellac, to repair old worn violin finishes, after, repair. Not to be used on modern violin, gloss finishes. It would blend in to any color.

It can be had from any violin makers parts house.

Herm.


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Re: tripple gear bushings

Post by Scott_Conger » Sat Sep 14, 2019 6:33 pm

Thank you Herm.

You just never know what you're going to find on this forum! The formula that referenced it was for (I now know) putting a slight tint on lacquer used on polished brass. I would suppose that the tint would not be obvious other than to perhaps give a richness of color to the brass substrate. This came from a book who's title in part was Henley's (?) 20th Century Trade Secrets and Formulas, and trust me, it was BARELY 20th Century when it was published! It was kind of you to put that info out there. Thank you again!
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