Do new brakes rods really stretch??

[BRENT in 10-uh-C]

I read here recently by one poster who stated that the new brake rods have been known to stretch, ...and I started down that road trying to decide whether I want to "buy-into" that mindset/theory.

So let me ask this in this light, ...the new brake rods are .305" in diameter ( 19/64 ) of what I am going to guess is mild steel. I suppose if I wanted to calculate the tensile strength, I could find a formula but I am going to guess-timate that there is a 5,000 yield strength. If someone knows for sure or can calculate this, please do so.

Therefore if that 5k strength on each rod is the case, how is a Model-A brake pedal able to generate that amount of force to effectively stretch a new brake rod? In our discussion around the shop, there are ways that original rods were stretched over time but most of the time we have found the rods were purposely bent to take up slack created by worn internal brake parts. So can anyone tell me of their first-hand experience where their new 50¾ inch brake rod has stretched to 51 or more inches long?

In addition to that, how does one of these brake rods stretch that much yet no one ever complains about the single rod that connects the brake pedal to the cross-shaft. Does it stretch?

[Mitch//pa]

brent thanks for posting this as i could not comprehend how the rods would stretch. of course i did not do any of the math

[Marco Tahtaras]

I'm on the same page. I would be shocked if the rods gained .005" in 5k miles which of course would have no impact. Other brake issues that would falsely leave that impression are more common than not.

[Patrick L.]

Maybe as other parts wear over the years there is an illusion that the rods stretch because if anyone adjusts the brakes like I do, there are times when the rods need to be readjusted. I've never concerned myself with stretching rods, just wearing parts.
I'm pretty sure I'm not strong enough to lengthen one all by my lonesome.
But, then, if these things are now being made in china, maybe they're made from lead.

[d.j. moordigian]

Brent,

5/16"...1018 steel yield strength is 40,000 psi,..and the Rockwell is in the
"B" scale...

Bolt torque on a 5/16" "grade 8" is 27 lbs...this part should make you think
about the "grade" and quality of the threads on the rods..

I wonder if Ford used some form of ChromeMoly.....it would be nice to
know whats on the print?....and the forged end?

[Jon]

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I think it's closer to 50,000 psi, don't know if you missed a zero Brent. Real quick math, 3,500 lbs. force before rod yields. A measly 1/4" bolt will hold 780 lbs. (Before anyone chimes in, I realize there should be a factor of safety and this is for a pure static load!)

[BRENT in 10-uh-C]

Originally Posted by d.j. moordigian

Brent,

5/16"...1018 steel yield strength is 40,000 psi,..and the Rockwell is in the
"B" scale...

Bolt torque on a 5/16" "grade 8" is 27 lbs...this part should make you thinkabout the "grade" and quality of the threads on the rods..

I wonder if Ford used some form of ChromeMoly.....it would be nice to
know whats on the print?....and the forged end?

So are you suggesting in the cut threads (in lieu of rolled threads) is where they are stretching??

[MikeK]

From a handbook on my desk-
5/16 -24 thread:
Grade 2- Proof: 3200 lbs Fail: 4300 lbs
Grade 5- Proof: 4900 lbs Fail: 6950 lbs

Even if the rods are fairly low grade, like 1015 steel, ONE should be sufficient to lift the entire car without stretch. Henry's were likely closer to grade 5.

Of course, the driver stompin' on the pedal may have looked like this:

[d.j. moordigian]

Originally Posted by BRENT in 10-uh-C

So are you suggesting in the cut threads (in lieu of rolled threads) is where they are stretching??

Ya,..I like the rolled threads, with a full grain structure vs. the cut threads!
I just hadn't thought about it much,...I use original rods. Also my car
has the "one piece" non-adjustable rods.

Rod stretch...I just don't know... This could be a good shop project for
some good guy with a bunch of A's in various forms of disrepair, or is
it repair....I guess it depends on which way there going. They could
pick a car with "bent too adjust" rods and a real big fishing scale...


lol

[gweilbaker]

Another consideration is what you get is what you think, I have busted, twisted and stretched many of "quality" tools with life time replacement warranty. But the so called stretch maybe from tolerances getting comfy.

[bikejunk]

I might think the eye might elongate(or wear oval) before the rod stretches.

[Phred]

I too doubt that straight rods stretch. I suspect the statement "stretched rods" might come from the later Ford mechanical brakes that used cables rather than rods. It is more likely that the cables would stretch and the term "stretch" became attached to mechanical brakes in general.

Just my thoughts

[RockHillWill]

Rolling the threads pre-disposes the grain structure towards more easily stretching than having cut threads which is more likely to produce stress 'fractures', but I believe the reason for going to rolled threads had more to do with not having to pay the additional labor to clean up the thread shavings and to haul them off than for any engineering concern. Also saving in re-cycling costs.
I am estimating all the numbers here, but at the 50,000 psi tensile strength number, and Area = (pi x r squared) the bottom of a 5/16" thread is closer to 1/4" in diameter and has about .08 square inches in cross section. .08 time 50,000 psi equals about 4,000 pounds. If the arm below the pedal shaft is about 2" and the pedal swing arm above the pivot shaft is about 12" long, than the force 'multiplier' at the brake pedal is 6. 4,000 pounds divided by the pedal arm 'multiplier' brings the load required at the top of the pedal to 'stretch' the metal to about 660 pounds. Not likely to stretch brake rods as an ever day occurrence, but a 'big boy' having a 'bad day' on a 'bumpy road' might be in a position to coerce a little elongation in the rolled threaded area.
Just a thought!

[Tom maxwell]

As steel gets longer, even a minuscule amount per inch will eventually add up to something in 50"
For example railroad track elongates in the heat and if rail was not fastened to every tie block, the track would never be straight.
Or take cable on a crane... It stretches.
The eyes have no space to expand, but 50" does.
I will pull the books out tomorrow, but we need to know the moment force the foot puts on the pedal to the rod.
I for one believe it stretches
Tom

[BRENT in 10-uh-C]

Mr. Maxwell, just so we are clear, I am speaking of a 'stretch' that does NOT return, ...not like a rubber band that stretches but returns. Please let us know what your findings are. Tomorrow morning when I get to the shop, I will take a picture of a brake pedal listing the measurements.

[Tom maxwell]

Yes... I understand.... Stretch... as does not come back. .
I will study more

[RockHillWill]

When you gentlemen start to measure, be sure to account for worn 'eyes' at the end.

[larrys40]

With brakes as one of my forte's I still never quit learning.... You guys amaze me... I am looking forward to findings as metallurgy in that sense is not my forte... I have done many a Model A brake job/restoration, and honestly the wear factor on the linings/drums and other parts I would think would be much more significant, and account for the majority in what is necessary to keep the brakes dialed in adjustment. Under normal circumstances following proper initial adjustment, wedge adjustment is the primary periodic adjustment, although if your brakes are not activating properly rod adjustment should/coulc be in order. I do concur that all rods, almost especially the service to pedal rod has the greatest amount of force applied to it. Thinking about the force and pivot nature of the cross shaft/bushings, etc, common sense would lend itself to believe that a significant amount of wear could occur there first with other soft bushings/shafts. That accounts for the wear at the rear service brake shafts.

We have seen some pretty horrible reproduction brake parts in the past, however, I will say that in my experience that a good amount of the current reproduced parts seem to be of very good quality these days. I compliment the suppliers like Brattons, Snyders, for improving the parts for us today from the junk of years past. A little adjustment is in order anyway. Unless a brake rod breaks, threads pull ( I've never seen that), then I'm not too worried about it. I am much more concerned about the single master cylinder on my '40 or like I've experienced, a stop light switch blowing out the back to lose all fluid ( fortunately that happened in my driveway).
Think about it.... the simplicity and knowing there is a solid pedal to drum contact on "A" is really a great feeling. I never worry about having good brakes!

Larry Shepard

[SteveB31]

the rod attaching to the pedal would be under MUCH more pressure.

I have never heard of any rods stretching. Ain't gonna happen.

Own mayn rods that have been shortened , due to worn out brakes, but I own porbably 1000 original brake rods, and I doubt ANY of them have been stretched, and I see no reason why the new ones would either.

Where did this idea originally come from?

[Karl]

Interesting how these urban myths start. The mechanic who does most of the local veteran and veteran motor rebuild work and who I respect greatly stores all his cranks vertical as he claims they will deform if stored horizontal. It just can't be true but I can't convince him otherwise . I asked him if they would warp under their own weight why doesn't a camshaft bend form the force the open valve springs exert on it when the car is stopped - No answer yet on that one -Karl

[ronn]

I agree with Maxwell, though the amount of stretch over the lifetime of a car most likely can not be seen by the naked eye..........

as an example, as I get older, I am shrinking.........

[Cool Hand Lurker]

Post #13 mentioned a big fella pushing 660 lbs on the pedal. 660 lbs pressure would require a right leg that could dead lift 660 lbs. all by itself. Not gonna happen with me.

I don’t think a brake rod will stretch, but it will change it’s length as the ambient temperature changes. In the early days of the country when the surveyors mapped out the townships and sections they used a 66 link steel chain 100’ long for measuring.

WHOOPS, got it backwards there. It is 100 links and 66' long. Sorry.

They had to adjust their reading of the length as the temp changed. A 20ºF change in temp would work out to about a 8” change in the measurement with the chain in one mile.

I think driving on a day where the temp is changing would affect the brake rod length much more than any stretching would. So for me it is not a problem. I don’t have to go to the gym now to build up my right leg. Mother Nature has me beat already.

Post #21 “stores all his cranks vertical as he claims they will deform if stored horizontal”
This can happen if the crank is stored horizontally without support under all the main bearing journals. If it is only supported on the ends, then the middle can sag.

[RockHillWill]

I was poster #13 and agree that it is VERY unlikely to happen.

Also, If I dig hard enough I might be able to find the receipt that I got from having to get a $3,500 NASCAR billet crank straightened along with a severe ass-chewing from solely letting it sit on a steel workbench too long. It was only out a small amount, but needed re-grinding, and the cost was as much regardless of the amount of distortion.

[Brentwood Bob]

If you took a kinked rod, straightened it in a large vice, Also straightened the forged eye, then trued it with a BFH you could lengthen the rod. I have seen a few junk yard rods that look amazingly good after the rework. As for factual lengthening I got nothing to add. Streching by mechanical force seems counterintuitive to me.
I think the extending of the threads would correct any length problems of an OEM Rod even if they are not rolled. Stick to the original rods.

[MikeK]

Temperature changing the length of the rod will make no difference, as the length of the frame between the parts attached to the brake rod will also change with temperature.

Both are steel with the same thermal expansion coefficient (0.00000645in/in/deg F).

With a 100F temperature change a 50" brake rod will change 0.032". The portion of the frame between the rod ends will change an equal amount, nullifying any effect.

[bbrocksr]

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Originally Posted by RockHillWill

I was poster #13 and agree that it is VERY unlikely to happen.

Also, If I dig hard enough I might be able to find the receipt that I got from having to get a $3,500 NASCAR billet crank straightened along with a severe ass-chewing from solely letting it sit on a steel workbench too long. It was only out a small amount, but needed re-grinding, and the cost was as much regardless of the amount of distortion.

I Agree, I experienced this with a freshly ground 6 cyl diesel crank. It was stored horizontal on a shelf for a month. When installed it would bind up when the mains were torqued down. I measured the runout at about .005. I left it lay in the block supported by the mainbearings for a few days while deciding what to do. I went back and torqued it down again and it turned freely.
Forged steel cranks probably are less prone to warp/sag than cast iron but why take a chance. Bill

[bbrocksr]

Originally Posted by Karl

Interesting how these urban myths start. The mechanic who does most of the local veteran and veteran motor rebuild work and who I respect greatly stores all his cranks vertical as he claims they will deform if stored horizontal. It just can't be true but I can't convince him otherwise . I asked him if they would warp under their own weight why doesn't a camshaft bend form the force the open valve springs exert on it when the car is stopped - No answer yet on that one -Karl

Karl, The camshaft is supported by its bearings when it is holding a valve open.
The cranks don't have a problem either when they're supported by their bearings.
A long shaft supported only at both ends will sag under its own weight.
Steel is more likely to recover/spring back where cast iron will take a set.
You should listen to that old mechanic, he knows what's going on.
Bill

[Dick M]

I was hoping that the Ford Barn member who posted the concept of the brake rods stretching would respond to this thread. He just may have some incredible information on this subject.

[BRENT in 10-uh-C]

Originally Posted by Dick M

I was hoping that the Ford Barn member who posted the concept of the brake rods stretching would respond to this thread. He just may have some incredible information on this subject.

http://fordbarn.com/forum/showpost.php?p=942403&postcount=7

[RockHillWill]

Even at my age, I look for older folks to ask questions of. If you look in some old 'mechanics' books from the teens and twenties like the 'Dykes' manuals, you will see all forms of 4-wheel brakes, 4-wheel steering, etc., etc. All we are doing now a days is 'polishing' what those old guys have already figured out.

Besides, comedian Richard Prior used to say that the reason you don't see many old fools, is that you don't get old being a fool!

[hupdoc]

Originally Posted by RockHillWill

I was poster #13 and agree that it is VERY unlikely to happen.

Also, If I dig hard enough I might be able to find the receipt that I got from having to get a $3,500 NASCAR billet crank straightened along with a severe ass-chewing from solely letting it sit on a steel workbench too long. It was only out a small amount, but needed re-grinding, and the cost was as much regardless of the amount of distortion.

Really. The crank was distorted but did solely sitting on a bench cause it. I Know that was the explanation and lecture you got but I remain a sceptic. There is cold creep is observable in peanut butter but I doubt you will ever see it in metal. Karl

[Karl]

Originally Posted by bbrocksr

Karl, The camshaft is supported by its bearings when it is holding a valve open.
The cranks don't have a problem either when they're supported by their bearings.
A long shaft supported only at both ends will sag under its own weight.
Steel is more likely to recover/spring back where cast iron will take a set.
You should listen to that old mechanic, he knows what's going on.
Bill

Ok You got me thinking . However if they set with sitting wouldn't all our rear axle housings be sagging badly after all these years of sitting

[RockHillWill]

Carl, are you familiar with the wear patterns on the rear hubs?

As far as engine issues are concerned: rotating issues at 3,000 RPM are some what more of a concern at 10,000 RPM.

[bbrocksr]

Originally Posted by Karl

Ok You got me thinking . However if they set with sitting wouldn't all our rear axle housings be sagging badly after all these years of sitting

Karl, The rear axle housings were designed to be supported only at the ends.
The fact that they were only supported at the ends required that they be designed strong enough to achieve this.
Cranks and Cams were designed to have intermediate support and without this support they will tend to sag.
Both when used as designed work quite well.
Bill

[dumb person]

If brake rods sag from gravity and are repeatedly subjected to pulling strains i guess it is possible they could stretch. Would be interesting to test. Or extremely boring to test.

[Mitch//pa]

Originally Posted by Dick M

I was hoping that the Ford Barn member who posted the concept of the brake rods stretching would respond to this thread. He just may have some incredible information on this subject.

Originally Posted by BRENT in 10-uh-C

http://fordbarn.com/forum/showpost.php?p=942403&postcount=7

maybe its an early April fools joke

[theHIGHLANDER]

I imagine a hopped up 'banger' getting a A up to about 95MPH (I'm sure some can do better so lets skip that). If one were to make a habit of running it that fast and stopping heavily on a paved surface, and with all due upgrades to the drums, shoes, etc, yet still on 'push n pray' brakes, they might see a stretch that would take a dedicated measuring practice to find. The actual force should be easy enough to calculate AT THE BACKING PLATE with all the rods, pedal and levers in play. All are multipliers designed to give a pantload of force at the shoe. I'll go out on a limb here and say the largest percentage of A drivers here will NEVER stretch their brake rods. I don't see many stock Model As traveling interstates at 60-70MPH, in fact I never see that and hope the 2 or 3 that can don't have to dodge an animal or texting driver

[Steve Plucker]

Mark Maron

Can you please elaborate on your claim: "HOWEVER, we are finding that the REPOP Rods are "STRETCHING" this is one the reasons people are fining they have to adjust them more than usual". for the rest of us?

Thanks.

Pluck

[whirnot]

Of course they stretch, just not much. My guess is you compensate for the stretch by tightening the adjuster 1/16 of a turn per lifetime.........

[BRENT in 10-uh-C]

Originally Posted by whirnot

Of course they stretch, just not much. My guess is you compensate for the stretch by tightening the adjuster 1/16 of a turn per lifetime.........

Ummmmm, would you explain how you tighten the adjuster 1/16 of a turn?? Looking at the illustration below, wouldn't turning the "adjusting clevis" 1/16th of a turn make the clevis pin not align??

.

[whirnot]

OK you got me, maybe just bend the arm?

Even a wise ass gets caught around here....

[bbrocksr]

Originally Posted by whirnot

Of course they stretch, just not much. My guess is you compensate for the stretch by tightening the adjuster 1/16 of a turn per lifetime.........

Are you turning the brake adjuster or the brake rod clevis?

No problem turning the brake adjuster 1/16 of a turn.
Bill

[Tom Foster]

[QUOTE=Brentwood Bob;943454]If you took a kinked rod, straightened it in a large vice, Also straightened the forged eye, then trued it with a BFH you could lengthen the rod. I have seen a few junk yard rods that look amazingly good after the rework.

I would think this scenario would be most likely to result in the snapped-off end pictured on Vince's site. I for one would be a-scared to use such a rod.
Fearless

[BILL WILLIAMSON]

Originally Posted by Mitch//pa

maybe its an early April fools joke

Dog here,
1-Maybe it's a LATE April Fool's joke?
2-April jist passed awhile back!
3-Is there another one comin'???
4- I ALWAYS stretch after catchin' DOG NAPS
5- I jist discovered thet this is AN OOOOOOOLD POST---WHERE'S THE MURINE???
Buster T.

[ericr]

Originally Posted by forever4

This one's for you Larry!

Stretched and Broken Brake Rod on Ford Garage

I'm confused about this subject. is the conclusion that repro parts will break but not stretch?

[Tom Foster]

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Years ago I bought '29 Roadster that somebody else had worked on, and had added hydraulic brakes. The 'rod' between the pedal and the MC actuating bellcrank was a bent, kinked, corroded, rusted, and SOLDERED piece of steel cable. After replacing it with a piece of actual Model A brake rod I now have good brakes on the car, which I've taken to calling the 'Sow's Ear.' [So I don't have a silk purse, but a clean, shiny sow's ear.]

[Steve Plucker]

I think Mark is pulling a BIG joke on all of us

[Brentwood Bob]

Tom Foster: Different part. the offshore actuater from the pedal to the cross shaft is junk! As vince showed(ford garage).
The OEM brake rods from the drums to the cross shaft are the subject of this thread.
They appear to be forged at the eye end and are mallable. A cautious person would only trust what he believes is safe. Have at it. Bob

[Mitch//pa]

for some reason this thread reminds me about the ground through the fuel line scenario causing vapor lock

[mshmodela]

Unlikely any human could generation that much force on the rods via the break pedal. I would think other components that are adjustable might become loose after the rods and other other new parts were replaced in some cases.

[C26Pinelake]

Bent or broken yes, but stretched ? If so I am sure it would take a micrometer to measure the result !
Wayne

[BRENT in 10-uh-C]

Originally Posted by bbrocksr

Are you turning the brake adjuster or the brake rod clevis?

No problem turning the brake adjuster 1/16 of a turn.
Bill

How many detents does those brake adjusters have machined into it? Still kinda difficult to adjust it correctly turning it 1/16th of a turn.

[BILL WILLIAMSON]

Duz anyone make 1/16" open end wrench? Ol' Bill dropped his .021" drill bit in the carpet, I FOUND IT! Guess who got a Doggy TREET?
Buster T.

[Tom Wesenberg]

Originally Posted by BILL WILLIAMSON

Duz anyone make 1/16" open end wrench? Ol' Bill dropped his .021" drill bit in the carpet, I FOUND IT! Guess who got a Doggy TREET?
Buster T.

My brother dropped his screw for his eyeglasses into a shag carpet. I told him to put a nylon stocking over the end of the vacuum cleaner hose and go over the area. He found it in a couple seconds.

[BILL WILLIAMSON]

Originally Posted by Tom Wesenberg

My brother dropped his screw for his eyeglasses into a shag carpet. I told him to put a nylon stocking over the end of the vacuum cleaner hose and go over the area. He found it in a couple seconds.

It's mind boggling to think of the things we learn here! BUT, once we've learned EVERYTHING, we DIE!
I almost "died" today, I BROKE my FAVORITE coffee mug, life will never be the same again! My coffee even tasted "different" in that funny shaped GREEN mug.
Bill W.

[whirnot]

Seriously though, Like Steve said in post #19 the rod from the pedal to the cross shaft sees 4 times as much pressure than an individual rod. Wouldn't it have to stretch 4 times as much first??

[KR500]

I have trouble believing brake rods stretch. If they did I believe DOT( Dept. of Transportation would be all over the manufacturer. I have supplied some classic cars with stainless brake cables. The cables are wound with an interior right hand wrap and the outside strands with a left hand wrap to prevent stretch or unwrapping. A friend of mine who used to handle DOT 5 brake fluid bought in 55 gallon drums repackaged it into quart containers. He had to have special DOT permission and inspection of his repackaging. IF brake rods stretch I should think that the liability put on the manufacture and selling of this type of item would not make it worth making and selling. Even wheel cylinders,brake drums, linings and other brake items are carefully scrutinized by DOT.

[BRENT in 10-uh-C]

Originally Posted by KR500

I have trouble believing brake rods stretch. If they did I believe DOT( Dept. of Transportation would be all over the manufacturer. I have supplied some classic cars with stainless brake cables. The cables are wound with an interior right hand wrap and the outside strands with a left hand wrap to prevent stretch or unwrapping. A friend of mine who used to handle DOT 5 brake fluid bought in 55 gallon drums repackaged it into quart containers. He had to have special DOT permission and inspection of his repackaging. IF brake rods stretch I should think that the liability put on the manufacture and selling of this type of item would not make it worth making and selling. Even wheel cylinders,brake drums, linings and other brake items are carefully scrutinized by DOT.

Just curious, are you suggesting that DOT is scrutinizing the Chinese-manufactured brake drums being imported for Model-As?

[larrys40]

Originally Posted by forever4

This one's for you Larry!

Stretched and Broken Brake Rod on Ford Garage

Vince,
Always enjoy your repro hall of shame......
Probably an old Rick's piece of junk.. or some other inferior part. I'll be the original rods wouldn't have done that! Thanks for sharing... it goes to show that stuff does happen. My take is that overall I really don't think the rods stretch to any degree.. but certainly in the repro world of metallurgy I agree that failures can occur. It wasn't too long back that the adjustable eyes were cast iron.

Thanks for sharing Vince..
Larry

[Mike V. Florida]

Originally Posted by RockHillWill

Even at my age, I look for older folks to ask questions of. If you look in some old 'mechanics' books from the teens and twenties like the 'Dykes' manuals, you will see all forms of 4-wheel brakes, 4-wheel steering, etc., etc. All we are doing now a days is 'polishing' what those old guys have already figured out.

Besides, comedian Richard Prior used to say that the reason you don't see many old fools, is that you don't get old being a fool!

Lets add electric cars, hybrids, one coil for each plug, and list will continue on. That is why i get a kick when people say, "if that was was so good why did they change it?". I wish I could send them a dykes manual.

[Randy in ca]

Originally Posted by ericr

I'm confused about this subject. is the conclusion that repro parts will break but not stretch?

Originally Posted by C26Pinelake

Bent or broken yes, but stretched ? If so I am sure it would take a micrometer to measure the result !
Wayne

Originally Posted by KR500

I have trouble believing brake rods stretch.......

An object will always distort (ie compress or stretch) before it breaks. Even the most minute force will cause some distortion - it may be so minute as to be virtually undetectable, but it still happens. The elastic properties of the object determine how much force can be applied before it doesn't return to its original shape when the force is removed. This property varies greatly in different types of steel - not quite like comparing bubble gum to writing chalk, but still can be significant.

When the force applied to an object becomes high enough, such that it no longer returns to it's original shape when the force is removed, it is said to have attained it's Yield Strength, after which permanent deformation (stretching) starts. If further force is applied, the object will continue to distort until it eventually breaks. This force is referred to as the Ultimate Tensile Strength.

The Yield Strength of steel is always lower than the Ultimate Strength, but the difference in the two can vary greatly from one type/grade to another. Some will break soon after they start to distort (like chalk) while others will stretch a lot before they eventually break (like bubblegum).

For a brake rod to stretch and not return to it's original shape, it must be subjected to a force greater than it's Yield Strength and additional force will always be required until the Ultimate Tensile Strength is applied and the rod breaks.

In short, the brake rods are constantly being stretched with every brake application. The question here is if the force on them ever becomes great enough that the don't return to their original shape and if enough additional force can be applied to result in breakage.

I hope this makes sense and I haven't miss worded or screwed something up too badly!!

[BRENT in 10-uh-C]

Randy, I am not going to copy what you wrote due to the lengthiness but the original reason why I posted this was because someone claimed that repro brake rods were stretching thus requiring additional adjusting. I do agree there is some in detectable stretching/compression from components throughout the system however I'm not sure any of those would require readjusting the brakes.

FWIW, sometimes it is fun to watch how a topic will receive an answer or two and then find itself making a 90 degree turn to chase a different --but quasi-related subject, ...such as the crankshaft deflecting while laying on the table. So for those of us who played with the Slinky when we were kids, shouldn't it be more disconcerting for a crankshaft left hanging on a rack to stretch longer? Remember what happens when a Slinky was picked by the top few coils and pulled upward. Surely it is plausible that a crankshaft hung by the flange would stretch over the length of the shaft just due to its' own weight! Why aren't we addressing that??

[RockHillWill]

I think that the issue with a crank 'distorting' radially from laying horizontally is of much more concern due to the fact that the highest loads are applied radially when in operation, whereas the fact that horizontal 'tolerances' (endplay) are actually part of the built in function of the crank. If the crank is balanced, the offset loads due to the rod journals are equally spaced, minimizing any radial deflection due to those offsets.

[BILL WILLIAMSON]

D.O.T. doesn't test EVERYTHING!! They just pretend they DO! It's called, JOB SECURITY & GREAT RETIREMENT BENEFITS!!
Bill W.

[briphaeton]

I agree with Bill. My machine shop teacher said the whole world is rubber, everything bends. While he was teaching at Lawrence Lab in Livermore, they measured someone leaning on the headstock of a lathe. Only the lab would have the ability to measure something so minute. My neighbor bracket raced a early camaro and painted a line on his axles so he could see how much the axles would twist. Those old mechanics and machinist really have a understanding how things work and we are losing so much knowledge as each one passes. Old Henry had many, many engineers working to give us this great car to enjoy today.
Brian

[Smog Tech]

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When I was much younger we would paint the line on axles used in drag racing cars. Quarter turn, replace the axle.

[BILL WILLIAMSON]

Originally Posted by Smog Tech

When I was much younger we would paint the line on axles used in drag racing cars. Quarter turn, replace the axle.

Trick idea! My drag racin' cars never developed enough power to wurry about axle twist. Unlike them ooooold stock Chevys, that would "POP" an axle when you backed up. A friends '29 Chev popped one on a tour, a welder/machinist slipped a water pipe coupler over it & welded it, then straightened it in a lathe. Drove it that way for a looong time.
Another time, he popped a sector shaft while making a "U" turn which resulted in a BROWN spot in his seat
Bill W.

[Patrick L.]

Originally Posted by Smog Tech

When I was much younger we would paint the line on axles used in drag racing cars. Quarter turn, replace the axle.

Yup ! It sure beat buying those super duper expensive Summers Bros units which would just shear at the splines.

[Patrick L.]

Originally Posted by BRENT in 10-uh-C

Randy, I am not going to copy what you wrote due to the lengthiness but the original reason why I posted this was because someone claimed that repro brake rods were stretching thus requiring additional adjusting. I do agree there is some in detectable stretching/compression from components throughout the system however I'm not sure any of those would require readjusting the brakes.

FWIW, sometimes it is fun to watch how a topic will receive an answer or two and then find itself making a 90 degree turn to chase a different --but quasi-related subject, ...such as the crankshaft deflecting while laying on the table. So for those of us who played with the Slinky when we were kids, shouldn't it be more disconcerting for a crankshaft left hanging on a rack to stretch longer? Remember what happens when a Slinky was picked by the top few coils and pulled upward. Surely it is plausible that a crankshaft hung by the flange would stretch over the length of the shaft just due to its' own weight! Why aren't we addressing that??

Now I know why all my cranks shrunk/shrink ! I'm one that sets them on the flange, so, thats why they get shorter !

[KR500]

Brent, If they aren't scrutinizing the drums, shame on us for having just another government subsidized useless department with no concern for our safety. Grade 5 bolts which aren't and the list goes on. I must agree the government doesn't give a hoot about us. I guess the manufacture of tires and tubes should be included.After hearing of General Motors faulty ignition switches any junk somebody turns out gets dumped on us poor fools.