Should I return this refurbished rod for exchange or is it close enough? The other three were good.
It's not going to do you any good for sure.
Wrist pin must be in perfect alignment with the rod journal. no such thing as close enough here.
What you posted a picture of has been a frequent issue on the rods sold by the major vendors for about 10 years now (that I know of).
I believe this happens when a rod is bent and does not get straightened before babbitting & boring. Typically these rods will have uneven babbitt thrust surfaces on the crank-shaft end of the rod. The manufacturer is probably utilizing the boring & facing step of the procedure to effectively "straighten" rods that are out of alignment. When rods are not initially straight before babbitt & bore, and are just "bored & faced" perpendicular to the piston pin, what you end up with is a rod that has bores that are parallel to each other but centers that are not perpendicular to each other.
I realized this was an issue for the first time about 10 years ago. I continued using the same rods the major vendors sell for a few more years (checking each set and sending them back sometimes multiple times before I had a "good set") before I finally invested several thousand dollars into new, modern, custom made equipment to do this job properly myself.
The main problem with the commonly available "re-babbitted" rods is that hardly anybody has a fixture for checking rod alignment, and even if they do, they often won't check a "new" rod. The second problem is that a rod that is slightly out of alignment generally won't start to make noise or shed babbitt off its thrust surfaces for at least 1,500 miles and by that point, any analyzing that can be done can not prove that the rod was bent when it left its original packaging.
I have volunteered multiple times in the last several years to check re-babbitted rods that some of the guys in the local clubs would mail-order from some place and every time I did, the rods were slightly bent, twisted, or off center and required adjustment. So I imagine there hasn't been any improvement unless it has happened real recently.
And as long as you are likely to have this motor apart again you may want to ask for some opinions about your cam...
Cams are highly subjective, but I've generally always regarded any lobes ground back into the actual shaft as a warning sign that maybe something isn't as good as its supposed to be.
I seem to have the same problem with my rods i think less than Lester but some,.any opinion on using or its all redo again ? everytime if not one its another ,..all 4
I seem to have the same problem as Lester,but a little less ,on all 4 ,is it redo time AGAIN ?
Sorry double post
Simple answer Lorenzo, no.
Sure there is some offset but the rod isn't jamming against the piston. I assume you don't have a ton of side to side clearance at the crank journal. So the rods should stay put.
We are also assuming the piston pin bosses are also the same length and faced exactly the same in relation to one another.
New rods of any kind, have never been shipped that you can just install them in an engine, and I don't care who the company it was, TRW, Federal-Mogul, Clawson & Balls, ect.
That is why there was so much rod alignment tooling around.
It wasn't, and still isn't the job of the rod builder to make or say rods are straight enough to use in an engine when they get installed.
The reason being, guys put the rods in a vice using the web and will break the nuts loose, and twist the rod out of alignment, or in the case of a wrist bushing, replaced, and honed will change alignment, damage in shipment, ect.
We NEVER try to check alignment of an Model T, A, or B rod before pouring, unless you can see it is bent with exaggeration, as there is no machined surface to check from, and then you are just guessing, and most likely, make it worst.
The last thing, there are no rod boring machines, that were built in 1930, or 2016 that will bore a rod that is straight, that you don't have to check alignment
There isn't a milling machine that will do it either.
Lester, pull your rods, get them aligned and your done with.
Bent rods will tear up cylinders, and rods.
When your motor gets hot and the crank expands forward, your clearance will be gone.
That is off set, if that is wrong, twist and bend will be wrong also.
Herm, with the off-set on the rod as shown, is correction made by bending the rod one way at one end and then correcting that by bending it back again at the other end to bring the pin alignment and bore in the bearing back into parallel? Sort of making a very shallow S bend in the rod.
Allan from down under.
Lots to think about in this old thread:
Yes, that is how you correct it.
Say if it is out a 1/4 off set, and being off that far, you bend as close under the wrist pin as you can, an have the Babbitt end, using the trust, move over 1/4, then as close as you can to the Babbitt end, bring it back 1/8th.
Doing it that way, you do not see, and there is no "S" curve, as then it is straight for offset.
I know it was a big enough debate back in 2012 and yes you can alter the off set but did you know Herm, that taking or moving the wrist pin over by that 1/8", increasing or decreasing the crank in the rod, you are altering the length of the rod by as much as .020"
What good are them cotter pins in the wrist pin bolts in lorenzo's pics?
The end of the cotter pin is resting on the rod, the bolt cannot come loose
the cotter has to be cut & removed for bolt remove
I know it was a big enough debate back in 2012 and yes you can alter the off set but did you know Herm, that taking or moving the wrist pin over by that 1/8", increasing or decreasing the crank in the rod, you are altering the length of the rod by as much as .020" "END QUOTE"
Ok, here is why you are wrong again.
1. The rod was right when it left the factory, for length, it got bad off set from the twist and bend was used, or not used on it's rebuilding over the years. Your are just putting it back where it was. Frankie, where did you pickup a figure like .020, I think on your best day you wouldn't notice any at all.
2. In the second place, it wouldn't make it longer because the rod is cut 7" C to C, no mater what. Moving it an 1/8 would make it with no noticeable movement.
that put you on top of your BS&I list Herm'
Did you fail simple geometry at school as well?
You said it, C to C is all ready set now that's it's machined.
If your lucy enough to find the crank, As it's called at our end of the world, or the off-set and straighten it, because you have C to C you will lengthen the rod, but because you decided to make 2 new bends, 1 top, 1 bottom, you now have 4 new corners that will shorten the rod.
do all this before your machining and you will still have your 7" C to C.
If you worked on diesel rods you would know how critical this setting is.
I am trying to make sense of this, and having some difficulty.
As I understand it, the rod length centre to centre, is set by the machining of the rod bearing. It isn't set by the rough poured babbit in the rod. It isn't until the bearing is machined that the C to C can be measured. It follows that the offset cannot be detected until the bearing is machined. Am I on the right track?
Herm, if the rod is bent to the side, and the bearing bored so it is parallel to the pin, then correction is as you stated. If I exaggerate the bend to an improbable 1/2", when the rod is bent back into the upright position, the centre to centre measurement will be longer, rather than shorter. Have I missed something?
Allan from down under.
Allan, twist, bend and crank (off set) can all be checked from the rod bolts, it's that simple.
Frank, can you detail how these checks are done? Do any of these checks rely on the accuracy of the rough machining done on big ends, prior to re-metalling? I can understand that this could be the case with modern precision machined rods which take bearing shells, but T rods are a bit hit and miss in this department.
Allan from down under.
Take your rod, dosen't need the cap on just a good straight set of bolts, spin them in a drill, mill or lathe will soon tell you if OK, fit the wrist pin in, I use my mill but can do in a lathe, chuck the pin, using a set square or the verniers measure the bolt heights from the table for twist.
Bent or off-set can be checked then by sitting the rod on it's parting line bolts squared to a pair of V blocks upside down and at least 1 of them clamped to the mill table, use the mill chuck to square off or a straight rod in the chuck, flip the rod around 180 and see if the pin is flush or not for off set and if it's bent you will have a air gap either on the top or bottom of the side of the wrist pin.
I do this because my machine relies on the wrist pin to be square to the bolts for machining, is set up say with .010" twist or bent the the babbitt is cut on an angle.
As we know, other set ups, machines, machinists ways and opinions vary.
Just read this and the related previous posts. I have just one two-part question for Frank and Herm:
How many engines have you built after redoing the rods "your way"; and how many of these have suffered rod related failure after being put to use?
Seems to my simple mind that that's all that matters.
My answer is simple, none.
It is like this Mr. Koke, Frank will never see as many Model T engines as we have rebuilt, and he sure will never see as many Model T rods we have spun poured, which is over 30,000 until we quite keeping book on them. That is not counting a little more on Model A's, and about 1/8th on Model B's.
We have done about every kind of rod and bearing make there is and still do, day in and day out.
In almost 53 years, we have never lost a Rod, Insert, or cam bearings we spin, or Jig pour.
When a bearing gives up there is never a mistake, to what has caused its demise.
That includes, dirt in the bearing, lack of a full oiling, lack of oil clearance, or to much of it.
A big cause of bearing failure is (overspeeding) which is caused by racing an engine, racing an engine cold, summer, or winter, speed shifting and missing the shift, using the engine as a brake, a big one in a Model T, along with a revved out low to shift into high, very hard on rods.
The thing people don't think about, revving a cold engine of any kind, lets use a Model T, When a Model T rod gets broke in, it normally has about .002-50 to .003-00 thousandths clearance. Now that my friends is to much clearance, it will beat your bearings out, by revving a cold engine.
So when the engine gets hot, the crank will expand about a .001-00 to .001-20, depending, so now the clearance would be back to, .001-50, to .002-00, which is fine.
These two Babbitt casting we poured in the same bearing shell, and then knocked out.
The first one is a perfect pour with all correct temperatures, and preparation. The second is not to get a defective bearing to show the difference.
The good one you will notice first, the color is Gray, that is because the Babbitt stuck 100 % to the tinning, and when pried out pulled out all the tinning.
The second one has only about 50% of the Babbitt stuck to the tinning, and as the pour was pulled out, it left 50% of the tinning on the shell that it was poured into.
The good bearing shows all grooving, because it pulled all the tinning out of the shell.
Is it my imagination, or is the piston not centered in the bore in the picture?
Not to inflame anything, but if you are selling rebabbited rods that are crooked you are producing a poor product. One would think that the machine shop doing the work is far more qualified to correct straighten and machine a rod than the average model t owner purchasing the rod.
There is no such thing as close enough here. I would remove the rods and check each for bend, twist and offset. If those are not tests that you are able to do, then I would send them back to whomever rebuilt them and ask that they "make it right". I agree with Andy, any reputable machine shop would do these adjustments before the rods leave their shop. I'm surprised to see Herm state that it's not the job of the rod builder to say that the rods they produce are straight enough to use "out of the box", so to speak. As to their being mishandled and bent after the fact, that's someone else's sin, but to ship them as-is, without aligning them first, well... that's on the rebuilder. Sorry. Really, if that's how a rebuilder wants to do business, then put a note in each box of rods stating that "Final Bend, Twist & Offset Inpsection/Adjustment Must be Done Before Installation".
That being said, and if all rebuilders do as Herm states, no rod should ever be installed without prior inspection. (Which I do anyway)
Jerry, I agree. I checked them all before I put them in, and three were good. I wanted to see how the fourth would look, so I went ahead and installed it. After reading all these posts, I took it back out and straightened it. It's kind of an iterative process - when you straighten the big end, it affects the little end, and so on. So you go back and forth, making smaller corrections each time.
I decided against returning it for exchange because it seemed there was a reasonable chance of getting another bent one. I found I could straighten it in about the time it would have taken to box it up and take it to the post office.
I would have done the same. Happy touring!
That being said, and if all rebuilders do as Herm states, no rod should ever be installed without prior inspection. (Which I do anyway) "END QUOTE"
In the case of Model T rods, they are always straight when they leave here, but after that we can't be responsible for removing rod caps, or installing pinch bolts, if done wrong, that is where they get sprung the easiest.
They do NOT get out of alignment running in an engine, no way, shape, or form.
When you have a bushing for the wrist pin, like a Model A, we put in the new bushing, and align the rod with what we have, and when the shop gets it back, they will hone the bushing for the new wrist pin, it is not now in the same alignment that I set it at, so it will be off a few thousandths again, and have to be checked for twist and bend, as off set will not be effected at this time.
This is why Jerry that I don't say they are straight enough to use "out of the box", as I have lost control after they leave here.
"In the case of Model T rods, they are always straight when they leave here, but after that we can't be responsible for removing rod caps, or installing pinch bolts, if done wrong, that is where they get sprung the easiest."
Thanks for that clarification. Much appreciated and good to see.
Someone made a remark about how they NEVER try to check alignment of a Model T rod before pouring because there is no machined surface to check from.
Actually, there is:
I check and adjust T rods prior to babbitting based on their bolt holes and the parting line where the rod meets the cap. I would conservatively estimate that about 80% of the original used rods I find are bent off center or twisted and require straightening prior to babbitting & machining. Doing so results in finished front and rear babbitt "thrust surfaces" and journal-bores that are extremely even and uniform in thickness. I have a suspicion that this is also very important in any higher performance T engine because very uniform babbitt thickness allows a more uniform compression of the babbitt if that would take place during heavy loads (The difference between a bearing that starts to sound a little noisy and one that suddenly burns out).