So, really, in a well tuned Model A, how much vibration is 'normal'?

[P.S.]

I have an unrestored Fordor that used to have the original motor in it, no balanced crank or anything, and it was pretty smooth. Got the motor rebuilt and it vibrates a bit more than it used to.

Also have a restored (fine point level) Tudor with a rebuilt motor that has all the fancy doo-dads like insert bearings, balanced crank, lightened flywheel, etc. and it vibrates the steering wheel right out of your fingers at certain RPMs! The body doesn't vibrate much, but you can sure feel it in the steerng wheel (all vibration is from the motor, not steering or road vibration)

So... How much Model A vibration is 'normal'? Is there any reason why the fully balanced motor should not be smoother than the unbalanced motor?

I'm not talking about Model As in bad shape, I'm talking about the Model As you guys poured your full effort into that you can reliably drive anywhere, anytime.

[mshmodela]

I cannot speak from a lot of experience but mine is smooth until the higher level rpm ~ 43mph... My engine has not been rebuilt with your above mentioned "doo-dads". I suppose
the only real way is to get some real life Model A's near you can get some LIVE opinions....

[Tom K.]

My stock 29 Tudor is smooth up to around 47 mph.

[BRENT in 10-uh-C]

Originally Posted by P.S.

I have an unrestored Fordor that used to have the original motor in it, no balanced crank or anything, and it was pretty smooth. Got the motor rebuilt and it vibrates a bit more than it used to.

Also have a restored (fine point level) Tudor with a rebuilt motor that has all the fancy doo-dads like insert bearings, balanced crank, lightened flywheel, etc. and it vibrates the steering wheel right out of your fingers at certain RPMs! The body doesn't vibrate much, but you can sure feel it in the steerng wheel (all vibration is from the motor, not steering or road vibration)

So... How much Model A vibration is 'normal'? Is there any reason why the fully balanced motor should not be smoother than the unbalanced motor?

I'm not talking about Model As in bad shape, I'm talking about the Model As you guys poured your full effort into that you can reliably drive anywhere, anytime.

Paul, one of the very issues with rebuilding an engine with parts today is the variance from original specified weights. When a crankshaft journal is machined undersized, then Babbitt fills the void in the rod. Now the big end of the rod is heavier. Next, a larger diameter piston is used which is heavier, ...and adding to that, the wrist pins are quite a bit heavier over the original pins weight. The bottom line is lighten the replacement parts to O.E specs, and you will likely find the smoothness returns.

[Pete]

Originally Posted by P.S.

I have an unrestored Fordor that used to have the original motor in it, no balanced crank or anything, and it was pretty smooth. Got the motor rebuilt and it vibrates a bit more than it used to.

Also have a restored (fine point level) Tudor with a rebuilt motor that has all the fancy doo-dads like insert bearings, balanced crank, lightened flywheel, etc. and it vibrates the steering wheel right out of your fingers at certain RPMs! The body doesn't vibrate much, but you can sure feel it in the steerng wheel (all vibration is from the motor, not steering or road vibration)

So... How much Model A vibration is 'normal'? Is there any reason why the fully balanced motor should not be smoother than the unbalanced motor?

I'm not talking about Model As in bad shape, I'm talking about the Model As you guys poured your full effort into that you can reliably drive anywhere, anytime.

Here is something that has been posted here several times before that may help.

The degree of balance in any rotating part is directly proportional to the rigidity of the mounting.
A 4 cylinder engine with a single plane crank cannot be be so called "completely balanced".
It has the same problem as a single cylinder engine.
You can only balance it for a narrow rpm range.
This is why you still feel a model A engine shake at certain rpm ranges even after being balanced.
You can change the rpm it shakes at but you can't eliminate the shake.
Certain types of industrial and racing 4 cylinder engines have achieved something close to ideal balance by using "balance" shafts. This is a counterweighted shaft that is mounted on the opposite side of the engine from the camshaft with the weights synchronized to counteract the vibration of the crank.
In a model A/B engine, the ideal situation would be to have the harmonic damper the same weight as the clutch/flywheel assembly to reduce harmonic vibration. This however will not eliminate the felt vibration.
It will prolong the life of the engine though.
We have achieved something about as close to this as is possible in the real world by using a 11 lb. aluminum flywheel with an aluminum clutch and a damper from a big block Chev. The only drawback to this as far as the car is concerned is you have to trim some off the back side of the front cross member to clear the damper. This damper weighs about 13 lb.
Reducing flywheel weight has an added advantage in making shifting easier and faster.
All of this modification will eliminate much of the TORSIONAL vibration but will not eliminate total engine vibration. You do not normally feel torsional vibration in the seat of your pants.
Crankshaft counterweights help reduce overall vibration by adding rotating mass and hence damping the felt vibration. There is not enough room in the "A" crankcase to add enough counterweight to achieve a comfortable "seat of the pants" vibration level. 60% is about all the weight that can be squeezed in without redesigning the whole engine.

[P.S.]

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Thank you Mike, Tom, Brent, and Pete.

Mike and Tom- Mine is too, but not perfectly smooth. It feels smoothest at about 52 MPH.

Brent- Yes, agreed. When I had the motor in the fordor rebuilt, it got reamed and sleeved, then original size pistons installed. No oversize or undersize anything. All exactly the same as stock (with exception of the valves). The original motor was silky smooth, almost unreal smooth. The motor having been rebuilt is not as smooth, but still much smoother than the Tudor's motor with oversize pistons, balanced crank, lightened flywheel, etc. Just wondering if that is normal.

Pete- Very well explained. OK, so this may almost sorta answer my question. So, the Tudor's super-touring rebuild isn't smooth, but the motor will last longer. Hmm... the rest of the car gets vibrated to heck, but the motor is happy. Sounds like I may have made a newbie mistake when I ordered the touring motor. I thought it was going to be smoother running. It sure runs strong though.

All- I don't want to rekindle the stock flywheel vs. lightened flywheel debate. I would like to point out that having put several thousand miles on both, I really prefer the stock weight flywheel driving experience.

[burner31]

It all depends on how smooth the road you are driving on is.

[Fred K-OR]

Originally Posted by BRENT in 10-uh-C

Paul, one of the very issues with rebuilding an engine with parts today is the variance from original specified weights. When a crankshaft journal is machined undersized, then Babbitt fills the void in the rod. Now the big end of the rod is heavier. Next, a larger diameter piston is used which is heavier, ...and adding to that, the wrist pins are quite a bit heavier over the original pins weight. The bottom line is lighten the replacement parts to O.E specs, and you will likely find the smoothness returns.

This thread is very informative for a person like me that knows little about the subject of "hopping" up an engine when rebuilding.

When I had my huckster engine rebuilt I was the "cheap" guy and ask my rebuilder to re-use everything that he could and only replace parts that needed to be replaced. From what is being said here on this thread, I may have made a reasonable decision in the area of having an engine that has little vibration but on the other hand is not the ideal touring engine. I feel I made the correct decision in that I only use it for a "driver" around my local area. Anyway I thought I would mention this for someone that may be considering doing all the things mentioned above and may not enjoy them after getting their engine back.

Brent and all, am I thinking correctly or am I giving out incorrect info? If so please correct me. And thanks for the informative info.

[Tom Wesenberg]

As far as too much vibration, I worry that the crank grinder may not get the flywheel mounting flange EXACTLY centered on the rear main journal. Or, I should say the rear main journal centered to the flywheel flanged, since the flange doesn't get ground.

[Mike V. Florida]

Originally Posted by P.S.

I have an unrestored Fordor that used to have the original motor in it, no balanced crank or anything, and it was pretty smooth. Got the motor rebuilt and it vibrates a bit more than it used to.

Also have a restored (fine point level) Tudor with a rebuilt motor that has all the fancy doo-dads like insert bearings, balanced crank, lightened flywheel, etc. and it vibrates the steering wheel right out of your fingers at certain RPMs! The body doesn't vibrate much, but you can sure feel it in the steerng wheel (all vibration is from the motor, not steering or road vibration)

So... How much Model A vibration is 'normal'? Is there any reason why the fully balanced motor should not be smoother than the unbalanced motor?

I'm not talking about Model As in bad shape, I'm talking about the Model As you guys poured your full effort into that you can reliably drive anywhere, anytime.

The answer is very little and for sure if it really "vibrates the steering wheel right out of your fingers" you have something wrong with the engine and or mounts.

[SSsssteamer]

From experiences: Our '29 Tudor had only 55,000 miles on it when we first purchased it in 1968. It was smooth all the way to 70 mph, until one day that number three rod lost its rod babbit. Replaced the rod with a used one that seemed to fit correctly. It vibrated there after. Eventually replace the original engine with a model B engine and still used the A flywheel. It has been smooth as silk to 70 mph. No vibration in the mirror or anywhere. Our 30 Phaeton has a touring motor by H & H. All the bells and whistles added including a lightened flywheel. Anything above 45 mph vibrates terribly. I will put the stock flywheel back on to the motor the next time that I have it apart. The moral of the story here is: original engine parts that came together from the factory are the best balance. After that, a full weighted flywheel over a lightened one will give a smoother running engine.

[mike657894]

mine is very smooth suprisingly so for a solid mounted engine. i haven't got it going more than 40 though i dont think. my speedo is broken, full stock

[H. L. Chauvin]

Hi P.S.,

Model A engines were designed to run smoothly.

One (1) shared experience:

Several years ago after calling him & speaking to him, I mailed my crank and flywheel to Mr. Ron Kelley, RK Designs in Royse City, Texas; (972) 771-1911.

He provided counterweights, lightened my flywheel, added a new clutch plate, and balanced all three (3) items and marked bolt hole positions for each. He also provided a new flywheel ring gear and Dan McEachern crankshaft gear.

I bought a new digital Gram scale, and bought four (4) new 0.125" oversized pistons & new rings from Rainmaker Ron at Standard Auto in Illinois, and found all four (4) sets of pistons and rings weighed the exact same number of grams.

Bought connecting rod castle nuts and washers from different Model A Supplier sources, and also bought same locally to interchange to achieve exact same number of grams on the Babbitt ends of connecting rods.

After some time, finally all four (4) pistons, rings, and connecting rod assemblies weighed exactly the same when weighed on opposite ends or individually as a whole.

Always takes just a little more time to do anything correctly and once.

Engine idles and runs smoothly at all RPMs; however, I never exceeded 55mph & have no idea of top speed.

If you call Mr. Kelley to inquire about remedies for Model A engine vibrations, I think you will be glad you did.

Just hope this helps.

[Synchro909]

The Ford crank with the additional side weights were one piece and shrink fitted on AFTER grinding the crank. The side portions are not removable. Some guys bolt on the additional section to facilitate crank service at a later date.

Here is a first-class job and picture posted by Bill Stipe in a previous related thread on the same subject. It appears that you started that other thread on 11/19/2014! Of note in Stipe's work, the attachment is through collars on the added side pieces. The side weights present no sheer load to the fasteners.
The above was posted by Mike K in a previous thread about crank shaft counterweights along with a picture of a crank shaft in Bill Stipe's workshop showing extra weights added to the side of the usual add on weights. Does anybody know how well this works. If Bill has been doing it, I expect it will be a good thing. The reason for my asking is that I am about to do the same thing to a new Burlington shaft so long as it works.
The way I see it, counterweights obviously work or Henry wouldn't have gone to the trouble, let alone the expense.

[Tom Wesenberg]

I'll try to find that picture of Bill Stipe's counterweights, but Mike V. is much better at searching than I am.

Bill's crankshaft is the one I'd like to use in my engine, and I was thinking of making some weights like it. I don't have the equipment though, so I bought the heavy weights that Dan Price sells, which are like the ones Ford installed.

[Kevin in NJ]

What is typically missing is the full understanding of what it takes to balance the A engine.

First you start with the crank. Few crank grinders are going to get even close to the required precision to make the crank right. They can not even get the modern cranks close to right and they are not going to spend the time to get your little simple 4 cylinder crank right. So expect a normal crank grinder to not get the radius right, grind the mains off centers, get the throws off in distance, and not get the flywheel close to center.
Keep in mind a NOS Ford crank (from early 30's production) will be spot on in all dimensions. Of course the big thing is getting that flywheel to something close to less then .001" from center.

Then there is the whole balance thing. The crank needs to be accurately balanced. That is not too hard to do since the machines today practically do the job for you. The rods are a different story. Ford made them to +-1 gram at each end. Rods today are done to 5 grams total weight, not good enough. Then the pistons, which were kept to a couple grams each, were added on and the units weighed and put in a bin. So on the line any 4 units taken from a bin would be within 4 grams of each other.

So you can see Ford did some precision race car type building on the engines. I do not think you get that with all the builders. I know in some discussions some flat out do not believe what I tell them even though I am reading what the print says and is backed up with parts that have been measured.

Then you have other areas the affect vibrations. Put in a worn cam or even a regrind and you introduce some variance in how each cylinder fires. You also need to consider the metal of the valves and the diameter of the head of the tappet. They all have a factor.

Oh and what about the play on the upper dist plate allowing the point gap to change a few thou each time you change the left lever?

A lot of little things add up to some odd behaviours in the engines. In fact, I believe many of the vapor lock issues are really just something not done right with the valve train coupled with other slightly out of wack parts.

To rebuild the A properly you have to pay attention to every detail if you want it to run right. It is not cheap, fast or easy to do it right.

[George Miller]

My experience is the crank is ground off the center line. Rods and pistons not weight balanced. Flywheel and clutch not balanced.

If the crank is ground off the center line, you will have 60 lbs of flywheel plus clutch and pressure plate jumping up and down. When ever thing is right, you will not feel bad vibration while driving your A. But A inline 4 cylinder does have some at certain speeds.

[ericr]

my question might be, are we to believe that when the engines were rebuilt by dealers when the cars were relatively new, that all of these finepoints were observed? I would find it hard to believe that they were, given how replete the Service Bulletins were with castigations about mechanics doing dumb things.

[BRENT in 10-uh-C]

Originally Posted by Kevin in NJ

Few crank grinders are going to get even close to the required precision to make the crank right. They can not even get the modern cranks close to right and they are not going to spend the time to get your little simple 4 cylinder crank right. So expect a normal crank grinder to not get the radius right, grind the mains off centers, get the throws off in distance, and not get the flywheel close to center.

Kevin, I am not disputing what you are saying but am questioning a few comments based on my personal experiences. I do not know if you own a crankshaft grinder but when I purchased mine (a Storm-Vulcan 15), I had a huge concern based on comments I had read by others. What I came to learn after experimenting with my machine and paying for tutoring is much of these concerns were really just fabricated hype by someone. In other words, it really isn't that hard to center or grind a crank correctly if you have a machine within spec, -and an operator who pays attention to what they are doing. My machine uses centers to hold the crankshaft which most knowledgable folks tell me that is more than adequate providing the machine is within specs. With a dial indicator, I can tell within a few moments whether the crank is running true with the machine. If it isn't, I can make it true in less than a couple minutes. If I can do it, I'm sure others more experienced than I can do the same!

What I have found is, every once in awhile I will encounter a crankshaft that is twisted or bent where there is major run-out in the center journal. This is a quick fix in a crank press. So, doesn't it really boil down to whether someone has a conscience machinist? Most quality shops (which I think are more predominant than we sometimes give credit for) have the equipment and the craftsmanship to be able to turn out a quality machine job.

The only downside to crankshaft work is the time involved. For me, I have about 3 hours in doing a quality job. Until recently, it seems the going rate was about $120 for a machined crank, ....which is about the same price shops were charging back in the 1980's. With the cost of good equipment and labor, it is unprofitable at that price.

[larrys40]

Brent, I agree with your aaseent as like mine now there are plenty of opinions with less experience than with more experience . I haven't ground cranks but have watched it done and the straightening process . It's incredible how easy a model a crank bends... In fact it's a wonder it stays good when running .
I believe most machinest who are still at shops doig this type if work are capable competent machinest, the just need to understand the crank and frailness of it compared to other cranks.
In my opinion the biggest vibration factor aside from the other simple factors of stuff like engine mounts etc is rods . The new inserted AER rods as a set straight and balanced will greatly run smoother than serviced originals that have been through the mill

Just my quick 2 cents worth . I've driven plenty if A's that were silk smooth as older babbited engines without counterbalance and other mods. Just goes to show you it can be so
Larry Shepard