Need Photo of Crank Counterweight

[Bob Bidonde]

I need a photo that depicts a counterweight welded to a Model "A" crankshaft. Also, is an overview of the process to attach a counterweight like this?
> Bolt & weld the counterweights to the crankshaft;
> Straight the crankshaft;
> Finish machine the welds;

> Machine the journals;
> Spin balance the crankshaft.

[Jim Brierley]

Most guys don't use bolts, just weld them on. Vee the weights and crank at the weld point to get a strong weld. Welding usually doesn't cause the crank to warp, as the weights are welded far away from the journals, but check it anyway.

[BRENT in 10-uh-C]

Bob, I have only done this once however I am set-up to do it. The issue I presently have is, I don't own a crank welder (yet!!) to weld/build the journals back to 'standard' size. It is a lot of work (i.e.: expense) to add weights to one, so having a .020/.020 (-or worse) crankshaft to begin with only to add weights to it is not the most prudent thing to do financially since you would potentially only get one or possibly two rebuilds on the crank.

With that said, fixturing is a big plus in this. I did use a bolt so that I could more easily locate the weight however as Jim said, it is not necessary. I built a fixture that clamps to my Bridgeport mill table that locates the crankshaft off of the flange dowels. This allows me to have two journals straight up, and then when the crank is rotated 180°, it allows the opposite side of the crank to be clamped in the exact position as the opposing weights.

I set the crank on a set of tall Vee blocks that were on a 2-4-6 blocks. Using a small Last Word indicator in the quill and a DRO on the table, I swept the top of the webs to find the exact location of TDC. That is where I drilled the hole. In a separate operation, you can find the center of the weight on the underneath side. You can do this in the vise. Then using a roll pin, insert it into the hole of the web and on the underside of the weight, and now the weight should be keyed in the proper location on the web. Using 2 sets of two ¼"x1" flat bars, clamp the weight and the crankshaft's web together for welding.

If a socket allen bolt is used to index, to keep the bolt from eventually loosening, the head will be welded to the outer edge of the weight. When the crank is mounted in the grinder, a skim pass will be made on all four weights so that each one is equal in outside diameter and the weld over the heads is all the same.

I don't know if this tells you what you wanted to know, but maybe this gets you started.

[kenparker]

here is pix that can help explain brents narrative. The duct tape around the journals help protect the journals during welding.

[Jack Shaft]

Early B crankshaft with welded cheeks

[Bob Bidonde]

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Thanks all for the photos. Brent, I admire the work you do, and your willness to share it on the Barn. Thanks!

[john charlton]

Dagenham model B cranks are fairly easy to obtain in the UK . These cranks have the integral counter weights no bolt ons . They have been used in A engines . The mains are ground down to the A size and B rods fitted . The oil pan has to be relieved at the top edge so the B big ends dont contact the pan . This setup seems to work OK . I dont know if anyone has turned all the journals down but should work OK I guess.B rods also available so maybe no one needed to do that . Maybe I ought to bring out a couple on my next visit Covid 19 allowing to sunny Chandler AZ .

John in Suffolk County England ,weather was cancelled today due to the pandemic .

[BRENT in 10-uh-C]

Originally Posted by john charlton

Dagenham model B cranks are fairly easy to obtain in the UK . These cranks have the integral counter weights no bolt ons . They have been used in A engines . The mains are ground down to the A size and B rods fitted . The oil pan has to be relieved at the top edge so the B big ends dont contact the pan . This setup seems to work OK . I dont know if anyone has turned all the journals down but should work OK I guess.B rods also available so maybe no one needed to do that . Maybe I ought to bring out a couple on my next visit Covid 19 allowing to sunny Chandler AZ .

John in Suffolk County England ,weather was cancelled today due to the pandemic .

John, the downside to doing this with a B crankshaft is, when the journal pins have been ground that far, you are through the original surface hardening (-typically about 0.035"-0.040" deep). Matter of fact, you can almost watch it as the color of the sparks change. Once you are thru this hardened area, the pins become very vulnerable to scratching & grooving from debris which potentially can set up stress risers. While I realize this practice has been performed for years, I personally don't find it prudent unless after the grinding the crank can be Nitrited to restore surface hardness.

[Synchro909]

Originally Posted by BRENT in 10-uh-C

John, the downside to doing this with a B crankshaft is, when the journal pins have been ground that far, you are through the original surface hardening (-typically about 0.035"-0.040" deep). Matter of fact, you can almost watch it as the color of the sparks change. Once you are thru this hardened area, the pins become very vulnerable to scratching & grooving from debris which potentially can set up stress risers. While I realize this practice has been performed for years, I personally don't find it prudent unless after the grinding the crank can be Nitrited to restore surface hardness.

Yes, if a journal is taken down that far, it has to be rehardened but I think John knows that (that doesn't mean everybody does).
I have weights made that encircle the crankshaft and are shrunk on. For something like this, I go for a belt and braces so a bolt fitted through the weight into the crankshaft gives me extra peace of mind.
If you're interested, I can post the pattern for the weights

[Pete]

It is almost impossible to get enough counterweight on a B or A crank to fully balance it.
That is why they all shake. The closest you can get for a reasonable price is to use
Dan Price press on counterweights. These are the heaviest things available and require NO welding. After installation if the crank needs to be ground, the weights need to be slid over to clear the wheel. Anyone can do this with a lead hammer.
If you install 4 one inch slugs of Mallory in each one before installation, you can approach balance weight depending on your rod and piston combination.
This makes a good crank assembly for street use and certain types of racing. Probably as smooth as you can get without redesigning the engine.

[Slotblog]

Here's some pics of the cranks that were being counterweighted at Bert's in Denver in Oct 2014.

[DBSHELTON]

Will Scat and Burlington cranks balance completely?

[Bob Bidonde]

Secondary unbalancing forces that occur every 90 degrees in the Model "A" and Model "B" engines cannot be balanced.

[Bob Bidonde]

Gregory,
Thanks for the pictures.

[johnneilson]

Bob,

so true, it occurs on ALL inline 4 motors to some degree.

You can reduce some of the effects by making the pistons as light as possible, next is the rods.
There is a ton of information about crankshaft counterweight design available, look for some of the pics of Miller and Offy cranks.

John

[Jack Shaft]

Ford increased journal diameter and ultimately counterweighted B engine to counteract torsional flex. Vibration is inherent in design.Reducing torsional flex (whipstocking) saves main bearings.

[Synchro909]

Originally Posted by Jack Shaft

Ford increased journal diameter and ultimately counterweighted B engine to counteract torsional flex. Vibration is inherent in design.Reducing torsional flex (whipstocking) saves main bearings.

The New Zealand made harmonic balancer also makes a difference. I have an engine with one fitted and 3 without. The difference is clear.

[Jack Shaft]

I have one of Murray Horns balancers as well, no clearer evidence of harmonic imbalance/ torsional vibration than a fractured stock crankshaft pulley. Lawrence Sheldricks engine team to a man cited the propensity for flex during development (benson ford research oral histories) and wanted a larger crankshaft journal.
Ford overuled them,stating flywheel mass will dampen the impulse.

[Jack Shaft]

your list is sound,I would add prior to any work crack and straightness inspection,do it again after welding..

[kenparker]

Syncro, does he "New Zealand harmonic balancer" have a website???