425 harmonic balancer

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Old January 1st, 2014, 08:55 AM
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425 harmonic balancer

As I am visiting the machine shop tomorrow.... does anyone have an exact dimension of the harmonic balancer's diameter where the front oil seal rides on? It' a '66 425 V8 out of my Toronado. I had to buy an aftermarket balancer 'cause mine fell apart... I have to work a little on the counterweight to make it fit..and I realized the outer diameter is 51,38mm and the oil seal sits a little too tight for my personal taste.. data from the national oil seal say it is for a 2" shaft and that's only 50,8mm. So before I modify mine I like to confirm with another original balancer...to be on the safe side. My original one is not for measuring.. the surface is shot... I modified it for a different oil seal and had to realize that I cannot find a company in Germany to overhaul the rubber part.


Thx a lot... and a happy new year for all of you
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Old January 1st, 2014, 09:14 AM
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I don't think you have a problem.
51,3 - 50,8 = 0,5mm or 0.020", which is not a bad interference for a rubber lip seal of 2.000" OD.

I could measure a stock balancer if you need, but if it's nominal 2" then it will measure 1.995 to 2.005 or so.

Last edited by Octania; January 1st, 2014 at 10:41 AM.
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Old January 1st, 2014, 09:42 AM
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Just for my own peace of mind... pls check a stock balancer... I am curious..

thx a lot

Harald

P.S.: I attached some details of the national seal. They are not very specific about the details except that it is a 2" shaft. Believe me 0.5mm is huge if it is to much for the seal. It will eat up of it sits too tight..
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Old January 1st, 2014, 10:55 AM
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Originally Posted by harascho
Just for my own peace of mind... pls check a stock balancer... I am curious..

thx a lot

Harald

P.S.: I attached some details of the national seal. They are not very specific about the details except that it is a 2" shaft. Believe me 0.5mm is huge if it is to much for the seal. It will eat up of it sits too tight..
OK I will go measure a balancer or two.
But, believe me, 0,5mm is not huge for a rubber seal
it's 0.020", on the diameter, so the seal rubber is displaced a mere 0.010" or 0,25mm - quite negligible...
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Old January 1st, 2014, 12:27 PM
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thanks a lot

Harald
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Old January 1st, 2014, 12:46 PM
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Originally Posted by harascho
thanks a lot

Harald
4 samples of used balancer, measured not of the wear groove, were:

50,74
50,76
50,78
50,76 mm

About 0,02-0,04 under nominal 50,8 or
0.0008" to 0.0024" under nominal 2.0000"

One was over 50,8 but it was not smooth shiny steel anymore, so that doesn't count.

PS there is a commonly used seal surface repair sleeve, which presses over this surface. I am pretty sure it is well over 0,25mm thick, and does not require a different seal.

So, we are back to... you don't have a fitment problem.

Last edited by Octania; January 1st, 2014 at 12:59 PM.
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