!970 radiator Fan blades very unusual to me

[Bill Balkie 24172]

Hello ,
    I would think that the radiator  fan blades  would be perfectly spaced and balanced on any automobile . But  looking at the fan blades on my 70 cadillac they  look very unbalanced and not evenly spaced . Am i missing something here or is there a reason for this . I have included a picture .

    Bill

[wrefakis]

7 blade flex fan replaced clutch fan on 69 much improved cooling

[Dan LeBlanc]

Even an old 4 blade fan from earlier years looks more like an x than a cross.

["Cadillac Kid" Greg Surfas 15364]

Uneven spacing
Is to reduce the auditory harmonics (noise)
Greg Surfas

[Scot Minesinger]

You are fortunate and have the commercial chassis 7 blade fan.  The standard was a 5 blade unevenly spaced as well.  Maybe a heavy duty cooling option utilized the 7 blade fan.  I have switched over to a 7 blade fan on all three of my Cadillacs just for that extra assurance.

The unevenly spaced fan blade is correct.

[chrisntam]

Uneven spacing
Is to reduce the auditory harmonics (noise)
Greg Surfas

I always thought the uneven spacing was so you could get to bolts (arm through the void) on the front of the engine.  That's what I've always attributed it to.

Eldorado also got a 7 blade fan.

[spolij]

Some engineer has a permanent migrain.

[Gene Beaird]

I always thought the uneven spacing was so you could get to bolts (arm through the void) on the front of the engine.  That's what I've always attributed it to.

Eldorado also got a 7 blade fan.

Nope.  As Greg noted, it's to reduce NVH (noise, vibration and harmonics).  They don't care if you have to ever remove it after they put it on when the car was built. 

[BlackCads]

Looking at the picture I noticed that some of the blades are larger than others.
I am guessing this was to offset any imbalance caused by the uneven spacing.
If so, another example of fine Cadillac engineering.

[wrench]

It’s also why there is an odd number of blades. It marginally reduces noise, but greatly reduces vibration and consequent structural issues with the blades or mounts.