What might be the limitations, cautions or dangers of trimming cooling fan blades to gain clearance?? Yes, I did a search. Regards, Twobit ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bad idea. trimming may get it off balance and it will vibrate or possibly explode. Buy the right sized fan.
We trimmed a bit before. I would not trim very much. That hunk of steel spinning like crazy can and could hurt someone real bad.
I modified the fan on my T, 283 6blade 15 inch mechanical from Speedway. The fan interfered with the cross spring u-bolts. Each blade has a 2x1 inch cutout on the front corner to clear the bolts. Careful layout, and a hole drilled at the corner of each notch and deburing so there are no sharp edges and places for stress risers to create cracks. Frank
X2 MILLION I used to work in a old style gas station where we actually repaired cars my bosses friend brought her car in running terribly he (old hand) calls me(youngin) over and says what do you think is wrong with her car while watching it run (mopar 318) it was trying to jump out of the car on its own .. I was looking and looking and finally said I have no idea he shut it off and showed me one of the fans blades had somehow broken off and im like no that cant be the whole problem so he took the fan and belts off then started the car engine ran as smooth as a new one scratched my head on that one for a couple of minutes he put another fan on it with all the blades and still smooth s glass well as smooth as a high milage not very well taken care of 73 318 could run
Curious how many thousandths of a gram difference there would be between each blade if a thin blade like a flex fan was cut off exactly the same amount? Would it really require re-balancing, and if so would there be enough difference for a balancer to detect? I think if the fan was properly cut by turning in a lathe or jig to hold it centered as each blade was cut, I'm not sure you could measure a difference between blades afterwards. Just a thought.
I've done it in small increments several times over the years and never have had any problems. As others have said, careful layout, careful trimming and be mindful of balance and you'll be just fine. I do have to stress this has always been with O.E.M. fans. I'm not sure how an after market flex fan or other would do with this sort of thing.
I trimmed one by making a template cut very carefully and so far so good. Anxious to hear others experience. Will probably look for one that is the correct size.
I've done it many times over the years with no problems after. I think the trick is to get an even cut off each blade as I have. I've done this by having the Blade mounted on the pump and make a steady rest for a Marker (I use silver lay out pencils) and turn the blade by hand to get a line on each one then cut off just outside the mark and finish file to it. So far so good. The most I've cut off one is 3-1/2". On the other hand I have seen the results of a blade coming off and it is scary. Both times it was factory un-modifyed blades. Some times Shit just happens and some times ya just gotta do what ya gotta do. The Wizzard
My cousin Eddie 'chopped' his flathead fan, it was atop an early 21 stud...attached to the generator, right on top. Eddie had it revved way up in the high school parking lot, and //BANG!// Fan blade broke off and punched ONE louver in that nice '40 hood.
I've done it, but it worried me so much, I looked harder for the size I needed and found it. The selection is so great, that cutting should be the very last resort.
As far as limitations, don't cut ant strengthening ribs. But it totally depends on your fabrication skills. Some guys have asked and I have told them don't you dare because I know their skill level. I have done factory steel and aluminum, also a couple aftermarket stainless and aluminum. If you make a template and make the marks and cuts all to the template, I see no reason to check balance. The first couple I did, I even went so far as to weigh the metal removed from each blade. Why have I done it? I hate waiting for parts, overpaying for parts, and having a part laying around because I won't pay to ship it back and go thru the hassle of returning it. Thru the years, I've done about 10 and never worried about any of them. Still have 3 of them on current cars. If you are not 100% confident, don't do it. I've seen them come apart too. No, nothing I cut. My 2 cents, Dan
Why risk trimming a balanced fan? You can buy new for like $20.... If a blade comes apart, your gonna wish you bought a smaller fan.... Ya, it can be done. It just seems not worth the risk
Wow. I'm sorry, but every time I read a post were some one asks a questinon about anything related to actually building a hotrod. They get at least a dozen "dont do it!" "You'll kill someone." you'll kill yourself."answers! I trimmed the fan on my RPU about 1 1/2" then I checked the balance by spinning it on a plum bob in my vise then I even re-curved the tips of the blades just like the bits I cut off .........amazingly the world didn't end.
I have trimmed the old green fiberglass flex fans. The blades are so light I didn't think any difference would amount to much. Nothing exploded either. Blue
and don't run a single resevoir master cylinder either. if your exploding fan takes out a brake line, you're fucked.
I find it hard to believe it two pages before some one said some thing about rebalancing a cut down fan blade. It's a simple thing to do,there is nothing scary about adjusting the size of your fan. .................Jack
I did it on my old t, I believe GV has over 15k on it now. I used 1/2" masking tape on the end of each blade to get the same cut and trimmed away. I needed an oddball size.
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