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Trimming back rad fan blades ????

Crazy Horse

Crazy Horse

Well-known Member
We have a Case 1410 (David Brown 1410) tractor and would like to be able to adjust the height of the radiator a wee bit to clear the hydraulic pump shaft a bit more which is below the lower rad tank. The shaft is rubbing a wee bit on the tank. Not much leeway to fiddle with between the 7-blade plastic fan and the radiator tin shroud. Can we trim back the 7 blades about 1/4" each (carefully and accurately) without worrying about fan efficiency or balance issues? Comments or suggestions are appreciated.
 
(quoted from post at 07:41:38 09/18/14) We have a Case 1410 (David Brown 1410) tractor and would like to be able to adjust the height of the radiator a wee bit to clear the hydraulic pump shaft a bit more which is below the lower rad tank. The shaft is rubbing a wee bit on the tank. Not much leeway to fiddle with between the 7-blade plastic fan and the radiator tin shroud. Can we trim back the 7 blades about 1/4" each (carefully and accurately) without worrying about fan efficiency or balance issues? Comments or suggestions are appreciated.
Click to expand...


Balance and efficiently are both going to be a problem. If you can get it balanced (unbalanced can cause the fan to fail and throw a blade) the question will be just how much efficiency will be lost. Have to remember that it's gotta cool even in the hottest conditions. That's the maybe part. Do you have enough room for an electric fan that attaches to the radiator?

On the other side what caused it to start rubbing? If there is a problem like rad mounts that should be fixed first, then see if it still rubs.

Rick
 
I think the electric fan might work but space
would be an issue I think. We had the whole rad
off earlier this spring (not for any rad or
cooling problem we did a lot of work on the
tractor and took it off so we could get at things
more easily) and focused too much on the fan
clearance issues when putting things back
together. We didn't notice the space clearance
problem at the bottom, and just did lately
actually. The shaft is just barely rubbing now,
we didn't notice that, it has a microscopic leak
now along one small part of the rubbed portion on
the bottom of the tank which we'll have to fix.
The rad mounts themselves are OK, I suspect we'll
have to shim the rubber mounting pad that is under
those mounts a bit upwards with a spacer washer or
something like that when we get it all back
together.
 
What else is wrong there when you have to move the rad? Just sayin' you should look very closely at that. On a Ford, the problem you describe often indicates a bad axle pivot pin.

If you must 'adjust' something... I think I'd leave the fan alone. A sheet metal shroud can easily be bent or cut/adjusted. That would be my course of action... Trimming the blades is sure to leave them unbalanced... and if they're unbalanced it's apt to throw the blade...

Rod
 
How is the shroud attached? Can you waller out the shroud bolt holes a little with a saw file or drill more holes right above the originals so that the radiator moves up and the shroud stays put?
 
Actually, the radiator itself (top and bottom tank, tubes, fins, side tin, L-mounts at the bottom of the side tin) attaches as a unit to the cast iron frame of the tractor (on stiff rubber pads). The shroud attaches to all of that with machine screws. Your method is an idea but the rad would stay put (or wherever it was mounted) and the shroud might be able to be moved up or down. I thought of that but a slotted hole might lead to movement (slippage) of the shroud which might not be fun. Something to think about for sure.
 
If the bottom tank is copper or tin and that close to the shaft give it a small tweak and give it some clearance.
 
Problem is that in one area of the wear spot on the bottom tank (brass)is a wee microscopic leak which we are going to have to fix so I want to stay away from tweaking it. If it was not worn, that would be a good idea.
 
(quoted from post at 15:41:38 09/18/14) We have a Case 1410 (David Brown 1410) tractor and would like to be able to adjust the height of the radiator a wee bit to clear the hydraulic pump shaft a bit more which is below the lower rad tank. The shaft is rubbing a wee bit on the tank. Not much leeway to fiddle with between the 7-blade plastic fan and the radiator tin shroud. Can we trim back the 7 blades about 1/4" each (carefully and accurately) without worrying about fan efficiency or balance issues? Comments or suggestions are appreciated.
Click to expand...
Hi I was wondering if you got the pump on the front mounted to high or changed the shaft and the new one is slightly bigger diameter,causing it to rub.
There has to be something wrong here thats changed recently.
Not trying to be ignorant, but try fixing it properly Hacking stuff up is not the solution. You should see some of the cutting torch fixes I get in my shop for this stuff. When I do other work in that area I usually find the problem was pretty simple, and the last thing it needed was Cutting to bits and absolutely wrecking good tin or tractor parts!..
Regards Robert
 
All good points made, it's just that we have what
we have as we got it in the spring, we've done no
hacking or modifying yet, but obviously we have to
correct this before getting it going again. The
pump is definitely factory, not sure about the
shaft, that would be difficult to tell I think.
Tractor isn't outside my back door right now,
we'll have to have a closer look at everything
before deciding which direction to go in. Funny
thing about the 7 fan blades, the spaces between
them around the circumference of the hub (all one
plastic unit) are not equal distance from one
another. 360 degrees divided by 7 would give you
something like 51.428 degrees between each blade,
that's not the case and no two spaces appear to be
the same. That's a question for an engineer I'm
thinking, way past my expertise.
 
Lot of fan blades are not equally spaced. Never made sense to me but I am not an engineer. As long as all blades are exactly the same length, I see no problem with trimming them equally a little bit, carefully. Some times you got to do what you got to do.
 
I would say nearly impossible (basically impossible to keep balanced but i won't say totally impossible)

I actually work for a company that makes plastic auto fans.

The best you could do would be to trim them in a lathe. Even then I think you'd have a tough time. those fans are often made from nylon with glass fibber or mineral fillers for strength which makes them very brittle if you're lucky it is made from polypropylene but not likely. but that would also have glass or mineral fillers

Might be easier to go to a pick-and-pull junk yard (auto or tractor) and find a smaller fan that would work.

someone asked why the blades aren't evenly spaced: =its for noise reduction

good luck
 
(quoted from post at 11:54:13 09/18/14) All good points made, it's just that we have what
we have as we got it in the spring, we've done no
hacking or modifying yet, but obviously we have to
correct this before getting it going again. The
pump is definitely factory, not sure about the
shaft, that would be difficult to tell I think.
Tractor isn't outside my back door right now,
we'll have to have a closer look at everything
before deciding which direction to go in. Funny
thing about the 7 fan blades, the spaces between
them around the circumference of the hub (all one
plastic unit) are not equal distance from one
another. 360 degrees divided by 7 would give you
something like 51.428 degrees between each blade,
that's not the case and no two spaces appear to be
the same. That's a question for an engineer I'm
thinking, way past my expertise.
Click to expand...
one in the interest of reducing noise.
 
Apparently, as another reply stated here and on a David Brown forum, the uneven spacing is done to reduce noise and in some cases to increase air flow. I looked at some stuff on a Google search, some of it looked like Albert Einstein might have trouble with it so it's way beyond my level, that's for sure.
 
If you can't find a smaller fan that fits, it might be simpler to drop the radiator back to its original position. Sometimes projects like that just turn out that way.
 
Hi Glad your not just gonna cut it! when i was talking about the pump mounting, I was kinda thinking the mounting might have slots in it or on the pump flanges so it would be possible to slide it up or down a little to adjust the alignment if needed.
I had a fan on something here in the shop spaced like that can't think what, but as you say sure looks odd, to any logical engineering point of balance and things L.O.L. Good luck with what you find or do.
Regards Robert
 
Never done it but don't really see a problem. I would carefully mark it first, then grind it with an angle grinder and a flap disc.
 
The Fords I mess with are always tough to adjust the fan shroud so the fan doesn't rattle against it.
I've never taken 1/4" off but have removed 1/16" off the ends of the blades. After making sure the fan was aligned and the blades not bent etc.
If you look at some blades on old tractor fans you'll see a lot of them bent, mangled and misaligned. Worst thing that will happen is you'll wear out your water pump a little early.
 
Could you elongate the mount holes for the shroud, and move the radiator up, and slide the shroud down the same amount?
SDE
 
I thought of that, with all the vibration though I don't like the idea of the shroud sliding. The rad is mounted solid to the frame (on rubber pads), then the shroud on this tractor is mounted to the radiator, a bit different than on most tractors, essentially the same thing.
 

I had to trim about two inches off the blades once, and ran it for a few months that way. Go ahead and trim it. Then take it to your local larger landscape lawn care company. Put it on their blade balancer and trim it and test until it is balanced.
 
Just do it and it will work just fine you arent taking that much off anyway. Ive seen where it had to be trimmed and they didnt have any problems you dont have a racing machine and no more RPMs than the fan runs no problem.
 
Can you mount an electric fan directly to the radiator, using those long plastic zip-tie thingys that go between the fins and the flat washer slides on over the end? Then you could put the radiator wherever you want it.
 
go ahead and cut it.
I've done it to a few mangled fans after beating them back into sorta shape, even made a six blade a three blade once. Like said, the water pump bearing will take some wear, but do what you have to.
Got one tractor around here, can't remember which that the PO cut at least 2 inches off each blade. still is holding together.

seems from your description, since you have to fix it anyway, just give the tank a whack dent before you repair it.
factories do it for clearance, even holes right thru the tank on some models.
 
You can trim the blades. You might also find that the hubs on which the blades are attached may have an adjustable pitch too. Uneven fan blade spacing is for noise reduction.
 
For everyone who says cut it I've seen cut down fans shed a blade. When one lets loose they do so with a great deal of velocity and can do some impressive damage.


Crazy Horse. Is it possible that the rubber pads are compressed somewhat and need replaced? I've seen that happen before with rubber pads if the is bolt pressure and weight against them and they are old.

Rick
 
How much clearance do you have now between fan and shroud? The original fan should fit with clearance on the shroud, and the radiator should not hit the shaft.

I would also expect the radiator mounts have settled.
 
Right now there is maybe 1/4" clearance, not much room for any movement of anything. I think trimming the blades will get us by, and then one way or the other the radiator has to be moved upwards a bit to clear the shaft (unless we remove the shaft and machine the area in question down in diameter, but I don't think that would be the solution). We'll just be careful in reassembling this, had we done that from the start, we probably wouldn't have had the problem.

Anyways, a lot of great comments and we appreciate all the feedback.
 
A heavy draft field tractor or a putting around loader tractor ?
You would be surprised how little an electric fan runs on a diesel putting around tractor.
Summit racing has thin fans for limited space. Always better to use a pusher fan instead of a puller fan.
 
Trimmed back the 7 blades about 5/16" each, was very careful and it looked good, rounded the corners nicely on the outside corners using a pattern. Mounted the rad about 5/16" higher with new rigid rubber blocks, everything fit together nicely and now there is about 1/4" of clearance between the pump shaft and the bottom of the rad tank (which I repaired). Works perfect, still have to put the tin back on, will get that done this week.
 
(quoted from post at 17:40:05 09/20/14) Trimmed back the 7 blades about 5/16" each, was very careful and it looked good, rounded the corners nicely on the outside corners using a pattern. Mounted the rad about 5/16" higher with new rigid rubber blocks, everything fit together nicely and now there is about 1/4" of clearance between the pump shaft and the bottom of the rad tank (which I repaired). Works perfect, still have to put the tin back on, will get that done this week.
Click to expand...

Sounds good thanks for posting back
 
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