A few years ago, I put a Ford Taurus two speed electric fan in my K5. While the Tauris fan REALLY sucks air, the shroud I fabbed up left a little (read: a lot) to be desired.
So for awhile I was searching for a Winstar setup, with no luck. I came across a three-speed dual fan setup out of an 89 Cadillac at P-n-P one day and snatched it up. It was too wide to fit on my oem sized radiator, so it gathered dust in the garage for awhile. Then, lately I’d been having cooling issues and decided I needed a new radiator. I went with the Summit brand aluminum radiator (Summit p/n SUM-380470 for 73-79 GM Trucks), and when it came, I saw that I had to fab up new mounts for it.
The top and bottom of the Summit aluminum radiator has ‘rails” that dont fit into the rubber radiator mounts the way the oem radiator does. So I got some stainless Unistrut that I had left over from a job I did, as well as stainless strut-nuts and hardware. Unistrut is steel channel used by plumbers, sparkys and other construction trades for conduit, pipe, and equipment supports, among other things. Unistrut is a trade name, it is also known as Powerstrut, Kindorf, channel-strut, or just plain “strut”.
There is a huge variety of fittings available. It’s like an industrial erector set. The strut nuts fit into the channel of the strut and lock onto it’s inturned lips when the fastener is tightened. This lets you position the nut at any desired location along the length of the strut.
I used a piece of deep strut, 1 5/8″ tall, and a piece of shallow strut, 7/8″ tall. I took the deep strut, channel side down, and bolted it to the radiator support using the existing holes, strut nuts, and some neoprene washers to keep the fender washers from pulling through the thin sheet metal.
Then I split a piece of 3/4″ heater hose down the middle and wrapped it around the top of the strut, to serve as a vibration isolator. The 1 5/8″ wide strut plus the 3/16″ or so of heater hose made for a perfectly snug fit in the bottom of the radiator channel.
Next I took the piece of shallow strut and a split piece of radiator hose, and wrapped the split hose around the strut and laid it between the upper radiator rails, channel side up.
I was then able to drill the upper radiator brackets to accomodate 1/4″ bolts that screwed into strut nuts in the upturned channel. I was pretty stoked that the whole thing fit together perfectly. The radiator is very snug in it’s mount, with less wobble than I had before with the oem setup.
So, with the radiator mounted like this, I was able to use the channel of the top strut to mount the dual Caddy electric fans. I only had to do some trimming on the top of the factory plastic fan mount, and then drill holes through it and screw it down into the top piece of strut. Worked like a charm.
I have the fan wired up so that it comes on medium speed with the ignition, and a switch inside the cab to turn on high speed if needed, I capped the low speed lead. Later I want to wire the low seed through an oil pressure switch,to turn it on as soon as the oil pressure is up, the medium speed wired to a thermostat to turn on around 210*, and the high speed to come on with the AC compressor (once I get the AC parts installed).