I bought a CX Racing radiator off ebay last fall, and I found that it didn't fit as nicely as I wanted. The main problem is the top mounting posts; they are uneven and not located in the same place on both sides. I could have "made" it fit without any modifications, but I wanted to do it right. So the first order of business was to get rid of the old hard rubber in the upper mounts, and replace it with something new that had the holes in the correct place for this radiator.
to the rescue! It is tough, flexible, and works really well for most applications, but it has to be some of the nasiest crap on the planet to work with. Wear throw-away latex gloves and change them often. If you get this stuff on your skin, a bit of acetone will clean most of it away if you catch it early. If you get it on your clothes...well you now have some new shop rags. :)
1. A tube of Window-weld
2. 2 large flat (fender) washers, about 1-3/4" OD x 3/8" or 1/2" ID, depending on the diameter of your radiator's upper mounting stem.
3. Latex gloves
4. A large plastic baggie (like a ziploc freezer bag)
5. Electrical tape
6. Spray paint (Duplicolor Semi-Gloss black engine paint works well)
7. Two rubber grommets, approximately 1-3/4" OD x 3/4" ID. Just about any Ace hardware store should have these.
8. A sharp utility knife blade (be CAREFUL with these!)
9. Optionally a die grinder or sander to modify the mount and frame slightly, if necessary)
The pictures below show the basic steps involved:
1. Remove the existing rubber insert. It isn't hard to do, since the rubber is usually old and brittle. A screwdriver and razor blade should make quick work of it.
2. Put a plastic bag over the radiator with the stem sticking through it, and then wrap the stem with electrical tape to keep the WW from sticking. You also need to place a large flat washer under each mount, to form a base for the new bushing. The washer should be large enough to overlap the metal part of the mount, so the urethane won't just push up and out of the center when it's clamped down and curing.
3. Attach the mount (snug but not clamped down yet) and pack it with Window-Weld. Use plenty and work out any air bubbles; the excess gets trimmed away later.
4. Check the radiator position and tighten down the mounts. This is where the large washers come in handy. They hold the radiator down tight, while the WW cures in place. My radiator was slightly warped, so I used a screwdriver on the passenger side to push it away from the front clip, and a clamp on the driver side to pull it in a bit. Use a couple of rags so that you don't scratch or damage the radiator.
Allow the WW to set up in place for a few hours, and then carefully pull the mounts up and away from the plastic and tape and hang them up to cure for a couple more days (you can now peel the large washers away from the window weld and discard them). You can then shave the excess Window-Weld off the tops flush with the metal ring, by CAREFULLY using a sharp razor blade in a sawing motion across the top.
Note: You may find it easier to apply the urethane in a couple of layers to help speed the curing time. Just be sure that the first layer forms a solid air-free ring in the mount to avoid cracking and weakness. You can then add more to the top for a nice smooth cut when trimming it.
You may also need to make a couple more modifications on both sides just to be sure that the radiator won't rub against the frame or mounts. In my case, I made a small notch in the mounts (circled in green below), and cut/radiused the corner of the upper frame with a die grinder (circled in red below). In hind site, I probably should have radiused the notch in the mount to help prevent cracking, but I don't think there is enough vibration or force acting on it to be that big of a deal.
Notice in the picture below how the stem of the radiator isn't centered, and sits off to the lower left a bit. Just replacing the stock mounts with new ones would have pushed the CX Racing radiator inwards and to the right in the frame. The other side is off center also, but more towards the bottom.
Once the mounts are cured and sanded, hit them with a coat of Duplicolor gloss or semi-gloss black engine paint. For best results, use a large grommet under the mount to help secure the radiator. This transfers the vertical force to the metal part of the mount, and helps keep the new urethane part from being pushed out by sloppy/sharp welds around the radiator's mounting stem.
It's also a good idea to check your lower mounts before reinstalling the radiator. If they are hard and brittle, replace them. If the rubber is still in good shape but they seem to fit loosely in the frame, apply a small amount of gray or black hi-temp RTV around the outside of the mounts under the upper "lip", and reinsert them.