After putting in the new front crossbar (see Part I and Part II), it was time to figure out a way to attach the radiator to it. The bar was made out of 1¾” tubing, which is likely overkill for this job, but it was chosen for two reasons.

1. It is the same diameter as the cage, so any leftover tubing can be used on a wide variety of projects.
2. It is the smallest diameter muffler clamp that I could reliably find at the autoparts retailers.

Why is number two important? Because it is how I intend to attach the radiator brackets to the crossbar.

After reading as much as I could on the subject of radiator mounts, it was clear to me that there wasn’t much available. Seems like no one actually gives it a lot of thought. The exception is Circle Track magazine; fast becoming one of the best sources of information on a variety of subjects germane to the Mongrel project. They spoke about how there needed to be a certain amount of flexibility or give in the radiator mounts so that light contact would move the mounts, not break the radiator. Furthermore, a mount which has some flexibility will isolate the radiator from vibration better than a rigid mount. If it is good enough for dirt modifieds that pound through ruts and asphalt late models that hit something with the nose at least twice a lap, I figured it was good enough for me.

What follows is a pictorial how-to on the making of my radiator brackets. My hope is that the utility of this information isn’t limited to radiator mounting. In fact, I hope it shows how you can make a bracket without welding for nearly anything. There are times when this might be preferable, such as when you aren’t sure if it is how you want or, as in my case, you want to have some give in the system.

What follows is the description of how I went from

to

For this project, I used metal you can buy at your local hardware store or BORG. No, not the Star Trek Borg, but the Big Orange Retail Giant, aka Home Depot. Actually, I bought mine at Lowes, because they have a much better selection of Grade 8 hardware, so I am more familiar with their layout. But it is all the same stuff so get it where it suits you most.

Step 1: Measure the tank

Pretty simple really, just lay the metal along the tanks’ width and make marks. The part marked F, for front, cannot be much longer due to the lower hose outlet limiting space. I am using a 48″ long piece of 0.125″ thick 1″ wide aluminum.

Step 2: Bend Number One

Put the metal in the vice and bend it to 90°. I started the bend with a piece of steel clamped to the aluminum, so that I knew that it would bend on the line. I then finished it with a hammer. If you have the skill to hammer exactly on the line without the steel, more power to you.

Step 3: Remeasure the Tank Width

You can put the bend on the tank and create a new line. This is also a great time to check to make sure that your first bend is actually 90°. While blurry, the following picture should illustrate whey you always remeasure.

Looking at the edge of the piece, you can see how the original line is further left than the new one. Bending uses a certain amount of material and changes the length of your piece.

Step 4: Make the Second Bend

Use the same process as before. In this picture, you can see how the black marker line is right at the very beginning of the bend. This is what you want. The metal used in the bend comes all from the side that won’t hold the tank. This will also make the piece larger than you need. Remember, larger is better than smaller since it is easier to add padding than shrink the radiator tanks.

Step 5: Duplicate Steps 1, 2, 3 & 4

You will end up with the above. Hindsight being 20-20, it would probably be easier to cut the piece in half as the first step. However, when I was building this bracket, I wasn’t sure if I would be able to make both out of one piece, so I kept it as one. Bending it before cutting it was easier than measuring around the bends.

Step 6: Cut it in Half

I used a bandsaw to make the cut, but almost anything will cut aluminum, which is why it is a good material for this project.

Step 7: Place the Clamp on the Crossbar

Putting the clamps on the crossbar will allow you to take your bracket and makes sure that it fits past any obstructions, is wide enough and measure approximately how low you want the bracket to hang. Part of the beauty of this system is that you rotate the clamps so that they will angle the radiator and change how low it sits. Also, you can spacers between the clamp and the bracket to move it up. Err on the side of too low, since moving it down involves remaking the bracket. Removing the nuts will allow you to lie the bracket flat and make your marks easily.

Step 8: Make the Third Bend

Based on the marks in step 7, use the same process as before, just be careful to not whack the bends you have already made and undo your hard work.

Step 9: Line Up the Clamp on the Bracket

Place the clamp flush against the bend, as it will help provide support. Mark the holes with a pen.

Step 10: Drill the Hole Away from the Third Bend

Punch on your mark and then drill through. You cannot drill the hole close to the bend since the chuck will not clear.

Step 11: Mark the Hole Near the Third Bend

Using the hole you just drilled to make sure everything is lined up properly, make the second hole.

Step 12: Drill the Second Hole

Punch your mark, then using a hand drill, drill the second hole. As you can see, I didn’t get it 100% straight. Get it as close as possible, but you can always oval out the holes later if you need to.

Step 13: Measure Side Rails

Using thinner 1/16″ thick 90° stock, mark off a length on each bracket to cover the sides. At this point, you will need to decide which bracket is left, and which is right, as henceforth, they will no longer be symmetrical.

Step 14: Drill the Holes for the Rails

The best method of attachment for the rail is riveting. Drill two holes on each bracket, close to the edge for maximum support. Remember right and left. What I do in that situation is flip one upside down, and drill them together. That way the holes are the same and the rails, when drilled, are interchangeable.

Step 15: Drill the Rails

Using the holes in the bracket as a guide, drill out the rails.

Step 16: Rivet the Rails to the Bracket

I have found that good quality rivets are worth the money. Skip the ones you find locally and get some from a race shop. I got mine from Muscle Motorsports; the large head really makes a difference and is a lot easier than using washers. I wish I had had them when finishing up the cowl project.

Step 17: Cut the Rails

Try to cut the rails flush with the bracket so that they cannot get caught on anything.

Step 18: Grind the Rails Flush

The cut can be close, there will still be a corner or two that you will want to round over. Now do this again for the other side.

Step 19: Find Some Grip

Since the aluminum radiator tank riding on the the aluminum bracket isn’t a high friction interface, it is best to find something that will provide some grip. Rubber feet for furniture are absurdly expensive, and since you are going to cut them to fit anyway, why not start with something cheaper? The rubber bungee cord fits the bill nicely and will provide some vibration resistance as well.

Step 20: A Little Bit of Planning

Along with the bungee (already cut in the picture) you will need some clamps and adhesive. The adhesive pictured didn’t do a very good job, so if you find something better, let me know.

Step 21: Cut to Size

First cut a piece of the bungee to fit in the bottom.

Then a piece for the trailing edge. I had mounted the brackets by this point, but it would have been easier to do these steps on the bench. I also did not fit a pad on the front edge because the top mounts will pull the radiator back. Thanks to my son, Colin, for lending a hand and fitting in the places I don’t.

Step 22: Glue It On

Put some glue on the pieces of bungee you have cut.

And some on the bracket.

Step 23: Clamp it Together

Fit the rubber pieces to the brackets, then use a variety of clamps and let the glue dry. As I said previously, the adhesive I chose didn’t work particularly well, but once the radiator is in, the rubber has nowhere to go. You will want to glue them, however, since you don’t want them to fall out when you put the radiator in.

Step 24: Paint It

When the glue has dried, paint everything. Normally, I don’t like to paint fasteners, but in this case I did it because cracked paint will give an early indication of any slippage.

Once the paint has dried, you can test fit and move on to the top mounts. That will be covered in later entry.

While this isn’t the only way to make a bracket or a radiator mount, it is how I did it. Hopefully it shows that you don’t have to have a welder in order to adapt universal parts to your project. A vice, a hammer, a knife, a drill and a rivet gun were the only tools used in making these brackets.

DISCLAIMER

Any and all content here is used at your own risk.  Take all necessary precautions to prevent harm and in no way am I responsible for anything that happens as a result.  You assume all responsibility for your own actions and must make the determination as to whether or not a course of action is safe.

With the new cross bar tack welded together, it was time for VK to weld it up completely. Vincent has been taking welding classes at his local community college and has been practicing at every opportunity. VK is also the most fastidious person I have ever met; I know that if it passes his standards, it is good enough for me.

VK decided to make the welding a two man operation. I would hold and rotate the cross bar while he would weld. It took some coordination, mostly VK telling me to speed up or slowdown my rate of rotation, but I think the result was worth it.

VK was using flux core wire, which explains the spatter. For the second plate, I found an old Focus front wheel bearing (of which I have far too many) and set the bar on top of it. I then could spin the unit more freely while VK applied the bead.

The semi-finished product.

Here is the obligatory shot of VK making sparks and bright light. This is not the cross bar he is welding, but it does show that all of this was done by regular guys, with regular jobs, in a regular two car garage. No professionals, just enthusiasts.

Once the bar had cooled, we made a quick test fit to ensure that there had been no warpage during the welding. It fit like a glove and the bolts went right in. However, this was not the end of the bar making process.

The factory cross bar actually passes through the front frame members. This means that it is not a T joint like the replacement we had made. In order to make sure that the new bar wasn’t weaker than the original, I asked VK to weld on some gussets.

Again, I have no way of actually measuring stiffness, but the theory behind adding gussets to a 90° joint is sound and should help. With the gussets welded on, we did a final test fit.

Once we knew the bar fit, it was time for a little celebration. This is why VK was playing with the bar in the way shown in the previous entry.

With the creation process out of the way, it was time for some destruction. Destruction, thy name is Kendt Eklund. Fresh from removing the front strut towers, Kendt set about cutting out the front cross bar once the new bar was bolted in completely. I wanted to try and keep the chassis true, and I felt like putting the new cross bar in before removing the old would help that.

It was a pretty standard cut and grind metal removal. Not much to describe, but since I had some extra hands around, I have pictures of the process. Since that is so often not the case, I will share them all as a way to say thanks to Kendt for doing the dirty work and salute whoever picked up the camera. If you remember taking these pictures, please let me know and I will give you the credit you deserve.

You can see that the driver side of the bar is cut already. Kendt is working on the passenger side.

Kendt has cut the bulk of the bar out and is now trimming the stubs back.

From this angle you can see the four bolts that hold in the new crossbar and the previous strut tower removal project.

Kendt went the extra mile to get the cut flush.

Here Kendt is trimming the driver side stub.

At this point, Kendt has traded in the saw for a grinder.

More grinding. In this shot, you can see how the factory bar extends into the frame rail.

With bar out of the way, the radiator can be test fit again. That will be a multi-step process as it will have to take into account the location of the strut rod and sway bar mounts. This was a big step forward, and I would like to thank everyone who came to help one more time. I hope you had fun and we can do it again.

I wrote before about how the radiator was proving a little reluctant to set up residence in the nose of the V8Mongrel. The main impediment was the cross bar which serves not only as the bottom mount for the radiator, but also supports the front mount of the strut rod and the chassis mount of the front sway bar. Chances are, it also adds some strength to the front end, although I have no way of measuring that. I did not decide to remove such an important piece without a plan.

When making the replacement I would have to consider five criteria.

1. Fixes the clearance issue
   Obviously this is the reason the whole project was undertaken. To accomplish this, the bar would have to sit in front of the large lip that marks the front edge of the engine bay.
2. Removable
   The factory cross bar was in the way when I installed the engine. Making the replacement removable will allow for the engine and trans to come out as a unit. I hope. And I hope I don’t need to find out if I am right about that for a long time.
3. Homemade
   I wanted to make the bar at home, out of parts that I could easily obtain. In part because projects like this are fun, in part because should anything happen to it I want to be able to replace it easily, and also in part because if it doesn’t work, I don’t have as much money involved.
4. Easily modified
   The strut arm and sway bar mounts still need to be added. Therefore, the new bar would have to be designed to allow for these additions in the near future.
5. Strong
   While I cannot measure the chassis stiffness, I can apply some general principles. The front end of the SA22C is basically a ladder frame with the firewall at one end, the cross bar at the other, and the subframe (engine cradle) in the middle. By moving the cross bar farther forward, the effect is the same as moving the rungs of a ladder farther apart; that is to say it becomes weaker. I hope that I can compensate by adding a strong rung, or cross bar as the case may be.

Vincent Keene (VK) drew up the concept for the replacement I showed before:

I had some extra 3/16″ plate in my stash of metal, but I didn’t have the tube required. I decided on 1¾” because it is the most common size used in rollcage and tubeframe race car construction. Not only does this help with regard to future utility of any leftover material, it also helps with any brackets that might need to be attached. Many race part suppliers offer mounts and brackets that are either notched for or designed to be clamped to 1¾” tubing.

I ordered my tubing from Lefthander Chassis; a 5 foot piece of 1¾” .095″ wall EW (Electro-resistance Welded) tubing. DOM (Drawn Over Mandrel) tubing is preferred for rollcages and other critical items, but in this case I couldn’t justify the extra cost. I also picked up some nice pre-made gussets from A&A Manufacturing. While I like to make most of my projects, at just 23¢ each with lightening holes, it is difficult to justify the cost to buy plate and DIY, not to mention the time it would take to make them. Both companies provided a first class experience with no problems at all. No doubt I will go back to them again with future needs.

A few weeks ago, Stephen Westerfield had come over for an evening and helped make the end plates. I didn’t get any pictures of the end, but they were just simple pieces of nearly square steel with a hole drilled near each corner. These were then used as templates to drill the required holes in the chassis.

Here is VK on the drill. We had already clamped the plates in place with large quick clamps and made the marks where the holes would need to be drilled.

Here you can see the approximate placement of the holes. If you are insane enough to be using the V8Mongrel as a guide for your own project, make sure that you don’t hit the two horizontal portions of the frame box with the drill.

The plates were then bolted to the frame in their final location, and the tube trimmed to the right length. This involved some welding magnets, patience, and VK tack welded the tube onto the plates while on the car. Doing it this way made sure that the bar and plate alignment reflected the reality of a nearly 30-year-old chassis that is probably not 100% straight and true. There is not point in making a cross bar that is square down to the minutes and seconds if the chassis is not.

Also, it is important to note that the existing cross bar is still in the car. Removing that structure before making the bar could very easily result in making measurement of the frame in an overly distorted state. Basically, I used the current chassis condition as my zero point, and then built the bar to fit it. I am sure that someone with a chassis jig and lasers is laughing at this, but for an at-home amateur, I felt that it was the best compromise available.

The next entry will detail the completion of the bar and answer the question “what the hell is VK doing here?”

Whenever a more powerful engine is added to a car, the support systems often require similar uprating. These add-on modifications are what keep a simple engine swap from being simple. One such case is the cooling system. The rotary engine requires a strong cooling system, due to its design, so the RX-7 has one from the factory. However, the particular RX-7 I purchased was a true rolling chassis, thus there was no radiator in the car. Therefore, I had a blank canvas.

After speaking at length with Rick Yancer at Howe Racing, I purchased one of their universal radiators. The unit was designed for a typical asphalt late model, not an RX-7. The sloping nose makes fitting any radiator a challenge. The unit would have to be angled so as not to poke through the hood or be too close to the ground.

With the help of Jon Rathbone, I attempted a couple of different mounting ideas. The first thing that became apparent was that the unit was wider than the factory RX-7 opening. We would have to clearance some of the area around where the radiator would sit.

The center area was trimmed as close to the hood latch as possible on both sides. Unfortunately, there is still a lip that might cause a problem. However, since these sorts of lips are often used to impart strength, I will keep it unless there is no choice.

The next step was to have Jon hold the radiator in place so we can see how it would fit.

No matter what we did, it seemed like the radiator would protrude too far forward or be at too great an angle. The source of the problem was quite clear.

The front cross bar is important because it anchors both the front sway bar and front of the strut rod. Regular readers of V8Mongrel.com will now understand why this entry is being made at the time it is. Everything is related.

My first idea was to cut out those brackets behind the bar and see if it would be possible to mount the radiator in the space between the engine and the cross bar.

I used a combination of saw, cutoff wheel and Oxy-MAPP torch to make the cuts. Unfortunately, the radiator still would not fit the right way. I have no pictures of this round of trial fitments since I was operating solo. Maneuvering the radiator took both hands so the camera stayed on the work bench.

Left with little choice, I have to embark on the project of eliminating the crossbar entirely and fabricating a replacement.

Vincent Keene was kind enough to make the above diagram. As you can see, the new cross bar will bolt in. Being able to remove it will allow for easier access to the front engine dress, and, if the engine has to come out for any reason, will greatly speed that process. It will sit in front of the current cross bar, just beyond the lip, and allowing the radiator to be in the more protected position behind it.

Tomorrow (3 May 2008) Vincent and others will be coming by to help fabricate this bar. The real difficulty will be in integrating the sway bar and strut rod mounts in a way that doesn’t recreate the same problem of interference with the radiator.