Make Your Own Motor Mounts

Overview:

Ever since I finished my KA-T project, I’ve had an issue with hood fitment. Basically, the turbo manifold left the turbo too high, and the intake manifold left the throttle body too high.

NISMO motor mounts only exacerbated the problem, leaving me with no clearance between the hood and engine.

I modified a set of OEM motor mounts, cutting out the center section and welding the two interior plates together. However, OEM mounts don’t hold up well to BIG horsepower. See below:

CA mounts, contrary to popular opinion, are no shorter. What to do?

With more than 2″ of space between the pan and the crossmember, there was only one solution – Drop the motor lower in the cradle.

So, out with the old mounts and time to make my own.

Tools:

– Wire brush
– Grinder or Dremel with cutting wheel

Materials:

– (2) plastic cups (the cheap kind)
– (1) 1-lb container of Flexane 94 (order online)
– (2) 4″ 12×1.25 allthread rods (Ace Hardware has them)
– (4) motor mount nuts (or any other 12×1.25 nuts)
– (2) flat washers
– Brake parts cleaner

Procedure:

First of all, take your 2 pieces of allthread and thread the nuts and washer onto them, making sure they’re centered on the rod like so:

Tighten the two bolts against each other with two wrenches.Then, take your grinding wheel or Dremel and cut some notches in the washers. Don’t worry about neatness, you want them to be all jagged and nasty-looking:

Next, break out the cheap plastic cups.T he size of cup will determine the diameter of your motor mount, so choose wisely. Or, just grab the cheapest crap they have.

Make a hole in the bottom center of each cup, slightly smaller than the allthread rod, and thread the rod through it from the inside:

Make a mark on the cup the height that you want the motor mount to be.You can see my marks in the pics above.

Find a “stand” to set the cups in, so the threaded rod can be suspended – I found that a spray paint can cap works perfect.

Now it’s time to mix the Flexane. The main ingredient is clear, and the catalyst, or hardening agent, is black. Follow the directions on the label, it’s approximately a 3:1 (Flexane to hardener) ratio. Mix ONLY the amount you need, because you can’t save the mixed product. It hardens.

Once your mixing is done according to the instructions, pour the Flexane mixture into the cups. Try not to get it on the threads.

Now, find a warm place to set the concoction. It doesn’t really stink, so if you live someplace cold, you can set it in the house.

It’s best to let it sit 24 hours, or you can let it sit 12 hours and then put it in the oven at 150 degrees for 12 hours (which is what I did).

Once it cools, you can tear away the plastic cup. The finished product is cool, functional, and cheap.

Flexane has a resiliency somewhat near polyurethane, and you can experiment with different mixtures if you want it softer or harder.These should have great vibration dampening, while retaining the rigidity of a solid motor mount.

But they’re clearly superior to the OEM mounts, as they won’t oxidize (like rubber) or deteriorate (like rubber).

As far as strength, it has a hardness of 97A (Shore D scale) and a tensile strength of 2800 psi. Even at 400hp, these mounts won’t see that kind of load.

As far as heat resistance, OEM mounts begin to degrade at 160 degrees F. I added heat shielding to mine, but I can’t imagine them seeing 180 degrees consistently.

At idle, it’s a little rougher than the Nismo mounts were, but nowhere near as rough as solid mounts.The Flexane provides some nice (but firm) dampening.

This project cost a grand total of $56, if you count the $50 for the Flexane.

EDIT:  Ten years have passed since these were made.  They’re still holding strong, and the car is well over 600whp now.