Make Motor Mounts for Anything
DIY custom motor mounts for your crazy project.
Motor mounts hold your 4x4's engine in place in the chassis. In fact, we're not really sure why they are called motor mounts because a motor is an electric motor, and a gas- or diesel-driven engine is an engine. Sure, some folks talk about motors when they mean engines, and that's fine. But why does it enter a technical name like this? Of course, most engines have at least one starter motor on them, if not more. Anyways, getting back on topic, when you swap engines between vehicles, you have to figure out how to hold said engine in place so the power it makes can be transferred to the transmission, t-case and axles. We've built custom motor mounts for engine swaps a few different ways, and it struck us that this could be done for just about any engine in just about any chassis.
This all came about when we decided to slowly start a crazy project we've long wanted to do. We've always been interested in building a mini Jeep or a smaller than normal 4x4. Something between the size of a golf cart or smaller side-by-side and an early Jeep. The idea is it could be fun for kids to tool around in off-road when I go out in my 4x4. Also smaller is lighter, more nimble, and (potentially) cool. The idea has been little more than just that until I tripped over an already tiny 4x4 chassis for sale on the internet. What I found is the rolling chassis of a 1972 or 1973 Suzuki LJ20. This is the predecessor to the Samurai and was imported and sold in the US in limited numbers in those two years. The LJ20 originally looked kind of like a mini Jeep and was powered by a 359ci, liquid cooled, 2-cylinder, 2-stroke engine that made 28 hp. That's cute, and also irrelevant because our chassis' body, engine, and transmission are long gone. But we got two tiny axles with brakes, a miniature transfer case (that was divorced so it was easy to make work with another power plant), suspension, most of the steering system, and a frame. It just needs an engine, a transmission, and some sort of body.
Start your motor mounts with the engine
After a while, we came across a Geo Metro 1.0L three-cylinder engine in a pick-a-part junkyard. Someone had pulled the transmission, but the motor and wiring harness were basically intact. We pulled it and lifted it onto the yard cart by ourselves. It's that light. This engine makes sense for us because it is built by Suzuki, and it shares enough design parameters with the 1.3L found in Suzuki Samurais that with a samurai flywheel, clutch, starter, pilot bearing, and throw out bearing, this engine can be bolted aft of a Samurai five-speed manual transmission. Perfect for this project. To start the motor mounts, we began by making cardboard templates of where the original motor mounts bolted to the 1.0L Geo engine. That helped us make 3/16 steel plates to bolt to the engine.
Isolating the motor, er engine from the frame
Engines make vibrations, rattles, and shakes, and these are things we would like to isolate from the cars chassis. To do this, motor mounts have incorporated some sort of rubber or polyurethane barrier to isolate the engine from the chassis. Now, we could have re-purposed some motor mounts intended for a Suzuki samurai, and the thought crossed our mind, but that would mean buying something when we have a shop full of scrap bits of metal and polyurethane spring bushings. Why not use them? What we ended up using were four Daystar bushings (PN: M02221) that fit nicely inside 2 -inch lengths of 1 1/4-inch 0.120 Wall DOM tubing. If you are building something with a larger engine, you can use larger bushings (PN: M02153) that fit snuggly inside 1 -inch 0.120 wall DOM. From there, you can insert an inner sleeve with an outside diameter of 3/4-inch and an inside diameter that matches whatever bolt you'd like to use (or just a -inch bolt). After that, two tabs, one on each side, can complete the general idea of a motor mount, though on a larger engine you might want to box the tabs in on one or more sides.
Placing the engine
Next, we had to get the engine in place. We used an engine hoist to support most of the weight of the engine, and we also used clamps, pieces of metal, and 2x4 wood scraps to hold the engine exactly where we wanted it. We then used some scrap tubing from the scrap pile filled with odds and ends we screwed up in earlier projects. On a heavier engine, you might want to add gussets to the mounts—and we might still. Better yet, if you can fit a crossmember that bolts in between the two places on the frame where the motor mounts are attached, that's the best way to add strength.
Heavy tack weld the motor mounts
With the motor mounts all mocked up and heavy tack welded together, we can remove the bolts and remove the parts that make up both sides of the motor mounts. Then these can be finish-welded off the car and then painted.
Finished custom Motor Mounts
With parts painted and fully welded, we can put everything back in place and fully weld the tube and or tabs to the frame. The finished product needs to be accompanied by a transmission mount and some t-case mounts of some sort, and we'll show you how we do that in another tech story later on. Once we get the main components of the drivetrain in place, we can start building the body of our mini 4x4. Our current plan is to build it for the kids, but it will need to be big enough that we can test drive it too! After all, it's good to be a kid at heart, even if your age says you aren't one.