Other Projects:
Vortex 3-wheel Vehicle
17' Wind Turbine
Bradly GT II Kit Car
1966 Ford Fairlane GT
Spinning Wheels

Engine Subframe

This page will show detailed information concerning how I constructed the engine subframe.

Before you start welding be sure that you have a good flat table to work off from. I have a metal table that was left at the house when I bought it, it is not very flat so what I did is to lay on top of it a large piece of 1/2" thick aluminum plate. It makes a good flat surface to work off from, you can also use this technique with a wood workbench, just make sure that it is stable. You can clamp your parts directly onto the plate to help hold them as you are welding, use a carpenters square to setup the parts and don't count on the cuts being real accurate, this way you can also ensure that when you are done it is flat and square.

Below shows the parts that have been cut up on my saw. Rather than butt weld everything and then go back and fill in the empty voids in the 'empty' ends of the tubing, I cut all of the mating parts at a 45 degree angle so that when welded they will not have open ends and be neater in the long run.

I drilled the tubing so that I could weld in the plugs. The plugs are essentially round steel tubing that are inserted where ever bolts go through the rectangular tubing, their purpose is to keep the rectangular tubing from crushing from the pressure of the bolt/nut. I had some tubing 3/8 ID x 5/8"OD for where the motor mounts attach onto the subframe, and 1/2"ID x 3/4"OD for where the pillow blocks and swing arm mounts bolt as well.

I TIG welded all of the plugs into the tubing and then using my mini-mill I milled the welds so that they were flush with the tubing surface, and then chamfered them to remove any burrs. As much as I like to see good TIG welds I needed to do this so that the pillow blocks and swing arm mounts sit flush and true with the surface. You could use a grinder to do this task, but it is easy to not get a perfectly flat surface grinding, and I have the mill anyways.

Then I TIG welded up both sides of the subframe, being careful to ensure that vertical tubing is as close to 90 degrees as possible. The beveled corners saved a lot of work so that I don't have to plug any open tubing ends when done, but make it a little tougher to get exact alignment.

This is where it really pays to have a flat welding table that you can clamp the parts into position so that the parts don't move as you are welding. Heat from welding causes a lot of pressure to 'pull' parts, tack weld all together and then re-check for alignment and squareness, if off once welded your only recourse is to take back apart and fix...

I still have to connect the 2 halves together with some horizontal pieces. I will have to flush grind any welds where these pieces go so that they fit flat.

Here is some pictures showing the completed welding up the engine subframe, the design is slightly modified from the original plans as I allowed for a similar mounting at the front of the frame as is used in the back. The Vortex chassis was built with this in mind.

Here is a better picture to show the frame dummied up into the chassis, if you look at the seat back portion you can see the modification. I can put upper as well as lower mounts in, rather than have a single mount that is in the middle, the red arrow shows the modification.

Below is a picture of the stainless steel pillow blocks. For convenience when I mount them I will be putting on 45 degree zerk fittings so that greasing them will be easier.

I finished modifying the engine sub-frame mounting brackets, I was able to rework the old ones by cutting off a section and welding/flush grinding some extensions both on the top and the side. I redrilled the brackets to accommodate 2 3/8" bolts on the top and 2 3/8" studs on the sides. After locating all of the mounting holes on the chassis, I took the brackets and TIG welded the 3/8" studs into place using a quick fixture to help hold things in place, then flush ground the weld. Here is a shot of a couple of them. Since I am using 3/8" bolts I decided that 2 on top would suffice.

If you go this route, before you weld the studs into the angle iron, drill the chassis where these studs will go so that you get proper placement of the holes and drill the chassis. Next put the angle iron inside the chassis and mark/drill these holes as well. Next weld the studs in place in the bracket and flush grid them. After cooling you can can treat studs with lock-tight, assemble the bracket along with inside angle onto the vehicle insert washers/nuts and tighten. Finally drill the remaining 3 top holes and add the remaining bolts.

I estimate that I will be torqueing the 3/8" nuts between 40-50 ft/lbs..

Here is a shot of the swing arm dummied up to the engine subframe.

Here is a picture showing how I mounted the front of the engine subframe. It shows the modification that I made behind the seat back area so that I could bolt the mounting brackets vertically instead of horizontally. Also shown is the rear mounts.

All of the mounting brackets are backed up with 2"x2" angle iron on the opposite side and bolted through in both directions. Be sure to mark which mounts and backing angle iron go where, if you disassemble them later on you can put them back in their proper location!

Basic engine subframe - Done!

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