Throttle Motor Mount

Motor Mount for Throttle Motor

Scott did all the design for this motor mount and linkage using AutoDesk Inventor (and also created the images and text for this web page).

This is our induction system, a TWM Induction 50mm IDA V8 system. The throttle bodies are bolt on replacements for Weber 48IDA carbs. The motor, a MicroMo 3564 12V brushless motor with a 164:1 Series 30/1 gearbox, is shown in red. This will attach to a revised throttle linkage, shown in blue.

		This is the motor, again in red, mostly obscured by a very heavy-duty motor mount. The motor mount and linkage is shown in blue. There are 13 parts in total: Main mount, upper mount, lower plate, front plate, rear plate, motor fitting, fitting key, throttle lever, crossbar
midpiece, crossbar left piece, crossbar right piece, right rail, left rail.

The motor and mount assembly is designed to slide in and out on a pair of rails. It is secured by a pair of 8-32 screws on the ends of the rails. This is required because there is not enough room between the throttle bodies to bolt them down with a motor in the way. With this solution, a pair of brackets will get bolted to the sides, on top of the throttle body flanges. A somewhat specialized fitting will be used on the motor that will allow the motor to slide out without decoupling it from the motor.

In addition to easy removal, the mount will feature water cooling, heatsink fins on the sides, large clamping surface area, mounting holes on the front and back for additional rotation prevention, and all Aluminum construction for heat dissipation.

All parts should be made out of Al 6061-T6 or similar. Black hard anodizing would be preferred but if this is not available standard anodizing is acceptable.

The crossbar mounts between the two rows of throttle bodies. Three 1/4" needle bearings are used, one at each joint, to reduce friction. Bronze sleeves will be used on the 3/16" studs on the TWM throttle levers. The spread of the two holes is adjustable to within 1/56" by means of a 1/4-28 stud across the center. The position of the center piece is infinitely adjustable by means of two hex jam nuts on the same stud.

The front mounting plate is made out of 1/4" think aluminum. Four small bolts secure the motor, although the motor is primarily held in place by the clamping force of the mount.

The rear mounting plate is also made out of 1/4" thick aluminum. There are no holes in the back of the motor, so the plate is mostly for retaining and position the motor during assembly, as well as further structural support.

This is the main portion of the motor mount. Threads are nothing fancy - 10-32 except for the two fittings in the front, which are 7/16-18 in order to use a -6AN port adapter with o-ring.

Here is the fitting that will go onto the motor shaft. We are undecided as of yet how to attach the fitting. We would greatly prefer to not damage the shaft in any way or make the part permanently attached.

One possibility is to use a keyway in the fitting and an 1/8" piece of aluminum as a key (red) against the flat on the shaft. The key would be a press fit or interference fit, and the fitting could just be a "tight" fit onto the shaft.

The lever that fits on the other end of the fitting. The interlocking forks will provide a means of sliding the motor out easily but still offer enough surface area and material to sustain the required loads.

This is one of the brackets that bolts on to the top of the throttle body flanges, and is one half of the rail pair that will hold the motor mount assembly. One side has a stop, the other side has a threaded hole for a 8-32 machine screw. The other side is a different part - very similar but with some different measurements.

The motor itself!

As shown, the diameter of the motor (and gearbox) is very very very close to spec. The shaft diameter is even within 5/10,000" of spec! Swiss made...