Converting to a Gear Reduction Starting Motor

April 2015

Need to learn how to convert from a straight drive starting motor to a gear reduction starting motor? When doing so, there are three main points that should you should focus on to ensure a clean transition:

  1. Design
  2. OE Spacer
  3. Integrated Magnetic Switch (IMS) Relay

Gear reduction starters like the Delco Remy 29MT, Delco Remy 35MT, Delco Remy 38MT, and Delco Remy 39MT incorporate a nose-less design and don’t include a cone around the starter drive. Despite this design difference, these starters are completely interchangeable with straight drive nose style starters. Some gear reduction starters like the Delco Remy 44MT DO have nose cones.

The OE spacer is actually part of the engine and designed to ensure proper clearance between the starter pinion and engine ring gear. If an OE spacer is being used with the straight drive starter, this should be transferred when converting to a gear reduction starting motor, or damage may occur.

The final part to understand is the Integrated Magnetic Switch (IMS). The IMS reduces voltage drop and helps ensure solenoid receives maximum voltage for starting. If the replacement gear reduction starter already has an IMS attached, you should never remove or uninstall it. Removing or uninstalling the IMS could result in control circuit problems and will void your warranty.

With the Delco Remy 29MT, 38MT, and 39MT models it’s strongly recommended that you have the IMS equipped during installation. On the Delco Remy 35MT and 44MT models the IMS is integrated into the solenoid, so these starters will not have the IMS attached to the motor.

Safety Reminder for Remy

The various electrical systems within a vehicle are highly charged and may include corrosive, poisonous, and hazardous materials. To remain safe, you must:

  • Know where the nearest eye wash station is located
  • Always wear eye protection
  • Remove any metallic items that could create an electrical charge including watches and jewelry
  • Never smoke near batteries
  • Never use batteries as a tool rest
  • Dispose of batteries properly when necessary
  • Follow usual safety precautions near rotating machinery