Installing a Gear Reduction Starter

My 25 year old starter was becoming a problem. When hot it became reluctant to turn the engine over. Symptoms indicated that the solenoid was the culprit. If I went through the trouble of taking that bad boy out, I was going to put a new one in.

Starter technology has not made great strides since 1978, however I was intrigued by the current gear reduction starters. The concept was simple. A small high-speed motor mated to a gear reduction system reduces the rotating speed of the armature to 1/3 - 1/4, which then rotates the pinion gear. The result: A stronger and lighter starter than the original that consumes less current and requires no permanent modification to install in my vehicle. Essentially a win win situation.

After some research I decided to purchase my starter from . This company mates a 1.2 HP Nippondenso gear reduction starter to a custom fabricated front plate that bolts to the V-12 bell housing. This starter is remanufactured by Gustafson Machine, a facility in Gloucester Ma. The solenoid, bearings and windings are replaced and exterior replated. Cost. approximately $200.00 US.

The photograph below starts the project. In the absence of a lift, jack the car up, preferably with all four wheels off the ground and supported with appropriate jack stands.

Remove the exhaust heat shield.

And the steering rack heat shield. Note that on right hand drive models the complete steering rack has to be removed.

To complete this project you absolutely must have a long 3/8 extension with 12 point 9/16-inch and 12 point 7/16-inch universal sockets.

All the nuts that attach the exhaust down pipe can be accessed from below the vehicle. Position the 9/16 socket and extension either side of the steering rack as needed.

Remove exhaust down pipe. Be careful not to damage or nick the sealing surfaces.

The 25 year old starter is now actually visible.

Remove bottom starter bolt.

XJ-S V-12 starter's top bolt. This is the bolt that will drive sane men to consume alcohol. (blue arrow) It is just barely visible and recessed in the bell housing casting. It can only be removed with a 12 point, 3/8 drive 7/16-inch universal socket. Don't even try anything else. You must get an absolutely good fit with the socket before applying pressure. Hammer it on lightly if necessary. If you round off or damage this bolt head you will require therapy.

Remove heat shield from the old starter's solenoid. (blue arrow)

Remove nut from large cable to starter solenoid.

Remove wire that triggers starter (from starter relay).

Identify the wires removed from the starter solenoid in photograph below. Blue arrow from the alternator. (actually two wires under a single sheathing). Red arrow from the battery bus and yellow arrow from the starter relay.

Comparison of the two starters reveal a significant difference in size and weight. The alternator and battery bus connection is identified by the red arrow. The blue arrow identifies the starter relay connection. Arrows point to correct connections on both starters.

The new starter cannot accept the old threaded bolt. A suitable nut must be used.

The starter might have to be rotated to fit. Remove the custom plate.

With the plate screws removed, trial fit the starter to the engine. Mark the plate location, and refit with loctite on the bolt threads. Although unverified, the manufacturer claims that the plate will only work with the marked side towards the engine block, maintaining that it cannot be rotated 180 degrees. (see instructions for marked side).

This is the plate orientation that I wanted. Note that the top bolt hole's location might not allow the original top bolt to extend before hitting the body of the starter. (red arrow) In addition, it would be difficult for one person to attach the top bolt.

Taking a tip from Phil Grey I cemented the top bolt's nut to the starter. Any cement that hardens will work. I left it overnight to dry.

I removed the top starter bolt after determining how much the bolt extends from the bell housing. Measure against the top starter hole and cut the part that extends beyond the glued on nut.

With the new starter now ready, the wires from the alternator must be lengthened. I removed the conduit that the alternator wires go through.

This allows me to lower the wires where I have easy access to them. Cut both wires in a convenient place.

You will need to lengthen both wires approximately 8 inches. (You can use one heavy gauge wire.) Due to the hostile environment, I used hose to insulate my solder joints. (blue arrow). The red arrow identifies the starter relay connection.

I wanted the other connection to fit inside the conduit. I used a small copper sleeve to solder the two wires together.

Duplicate the soldering procedure on the wires from the alternator. Tape joint.

I used a hose to augment the insulation, then forced the connection back into the original conduit. I then reinstalled in it's original location.

Next, the original starter relay (bolt and nut) connection had to be changed to a spade connection to fit the new starter. Cut, solder and heatshrink. (blue arrows)

Getting the top starter bolt back in was no easy chore. I used a mechanical, flexible claw to hold and guide the bolt.(red arrow).

Install and tighten top and bottom bolts and nuts. Route and secure wires away from exhaust. Check starter operation before installing exhaust down pipe.

Tiny starter sounds different, but even with less than a fully charged battery, it starts every time!


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