View Full Version : CJ-3A starter grinding. Adjusting a CJ-3A Starter Foot Switch

08-18-2019, 10:38 AM
I had some trouble with my starter as I was restoring the CJ. Frequently when depressing the foot pedal the starter pinion would not engage the ring gear on the flywheel. The gears would clash and the starter would energize and spin up, grinding the gear and sounding horrific! The switch needed to be set correctly.

When you read this process in the service manual, it is brief to say the least. Here is how you do it. I have attached some photos of the switch. The switch "button" is crimped to a threaded rod. It will move in and out far enough that, the starter will energize to soon or not at all. When you get a new one, they seem to be set in the middle of adjustment. I had to adjust mine down about 1/4 of an inch. The foot pedal as it moves, slides the stater pinion into the ring gear. The starter gear needs to be well engaged into the flywheel ring gear, before the starter switch makes contact. "Timed" for lack of a better term. To soon and it will "screech" grind and destroy teeth. To late and you won't be able to get the switch to make contact, and the starter will not energize.

Under the switch "button" there is a spring. It is the locking device and, the return mechanism for the contact. It locks the cap in place with a spring tail that fits into a grove in the cap. On the bottom of the spring it has a tail that catches on the bottom switch housing against small stops. You can turn the cap and it will move up and down. The easiest way to turn the cap is one turn at a time, by releasing the spring from the groove. Push the top tail of the spring down out of the cap groove. The cap will turn easily and as the spring tail gets back to the groove in the cap, it will snap back in and lock it in place. One turn at a time. You can also turn the cap without releasing the top and "winding" the spring around forcing the bottom of the spring to "hop" over the small tabs on the bottom that hold it. This is easier than it sounds, but it can be done. As you wind it around you have to turn it till it "hops" over the stops. It will then hold there. If you don't get the spring to wind around till it hops over, the cap will return to its prior location.

Properly adjusted the starter foot switch should not energize the starter until the pinion gear is engaged in the flywheel. I have a few bad spots on the flywheel from bad adjustment. From time to time you can not get the pinion gear into the ring gear. When those spots on the ring gear align with the starter pinion gear, I cannot get the foot pedal to push the gear in. Consequently this creates a no start because proper adjustment prevents the switch from making contact unless there is engagement. That is a good thing since a partial engagement can rip the teeth on the flywheel. I have to step gently on the pedal a few times until I actually feel the gear go in. Then once the gear engages, a little more push and the starter energizes.

I have seen a lot of people chasing this issue on 3A's. It is interesting what people do to try to figure it out. There is very little reference to this very important step. Incorrect adjustment will ruin the gears. Most forums seem to focus on wrong ring gear tooth count and other things. I found one reference to adjusting the switch in the service manual.

08-19-2019, 07:19 AM
Great bit of research!

Here is a link to a CJ-3A page that talks about early and mid-CJ-3A starter linkages. It shows the relationship between the mechanical toggle and the actual switch nicely and helps folks understand the relation between the two.

There were two different starters used in early and mid CJ-3A's'; Autolite MX 4137 on the early and Autolite MZ- 4162 on the later. My eyeball sees a difference in the toggle that does the actual pushing on the Bendix drive, so a different starter rod assembly makes sense.

Of course, this sets us all up for getting the wrong starter and starter rod assembly paired up. Then, if you try to put an early or mid CJ-3A starter back into a late key-start vehicle – SHEESH!

Rule of Jeep 2. Never say “Willys-Overland never … “.


(And there is probably a really old guy out there who would say "Everybody knows you always have to adjust that switch when you replace it in a CJ-3A.")

08-19-2019, 07:50 AM
Good info LarrBeard. The difference between the Early CJ-3A starter and the late one, lies in the length of the starter nose and lever arm. If you swap from the long to the short, the starter rod is long and the lever is short. But if you switch from the short to the long, the starter rod is short and the lever is long.

The starter rod I bought was made for the long lever long nose. I had to modify it for the short nose short lever starter, I have.