24V Gear Reduction Starter - Need Shim?

My M1009 has a 24v gear reduction starter on it, with the correct GM starter bolts, and the correct GM starter bracket installed. When I installed I did not use any shims. The teeth of bendix and flexplate/ flywheel lined up well, and the truck starts strong. Most of the time.

There have been several instances where I would only get a "click" when turning the key. At first I thought it might be an electrical issue. I checked voltage at batteries (relatively new, load tested, fully charged) and they read 12.4-12.6 with engine off. I also checked voltage at the starter relay (Doghead mod installed). That was good. The Doghead relay was the click sound I heard. I also can hear the GP relay cycling on and off with key in the on position.

I thought that maybe the starter solenoid might be bad? I checked connections on the solenoid, they are tight and clean. I tried shorting the solenoid out with a screwdriver with the help of a friend in the cab turning the key. I got sparks, but the starter did not engage. My friend then manually turned the flywheel by moving the crank pulley by hand. When he turned it there was an audible "clunk" from the starter/ flywheel housing. This friend told me that the teeth of the starter and flywheel were too close and that was causing it to stick in place and not engage.

This happened again this morning, and while frustrated I turned the key a number of times, getting the "click" from the starter relay. On maybe the tenth try, with no force or action applied other than repeated turning of the key, the starter engaged and the engine came to life. This confuses me even further.

Has anyone else experienced this? Would pulling the starter away from the flywheel by use of shims fix the problem?

To properly install a starter, you must check for gear mesh clearance.

That is what the TM says. When I installed the starter I pulled the flexplate housing cover and visually checked the clearance. I did not use a gauge or any other implement of precision other than my eyeballs. I do not have the correct tool to do this, and thought I would get by because it "looked good". Shame on me.

I am looking for validation if anyone wants to chime in. I am pretty certain that the mesh clearance is the issue that is causing my starter to hang up. Would any of you agree or have alternate explanations/ suggestions I should look into?

Pull the cover off and watch it while someone cranks it over.

You'll see what's happening.

I own several gm"s with the 6.2 liter, and yes i would recommendthe shim"s. The later models with the 6.5 liter do not have that problem,if i were you i would remove the plastic inspection cover on the bottom of the bellhousing, and really inspect the flywheel to make sure there is no damage to the teeth. Good luck sfc rock

Cucv starter problem

THE SPEC"S CALL FOR 0.002 TO 0.006 BETWEEN THE TEETH WITH A WIRE GAUGE

stranger75 said:

I am looking for validation if anyone wants to chime in. I am pretty certain that the mesh clearance is the issue that is causing my starter to hang up.

Click to expand...

Not sure if this counts, but I just had this exact issue on my riding mower. Click, and nothing. Starter alignment.

You have a riding mower powered by a Diesel V8? cool!

Yes, it's very cool. Does a great job on the high grass, and for hauling wood in from the woodpile it can't be beat!

Picked up shims at O'reilly. I was able to install without removing starter. I loosened the bracket from the block, removed one starter bolt, and loosened the other. I was then able to install the shim, replace and tighten the bolts, and check for clearance. The truck started up fine. Thanks for your help.

A little off topic but what is the reasoning behind using a gear reduction starter with a 24v system? I realize they draw less current, but if you have 2 batteries and 2 alternators it seems like you'd be golden with a fast cranking engine.

The gear reduction starter is the most common after market replacement starter to my knowledge. I have the original GM direct drive starter, but it needs to be rebuilt.

My original direct drive starter worked just fine until I made a mistake one day and fried the starter solenoid. I replaced it with the GR starter, and have noticed faster starts, less cranking.

The 2 batteries wired in series, charged by their respective alternators, deliver 24V to the starter. This was adequate power for the original starter, but the design of the GR starter seems to aid in faster starts. I am not entirely familiar with the difference between the two types of starters. By the performance results I have seen, I favor the GR starter. The only downside I see is that was manufactured in China.