Flywheel tooth count

84GMCSierra · Sep 5, 2024

Is there a way to find out the tooth count on an original flywheel for an 84 Sierra 2500, with a 250 and TH400? I could get under the truck, Mark one tooth and rotate the engine counting the teeth but I'm looking for an easier way if there is one. Engine has been changed in the past and I'm having starter problems and the teeth on the flywheel are worn. Thanks

Ricko1966 · Sep 5, 2024

If the engine has been changed,and you think they put on the wrong flexplate,you are going to have to count teeth. Doesn't matter what a stock anything came with,if they didn't put back on what they took off.

Rickf · Sep 5, 2024

Does the offset starter bolt pattern indicate the flexplate tooth count?

Ricko1966 · Sep 5, 2024

Rickf said:
Does the offset starter bolt pattern indicate the flexplate tooth count?

Yes, but he doesn't know if they put in the right flexplate when they did the engine swap. Offset is 168 toothflywheel straight across is 153

ali_c20 · Sep 6, 2024

Rotate the engine till one tooth of the flexplate is pointing straight down. Mark that tooth. rotate engine 90°. Mark the tooth that is pointing straight down. Count the teeth between the markings. On the 153 flexplate the tooth pointing down will not be completely straight as 153 can not be divided by 4 in a whole number. 42 is 168 flexplate. 38 is 153 flexplate. Saves you a lot of counting and rotating the engine.

bucket · Sep 6, 2024

Ricko1966 said:
Yes, but he doesn't know if they put in the right flexplate when they did the engine swap. Offset is 168 toothflywheel straight across is 153

Yes, but it will still tell the tale. I see the offset style starter is installed, so if the flexplate is able to engage the starter (even poorly) then it is the proper 168 tooth flexplate. A 153 tooth flexplate wouldn't even be in the same neighborhood.

84GMCSierra · Sep 6, 2024

bucket said:
Yes, but it will still tell the tale. I see the offset style starter is installed, so if the flexplate is able to engage the starter (even poorly) then it is the proper 168 tooth flexplate. A 153 tooth flexplate wouldn't even be in the same neighborhood.

The starter worked fine for a few weeks but now it really "screams", and occasionally won't even turn the engine over. Can't figure out why. Just a big clunk, then nothing. I keep trying and it will eventually start.

jtbartsch · Sep 9, 2024

Is it a new starter? Sounds like it may be on the way out if nothing happens. Inspect the wires to the starter. Make sure the starter has proper clearance to the flywheel. Mine would do the same. There needs to be just enough room that an 1/8" drill bit can fit between the teeth of the flywheel and the bendix shaft of the starter. You can adjust the clearance by the use of shims. Here is a video of someone doing this adjustment. Be sure to do this adjustment before trying to use new flywheel or else you make cause damage to the teeth.

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Flywheel tooth count

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