684 orchard special tach drive

Walnut1 · Sep 18, 2022

I have a 684 orchard special, the tach quit. I started at the tach drive first a discovered the end that goes in the block(camshaft?) broke the "half" drive part. I ordered a new one, how do I get the old broken part out?

JimB2 · Sep 19, 2022

The old tach drive just screws into the front cover, there is usually a thin lock nut on it.
Hopefully it didn't break off at the front cover.

JimB2 · Sep 19, 2022

See link below for a good photo of the tach drive.
684 Tach Drive

Walnut1 · Sep 19, 2022

I took the drive unit off and the machined portion(the flat portion as shown in your photo) that goes in the cam is gone, it looks like it broke off. I m hoping it s not stuck in the cam, I ll find out when my new one arrives and I try to put it in.

JimB2 · Sep 20, 2022

Maybe a strong magnet will pull the broken piece out.
Usually the spacer washer wears out and the gears no longer mesh in the L part of the Tach drive.

Walnut1 · Sep 23, 2022

I fixed it! The new drive arrived, I took the old one off and the seal housing that the drive screws into which let me take out a small driveshaft with a magnet. The piece that had broken off came out with the magnet. If you ever take the seal housing off watch for the small driveshaft, it looks easy to lose.

684 orchard special tach drive

Walnut1

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JimB2

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Walnut1

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