Cummins/Onan — Aligning Generator with Engine
Adjustments · Generator-to-engine coupling
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DFHA, Cummins/Onan DFHB, Cummins/Onan DFHC, Cummins/Onan DFHD, Cummins/Onan QST30 engine
Before you start
- Accidental starting during this procedure presents a hazard of severe personal injury or death; disconnect negative battery cable first
Procedure
- Fasten a dial indicator to the generator shaft or cooling fan with the point on the capscrew head or drive disc flat.
- Bar the engine over clockwise one revolution; record the total indicator reading (T.I.R.).
- Measure distance from generator shaft center to indicator point and from flex discs to mounting bolt center.
- Compute shim change: multiply distance ratio by one half the T.I.R.
- Keep T.I.R. not more than .001 inch for each inch of radius.
- If axial runout is excessive, rotate drive discs 180 degrees (or 30/60/90 degrees) and retorque.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- T.I.R. should not exceed .001 in per inch of radius
- Example SAE 18 disc coupling distance 10.7 in
Full service-parts list: Cummins/Onan DFHA →, Cummins/Onan DFHB →, Cummins/Onan DFHC →, Cummins/Onan DFHD →
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.