Autohelm Parts

Offered here are explanations of the situations regarding spare parts for some Autohelm products.

Original (Mark I) Wheel Drive

Parts (including belts) are no longer available from the manufacturer for what is now called the Mark I Wheel Drive (this is the black version made under the Autohelm or Raytheon names). The newer Mark II version is grey, and has no spares common to the Mark I. We still have a few odds-and-ends, as well as a small collection of discarded units from which we are sometimes able to obtain a necessary part to effect a repair.

Here is a list of some of the Wheel Drive parts, with explanations of their availability.

Roll Pin

We have found a source for the Roll Pins used with the Drive Eccentric Assembly, as replacing one or more sheared Roll Pins restores operation to about 80-90% of the units we service. The typical symptom of one or more sheared Roll Pins is the failure of the Drive Lever to remain engaged under load, or to even swing back-and-forth with little resistance.


While we are sometimes asked about a replacement Belt, our experience has been that even when these belts were available, it was actually rare for a spare to be needed. If a Wheel Drive is eating belts, it may be an indication of a more basic problem, such as improper tensioning. We’ve found that in most cases the Adjustment Eccentric Assembly can be set to its loosest position for optimum tension. This is the normally-capped adjustment point opposite the motor from the Drive Eccentric Assembly (which has the Drive Lever attached). To adjust, the Protection Cap is removed, the Adjustment Locking Nut is loosened (snap-ring pliers work well) and a hex key is used to rotate the Adjustment Eccentric Assembly until the desired tension is applied, then the Adjustment Locking Nut is snugged down (not too tight - we’ve seen these crack apart, in which case a 4mm stainless nut can substitute). Internally, this works just like the Drive Eccentric Assembly, except that it has no external lever for rapid adjustment.

We have been able to locate a belt manufacturer who will make more belts, however there are two key reasons we haven’t had this done. First is the 10-piece order minimum, and second is that we’re not 100% sure the new belt will work properly. While 10 pieces doesn’t sound too bad, we just don’t get much request for these. And our uncertainty about their suitability is not over the number of teeth, pitch, thickness, length or width; rather, it is that we don’t know if the material will have a similar coefficient of friction. The Drive Ring is driven by friction from the belt; too little friction will allow unwanted slippage when engaged, whereas too much friction will not allow the slippage required when disengaged.

Drive Lever

The Drive Lever is simply no longer available. We have one cracked (and therefore unusable) sample we're keeping for the remote possibility that we might have some replacements fabricated. We have known cases of users fashioning their own lever, though typically of little resemblance to the original. Not that appearance is as important as function. This lever should allow full engagement and disengagement of the Drive Eccentric Assembly to be effective. Note that the factory Drive Lever is curved to accommodate the Gearbox during engagement.

Pinion Sprocket

The Pinion Sprocket, which is what transfers the Motor's movement to the Belt, is no longer available. We have a single piece saved for reference purposes only. However, it is very rare for one of these to need replacing.

Idler Roller Assembly

The Idler Roller Assembly (not officially a separate item) is actually part of the Back Mounting Plate Assembly — that is, it is part of the static ring that the Motor is attached to. While the Idler Roller Hub has been known to break in some cases, the best solution we've found is to save the broken parts and through-bolt them to the Back Mounting Plate Assembly using a stainless machine screw and lock-nut in place of the original thread-cutting screw.


The Gearbox is no longer available. The best solution for a bad Gearbox is probably to replace the entire Wheel Drive.


The Motor is perhaps the only part that is still available! Ask for Raymarine part number N012.

Wheel Drive

If your autopilot control electronics are in working order but the Wheel Drive is not, consider replacing the entire Wheel Drive. Note that the current Mark II Wheel Drive is electrically compatible with the older Wheel Pilot systems, though early Mark I Wheel Drives that used a hard-wired motor power cable (no disconnection at the drive end) will need to be adapted to the later style two-pin connector on the Motor Assembly (male on the drive side, female on the cable). This can be done without much difficulty in most cases. We can supply a solder-type connector to attach to the original motor power cable which then mates to the Mark II Wheel Drive. A Mark II Wheel Drive also includes a power cable with this connector already attached at the drive end, and bare wires at the opposite end (appropriate for connection to the later style below-deck Course Computers.

If you are interested in a part we did not cover above, it is likely no longer available.

If you would like to have us service your item, you may bring it by our store during business hours, or ship it to our address to the attention of the Service Department.

Copyright 2009 · The Offshore Store · PO Box 9480 · Seattle, WA  98109 · USA · Phone +1-206-632-3025 · FAX +1-206-632-0971