OMC Stern Drive U-joint type gearing??

[Lyndon]

I have a '73 IMP INCA with a 350 chevy and a omc stern drive. My question is their are 2 gears of effect that work in my opinion as a u joint when the motor is tilted up you can see the gears and one is connected to a shaft from the motor the other to a shaft on the upper gear unit. How do I replace those 2 gears and what caused them to become so worn, I just recently bought this boat and they were already in this condition. Any help appreciated.

 

[CharlesW]

Re: OMC Stern Drive U-joint type gearing??

Lyndon:<br />Those are called ball gears and some wear is normal. I have no idea how to replace them, but I don't think it was major operation. I'm pretty sure it required tearing down the outdrive which probably will take it out of the DIY category. Seems like OMC used lots of special tools.<br />One thing that is very important with the old OMC ball gear units is not running the outdrive in any sort of up position. Many people used to run them at idle in a slightly tilted position for shallow water. They then forget to put the oudrive down, destroy the ball gears and usually wreck the entire lower unit.<br />I had a V-8 Chevy OMC for 18 years that still had the original ball gears with very little wear on them when I sold it. I did NOT run the outdrive in a tilted position, period! I think that is the reason I never had any ball gear problems. Find yourself a mechanic that is familiar with the Older OMC's and keep him happy. They had their quirks, but like I said, mine lasted for 18 years and as far as I know might still be going. <br /><br />Charles

 

[davidedgar]

Re: OMC Stern Drive U-joint type gearing??

The gears that you describe in your "post" sound to me like they are the "pinion" gears and the wear is not a real problem. Broken teeth ARE a major problem.<br /><br />I have a 1988 IMP that came with a 460 cu.in. "King Cobra" engine and an OMC "King Cobra" stern drive. I have broken the teeth off the uppermost gear twice. To replace requires removal of the sterndrive and disassembly. It is a major job. <br /><br />I am in the process of replacing the stern drive with a Volvo-Penta SX Cobra stern drive. There are several advantages to this changeover. Volvo-Penta parts are readily available. Not so with OMC. Also, the V-P setup utilizes a completely different clutch configuration internal to the stern drive (cone vs.. dogged). Additionally, the bearing for the uppermost "pinion" gear appears to be about 3 times as large as the same bearing in the OMC stern drive. This should mean better wear and more logevity for the gear.

 

[CharlesW]

Re: OMC Stern Drive U-joint type gearing??

The 1988 and the 1973 seem to share only the OMC name. Lyndon's ball gears are actually outside of the gearcase and totally exposed.<br /><br />Charles

 

[dick]

Re: OMC Stern Drive U-joint type gearing??

If you have more then 2/3 of the gears left leave them alone. If you have to replace them you need both the gears , seals on the drive side and the shield side, gear oil (you have to drain the upper part of the drive and the oil in the intermediate shield ) new nuts that hold the ball gears on and plugs that cover the nuts.Also if you havn't got one yet get a manual , it will walk you through the procedure.It's not to bad of a job if you are up to it.<br />What causes them to wear is easy , running the boat. They do wear faster because people will use the tilt as a trim and not have the drive all the way down while runng the boat. Those drives have to be all the way down when running or the gears aren't properly alligned.