1957 Johnson Javelin regularly bangs at high speed.

Hi, guys!

I just started working on a 1957 35HP Johnson Javelin (RJE-19). I bought the boat a couple of years ago and finally started getting it operational this summer. This is my first boat and outboard, but I am pretty handy working on mowers and other small engines.

I took the boat out for the first time a few weeks ago, and I noticed that it would regularly make a banging noise, and bounce up a bit, when I gave it around 1/3 throttle. I noticed that when shifted into forward, the cable wasn't fully pulling the gear shift knob on the motor forward. I adjusted the cable from the Johnson Shipmaster shift and throttle controller so that the shift knob on the engine was completely engaged in forward. This helped some, and I could give the engine a little more than half throttle before it would start the banging again.

The banging is quite regular, about two seconds between bangs at first, and the interval between bangs decreases as I give more throttle. I don't believe it to be a misfire, it seems too regular for that. At half throttle or lower, the engine runs very smooth.

I recently replaced all of the ignition components: two new coils, condensers, point sets, spark plug wires and spark plugs. I also took the carb apart, cleaned it, and installed a new needle and seat, as well as replacing all of the gaskets. Gas to oil is 25:1. I haven't done anything to the bottom end yet.

I figure the problem is that the forward gear is disengaging, but I'm not familiar with how the gearcase works in these old outboards. Is there a shift fork that could be bent, or something else that I could repair? Any other ideas?

Thanks!
Colin.

Re: 1957 Johnson Javelin regularly bangs at high speed.

First thing I would do is remove the plug from the bottom of the lower and look for metal chunks. Also check for water intrusion.

Sounds to me like a problem with the gears which is not a good thing.

Re: 1957 Johnson Javelin regularly bangs at high speed.

The problem is that the ears on the clutch dog are worn, and possibly the precisely machined edges of the forward gear. I would replace them as a set. This failure is usually caused by improper shifting, but can also be due to worn shift linkages or improper adjustment. The shifter needs to be snapped into gear in a sure/swift movement. Gently easing it into gear causes the dog and gear to grind against one another, eventually leading to failure. It is usually noticed at higher RPMS as you noticed. If you need help with a part number, PM me.

Post a pic if you can of the Javelin, I collect them and love checking others out.

Re: 1957 Johnson Javelin regularly bangs at high speed.

No doubt about it, the symptoms are classic and well known. As High Trim said, the clutch dog is worn out. Probably forward gear too. Yes, improper shifting is a killer. So is wornout, or mis-adjusted linkages or controls. And of course, just plain wear from use. When you fix it, you have to check everything related, or you will just have it happen again.

Re: 1957 Johnson Javelin regularly bangs at high speed.

Thanks for the help, guys!

I took the bottom end apart last night and cleaned all of the "oil" out. Indeed, the ears on the clutch dog and the ears on forward and reverse gears are both with quite rounded corners. It looks like someone may have switched the gears before, as reverse looked a lot worse than forward.

I was thinking, as a last ditch effort, to weld on some filler metal and machine a sharp corner back onto it again. Has anyone been able to do this with success before? I have a family member coming in from Texas (to little, old northeast Ohio) that is expecting a boat trip, so I can't really wait on parts to arrive and get it fixed in time for that. :redface:

In the meantime, I will start looking for a clutch dog and gear set. I'll also post up some pictures when I get home tonight.

Re: 1957 Johnson Javelin regularly bangs at high speed.

I have a buddy that worked in a machine shop and he milled new edges on the dog and gears on his motor......About a dozen times. Yes it works for awhile, but does not last because the case (hardened surface) is gone. So he just did it again....and again.

Re: 1957 Johnson Javelin regularly bangs at high speed.

Post a wanted ad at aomci.org in the webvertize. There are plenty of guys that will be able to help you out.

As Frank stated, it will help, temporarily, if you are a real good machinist, but is just a temporary fix. Much easier to find a good set and seal the gearcase and be done with it in my humble opinion.