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Post War Gemmer Steering Gear

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offshorespars
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Post War Gemmer Steering Gear

Post by offshorespars » Tue Jan 24, 2012 8:09 am

I have had a problem with the steering wheel locking during a turn. I removed the steering gear box, column, etc. but did not try rotating rotating the steering shaft so I have no idea if it locked prior to my disassembly, degreasing, etc. All components appear to be good shape. During reassembly I find the gears locking with the problem being the gear in the photo. There is some brazing on the edges of the gear that prevent the gear from rotating 360d. The brazing looks well worn. First, is the brazing meant to be there? If so, should I apply more brazing where it seems to be worn? There is no question that the brazing stops the gear from rotating once it reaches a certain position and that locks the steering shaft.

Thanks for the help.
Mike
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1978 30' CC Sportsman
1948 22' CC Sportsman

tph
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Post by tph » Tue Jan 24, 2012 9:18 am

Mike,
I had a fellow come in the shop last week with his
disassembled steering gear. It had the braising
just like yours. We took one of my spare boxes apart
and it didn't have the braised spots on it. I think
it's definitely a stop of some kind.
tom
vintage marine

boats in the shop:
1946 chris craft 17' deluxe 17-R-061
1946 chris craft 17' deluxe 17-R-176
1947 chris craft 17' deluxe 17-R 537
1948 Shepard 22'

Trick414
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Post by Trick414 » Tue Jan 24, 2012 12:54 pm

I had the same question when I was doing mine.

I spent a bunch of hours researching all around the net (and I'm a computer dork that can usually find anything).

I couldn't get any answers on why this was done.

One side had popped off and was in the bottom of the box. The other side was popped free as you can see in the photo below.

I can only assume that the gear was welded to give a consistent feel across the movement range. I did some experiments with it fixed in place (like the welds held it), backed off on the adjusting nut, and played with the number of gaskets. It did give a more consistent feel but I figured the welds would just give way at some point again in the future.

I finally just put it back together as is. I did notice a spot in the rotation of the steering wheel where it gets quite a bit easier. Once I hooked the steering box up to the rudder hardware, the slight extra drag calmed it down some.


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offshorespars
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Post by offshorespars » Tue Jan 24, 2012 1:47 pm

Guys:

Great help! The problem which was not immediately noticable on my gear but I could see on trick 414's photo is that the brazing is done to make the gear stationary. When the brazing broke away the remaining brazing on the gear allows the gear to spin perhaps 300 degrees and then stops when the brazing reaches binds against the walls of the casting. In that position the gears do not mesh properly and bind. I imagine I will find the broken brazing pieces in the bottom of the gallon can of carburetor cleaner which worked wonders on the thick gear box grease. Now out to the shop for some brazing work. Thanks again.
Mike
1978 30' CC Sportsman
1948 22' CC Sportsman

Trick414
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Post by Trick414 » Tue Jan 24, 2012 3:23 pm

Here's my best theory:

In the 1st picture below you can see the steering stop bar. That stops the steering arm from moving backward so far that it punches out the back of the boat. You can see in the second picture that if the arm continued to move toward the stern the arm on the rudder box would hit the transom.

In my boat, the steering arm moving aft causes the rudder to pivot and produce a left turn. The amount of left turn, then, is limited by this arrangment.

There is no similar obstruction for a right turn. In fact, when we initially put it back together, we centered the steering box exactly and put the steering arm on. This resulted in the limited left turn, but the right turn would only stop when the steering box hit the internal limit of its movement. At that point the rudder would be at a 90 degree or so angle to the boat, whereas the left turn movement only resulted in about 45 degrees or so.

So, we pulled the arm and turned the wheel until such a point that when we reconnected the steering arm we were able to have the rudder only move the same distance off center in both directions. The left turn, as mentioned, was stopped by the steering block bolt, and the right turn was stopped by the internal limit of the box.

Now, going back to the steering box. As I mentioned I did some experiments with the box and the gear. When the gear is allowed to rotate freely (as on mine with the broken brazings), the box rotates smoothly in the "middle" rotation. At the extreme far left and right turns it starts to bind up because of the angle on the sector shaft gear. I say "bind up". It rotates quite freely, but there is a definite difference in force required to move it.

If you seize the gear, like the brazings originally did, the turning force stays more consistent. The box is "binding" all the way across it's turning ability. Again, it's not completely bound up, just that there is not nearly the noticeable difference when you get to the extreme ends.

So, my theory assumes that the factory "pre-turned" the steering box like I did so that the right turn was stopped by the internal lock of the box and the left turn was stopped by the blocking bolt.

However, because the box was "pre-turned" toward one end of the box the steering feel wasn't consistent. Turning left was much easier than turning right. So, they brazed the gear so that the feel was more consistent.

The sector shaft rotates so slowly that having it brazed wasn't a worry. There's no real wear going on there. It rides just fine when it is seized by the brazing.

In the pickup trucks that used this particular box (old Ford's if I recall correctly from my searches), the binding at the ends probably wasn't a problem. The weight and friction of the tires and steering components masked the inconsistent feel of the turning force.

In our boats, though, the effort required to move the steering components is significantly less, so the inconsistent feel isn't masked.

I left mine "unbrazed" rather than fix it. I used the adjusting nut and gaskets to pre-load the box so it feels pretty consistent. However, the factory decided not to do that for some reason. It could be that my steering effort is now much harder than it would have been from the factory. Maybe they decided their solution gave a consistent feel without requiring the box to be pre-loaded as much as I had to. It feels ok to me, but I'll know more when I put it in the water for some tests this weekend.


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1951 Riviera 18' KLC
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