Make Your Own Strut Bushings

How-to Article ...

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Learn how to make your own strut bushings...









During my latest build I got to the point of installing the flex cable in the boat and realized I was out of strut bushings! Needless to say I wasn't really happy because ordering new ones would set me back about a week or so and I was on a tight schedule. I started looking through my parts and discovered that I had what I needed to make my own so I decided to take a few pictures of the process and share it with our readers.

The bushing type bearings, commonly known as "Speedmaster" bearings are really nothing more than a piece of 9/32" brass tubing. This tubing can be purchased at most hobby shops. A common brand is K&S tubing. You can usually purchase this tubing in 12 and 36 inch lengths. You can easily make a dozen or so bushings out of a 36" piece of tubing, which will cost only a few dollars ($3-$5 or so).

For those who are not so familiar with these bearings (bushings) they are used with welded cable setups. In this kind of setup the flex cable is welded to the prop shaft and held onto the engine by a compressing collet at the engine's output shaft. Since the flex cable and prop shaft are one piece, there is no use of ferules. The stuffing tube that holds the flex cable runs all the way from the inside of the boat to the back of the strut or drive. Since the stuffing tube is 5/16" outside diameter (O.D.) it fits perfectly in struts and drives designed for this purpose. The inside diameter (I.D.) of the stuffing tube is 9/32". Prop shafts for gas boats are typically 1/4" O.D. so for this reason we need some sort of bushing in the stuffing tube to properly support the prop shaft. This is where the 9/32" brass bushing comes in. It is 9/32" O.D. which fits snuggly in the stuffing tube and its I.D. is 1/4", perfect to support the prop shaft. The bushing is inserted in the stuffing tube at the propeller end of the tube and should rotate freely inside the stuffing tube.

There are two types of bushings sold on the market. The first is the "flared end" bushing and the second is made with a short ring soldered to the end instead of flaring. Both types work equally well and I will demonstrate how to make each type in this article.


Here is what you will need to make your bushings:

  • 9/32" K&S brass tubing
  • tubing cutter
  • flaring tool (if doing the flared end bushings)
  • small torch and solder (for ring type bushings)
  • drill and drill bits
  • a file and some sanding paper
  • an Inner-Outer reamer (optional but handy)
  • a good pair of gloves will also come in handy
* if you do not have a flaring tool, do a search on Ebay...you can find some for under $20. The same goes for the Inner-Outer reamer.

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The first step is to setup your length of tubing in the flaring tool and do the actual flare. The sole purpose of the flare is to prevent the bushing from creeping inside the stuffing tube so it doesn't have to be very wide.

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When you are satisfied with the flare, remove the tubing from the tool, measure and mark a line where you want to cut it. I make my bushings 2 1/8" to 2 3/8" long, but that is up to you and dependant on your setup. Cut it to length with the tubing cutter and deburr the cut end with the reamer.

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The next step is to cross-drill the bushing. These holes will help keep grease in the bushing to lubricate the prop shaft. I use 7/64" or 1/8" drill bits for this. The holes can be drilled using a hand drill or press drill depending on what you have at available to you. It really doesn't have to be accurate they are just for lubrication. On some bearings I drill all the holes lined up, on others I do them at 90 degrees from one another. Again just do whatever you prefer. I have not noticed any gains one way or another.

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With the holes cross-driller, insert a 1/4" drill bit in your drill and run it through the bushing. Now is a good time to wear those gloves, as you will notice that the cross-drilling left a lot of sharp burrs. Use a file to lightly sand the bushing as you turn it with the drill. This is just to remove the burrs. The use a piece of sand paper (220-400 grit) to sand the bushing while turning it at high speed on the drill. Once this is done you can hold the bushing with your gloved hand and run the 1/4" drill bit through it several times to make sure the inside is deburred and clean of obstructions.

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This is what the finished product should look like. You will want to test fit it inside a piece of 5/16" tubing (stuffing tube) to make sure it rotates freely. If it doesn't, put it back on the drill and sand a little more with the sanding paper. Test fit again. You want to test fit it on a prop shaft also. Again, it must rotate freely. Not excessively loose, but just freely. If it doesn't, run the 1/4" drill bit through it some more until you get a good fit on the prop shaft.

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To make bushings without a flaring tool you will follow the same basic steps with the exception of the flaring process. You start with a 9/32" tubing cut to length for the busing. You will also need some 5/16" tubing to make the retaining ring. Cut a piece of 5/16" tubing about 1/8" long. You will have to deburr it and get it to fit over one end of your bushing.

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The next step is to solder the ring to the busing. Use a small torch and good quality solder. I like to use Stay Brite silver solder and flux for this. Try not to overheat the bushing. Use only as much heat as is required to get the solder to flow.

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Once the ring is soldered and the bushing has cooled, use deburr the ends. Cross-drill and finish up as explained earlier. Then proceed to test fitting in stuffing tube and on prop shaft.

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Happy Boating!

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marc's Avatar
marc replied the topic: #14396 7 years 11 months ago
Icman69 wrote:

Yea I make my own it is easy and quick and you can make them your needed length if you have a different setup. The only thing I do differently is I put a 1/4 wood dowel inside them when I am drilling the holes come out pretty clean and no chance of bending the tubing.


That's a very good idea using the dowel inside.
Icman69's Avatar
Icman69 replied the topic: #14378 7 years 11 months ago
Yea I make my own it is easy and quick and you can make them your needed length if you have a different setup. The only thing I do differently is I put a 1/4 wood dowel inside them when I am drilling the holes come out pretty clean and no chance of bending the tubing.

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