William Wynne

Starter Brackets for Front Starter System

These precision made steel Brackets mount the Subaru Starter in a new, lower position, making the Front Starter installation aerodynamically cleaner. The Brackets, Part No. FS-4, are made of 4130 steel and the studs are made from NAS aircraft hardware. The Mounting Brackets also come with an aluminum Link Plate, which forms the third member of the very rigid mount. Altogether, these Brackets weigh just under a pound. This new Bracket design is a dramatic improvement over the original Front Starter style, which employed an angled aluminum bracket. The new design mounts the Starter lower, is lighter in weight, and is available at a lower cost. All hardware and instructions (reprinted below) also are included. These Brackets supersede all previous designs of Front Starter mounts.

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Installation Instructions for Front Starter Brackets

Thank you for buying a set of Starter Brackets, Part No. FS-4. Your purchase makes possible my further research and development on the Corvair. In this way, you’re investing in the future development and perfection of your chosen motor.

These notes are supplementary to my most current Conversion Manual. These Brackets are developed as part of the system that we use to convert aircraft motors. This system is outlined in the Conversion Manual. The parts alone, without the information contained in the Manual, will not allow you to develop as reliable an aircraft conversion. When I develop and market a part, it is fully flight tested, and designed to work in concert with the other parts in the conversion. I take into account the way that most people are capable of installing and operating the part. There’s a great deal of consideration that goes into these issues, and I urge you to utilize all the information in the Manual and the parts in the way that they are intended to be used. Of course, contact me at any time with any question you may have.

To be fair, everyone needs to understand that these are not certified parts, and it's not a certified motor. Experimental is not a misnomer; everything we do in this field is of increased risk. If anyone even suspects that they have a problem, E-MAIL OR CALL ME. If you have never worked with torque wrenches and precision fasteners, get help from an A&P. Let's all remember to use our heads and not take unnecessary risks. I have gone to great lengths to make these components as reliable and easy to install as possible within the bounds of affordability. I have personally flown all of these parts, because I have a low opinion of people who market aircraft parts without flying the parts themselves. I believe that each and every part I sell is the best solution to its respective aspect of converting a Corvair engine. Take your time and do good work. The system is proven and will reward you with the same type of reliable flight performance we have always had.

Front Starter Brackets

The Bracket with the 7/16" stud goes on the dipstick side of the engine. The one with the 3/8" stud is bolted on the other side. Each bracket is held down with two 1-3/4" x 5/16" bolts, which are enclosed. Each of these bolts has one stainless steel split lock washer under the head. They can be safety wired, but all the installations I have done have secured them with LocTite. Please note that my Top Covers are .125" thick. If you use a top cover with a different thickness, the bolts will not be of correct length, and the Starter will not mesh properly with the Ring Gear.

The Starter is installed by sliding it over the 7/16" stud. The main power terminal on the Starter will point nearly straight up. At this point in the installation, the Prop Hub and Ring Gear should be permanently mounted. When a Starter is engaged, the solenoid makes the Starter Nose Gear jump forward. You can simulate this by lightly prying the gear forward with a small screwdriver. This is the position it will move to when you turn the key. The Starter Gear has a shoulder on it which should not contact the Ring Gear. You’re looking for full tooth engagement only. Using washers, the Starter can be shimmed forward and backward on the 7/16" stud to get the desired engagement. Put the nut on and snug the Starter down when it’s shimmed properly.

With the Gear projected outward, and the Starter pivoting on the 7/16" stud, swing the Starter down until both Gears completely mesh. Take a 3/32" drill bit, and put it in the bottom of the valley between the two teeth on the Ring Gear with which the Starter Gear is meshing. You need this clearance to make the two engage each other smoothly. This is the basic position in which the Starter will stay.

The 3/4"x1/4" aluminum Bar forms a link between the 3/8" stud and the 7/16" upper mounting bolt on the Starter. This Bar comes with a punch mark on one end. Drill this punch mark to 3/8". Slide this Bar over the stud, and move it into a position where it covers the 7/16" hole in the upper Starter ear. As you did with the Starter, shim this Bar with washers to line it up. Put the 3/8" nut on, and snug it down. Temporarily put on a C-clamp pinching the Bar to the upper Starter ear. This will allow you to test crank the Starter and check its engagement.

Proper engagement results when the Starter cleanly engages the Ring Gear and cranks smoothly without grinding sounds or excessive stress. This is a common sense thing - you’re looking for it to sound like starting a car. If you don’t have the right sound, make a slight adjustment and re-clamp the Bar. Please note that you should have the engine assembled and the spark plugs in. This test should put a load on the Starter.

When you’re satisfied with the engagement, carefully remove the C-clamp without disturbing the setup. Reach through the Starter ear and mark the Bar with a transfer punch. Remove it and drill it to 7/16". Install it using the AN-7 bolt and nut provided. Torque everything properly, and re-check its operation. With a little care, virtually every person gets it right the first time. If you’re not happy, make another aluminum bar (it’s 6061 T-6). Do good work and get it right. You’ll be happy you took the time to do so.

A common question is, “Why don’t you drill the bar for me?” There are variations in the deck height of blocks the thickness of gaskets and the exact position of the studs on the Brackets that preclude me from having one set length that would work for everybody. Keep the big picture in mind. You’re building an entire plane. I’m sure you’re qualified to make a bracket with two holes in it.

Tail Bracket

I’ve recently added the following change to further strengthen the Front Starter Installation. Over years of service, I’ve noted that two customers’ installations had broken the 7/16” ear on the starter. This was caused by the engine kicking back on start up. In normal operation, this does not occur, and the starter installation is very reliable. However, one starter was broken when the customer had the engine mis-timed on startup, with the ignition timing excessively advanced. Similarly, another ear was cracked when the engine was started after a tune up, but before the builder had a chance to put a timing light on it. I’d had kickbacks before on starters, and didn’t have a problem. However, all of my original test starters were OEM Subaru starters. The Subaru starters are directly interchangeable with the current light weight starter, but were several pounds heavier, an undesirable feature in aircraft.

The final cure, to ensure that your light weight starter will not crack the 7/16” ear even if it does kick back, is to add the very small and light weight Tail Bracket. The raw material for this tail bracket is supplied with your starter. This small aluminum angle is drilled in two places by the customer. After checking the installation with the original directions on the reverse, remove the lower bolt from the starter motor. This is the approximately 1/4” bolt that is 5” long. Lay the aluminum angle so that one leg is flat on top of the Top Cover, and the other vertical leg is up against the hole for the starter motor bolt. The tail bracket will be held down by the top cover bolt immediately behind the 3/8” starter bracket. Carefully mark and then drill the two holes in the bracket. The hole for the top cover bolt will be 5/16” and the hole for the starter bolt will be 15/64”. Many builders find the easiest way to mark the motor bolt’s location is to insert a long drill past the Ring Gear through the threaded hole and scribe the aluminum bracket. After it is drilled and deburred, it can be permanently installed. With this bracket in place, the front starter will be an extremely rigid installation that will give you years of trouble free service.

Like the aluminum link, the exact dimension of this bracket will vary with each individual installation. Therefore, it is not possible for me to drill the bracket for you. Again, keep in mind that the description makes the job sound harder than it is. In the construction of your aircraft you’ll face a thousand tasks more difficult than this. Go to the shop with the directions in hand, study the problem firsthand and you’ll see it’s a fairly easy installation. Call or e-mail me if you have any difficulty whatsoever.

Thank you. Happy learning, building and flying.