William Wynne

Machined Ring Gear For Use With Low Profile Front Starter Kit

My Ring Gear is a modified Ford Taurus flex plate. The Ford part was selected because it offers a unique combination of light weight, stiffness, small diameter and correct offset. Each Ring Gear, Part No. FS-7, starts out as a brand new part. The center is precision machined to mate with the Hub, and it is drilled for six AN-3 bolts to mount it. When you receive it, the Ring Gear is ready to be bolted on the motor with no further work required to this part. Although it can be further balanced, I checked 20 of them and found the manufacturer's balance to be extremely good. My earliest front starters used Nissan Sentra flex plates. At 2 pounds, 12.8 ounces, the Ford Ring Gear is significantly lighter and available at a dramatically lower cost. This new Ring Gear supersedes all previous recommendations, and is now the new standard for all Front Starter Systems.

The $99 price includes instructions (reprinted below) and shipping in the U.S. I accept payment by check or money order in U.S. dollars payable to William Wynne, 5000-18 HWY 17 #247, Orange Park, FL 32003, or credit cards via PayPal by clicking below:

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Thank you for your order.

Instructions for Ring Gear Installation –
Please Read And Follow Entire Instruction Sheet, i.e. to The End

Thank you for buying a Ring Gear. 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. This Ring Gear is 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.

Ring Gear Instructions - For Use With Puck and Black Hub;
(Gold Hub Instructions Reprinted Below)

This Ring Gear is completely machined and ready to bolt on to your motor. However, I suggest that you first clean it and paint it the color of your choice. The Ring Gear by itself will get a light coating of rust without some type of protection.

This Ring Gear’s original application was a Ford Taurus. It was selected from countless other ring gears by virtue of having the right combination of weight, stiffness, offset and availability. Although we had previously used Nissan ring gears, these Ford Ring Gears are the last word in Front Starter Ring Gears, and supersede all previous designs. All of the engines I have built in the shop since 2002, and all of my personal engines, all have this Ring Gear.

It may not be obvious at first glance, but the Ring Gear is bolted on the propeller side of the Puck. The original Puck has square corners on the flange faces. All Pucks that are compatible with this Ring Gear will have a heavily radiused front face. This includes all the Pucks I’ve sold since 2002. If you’re making your own puck, make sure that you’re working from the drawing dated 2003 showing the radius. Other than this detail, the Puck has not changed since 1996.

The Ring Gear is bolted to the Puck using appropriate length AN-3 bolts. These will either be -6 or -7, depending on whether you’re using a Front Alternator Pulley. To ensure that your Ring Gear is concentric with the crankshaft, and is not interfering with the fit between the Prop Hub and the Puck, follow this assembly procedure: Put the Prop Hub on the bench, propeller side down, and slide the Ring Gear over the 3" boss on the back of the Prop Hub. The offset on the Ring Gear will face forward, toward the propeller. Then, install the Puck into the back of the Prop Hub. When these are completely mated, it will then allow you to install the AN-3 bolts, and the Ring Gear will be held concentric to the assembly.

Thank you. Happy learning, building and flying.

Gold Prop Hub Instructions (Reprint)

The Gold Hub is a highly refined version of our earlier work. The Gold Hub takes the place of three prior parts: The Black Hub, Puck and Front Alternator Pulley. The Gold Hub uses the same Hybrid Studs, Safety Shaft and Ring Gear as the Black Hub. However, the Gold Hub uses different nuts on the Hybrid Studs. The new nuts, which are included, are MS21042-6. Even though they’re smaller, these MS nuts are stronger than traditional AN nuts. They’re torqued with a 7/16” socket instead of the usual 9/16”. The Gold Hubs are also supplied with the AN3-10A bolts that hold the Ring Gear to the Gold Hub. These bolts must be installed with the heads close to the engine and the supplied nuts close to the propeller. The NAS679-A3 stamped steel nuts have a particular shape that fits the radius on the Hub. Torque these to 7 to 10 foot pounds.

We inspected a Hybrid Stud/Prop Hub installation several years ago where excessive Loctite had been used and was preventing the Prop Hub from seating completely flush with the flange. Make sure that you clean off the excess Loctite very carefully after installing the Hybrid Studs. When installing the Prop Hub, I torque the stud nuts to 25 foot pounds, then torque the Safety Shaft nut to 150 on steel Safety Shafts, 100 foot pounds on aluminum Safety Shafts. I then go back and do the Stud nuts at 25 again. The best way to restrain the engine when torquing the Safety Shaft nut is a carefully placed wooden block between the crank throw and the case near cylinders 5 or 6. This is why I put the Top Cover on the engine only after the Prop Hub is installed.

After it’s installed, you must check the Hub to ensure it’s running true. This can be done with a cheap dial indicator measuring the run-out on the end of the Hub. The Hub itself is CNC-manufactured so accurately that tools available to typical homebuilders could never detect a flaw in it. What you’re looking for is confirmation that your crank flange did not have a burr on it or excess Loctite from Hybrid Studs. The prototype installation showed less than .001” run out measured at the edge of the prop flange.

Gold Hubs all have the SAE-1 propeller flange pattern. The correct prop bolt diameter is 3/8”. The length of these bolts will be sized to the thickness of your individual propeller. The appropriate nut for these bolts is an AN363-624. When installed on our Nosebowl, this nut can easily be accessed by reaching through the pilot’s side air inlet.

This installation should be checked for torque frequently during the test phases of the engine. Again, I have never found a properly installed Prop Hub to ever lose its torque. But vigilance pays, and that's what flight test periods are all about. If you have any doubt at all or questions about the installation, call me. I’ll be glad to spend the time to get your questions thoroughly answered. Remember, safety is paramount. By choosing a Gold Hub, you’re taking advantage of our years of flight experience which went into the design of this highly evolved part. Thank you for your purchase and congratulations on your good judgment.

NOTE: In the past 10 years, we have machined several hundred Ring Gears. The total amount of flight time on the Taurus style Ring Gear is in the thousands of hours. About a half dozen Ring Gears have cracked through one of the four spokes in operation. The propagation is slow. The issue was discovered in annual inspections. The part has never experienced a sudden failure and evidently is not prone to it, however more frequent inspections would be prudent, good risk management. As manufactured, these openings are stamped, leaving sharp edges that are stress risers. For the past several years we’ve recommended that builders take the time to debur and smooth all the edges on the four openings on both sides with 100 through 400 grit sandpaper. Ring Gears with polished edges have been operated for hundreds of hours without issue. Having an out of balance or track spinner, or a propeller that was not dynamically balanced, has shown to be a large contributing factor to cracking. Simply using a much heavier flywheel is not an effective solution, as it puts additional load on the crankshaft and is no guarantee that it will not resonate. Reducing stress risers, proper assembly and balancing, combined with including the Ring Gear on inspections is the engineering approach to risk management.