Hello All

I only know of 3 current shops for the 5th bearing ...let me know if I'm missing anyone

William Wynne/SPA

Azalea Aviation

and Roy of Roy's Garage

Has Roy gone out of business? The web site I had appears to no longer work

we all love and promote the specific one we choose over the others, I understand that.

I have yet to choose..... I am not looking for specific recommendations but  more interested in the differences in how things are done between the different suppliers, technically or mechanically etc

If they all work equally well then it gets down to who is easier to work with, delivery time, and of course price

Just looking for some info to make a decision

thanks for any input


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I am surprised that no one has offered there opinion on this yet as it is usually a somewhat hot topic with people having a very definite opinion on which is best so I will share what I THINK I know. I have not seen any of the three designs in person, I have spoken to William on the phone several years ago and had e-mail contact with Dan (SPA) during that same time period. I am working on my 5th bearing which is similar to the SPA bearing (hopefully sucessfully) which is for my own use and will not be offered for sale so I have nothing to gain from recommending any particular bearing.

As we know there is not a good relationship between the three producers of the available bearings and some are more vocal than others which is a turn off for many. The first on your list has been around the longest and has provided the most available documentation for the corvair, product availability and delivery times have been poor for long periods, I think this has been largley cured with business maturity and stock and delivery control being handled by SPA. Dan's fifth bearing, (especially the gen 1) I think is more in line visually with the corvair look. I know little about the second suppliers bearing, Some swear by it but it has had a bad reputation (deserved or not) in running it's business. (businesses) The bearing they produce looks very aerospace-ish and I see no reason it would not work well. The third supplier has always apparently had long delivery times as each was individually machined. 

For me if I was buying I would still choose the first supplier as I have been provided with the most info on the corvair thru build manuals and dvd's which guided me in the direction I needed to go and the original fifth bearing could be installed by me in the field.With the gen 2 bearing the playing field is somewhat more level between the first and second suppliers as I beleive both of those products have to be installed by the manufacturers. The third I never considered because of the delivery times. All things considered and personalities aside I still think that WW and SPA provides the most information and support for the corvair. Haven't looked at cost lately so I have no comparison there.

Hello Dan

Thanks for your reply and in sites !

I agree I was expecting this to run away from my intentions, which is just to be a question on the merits of the mechanical systems of the various styles and why, and not get into the personalities involved.

some of that other stuff might be involved in the ultimate decision..just trying to keep it on the technical merits of each style



I think an important aspect of deciding should be actual performance of the various products. You say, "If they all work equally well then it gets down to who is easier to work with,..." You should inform yourself if they do in fact all work equally well. While informing yourself make sure that you are comparing "apples to apples". Any installation where the installer did not do so in compliance with the manufacturer's instructions should be disregarded. Yes, this is experimental aviation and you are free to do as you wish but, any deviation from a standard installation may have effects that may not exist otherwise and change the products reliability. Do your homework. Look for those that have installed the products. Talk to them if able. Go to a workshop that WW and Azalea give. There you will be able to get "hands on" with the product.

I have done some of these things myself. I have attended one of WW "Corvair Colleges". Also watched as engines were assembled and run at two of Zenith's gatherings they have in September. There were parts on display and available to be handled and inspected. Dan and WW were there and answering any and all questions. There were planes with corvair engines there and their owners were there and glad to answer questions. Some of these owner/operators have a decent number of hours on the product. In fact, at the Corvair College I attended one of the owners gave me a ride in their plane.

I have not attended any of Azalea's workshops. I have explored their website and watch their Facebook page, but that only serves to briefly familiarize me with their product. From what I see they seem to be making inroads in this market and increasing their number of installations.

I know almost nothing about Roy's product.

The gist of what I am getting is, reliability, this should be your prime motivator as to which way to go. Opinions, personalities, product aesthetics and any other aspect that doesn't have anything to do with whether or not the engine keeps running means little. The only way for YOU to know this is for YOU to find it out.

Good luck.

Keep building.


Hello Ernie

thanks for your input....


Hi John,

I tend to go with what has the longest proven track record.  I believe the majority of flying corvairs with fifth bearings are using the SPA version.  I have the SPA Fifth bearing on my corvair and have had zero issues with it.  I started with a 2.7L corvair and then upgraded to a 3.3L corvair.  I used the same bearing housing for my new build after SPA replaced the bearing shells and the bearing itself.  I was amazed with how little wear the original bearing had after 502 hours in my 2.7L corvair.  I now have 160 trouble free hours on my 3.3L.  Mind you that I don't baby my corvair. I often joke that I only have two throttle settings on my corvair...idle and wide open.  The funny part is its not a joke...once the throttle goes to WOT for takeoff  that's where it stays until I throttle back for landing! 

Anyway, I've heard the spiel about why the other two bearing designs available are better and why some people go with them.  I don't have the qualifications to prove or disprove their claims, but I can say that for such a simple and elegant design the SPA bearing simply works and works well.  Maybe getting the case, crank, and fifth bearing all aligned to within a micron  or nanometer of each other is important.  Maybe having the thrust bearing surface moved to the front of the engine is better. I don't know, but after 660 plus hours of operating my corvair it looks like thousandths of an inch and stock thrust bearing surface works pretty darn good, too.

The features that attracted me to the SPA design are it's simple straightforward installation, the entire installation can be done by me without having to go through the time and expense of sending my case to be modified, the price is more than reasonable for what you get, and the manufacturers support is top notch. 

Good luck and happy building,



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