Paging Randall re: Judson Supercharger Vanes

[karls59tr]

In one of your previous posts on the original Judson supercharger you mentioned that there was an issue with the cooling vanes where pieces would break off and fall into the engine once the vanes wore down. You said the vanes were made from "phenolic linen" I believe. Why was that material used and what kind of material do you suppose they use for the vanes on the newer Judsons?

 

[TR3driver]

How they arrived at that material, I don't know. But from having spent some time trying to find a better material, I suspect it was simply the best one available at the time. The vanes have to be dimensionally stable (can't grow or shrink with changes in temperature, pressure or humidity), and have a long life with very minimal lubrication. They also have to handle impact well without chipping or breaking, and not tear up the housing they run in.

Oddly enough, I happened to have a relatively recent air impact gun apart the other day. It not only has an air motor that works on basically the same principle (in reverse of course, instead of turning the crank to move air, it uses air pressure to turn the crank); but the vanes in it appeared to be exactly the same material!

As far as I know, no one has made new Judson-type superchargers in a long time (like 40 years or more). Rootes-type blowers are better in almost every way and are now readily available in sizes that suit a 2 liter motor. (For example, the TR2-4 blower kit from Moss uses a Rootes-type blower made by Eaton I believe.) However, I found a web site that purports to be by the Judson company:
https://www.judsoncompany.com
It talks about having some new parts made to the original specs, but hasn't been updated since 2008 (which I suspect means it never happened).

One of the users on the Team.Net Judson mail list posted back in 2003 that he was going to try Torlon vane material. Unfortunately I seem to have missed his report on how well it worked, and the archives don't work. Just for kicks, though, I looked up Torlon sheet. $652 for a square foot! (which wouldn't be enough to redo a TR3 Judson)
https://www.professionalplastics.com/TORLON4203

 

[karls59tr]

Thanks for the info. I know someone with a Judson on his 3 and apparently a piece of "metal" got into the valve seat area of a cylinder and destroyed the valves and the piston. Remembering your first post I thought it was likely a piece of vane. How hard would it be to access the vanes in the supercharger to see what kind of shape they are in?

 

[angelfj1]

I grew up near Judson's plant. Later in high school, me and my friends would hang out there and watch hot rodders attach Judsons to their cars right in the dirt parking lot. I later met some of the guys who worked there. The original designs were made just after WWII and at that time there were probably few non metallic materials to fit the application.

 

[TR3driver]

Thanks for the info. I know someone with a Judson on his 3 and apparently a piece of "metal" got into the valve seat area of a cylinder and destroyed the valves and the piston. Remembering your first post I thought it was likely a piece of vane. How hard would it be to access the vanes in the supercharger to see what kind of shape they are in?

If the cylinder head is already off, then inspecting the vanes should be pretty easy, I think. But I still haven't gotten around to disassembling mine, so I'm just guessing. Here's the service instructions for the VW version; I'm guessing the TR should be similar:
https://docs.google.com/open?id=0B2H2NJt34OffNDkxMDY3NDItYTM4OC00MGQzLWIwYzctNmY3MGViOWYxYzAy

And here is a photo from a friend, where you can see the bolts to remove and one of the holes for the forcing screws:

 

[MadMarx]

Oh, I had seen once a Judson on a TR4 in action. Very noisy. From what I remember the power output is not comparable with the noise.
A simple Weber with hot cam has more punch.

Chris