McCulloch Worm Gear Question

[Dave/Green Bay]

I have a Model 37 McCulloch supercharger and am in the process of rebuilding. We have found that the bronze worm gear is worn on the teeth. We have tried many gear manufactures in Wisconsin Michigan and Illinois and can’t find one that has the proper Hobb. The 8 lead on the gears is what has presented the problem. Does anyone have a recommendation of a gear manufacturer that they have used. We have talked to a local gear manufacture and he says they can have the hobb made for 800 to 1000 dollars and then the cost of making the gear. Are there any McCulloch owners that would be interest in a replacement bronze gear? Trying to split the cost of making the hobb. Thanks Dave/Green Bay

[SUHRsc]

Dave,
I am no help on the subject as I have yet to dig into mine. But I'd be interested in seeing some photos of the gear box all apart. If its not too much trouble.

Zach

[super flat]

Originally Posted by SUHRsc

Dave,
I am no help on the subject as I have yet to dig into mine. But I'd be interested in seeing some photos of the gear box all apart. If its not too much trouble.

Zach

Times 2 please

[Dave/Green Bay]

Here are some pictures of the bottom end. If there is something else you would like to see let me know.

The Street Rodder Magazine August 2013 and September 2013 has a 2 part article on rebuilding and installing a McCulloch. The title was "A Mighty Wind" Great article with lots of information. Dave/Green Bay

[hotrodderhaag]

I know a small local machinist with a very expensive CNC mill. I'm sending him pictures , he claims he can do that easily!

[Pete]

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Originally Posted by Dave/Green Bay

I have a Model 37 McCulloch supercharger and am in the process of rebuilding. We have found that the bronze worm gear is worn on the teeth. We have tried many gear manufactures in Wisconsin Michigan and Illinois and can’t find one that has the proper Hobb. The 8 lead on the gears is what has presented the problem. Does anyone have a recommendation of a gear manufacturer that they have used. We have talked to a local gear manufacture and he says they can have the hobb made for 800 to 1000 dollars and then the cost of making the gear. Are there any McCulloch owners that would be interest in a replacement bronze gear? Trying to split the cost of making the hobb. Thanks Dave/Green Bay

Just stab in the dark but these guys claim they can do just about anything.
The Gearworks
Seattle,Wa.
(206) 762-3333

[4tford]

paxton / mcculloch superchargers

805-487-3796

[email protected]

[Fordors]

Originally Posted by 4tford

paxton / mcculloch superchargers

805-487-3796

[email protected]

They sold off all the old ball drive stuff that McCulloch produced from 1950 to 2000 years ago. Paradise Wheel bought everything and services the ball drive superchargers but there were no earlier parts in the lot.

[SUHRsc]

Thanks for the photos Dave.

[wga]

8 DP gear how many teeth or pitch diameter ?
Face ?

[Dave/Green Bay]

I by no means know anything about gears but from what I have gotten from all the gear manufactures so far I have been told:

8 Lead
880 Root
1208 Low point in center
12 Pitch
20 degree PA

If that makes any sense to any Fordbarner's I need your help.
Thanks
Dave/Green Bay

[Dave/Green Bay]

hotrodderhaag:
When I took it to the local CNC shops they looked and said that the "compound" angle on the gear made it so they didn't have a cutter for the gear. My problem is that I am very nervous to send anywhere for fear of getting lost in shipping. What do they need to see to know if they can make it? Thanks Dave/Green Bay

[wga]

Dave -- looks like 40 teeth. 12 diametral pitch, gives a pitch diameter of 3.33"
What is the face width of the gear - width across the teeth?
Please clarify 1208 low point in center -- and is 880, 8.80 inches "root diameter",?

Also, check the worm, if it is made from hardened steel or unhardened.

[hotrodderhaag]

another thought, if you made both the ring gear and a new shaft, you could make them any gear you want basicly. as long as it drives the rotor shaft your good .

[Dave/Green Bay]

I have included more picture to try provide additional information of the setup. The worm gear has an hour glass shape to it the middle is narrower than the ends. The worm gear also has splines on the inside that mount to the shaft also with splines. I think the worm is hardened. 39 teeth on the bronze gear.

[awelker]

Dave,

Some info that may help your search:

What you have is a double enveloping worm gear set. This is the correct term for the hourglass shape you are referring to. The worm pinion (the steel gear) is an 8 start which gives the high lead which would be why many gear shop do not have a cutter.

Your best bet to reverse engineer this set is to have somebody accurately measure the housing these go into (preferably with a CMM machine) to determine the actual operating center distance. With that info and some basic gear measurements you would be able to get a new set designed. Finding a shop that already has the tooling may be a different story.

If you replace both pieces you may have better luck finding someone with a metric cutter which could create a replacement set but they would need to be replaced as a set.

Andy

[Dave/Green Bay]

Originally Posted by Pete

Just stab in the dark but these guys claim they can do just about anything.
The Gearworks
Seattle,Wa.
(206) 762-3333

Pete:
I checked with them this morning and they said if I had the hobb they could make the gear. Back to square one.
Thanks
Dave/Green Bay

[Dave/Green Bay]

Originally Posted by awelker

Dave,

Some info that may help your search:

What you have is a double enveloping worm gear set. This is the correct term for the hourglass shape you are referring to. The worm pinion (the steel gear) is an 8 start which gives the high lead which would be why many gear shop do not have a cutter.

Your best bet to reverse engineer this set is to have somebody accurately measure the housing these go into (preferably with a CMM machine) to determine the actual operating center distance. With that info and some basic gear measurements you would be able to get a new set designed. Finding a shop that already has the tooling may be a different story.

If you replace both pieces you may have better luck finding someone with a metric cutter which could create a replacement set but they would need to be replaced as a set.

Andy

Andy:

I took your advice and found a gear manufacture that could produce both gears. I contacted ConeDrive in Traverse City Michigan. It turns out that there would be a 1300 dollar setup fee and then the first set was 4200 dollars and if I made 2 to 4 sets the price would dropped to 3300 dollars plus setup fee.

After seeing this I decided that the Hobb route was the way to go. So I have contact a local gear manufacture and we are sending the worm gears off to have a Hobb make which should take 8 to 10 weeks.

If there are any McCulloch owners that would be interested in the bronze drive gear for their supercharge PM me and we can discuss. Estimated cost is around 500 dollars.

Thanks everyone for the help and advice. Dave/Green Bay

[Dave/Green Bay]

Just an update on the worm gear project. The first Hobb arrived and the gear maker made a prototype that didn't work. He has contact the Hobb maker to make another one. The Hobb manufacture isn't to pleased but agreed because the gear maker does a lot of business with them.

On another note we have been trying to determine the optimum level for the oil in the supercharge. We have mock the oil pump and supercharger with plastic cover on the Bridgeport. Quite a Rup Goldberg arrangement. We have played with different size orfaces on a plug in the oil line and just about have the levels determined. Drain back pipe size is the only thing yet to be determined.

[Jason in TX]

Hi Dave. I will be tearing mine down soon to fix the oil leak issues. I also feel like there is a little play in the front shaft pulley and was thinking that it was a brass front bushing. Seeing yours blown apart has me thinking it's all a little more intricate than that.

Keep me updated on the Brass gear. I'm not sure that mine will need one yet, but it may!

https://igcdn-videos-h-4-a.akamaihd...._7468858_n.mp4