Installing starter ring gear on Burtz flywheel

J

JayJay

Well-known member
I know we've discussed this topic lots of times, but I have a couple of data points to share on installing the starter ring gear on Burtz flywheels. All temperatures reported are from my IR thermometer I got off the river store - a cheap one, not a good one like a Fluke.

Trial 1: I put the new flywheel in the freezer overnight, and heated up the new ring gear on my propane barbeque. Got the gear up to around 550F. The gear started, but I had to finish it up with a hammer and a brass punch.

Trial 2: Second flywheel, new gear. I chilled down the flywheel by placing multiple ice packs inside and leaving it for several hours. Ring gear went into the same barbie, also got to around 550F. Several tries, but I could not get it even started.

Trial 3: Same parts as Trial 2. Got the flywheel into the freezer, left it all day. Ring gear into the barbie as before, but this time I helped it along with a rosebud oxy-acetylene torch. Heated it up but no color change. Got the gear to around 850F. Gear dropped right onto the flywheel sweet as can be.

I believe both ring gears were sourced from Snyder's. And (obviously) both flywheels were sourced from Burtz (burtzblock.com).

Conclusion: chilling the flywheel in the freezer is essential, heating up with a torch over and above the propane BBQ is desired.

If you have a source of dry ice (alternative to the freezer), I calculated that you would need about 13-15 lb of dry ice to fill the inside of the flywheel (where you would put the dry ice). Around here dry ice is about $2.00/lb, and that was $30 I wasn't willing to spend if I didn't have to.

YMMV
 
How can you conclude that chilling the flywheel is essential when you didn’t do any trials in which you didn’t chill the flywheel? You put it in the freezer twice - one time installation was easy and the other time it was hard. I don’t see how you can draw any conclusions from that.

Keep in mind that putting the flywheel in the freezer only lowers its temperature by about 60°, whereas you’re raising the temperature of the ring gear by 800°. Seems like one of those is more critical than the other.
 
alexiskai said:
How can you conclude that chilling the flywheel is essential when you didn’t do any trials in which you didn’t chill the flywheel? You put it in the freezer twice - one time installation was easy and the other time it was hard. I don’t see how you can draw any conclusions from that.

Keep in mind that putting the flywheel in the freezer only lowers its temperature by about 60°, whereas you’re raising the temperature of the ring gear by 800°. Seems like one of those is more critical than the other.
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alex - you are correct, I did not try the flywheel at room temp and the ring heated above 550. My nudge in coming to that conclusion was that partially chilling the flywheel (Trial #2, I do not believe that putting cold packs in the flywheel was as effective at cooling as full freezer) did not work at all, while Trial #1, which differed from #2 only in the extent of cooling the flywheel, did - sort of. Unfortunately, I do not have a freezer at my shop, which is where my torch normally lives, and didn't have it at home when I tried Trial #2. I had to bring the torch home.

And once I finally got enough room in the freezer to put the flywheel in, I could have repeated Trail #1 to see if I could duplicate the results with the second flywheel and the second ring gear. However, after having failed to get the ring on in Trial #2 I wanted to stack the deck towards success and get the job over with. Bring on the torch, and Trial #3. Which was a resounding win.

I do not anticipate having to do this again for a long time if ever. Of course, I did not anticipate doing the second gear/flywheel either until I was asked by a club member. And now I know how I will approach it if it ever does happen again. If I remember.

With some careful measurements I could have calculated the difference in temperature necessary to allow the ring to be installed. I thought about that but then decided on brute force instead.
 
JayJay said:
My nudge in coming to that conclusion was that partially chilling the flywheel (Trial #2, I do not believe that putting cold packs in the flywheel was as effective at cooling as full freezer) did not work at all, while Trial #1, which differed from #2 only in the extent of cooling the flywheel, did - sort of.
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That’s true, but notice that in trial 1 you barely got the gear on. So it seems like a more accurate conclusion would be that, if the only method you have to heat the ring gear is a grill/oven, chilling the flywheel may give you the extra fraction of a millimeter needed to get the ring on. However, the preferred method would be to heat the ring gear with a torch to 700-800°, in which case the extra hassle of freezing the flywheel is unnecessary.
 
alexiskai said:
That’s true, but notice that in trial 1 you barely got the gear on. So it seems like a more accurate conclusion would be that, if the only method you have to heat the ring gear is a grill/oven, chilling the flywheel may give you the extra fraction of a millimeter needed to get the ring on. However, the preferred method would be to heat the ring gear with a torch to 700-800°, in which case the extra hassle of freezing the flywheel is unnecessary.
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Well said.
 
katy said:
What temperature is the freezer at? Is this the "freezer" on a refrigerator? Or a stand alone freezer AKA a deep freeze(r)?
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Freezer below the refrigerator. Shared with the bagels and the ice cream. Currently at 4F.
 
I've never had to freeze a flywheel. I just use a torch with a rosebud, heat the gear and it drops right on no problem. Same for removing a ring gear from the flywheel.
 
I've been doing the rosebud method with great success. I did have one ring gear walk on a
Burtz flywheel with a Snyders ring gear. I'm going to put set screws to hold it in place.
 
Burtz flywheel at room temperature, torched the ring gear and it dropped right on. Also removed the ring gear from the original flywheel with torch only.
Warren
 
Well, based upon this feedback, I think I’ll forego the freezer in the future (and avoid a potential source of domestic friction). Straight to rosebud! Thanks all.

Dodge - good luck drilling that ring gear for a set screw. It’s hard!
 
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