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I have an aluminum flywheel complete with ring gear. I'd like to get the ring gear off the flywheel. I don't have a welding rig or any other way to apply localized heat. I thought I'd just put the whole thing in the oven but first I checked the relative CTEs (coefficients of thermal expansion) on wikipedia and it turns out Aluminum will expand at a greater rate than steel (CTE for Aluminum is 23, for steel it's 11-13)...so if I heat it up, will it just be on there tighter? What if I freeze it?

Doug Bender
 

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I meant, how do you get a ring gear off intact to swap in another one? (Incidentally, putting one on should be easy--just heat it up, should slide on.)
 

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Liquid nitrogen on the aluminum does the trick, but the burns are nasty. Seriously, most ring gears on aluminum wheels have a couple of pins or cap screws to lock them in place. Once removed, I push them off with a hydraulic press with various very odd holding fixtures. You can push just a little around as many spots as you choose around the ring. just push it off evenly.
 

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I now only use aluminum flywheels. In my earlier note, I said,"... push them off with a hydraulic press with various very odd holding fixtures. You can push just a little around as many spots as you choose around the ring. Just push it off evenly."
The key words here are, " ... odd holding fixtures..." This avoids damage to the wheel. Some are lead, others soft aluminum. The ring gear pusher is brass. I once tried a hunk of dry ice on the flywheel friction surface and the ring gear came off, but since I had not pushed that one on or off before, I've no idea if the dry ice did anything. It did make odd noises that were distracting from the job at hand. That helped.
 

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Richard Jemison
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Removing Ringgear`

You really shouldnt press a ringgear off of an Aluminum Flywheel as it will brpoach metal from the flywheel. Cutting wilkl require some damage to the aluminum as well. Best to take it to a shop and have it removed with a torch as it should be.

Easy to put one on..
Put the flywheel in a freezer and the new RG in the oven at 400 degrees. RG will drop in place after reaching temp...
 

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Easy to put one on.. Put the flywheel in a freezer and the new RG in the oven at 400 degrees. RG will drop in place after reaching temp...

Richard you (as usual) took the words right out my mouth. :) A little judicially applied heat will work wonders getting a ring gear on (and off).
 

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Securing it to a work bench is the trick. I have a huge bench vice that will let me sandwich the FW between short 2x4 blocks. Alternately, cut out a disc of plywood and bolt/clamp the FW over it on the work bench. Either way you can now take a drift, preferably brass, and gradually peck around the circumference, keeping it even as possible, until it drops off. The danger of pressing it off is that if it gets ****ed at even a slight angle it will move aluminum. There is only .001-.002" shrink fit.

The installation procedure has been expertly addressed. The finishing touch is that you should use a .0015" feeler gauge to be sure it goes on flush. This ain't gonna happen. So take the (brass) drift, clamp the FW down again and go to work pounding it one spot at a time until the feeler gauge tells you it is flush for 360 degrees.

Good luck, Paul
 

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I have used the lower timing chain from a four cylinder engine to support the back side of the flywheel with a piece of sheet rubber to act as a cushion against the aluminum, and setting it on a solid work bench, by using a brass drift about 3/4 inch in diameter and a large hammer, tapping all around the ring gear equally will remove it easily.

Following the above good advice will reinstall it.

Hope this helps, G
 

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The dry ice does make an annoying sound though ... The brass drift method works for me.
It's slow, and without the huge vice, it requires resetting on your base, In my case lead blocks, but this does work. In the cold of winter, you can work up a sweat!
 

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Question: Let's say I have a new aluminum flywheel and a new or servicable ring gear. Will the press fit of the ring gear to the new flywheel be suffient to work reliably or should I pin the ring gear to the flywheel?

I presume that doing a good job of pinning the ring gear to the flywheel is a machine shop job?
 

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The old Tilton on my GTA engine was just shrunk on. When it last apart, I had a friend mill four cap screw holes at the edge of the flywheel into the ring gear. It had never moved, but the most recent aluminum wheel I used had four cap screws. If you have the correct shrink relationship as mentioned earlier by Paul, you probably don't need to pin it.
The first two pictures are the newest aluminum flywheel, the last is the old GTA Tilton with clutch just before installation.
 

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Pardon me for being obtuse, Gordon, but I'm not sure what I'm looking at. Does photo 2 show the pinned ring gear? Could you explain how this is done and how it works? Can you show/draw how the cap screws are mounted? Thanks.
 

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I left OUT the picture you need Jim! Here it is. This is the back side of the newest flywheel, the first two pictures. The backside if the Tilton, picture three above, now looks the same as this photo. The four cap screws on the outside run through the aluminum into the ring gear.
The other back side picture (#2) through the starter hole shows the gear bevel to kick out the starter drive.
This is better!
 

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