Flywheel & ring gear

Putting a clutch in my 1990 XJ 4.0 AX-15 and also replacing the original flywheel. FSM calls for new flywheel bolts and thread locker (thanx to 5-90 for info on breaking the old bolts loose). Does anyone know if the ring gear should also be replaced? The original has over 300,000 miles on it, but it looks good, no damaged teeth. Flywheel is a different story though, it's really a mess. Service manual doesn't say to replace the ring gear with the flywheel, so I guess it's OK to reuse it. Just wanted to make sure. TIA for any advice.

If it looks good it should be fine. As long as your starter/bendx works right the ring never goes bad.

badron said:

If it looks good it should be fine. As long as your starter/bendx works right the ring never goes bad.

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Never say never.

The new flywheel should come with a new ring gear. Failing that, get a new one anyhow. The press fit for the ring gear calls for a significant amount of interference - you usually end up destroying the thing removing it (cut to relieve tension.)

OK. That's why I asked, because the flywheel and ring gear have seperate part numbers, but the parts catalog shows them together. So the two are press fit together? Man, I can tell this is gonna be fun.

otto said:

OK. That's why I asked, because the flywheel and ring gear have seperate part numbers, but the parts catalog shows them together. So the two are press fit together? Man, I can tell this is gonna be fun.

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Yes. Actually, it's a "thermal interference fit" - the ring gear is heated up to about 500* in an oven and slipped over the flywheel.

They have separate part numbers because it's fairly common to have to replace the ring gear on a good flywheel - since it sometimes gets chewed up. However, just about every new flywheel I've seen comes with one (check anyhow.)

But, if you have to remove a ring gear, it will be wrecked. So, if the flywheel doesn't come with one, order a replacement. Don't bother trying to save the old one - it's not worth the amount of effort you'd have to put into it.

Freeze the flywheel, heat the ring gear and it drops on. Ive always used a good cold chisle and sledge hammer with a few heavy blows between the teeth and it pops apart then falls off.

Thanks. Standard Flywheel (#1004) does come with ring gear and a $40.00 core charge. They tell me if I mess up the old one I can forget about getting that back. And of course no flywheel bolts, they're not even listed. Guess I'll hunt around tomorrow for them, or else use the old ones.