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How to Remove 12mm Lock Nut on KYB Shock Shaft?

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I'm working on a 2012 KX450F with KYB shock. How do you remove the 12mm lock nut at the end of the shock shaft. I don't see any peening on the nut and the lock nut seems to be torqued pretty tight. Is it secured with lock-tite? I don't want to do something I'll regret and force it loose and break something. I have the service manual, but the service manual doesn't address this.

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If you mean the one on the top of the shaft, holding the piston and valve assembly, all of the YZ's I've done have been secured with a thread locker, although it looks more like "super glue" than Loc-Tite. The shaft is peened over the nut, too, so that has to be cut back enough to allow the nut off before you can get anywhere with it.

Here's some more info from a post today by Dave Johnson:

Shock Nuts

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Showas have a peening and Kayabas have some kind of compressed last threads to secure the nut.

Both manufactureres don't use a thread locker since the peening is sufficient.

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Showas have a peening and Kayabas have some kind of compressed last threads to secure the nut.

Both manufactureres don't use a thread locker since the peening is sufficient.

Also, to add to frezno post, on KYB you can grind flat on a bench grinder the

Showas you have to grind at an angle or do the Davej method as grey mentioned and preserve the material near the center

of the shaft as much as possible. On KYB the needle seet is down in the shaft.

The Showas are at the top held in place with the factory peen.

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So I got the shock shaft nut off with no problems. But when taking the shim stack and valve off I dropped the valve. Which way does the valve face, the entry side of the large ports toward the compression stack?

Edited by keller317

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The OD of the port circle matches the diameter of the face shims in each stack. The compression is the larger of the two, so the entry side of the large diameter port circle faces away from the comp stack and the comp stack sits against the opposite side so that the face shims close off the ports.

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Showas have a peening and Kayabas have some kind of compressed last threads to secure the nut.

Both manufactureres don't use a thread locker since the peening is sufficient.

The KYB uses some sort of machine operation, either some sort of rolling under pressure or a machine driven impact tool to produce a very uniform "mushrooming" of the top threads. It isn't exactly like peening or staking, but the effect is the same.

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