LSD and 5th Gear Parts – Information Center

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This Guide was copied from the Forums online and archived on King6fab.com for future reference.

King6fab has no affiliation or experience with the process shown in the guide and therefor cannot answer questions regarding the guide.

21. When purchasing the LSD, you’ll want to also get some new parts to go along with it. This is where being a member of MMS (Mazdaspeed Motorsports) comes in handy….the parts are not only cheaper, but you are able to order them all online. Shipping has always been incredibly fast.

It has also been discussed and documented about the earlier versions of the LSD having a weak point. The rivets used to hold the ring gear to the differential case. The ring gear breaks away from the differential case, rendering the LSD useless. Later and current versions have been upgraded with stronger rivets, but since this transmission will see 99% of it’s use on the track racing, and see close to 200whp, the ring gear and pin have been welded in place.

22. LSD Parts Needed

Part	Old Part Number	New Part Number	Quantity Needed
(MSP) Mazdaspeed Protege LSD Differential Gear	GS01-27-190A	GSY1-27-190	1

23. Primary Shaft Lock Nut

Part	Old Part Number	New Part Number	Quantity Needed
Primary Shaft Lock Nut	F520-17-628		1
Secondary Shaft Lock Nut	F521-17-628A	G501-17-629A	1

24. Speedo Drive Gear

The speedo drive gear will need to be be modified to fit the case and allow the carrier bearing to seat properly. The gear tabs are offset and it must be installed properly. When looking at the gear, the tabs sit flush to the carrier bearings seat. You’ll notice on one side of the gear, there are 6 small square notches on the face, But on the other side, there are 2 larger square notches. The side with the 2 larger square notches faces up. These notches are there to allow the bearing removal tool access under the carrier bearing to pry it off.

Part	Old Part Number	New Part Number	Quantity Needed
Speedo Drive Gear	G501-17-341A		1

25. Carrier Bearings

Part	Old Part Number	New Part Number	Quantity Needed
Carrier Bearings	G5R0-27-350B		2

The carrier bearings need to be pressed onto the differential. For those who do not have a hydraulic press, the services of a machine shop will be needed. Make sure you hang out and show them the correct placement of the speedo drive gear, otherwise, once pressed on, the bearing will not spin freely and a new drive gear and bearing will need to be purchased as they will be destroyed when removing them.

Only 2 parts are needed for the 5th gear swap. The 2 gears themselves. This is a direct swap and could even be done with the transmission still in the car.

Mazda MX6 or 626 Sourced 5th gear Swap