S2000 Final Drive
Shhh...interested in a dirty little secret the industry doesn't want you to know? There's a growing trend among aftermarket retailers unnervingly price gouging consumers while laughing themselves senseless all the way to the bank. Smart businessmen you ask? Perhaps, but little did we know that these wolves in sheep's clothing made a fortune off unknowing chumps (individuals) like you and I by selling factory-manufactured parts and re-badging them. From a business perspective, we understand that it's a dog-eat-dog world with plenty of money to be made and spent, but knowing that some of the more well-known shops have sold and continue to sell the exact ring and pinion set we recently bought for $267.93 shipped from a dealership parts' distributor for over $1,000-well, we were just sick to our stomachs.
The terms "big" on style, comfort and best value, is just a few of the catchphrases that highlight the new Kia Sportage. While the selling points of the Sportage obviously cater to your average suburban housewife, don't be surprised if you find some teen in a pair of baggy jeans roaming the showroom floors perusing through Kia catalogs. Soccer moms carting their kids around in their Kia Sportage beware; Honda S2K owners are lusting over your car.
It's no surprise that competing manufacturers rely on one another to engineer various components. It's been long rumored that Mazda has lent a helping hand to a number of big-name companies, including Honda and Kia. While these rumors have yet to be established and continue to be highly debated among automotive enthusiasts and Internet forums, we stumbled across an interesting find that would tie all three of these big automotive manufacturers together, namely their ring and pinion setups.
The biggest surprise of them all was finding out that Honda sourced the Mazda 7-inch rear for the Honda S2000. This doesn't necessarily mean you can simply bolt a Mazda rear end on your S2K and call it a day because of the difference in rear housing and axel designs. It seems Mazda has been sourcing out its gears to Honda S2Ks and '94-'02 Kia Sportages 4x4. The front axle of the Sportage has a Mazda 4.778 ring and pinion (part number MM05727110), which high-performance retailers have been secretly selling as an aftermarket gear for over $1,000. The only difference between the $1,000 unit and the $267.93 gear set we bought is, of course, the price gouging and the possibility of a few retailers who add cryogenic treatment to the units as a bonus. The same 4.77 final gear set found in the Kia is interchangeable to fit on the S2K as a direct bolt on, as well as the Mazda final drive off a stock RX-8 with a 4.44 ratio. Upon further research, we found numerous final drive setups that were all interchangeable between the S2K and Mazda, including a n/a powered S2K's dream come true 4.625 ratio, which is available on the New Zealand Kia Sportage. When comparing the S2K factory 4.1-ratio final drive to the 4.77 final installed in our factory pumpkin, we found numerous pros and cons attributed with this setup.
Before you begin the disassembly process, remove the oil drain and fill plug to ensure the differential fluids have been completely drained. | 
Use a rubber mallet to gently tap on the output shafts for removal. Be sure to inspect the oil seals for any tears or excessive wear. We recommend replacing the oil seals as a precautionary measure, which can lead to fewer headaches in the near future. | 
Remove the 10 mounting bolts (19 lb-ft) by holding the differential case assembly together in a crisscross pattern. |
Securely fasten the differential to a bench vise and gently tap on the base of the lower housing to remove the differential cover. | 
Be sure to mark placement on the bearing cap, adjustment screw and differential carrier case before you begin disassembly of the LSD unit. Remove the two lock plates (16 lb-ft) and the four bearing cap bolts (33 lb-ft). | 
When pulling out the factory Torsen LSD, remove the adjustment screws and bearing outer races and set them aside to be reused when reassembling. |
Remove the pinion washer and locknut holding the pinion gear (210 lb-ft) and replace with a new unit when reassembling. The companion flange can be loosened using a bearing puller sold over the counter. | 
Remove the drive pinion and pinion spacer by tapping out with a rubber mallet. We used a press to carefully remove the stubborn unit. | 
Using a bearing separator, we used the press once again to remove the tapered roller bearing. Honda recommends replacing the tapered roller bearing with a new unit before reinstalling. We'll reuse the bearings on the drive pinion and LSD assembly in our install for cost efficiency and their excellent condition upon inspection. We recommend having your installer thoroughly look over both units if your budget is holding you back from purchasing a new set of bearings. |