How to: DIY diff removal / LSD install 987.2 PDK

I couldn't find any info on this. so I decided to document the journey for others in the future. I felt this was slightly above my comfort level but decided to tackle it myself. It's more scary than hard. 1. Remove the two rear braces, eight 16mm nuts, and two 16mm bolts (front). Remove two T25 screws in black plastic near two brace front bolts. Be sure your Jack stands/ quick jack aren't in the way of the two front bolts when you start this process. mine were. 2. Remove the sheet metal pan, two 16mm nuts, and two 15mm bolts. 3. Remove twelve (6 per axle) M10 "Triple Square" axle drive flange bolts. 4. I took this opportunity with the braces and sheet metal removed to degrease (engine foaming degreaser) and to power wash the entire engine, transaxle, and suspension assemblies. It's so much nicer working on sparkling clean parts. and later will be important to help prevent any dirt from falling into the open transaxle. 5. Remove the 8mm upper fill plug. it's on the passenger side near the rear. have a drain pan ready mine leaked. It's important to remove this first, if it was seized and you remove the drain plug first, you'd have no way to refill the differential. Then remove the 8mm bottom drain plug and drain the gear oil. Both are well behind the axles in the rear section. I didn't take pics of these. Now remove the smaller front 5mm drain plug just below the differential also on the passenger side. See pic. In total 2.5 to 3 quarts should come out. 6. On the passenger side use two of the M10 triple square bolts to push the drive flange out by screwing them in against the transaxle case.

7. On the driver's side use a slide hammer to pull the axle flange. After initially freeing it with the slide hammer, you can pull it out by hand. Be very careful to pull it STRAIGHT out as possible to avoid pulling the axle seals out with it. The driver's side is much longer than the passenger side. low to medium effort to initially pop out both(the circlips compress). The sway bar drop link is in the way to remove the drive flange. Remove the 18mm nut and use a 17mm narrow open-end wrench to remove the sway bar drop link. My circlip did not stay on this driver-side drive flange, but later came out with diff (laying in the bottom.) You can now pull out the drive flange (again as straight as possible ) 8. Remove four 15mm bolts in the black subframe brace. a ratcheting wrench with a pivoting head is very helpful for the upper passenger side bolt. You just need this brace moved 1-2" forward to uncover a couple of the bolts in the differential side cover. no need to remove this brace from the car. 9. Use a T45 to remove the passenger side twelve differential cover bolts. I had to get creative with a 1/4" drive setup to remove the final one of these next to the black metal pipe. (I bought a thin T45 Allen wrench off Amazon for this purpose for reinstallation.) 10. remove the wire clip from the top of the differential side cover, it just slides up. To remove the side cover pry here. Have a drain pan ready! It will leak. It will easily come off. Be careful, the differential will try to flop out with it. Hold the differential in with one hand, and pull the cover out the bottom with the other hand. 11. Remove the differential. It helps to have a friend hold the axle out of the way while kneeling outside the wheel well (wheel removed). Its a very tight fit but it will come out. BE VERY CAREFUL with bearings. do not bang them on anything! (More on this later) it took some playing and wiggling. they came out through the hole created in the bottom front. It's out! The hard parts are over right? Wrong! In Porsche's infinite wisdom, these bearings are not replaceable and must be reused. No one in the world sells these bearings not even Porsche. and to make matters worse they designed the case so that you cannot get a traditional bearing puller behind them to remove! More on this later.

12. Remove the 17mm ring gear bolts. Fair warning - we tried an 18" breaker bar, and 4 impact guns, before finally finding an old-school all-metal air-powered 1/2" impact driver that was strong enough to break them loose. Use the short drive flange and two of the triple square axle bolts in a vice to hold the differential. 13. I shipped the differential off to Bill Rader Motorsports for bearing removal. After calling 4 local Porsche race shops that had no clue about the bearing situation on these, I was finally given Bill's info. and when I called he was the first person completely familiar with the issue and had done the removal before. The old differential case must be opened and drilled, and then the bearings punched off. He was able to do this quickly and for $100 including the shipping back. I marked my bearings and which side they came off of before I sent the differential. The bearings are different heights. They must go back on the side they came off of. REASSEMBLY 14. Put the short drive flange with two bolts in the vice again. Slide on new LSD. slide on ring gear (I heated mine slightly). Tighten 17mm bolts to 44 ft-lbs plus 45 degrees, with red lock tight. Alternate tightening side to side like wheel lugs. no pic. 15. Press on the bearings. Be sure each is on the correct side. They are different heights. Be sure they fully seat at the bottom.

16. Reinstall the circlip on the driver's side long axle if it came off. Check for loose axle seals. My passenger side metal seal backer came loose. you can push it back into place in to back of the seal with a finger. Although it's not critical if it stays in the back of the seal, just make sure the axle goes through it so it's not loose in the transaxle case. It can holla hoop on the axle and not cause any issues. Insert driver's side long axle flange. again inserting as straight as possible. And through the seal metal ring if yours came loose. (metal seal backer seen loose in photo.) 17. Move the passenger axle to the rear lowest droop angle (friend held from outside the car). Insert LSD from the bottom front hole in front of the axle. Watch the bearing. Slide onto drive flange splines with light/medium force (compresses circlip) 18. Install new cover oring seal. Install side cover with twelve T45 bolts to hand tight . Manual states to torque these to 17 ft-lbs. DONT! These are aluminum bolts (and likely intended for one-time use). Neither of us felt comfortable going that tight, it felt bad/wrong. We finally decided to just tighten one to 17 ft-lbs.... it snapped the bolt in the case. We tightened the rest in an alternating wheel pattern to "just tight" with a 1/4" rachet or T45 Allen key. i.e. only a 5" handle or so. You'll know when to stop. went around several times till there were no more loose as they pulled the cover in. 19. Reinstall the black subframe brace with four 15mm bolts. Make it as tight as you can with a 3/8" rachet. BE SURE to put the silver ride height sensor back on the top driver-side bolt! 20. Slide in passenger side short drive flange. Push in with light/medium force (that compresses the circlip) no pic

21. Install the axle m10 "triple square" bolts to 60 ft lbs. Don't forget the two hole straps first. 3 each side. It helps to have a buddy. put the car in neutral. Have the guy on the outside spin axles with a breaker bar in wheel studs, then hold while the guy underneath torques each one. torque one, spin next , repeat. Sensitive content, not recommended for those under 18 Show Content 22. Reinstall driver's side sway bar drop link. 18mm nut, skinny open-end wrench on 17mm drop link side. no pic. 23. Tighten the two bottom drain plugs, rear 8mm and front 5mm. I put a new seal on the big drain plug, but i don't feel this is necessary. threads do all the sealing. just hand tight with Allen key or 1/4" rachet. You'll know when to stop. bottoms out hard. no pic 24. Refill with Motul 75-140. Mine took about ~2.8 quarts. Be sure the car is level. I bought a $12 battery-powered pump from Harbor Freight. it worked but wasn't any faster than a hand pump. It really struggled once the bottle was below 1/3 full. Fill till you have a decent steady flow of overflowing oil leaking from the fill plug. I started the car, put in drive and reverse a few times, and rechecked. It hardly took any more oil, maybe 5 pumps with the hand pump. and most of that overflowed back out. but peace of mind - it was full. 25. I degreased and power-washed the braces and the sheet metal pan. I also did the flat bottom plastics as I was doing front power steering lines at this same time and I had them removed. Reinstall the sheetmetal pan. Two 16mm nuts and two 15mm bolts. Tight as you can with a 3/8" rachet. I had to do some prying to get over the side/outer studs through the sheet metal holes. 26. Reinstall the two aluminum braces, all 16mm. The brace goes above black plastic at the front where the bolts are. Tight as you can with 3/8" rachet. Reinstall two T25 screws in black plastic. no pic 27. Do skids and enjoy the car how it should have come from the factory! The OS giken diff will make HORRIBLE clunking and banging sounds on tight corners or circles sub 10mph on power. but shouldn't make any when driving normally. This will get better or go away completely with time. but at first, it will sound like something is horribly wrong, like metal-on-metal banging. Using OS Gikens official 80-250 oil can greatly help with this. Also doing 10 super tight, super slow (but with a tiny bit of gas to engage the differential) figure 8s in a parking lot can also help.

One question, how did you measure the bearing preload with the gearbox in site? This preload is very important in order to keep proper pinion and crown contact.. I installed a OS Giken on my 07 Cayman S but the gearbox was sitting on the bench sideways. PS: I am Not an expert by any means, just curious..

I talked to a couple of race shops that have done this many times on the 987 and have several of these with years of racing on them now. OS giken did their homework and got the tolerances exact. It's literally a remove and replace and it works out every time. no shimming is needed. Bearing preload and gear lash is spot on. otherwise, I never would have even thought about attempting this on my own. I'm sure Porsches tolerances on the case etc. aid in this, vs. an old-school Chevy straight axle.

Thank you for the explanation!

Wonderful DIY! Looking forward to more... thanks much for taking the time and effort to document what's a complex job. I don't think most people realize how taking photographs interrupts the flow of work when doing a job, and how difficult it is to remember all the steps and lessons learned and put it down in text in an understandable form. MANY THANKS!

thanks, your correct. doing a write up makes the job twice as long. and thats even before you get on the computer! but i couldnt find any details on our 987s, so i thought id fix that. i took pics and had a note pad on my phone. jotting down and numbering steps along the way with bolt head sizes. and anything special i ran into. unexpected bonus, i got a cool little logo under my name!

I didn't know you could do this without taking the trans out. Very good to know. Re: cover bolts. If it were my car, I wouldn't be comfortable leaving the outer half of the diff "just tight". The cover has one of the carrier bearing races in it and resists the pushing force from the pinion, which can be significant. IMO replace the bolts and torque them to the proper spec.

Update: drove the car 3 hours to and from Circuit of the Americas. Tracked the car all day and drove home. LSD did great, never made any noises, or any weird jerks. performed flawless. did help with throttle steer and more rotation on sweepers, less push. turn in seemed about the same. or at least not any huge differences. it did not however help with PSM (even though off it still interviens) on slow 2nd gear tight corners the PSM/TC light would still flash and drag the rear brakes and pull timing from the motor. this was a bummer as this was the whole reason i installed the LSD was to help decrease the PSM running (even when off) in the background and killing my exit speeds. however the good news is the LSD performed great zero issues with it or gear mesh etc everyone was concerned about.

What I noticed most after installing the OS differential was the fact that the car felt way more planted during heavy braking (no more rear end wondering), this was on my old 987CS PS: I believe that OS recommends replacing the differential oil after the first 500 miles

@STANG KILLA SS its been a year since you installed the LSD - How has it performed? Any issues, noise, strange behavior? Thank you for the incredible DIY write-up. Really well done. Bill Radar Motorsports in Las Vegas is where you sent your diff for bearing removal? Too bad you still get the PSM intervening, but I thank you for running this rather expensive and time consuming experiment. Knowing what you now know, would you recommend installing an LSD in PDK track car?