Ditching the Electronics: How to Convert Your Skyline R34 Active LSD to a Welded Diff
You stomp the throttle mid-drift, expecting the rear to step out predictably—but your R34’s Active LSD decides to play games instead.
If you own an R34 GT-R V-Spec or any Skyline with Nissan’s Active Limited Slip Differential (A-LSD) , you know the struggle. The system uses hydraulics and electronics to decide when to lock your rear wheels. On paper, that sounds brilliant. Open diff when you cruise, locked when you send it. In reality? The A-LSD system is complicated, failure-prone, and often unpredictable when you’re pushing hard on track or at a drift event.
Here’s the raw truth: Many R34 owners ditch the Active LSD entirely and swap in a welded differential or a mechanical LSD. A welded diff forces both rear wheels to spin at exactly the same speed, 100% of the time. No computers. No sensors. No surprises. Just pure, predictable lock. But is it right for you? Let’s break it down.
TL;DR (Too Long; Didn’t Read)
Converting your R34’s Active LSD to a welded diff means pulling the factory differential, welding the internal spider gears together, and reinstalling it. The result? Both rear wheels spin together at all times—perfect for drifting but rough for daily driving. You’ll also need to cap off the hydraulic lines that fed the A-LSD system, since they won’t be used anymore. Expect aggressive tire wear, chirping in parking lots, and a car that wants to understeer on corner entry. But for $100 vs. $1,500+ for a proper 2-way LSD? Many drifters say it’s worth it.
Key Takeaways
- The R34 A-LSD (Active LSD) uses a computer and hydraulics to control rear wheel lockup. It’s complex and prone to failure .
- A welded differential permanently locks both rear axles together—no electronics, no surprises .
- The conversion involves welding the spider gears inside your existing diff housing, then capping the hydraulic lines that fed the A-LSD.
- Welded diffs are brutal for daily driving—expect tire chirping, understeer, and a workout in parking lots .
- Did you know? Many V-Spec owners remove the A-LSD entirely and replace it with a mechanical 1.5-way or 2-way LSD, calling the factory system “junk” for serious track work .
Understanding What You’re Working With: The R34 A-LSD
Before you start wrenching, let’s talk about what the Active LSD actually is—and why you might want it gone.
The R34 GT-R V-Spec (and some other high-spec Skylines) came with Nissan’s ATTESA E-TS Pro system. That fancy name covers two things: torque-splitting to the front wheels AND active rear differential lockup. The rear diff is an active hydraulic unit. A computer reads inputs like throttle position, steering angle, and lateral G-forces. Then it sends hydraulic pressure to a clutch pack inside the diff, locking the rear wheels together when it thinks you need it .
Here is where it gets interesting. The A-LSD is supposed to be the best of both worlds—open diff for easy parking, locked diff for maximum traction. But in reality, the system has major flaws. The computer relies heavily on the throttle position sensor (TPS) . Off-throttle? The diff opens up. That means if you lift mid-corner, the diff unlocks and your rear grip disappears . Not ideal.
Why owners delete the A-LSD:
- Unpredictable behavior – The computer decides when to lock. You don’t.
- Expensive repairs – When the A-LSD fails, replacement parts are rare and costly.
- Heat sensitivity – The system doesn’t like sustained abuse (track days, drifting) .
- Weight and complexity – All those hydraulic lines and pumps add weight and potential leak points.
“Forget the A-LSD junk. A proper mechanical diff will always win. My car is a V spec… the only thing v spec about it is the sticker on the boot and it’s MUCH better for it.” — R34 V-Spec owner, after converting to mechanical LSD .
Welded Diff vs. Mechanical LSD: Which Should You Choose?
Before you grab the welder, understand there are TWO paths. Both remove the Active LSD, but they feel completely different.
| Feature | Welded Differential | Mechanical LSD (1.5 or 2-way) |
|---|---|---|
| Cost | $0–$100 (DIY weld) | $800–$1,500+ for quality unit |
| Lock Behavior | 100% locked, always | Adjustable lock percentage (varies by setup) |
| Street Manners | Poor—chirps tires, binds in parking lots | Good—street-friendly with minor quirks |
| Drift Performance | Excellent for beginners | Excellent for advanced drivers |
| Rain/Safety | Dangerous—snap oversteer risk | Manageable with care |
| Corner Entry | Understeer (car wants to go straight) | Predictable rotation |
| Tire Wear | Severe—inside tires drag constantly | Normal to moderate |
Here is where it gets interesting. A 1.5-way LSD (like a Nismo or Kaaz unit) locks on acceleration but stays partially open on deceleration. That gives you traction out of corners without the aggressive understeer of a welded diff. A 2-way LSD locks on both acceleration AND deceleration—great for advanced drifting but still more street-friendly than a welded unit .
The budget verdict: If you’re building a dedicated drift missile and don’t care about tire wear or comfort, weld it. If this car sees any street duty, save for a mechanical LSD. Your wallet (and your chiropractor) will thank you.
How to Convert Your R34 A-LSD to a Welded Diff (Step-by-Step)
Alright, you’ve decided. You want that sweet, sweet 100% lock. Let’s get to work.
Safety reminder: Always support your car on jack stands—never just a floor jack. Differential fluid is hot and smells terrible. Wear gloves and eye protection.
Step 1: Remove the Differential from the Car
First, you need to get the diff out of the subframe. This is a heavy job, so grab a friend or a transmission jack.
- Jack up the rear of the R34 and secure it on stands.
- Drain the diff fluid – Remove the filler plug FIRST (make sure you can open it before draining). Then remove the drain plug .
Pro tip: Warm the car up for 10–15 minutes before draining. Hot fluid flows out faster and carries more suspended particles . - Disconnect the driveshaft from the diff input flange.
- Unbolt the axle shafts from the diff output flanges.
- Disconnect the A-LSD hydraulic lines – These run from the diff to the hydraulic pump. You’ll be capping these later.
- Remove the diff mounting bolts and lower the differential out of the subframe.
Step 2: Open the Differential and Weld the Spider Gears
Now the messy part. You need to open the diff housing and weld the internal spider gears together.
- Remove the rear diff cover – Expect old, stinky fluid to drip out.
- Remove the differential carrier from the housing.
- Locate the spider gears – These are the small gears inside the carrier that allow the axles to spin at different speeds.
- Clean everything thoroughly – Oil and welding don’t mix. Use brake cleaner.
- Weld the spider gears to the carrier – This is the critical step. You’re welding the gears together so they can’t rotate.
Warning: This is not a beginner welding job. If your welds break inside the diff, they will destroy everything. Pay a professional if you’re not confident. - Weld the side gears to the carrier (optional but recommended for extra strength).
What your welder needs to know: Use a high-strength steel rod (7018 or similar). Penetration is everything. A cold weld will snap the first time you dump the clutch.
Step 3: Reassemble and Cap the A-LSD Hydraulics
Once the diff is welded and the housing is cleaned, it’s time to put it back together.
- Reinstall the carrier into the diff housing.
- Bolt the rear cover back on with a new gasket or RTV sealant.
- Reinstall the differential into the subframe (reverse of removal).
- Cap the A-LSD hydraulic lines – Since you’re no longer using the active system, you need to cap the hard lines at the diff or at the pump. Some owners remove the entire hydraulic pump and lines to save weight.
- Refill with fresh gear oil – The R34 rear diff takes approximately 1.6L of 80W-140 gear oil . No special LSD additives needed—there’s no LSD clutches anymore.
“When taking the plugs off, always remove the filler hole first. It can leave you in tough situations if you can’t get it off or thread the plug.” — SAU Community diff guide .
Driving Characteristics – Welded Diff vs. OEM A-LSD vs. 2-Way LSD
Below is an interactive chart comparing the behavior of different differential setups across key driving scenarios.
The radar chart shows the trade-off: welded diffs excel at drift performance and cost, but punish you in every other category .
Real-World Driving: What to Expect After Conversion
Let me be brutally honest with you. A welded diff changes everything about how your R34 drives. Some of it is awesome. Some of it will make you question your life choices.
The Good:
- Predictable slides – When you stomp the throttle, both rear wheels break loose together. No guessing which tire has grip.
- Cheap – You just saved $1,000+ vs. buying a mechanical LSD.
- No electronics to fail – The A-LSD pump, sensors, and computer are now irrelevant .
The Bad:
- Parking lots are a workout – Your inside tire chirps and skips every time you turn. You’ll sound like a bus doing a three-point turn.
- Understeer on corner entry – A locked diff pushes the front wide. You have to drive aggressively to overcome it .
- Terrible in the rain – A welded diff on wet roads is genuinely dangerous. The rear end steps out with zero warning .
- Tire wear is brutal – Your rear tires will wear unevenly and quickly. Rotate often or budget for replacements.
Did you know? Some drifters prefer a welded diff because it forces you to drive more aggressively. As one Skyline owner put it: “With a welded diff, you have to drive like a hooligan. It bites back if you don’t use it properly” .
FAQ Section
Q: Can I just swap in a diff from a non-A-LSD Skyline instead of welding mine?
A: Yes, but it’s not completely straightforward. You’ll need the entire differential assembly from a non-V-Spec R34 or an R33 GTST. The housing may have different mounting points, and you’ll need matching axle shafts. Some owners swap R32 GTR diffs as well—just know that ratios vary .
Q: What happens to the A-LSD warning light on my dash after I weld the diff?
A: It will likely come on. The ECU expects to see feedback from the hydraulic system. You can either remove the bulb from the cluster or wire in a resistor to fool the computer. Most drift cars just ignore the light.
Q: Is a welded diff legal for street driving?
A: That depends on where you live. Some regions have strict vehicle safety inspections and will fail a car with a welded diff. Many consider it a “track-only” modification . Check your local laws before committing.
Q: Can I daily drive an R34 with a welded diff?
A: You can, but you probably won’t enjoy it. The constant tire chirping, heavy steering, and aggressive tire wear get old fast. If this is your only car, buy a mechanical LSD instead. If it’s a weekend drift car, weld away .
Q: What’s the difference between a welded diff and a “spool”?
A: A spool is a purpose-built solid piece that replaces the differential carrier entirely. It’s stronger than a welded diff but more expensive. A welded diff is just an open diff that’s been locked—cheaper but potentially weaker if the welds fail .
Q: Do I need to change my driving style with a welded diff?
A: Absolutely. On corner entry, the car will understeer (push wide). To counter this, you need to stay on the throttle or even add power to rotate the rear. Feathering the throttle is key—lifting off completely mid-corner can cause a spin .
Q: How much fluid does the R34 rear diff take after welding?
A: Approximately 1.6 liters of 80W-140 gear oil. No friction modifier is needed since there are no clutch packs in a welded diff .
References & Trusted Sources
- Nissan R34 GT-R Service Manual (A-LSD System Diagnostics) – Nissan Technical Information Portal
- Skyline Owners Forum – Welded vs LSD Track Comparison – Skyline Owners Forum
- SAU Community – Changing Rear Diff Fluid (R33/R34 Guide) – SAU Community
- GTR Forum – R34 V-Spec A-LSD Upgrades Discussion – GTR.co.uk Forum
- LSD vs Welded Diff Full Technical Comparison – XJX Differentials
- ATTESA E-TS Pro System Explanation – GTR USA Blog
Call to Action:
Have you converted your R34’s Active LSD to a welded diff—or did you go the mechanical route? Drop your setup in the comments and tell us what you think of the A-LSD system. Is it truly “junk,” or does it just need the right driver? 🔧
Keep the rear pointed where you want it, watch for understeer on corner entry, and for the love of all that is holy—don’t daily a welded diff in the rain. Your R34 will thank you.
