Performance Gearing: it's why you drive
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Press | Racing | Testimonials
Press
Jim Blanton and Brett Anderson discuss the limited slip options for BMW final drive units in a Roundel article from their June 2006 issue.
Testimonials
Acceleration from a stand is greatly improved, traction is so much better than before, and the higher gearing does something quite nice. Although, acceleration from 2-3000rpm is a little more sluggish, perhaps the LSD is eating quite a chunk of engine torque??
Through the streets it is a little on the wild side. Traction control does not like it when I punch it out of corners, but I do love it so much, so off the traction control goes, then things really start getting fun. High speed entries result in very nice control through corners, going slower in it feels very much to be stock, although planting it on exit has me grinning again. I have found some rear end instability on hard straight line acceleration, especially at the higher rpm side of 2nd and 3rd, the back end just sways a little side to side, manageable, but unnerving for certain passengers!
Deceleration is much improved regardless when in straight line or turning in, most apparent when on the track, when balance is at the very edge, the rear just seems to hold together so much better. Managed to shave 3-5 seconds of my track time though, so something must be right!
Overall very impressed, great service, great product.
Robert Chan / Shanghai, China
"the new diff is absolutely magnificent. acceleration is much better , the spacing of 2,3,4 now makes driving a pleasure. especially the 2 to 3, car is flying!! 6th gear turns about 3600 at 90 mph, so highway driving is fine as well. the power on engagement is very smooth. 40-60 deg turns in second are astonishing. a little bit of tire chirp, and the car just explodes out of corners. phenomenal. much better than torque-bias diff, no comparison. power off seems also actually very good. i tried to unsettle the car by stuffing 2 gear at 40 mph, no brakes, and dumping the clutch. tires chirp, but the rear does not come out. thank you for this excellent product, it puts smile on my face every time i drive."
- Peter Kulesza, Baltimore, MD
"Ordered a 3:64 limited slip differential from Jim Blanton (great guy by the way) at Performance Gearing for my 2001 540ia with sport package. The diff was shipped when promised and it was securely packaged. Install took about 3.5 hours. Filled the diff with Redline 75-90W with limited slip additive per Jim’s recommendation. Special thanks to Tristan at German Motorwerks for letting me assist with the installation! Great BMW shop for any of you central Florida guys.
Initial impressions after approx. 600 miles. The car is much more responsive and acceleration through the gears is much quicker. 60’ times measured with my Vericom are almost 2 tenths quicker. Car launches much harder with the limited slip. I’ll update with some real times once I’ve had a chance to get back to the drag strip again. Subjectively, the car feels about 300 - 400 pounds lighter.
Last Sunday was my first autocross with the new diff. Only got 2 runs in before it started raining. Initial impression is the new diff allows much harder acceleration off the corners without that annoying right rear tire smoke. Next autocrosses are 9/10 and 9/30 so I’ll be able to give more definitive feedback later.
Gas mileage on the first two tanks is off about .5 to 1 MPG, however, I must admit I’ve been driving a little harder since the install to enjoy the responsive acceleration! I’ll have to average over a longer period to be able to give a definitive answer on this.
Best news of all. The cruise control still works, despite warnings from some that it wouldn’t! Also, the new diff is just as quiet as the factory unit.
It was expensive. $3950 for the diff shipped, but no core charge or return so I still have my 3:15 to sell or re-install if I should ever decide to sell my car. Install and fluid cost $300. Would I do it again? In a heartbeat, however, I would probably consider going with the 3:91 ratio Jim offered.
All in all, one of my favorite mods to date from the standpoint of being able to feel the difference at all times."
- Chris Cochran, FL
"I just wanted to give you some feedback on your excellent 3.64 limited slip differential. It was installed last Wednesday, and filled with Redline LSD gear oil w/ friction modifier.
First, I want to compliment you on your honest, detailed advice and explanations. It truly was a pleasure trading e-mails and talking with you. With so much misinformation on the internet and elsewhere, it is a real pleasure to talk with a professional who knows this stuff backwards and forwards.
Second, thank you for the prompt shipment. The differential was packed extremely well and arrived in perfect condition when you said it would.
Third, the fun stuff, driving impressions. Here's a word: WOW! The 3.64 was just what this car needed to wake it up a little bit. I took it very easy for a couple of days to get the moving parts to know each other. But after driving it over the weekend and today, all I can say is, again, wow! No more of that lull taking off from a stop or accelerating in stop and go traffic. The acceleration is instantaneous. Whether it is accelerating in top gear on the interstate or trying to change lanes in slow traffic, the 3.64 ratio is a big improvement over the 3.15. The car just goes, regardless of the gear it is in. As others have said, the car feels 300 pounds lighter because it is so much more responsive. The unit is just as quiet as the stock unit, as well. There's no noise, grinding or other issues. Crusing rpms are, obviously, higher, but not really noticeably so. The car does not feel buzzy at normal highway speeds at all. I cannot wait to try this out on the track in a few months.
Jim, it truly has been a pleasure doing business with you. You exceed your reputation. Now we'll have to see about doing something about our 330i performance package's open diff."
- Sean Costello, GA
