Jeff - good luck with the Wavetrac. I am surprised that they had to remove the differential to install the LSD. I know on some cars you can install the LSD by simply removing the rear cover on the diff. Is there a different recommended differential fluid?
That's not a bad price. I hope it works out well for the supercharged beastie.
I'm a little surprised that the SLK doesn't have a LSD as standard, to be honest. Never thought to look there. All the 2L Alfa Spiders from 1971 on had LSD as standard equipment, set with an unusually low torque transfer figure IIRC so as to enhance handling and not get into the kind of stutters that a high torque transfer LSD could produce on a wet road. Most later Alfas had them, the Jaguars all had them starting with the first IRS models in the early 1960s.
I guess the ESP traction control system obviates an LSD to a great extent ... ?
I was actually thinking more high-level, from a design perspective.
Generally, a Limited Slip Differential is used to ensure that power is distributed across the driving wheels through the differential even when one of the driving wheels is on a slippery surface where without an LSD that wheel would free wheel and power would flow there rather than to the driving wheel. With ESP traction control, when a wheel begins to slip, the car applies the braking system to that wheel, pushing power to its mate on the opposite side of the differential thus performing the same function.
The difference is that the ESP system costs some power and braking performance where an LSD operates typically via some type of clutching mechanism in the differential, which doesn't affect the braking system at all and absorbs a minimum of power. So an ESP system can effectively be used in place of a LSD and probably costs a lot less.
(My old Land Rover Freelander did something similar to ESP but for rough terrain crossings: you enabled the "descent mode" traction control system, took your feet off the brake and throttle, and it balanced the operation of braking system and throttle control to successfully negotiate incredible inclines at low speed, maximizing tire traction without having to go out and lock up hubs or switch a transmission transfer box into a fore/aft or side-to-side locked 4WD configuration.)
'Full-locker' differentials are often used on dirt track race cars to ensure that the driver can break traction and slide through corners, but allowing the wheels to rotate at different speeds on drying surfaces when otherwise they might break pieces in the drivetrain. LSDs with lower torque transfer percentages are generally used for road cars to enhance traction on varying surfaces, based on the amount of power that the car has and the intended about of drift and wheelspin that the designer feels optimizes handling characteristics. ESP systems are significantly less expensive and much more adjustable to work with, considering the downsides of braking performance and power consumption they imply.
I like to study and consider the engineering bases of these things ...
But now I think I'm going to get into the SLK and go for a drive.
From my experience (SLK55 with S/C & LSD), the ESP is less intrusive but it still happens on hard launches or accelerating "medium fast" from a stop around a corner turn.
I still turn the ESP off if I know I'm going to floor it from a launch, or at the stop sign from my corner onto the main road where I have to turn and accelerate quickly to get into traffic.
I think the LSD basically puts the S/C car back to about how the stock car does with ESP, although it's been a while since I drove that way so who knows. I'm curious whether Jeff's experiences mesh.
edit: my LSD is a Quaife, so results may slightly vary ... the quote below is from a different forum in response to a question asking to compare the two (Quaife & Wavetrac):
Jacob@ACGautomotive said:
All pro's vs an open diff. No Con's.
Difference between the two diffs are the wavetrac will keep the axle spinning under zero load conditions, ie if you lift a wheel the wavetrac can still deliver power to the wheel off ground.
Personally I don't think most people would ever know a difference in either diff they both perform amazingly even over the stock LSD in performance package cars.
Just to clarify, Jeff does not have a LSD, he does not have a Locker, he does have a TBD! A Torque Biasing Differential.
The Quaife and the Wavetrac are not LSDs or Lockers they are torque biasing differentials.
A differential that attempts to maintains equal torque to both driving wheels.
A Locker or a LSD under power will break the inside the turn wheel loose. TBD will not. (but with adequate power you can brake both wheels loose, like a locked differential)
With the SC on the 55 and a TBD you can point in the opposite direction with a blip of the throttle in about halve a second from a stand still.
Jeff reads EVERY post, and he misses nothing... you'll soon learn that.
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