How Can You Tell If You Have A Limited Slip - LotusTalk - The Lotus Cars Community
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post #1 of 22 (permalink) Old 11-12-2006, 12:32 PM Thread Starter
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How Can You Tell If You Have A Limited Slip

MY S IS SUPPOSED TO HAVE A LIMITED SLIP .I PUT THE CAR WAS IN THE AIR AND I ROTATED ONE REAR WHEEL THE OTHER WHEEL ROTATED IN THE OTHER DIRECTION THE SAME AS A OPEN DIFFERENTIAL DOES. EVERY OTHER CAR I'VE HAD WITH A LS THE WHEELS ROTATE IN THE SAME DIRECTION. WHATS UP? IS THERE SOMETHING DIFFERENT WITH A TORSEN ? WHAT CAN I LOOK FOR,. HOW CAN I TELL? IF IT ISNT IN THERE LOTUS AND I ARE GOING TO HAVE A TALK. THE CAR HAS THE PERFORMANCE GROUP THAT INCLUDES TC & LS. SORRY FOR ALL THE CAPS BUT I DONT KNOW HOW TO UN LOCK IT. THANKS CARL
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post #2 of 22 (permalink) Old 11-12-2006, 12:43 PM
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I don't know about the LSD, but there is a key to the left of the A on your keyboard that will turn off caps lock.

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post #3 of 22 (permalink) Old 11-12-2006, 12:53 PM Thread Starter
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thanks i just found it c
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post #4 of 22 (permalink) Old 11-12-2006, 12:55 PM
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Was the car in GEAR when you did it? If not, do it again, with the car in gear and report back.




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post #5 of 22 (permalink) Old 11-12-2006, 12:55 PM
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Mine actually says LSD written in Sharpie! Can see it when you pop the boot and look straight down into the engine bayfrom the back center.

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post #6 of 22 (permalink) Old 11-12-2006, 01:14 PM
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Quote:
Originally Posted by MyElise
Watch "My Cousin Vinny".
But how could you be so sure??

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post #7 of 22 (permalink) Old 11-12-2006, 01:26 PM
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Quote:
Originally Posted by Rugbyduck
Mine actually says LSD written in Sharpie! Can see it when you pop the boot and look straight down into the engine bayfrom the back center.
Mine, too. I bet they use an official Lotus-brand sharpie to do it

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post #8 of 22 (permalink) Old 11-12-2006, 04:11 PM
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Quote:
Originally Posted by 4carl
I ROTATED ONE REAR WHEEL THE OTHER WHEEL ROTATED IN THE OTHER DIRECTION THE SAME AS A OPEN DIFFERENTIAL DOES.
Not here too... This pops up over and over on the Miata forum.

Quote:
Originally Posted by MyElise
Watch "My Cousin Vinny".
That only works for American made/GM cars equipped with a clutch pack differential.


There are different types of Limited Slip Differentials.

The typical American car usually has a clutch pack type of differential - there are spring loaded clutches that "lock" one axle to the other side. If you turn one wheel, the other will turn in the same direction. One wheel will not turn without the other unless you can apply a lot of force (like the weight of a heavy car turning sharply). There is very limited slip. They have a tendency to wear out over time as the clutch packs wear.

Torsen type of limited slips do not use clutches. They have a series of worm gears inside the differential. They "lock" the two axles together when there is force being applied from the input of the differential - when power is being applied. When there is no power being applied, a Torsen behaves like an open differential. One other quirk is that if one wheel completely looses traction (is raised in the air), the Torsen will no longer "limit the slip" - all the "power" goes out the spinning wheel, and you essentially have an open differential. Torsen differentials do not wear out, they work by mechanical forces, not friction forces (that wear).

There are also Viscous Limited Slips what have the two sides connected by a sealed container of very viscous fluid - as differential rotation occurs, the viscous fluid heats up, and "locks" the two side together. The downsides are that the viscous LSD tend to wear out, and they don't do much limiting in the first place.

There are other types of Limited Slip Differentials, but but the main ones of interest are the ones above.

The Elise has a Torsen Limited Slip Differential.

There is specific tests to determine that a Torsen LSD exists, but it requires careful measurement of the forces exerted when compared to a specified turning force.

Many people can simply "feel" the handling with/without the Torsen. Some can tell by it's behavior during a tight turn. But the only real way that I know of to really demonstrate the existence of a Torsen LSD is to stop your car on the side of the road. One wheel on drive pavement. The other wheel on sand/grass/dirt. Rev up the engine and dump the clutch. If both wheels spin, you most likely have a Torsen. If only one wheel (the one on the pavement), you most likely have an open differential. If neither wheel spins, you did try hard enough - rev the engine more, and/or dump the clutch quicker. Anything that happens as a result of the ECU dump is not my problem.




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post #9 of 22 (permalink) Old 11-12-2006, 05:00 PM Thread Starter
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well i looked and there is lsd in green sharpie on the top of the gearbox.i wonder if there all the same and they just charge you $1700 and take a marker and put LSD on the trans. carl
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post #10 of 22 (permalink) Old 11-12-2006, 05:25 PM
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Quote:
Originally Posted by 4carl
well i looked and there is lsd in green sharpie on the top of the gearbox.i wonder if there all the same and they just charge you $1700 and take a marker and put LSD on the trans. carl
I just converted mine to LSD for $2.98.

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post #11 of 22 (permalink) Old 11-12-2006, 06:25 PM Thread Starter
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you may have also increased the resale value.carl
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post #12 of 22 (permalink) Old 11-12-2006, 07:36 PM
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Quote:
Originally Posted by TimMullen
If both wheels spin, you most likely have a Torsen. If only one wheel (the one on the pavement), you most likely have an open differential.
Why would the one on the pavement spin with an open differential? I would have thought that the wheel with less grip spins.

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post #13 of 22 (permalink) Old 11-12-2006, 09:21 PM
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Quote:
Originally Posted by ConeFusion
Why would the one on the pavement spin with an open differential? I would have thought that the wheel with less grip spins.
Power is biased to the wheel with the least amount of traction so that inexperienced drivers dont wreck every day.

Its the same design philosophy that brought us understeer.
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post #14 of 22 (permalink) Old 11-13-2006, 06:13 AM
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Quote:
Originally Posted by wts
Power is biased to the wheel with the least amount of traction
That was my point. Tim suggested that the wheel that has more traction spins, which would mean that power is sent there.

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post #15 of 22 (permalink) Old 11-13-2006, 06:29 AM
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Tim must be talking about the Touring version (Just kidding). On an open diff the wheel on the sand/grass/dirt will spin.
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post #16 of 22 (permalink) Old 11-13-2006, 06:58 AM
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Quote:
Originally Posted by 4carl
well i looked and there is lsd in green sharpie on the top of the gearbox.i wonder if there all the same and they just charge you $1700 and take a marker and put LSD on the trans. carl
You've got it -- it says lsd/understeer in green sharpie.

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post #17 of 22 (permalink) Old 11-13-2006, 07:19 AM
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Quote:
Originally Posted by fpitas
Mine, too. I bet they use an official Lotus-brand sharpie to do it
+2

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post #18 of 22 (permalink) Old 11-13-2006, 07:41 AM
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Actually, if the LSD is working properly, both tires should spin equally even though one is on the slick grass. That's the whole point. If you DON'T have LSD then the one in the grass will just spin by itself and the one on the pavement won't help you.

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post #19 of 22 (permalink) Old 11-13-2006, 08:16 AM
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Quote:
Originally Posted by Jack
You've got it -- it says lsd/understeer in green sharpie.
Mine must be the version that doesn't understeer... LSD was written with a black Sharpie!

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post #20 of 22 (permalink) Old 11-13-2006, 08:25 AM
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Was the car in GEAR when you did it? If not, do it again, with the car in gear and report back.
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