2010 Torsen LSD Diff - Lexus ISF / IS-F / LFA / LF-A Forum
 
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post #1 of 35 Old 09-04-2009, 05:26 AM Thread Starter
Joe Z
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Lightbulb 2010 Torsen LSD Diff

Hi Doug,

Since you guys did a ton of home work on the Differential swap on the IS-F..

The next best thing is to see if we can get the factory Torsen LSD unit into our 2008-2009 IS-F's...

Do you think it would be easier / less expesnive to see if the actuall Torsen unit can be ordered and installed into our OEM Diff..

or

Just order up a whole new 2010 IS-F Diff with Torsen in it..


Lets discuss..


Feel free to call me too.


Regards,

Joe Z

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post #2 of 35 Old 09-04-2009, 05:28 AM Thread Starter
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Lightbulb

Quote:
Originally Posted by Lexus TIS

6. Differential

The rear differential has been changed from FD21A type to FD21AT (TORSEN* LSD) type.
*TORSEN is a JTEKT registered trade mark.








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post #3 of 35 Old 09-04-2009, 05:25 PM
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Hi Joe,
from first glance, it appears that the complete rear end housing with gear and torsen would "bolt in". I have not confirmed that yet but I have sent an e-mail off in hopes of getting a response that will confirm or deny that fact! I will keep you updated.

Doug
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post #4 of 35 Old 09-07-2009, 08:00 PM
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Yes please!!
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post #5 of 35 Old 09-07-2009, 08:50 PM
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BUY A NEW ISF...

The 2010 has a good list of new features that would be worth the trade in. Torsen LSD would be about $2500+8 Hours of labor, plus wouldn't it need an ECU update?


If I can get a new ISF at invoice and trade in my 08 ISF for 42K.


I'd be willing to pay the difference for the additional upgrades...(Navi, music interface, streaming bluetooth, new moonroof controls, better looking dash, etc...)

They need to add remote start to the 2010 ISF...


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post #6 of 35 Old 09-11-2009, 09:37 PM
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I have some encouraging information to share about the planned Torsen limited slip for the 2010 model IS-F. Please keep in mind this info is unofficial until a swap is actually performed and tested!
The 2010 IS F offers a Torsen limited slip differential installed in a type
FD21A rear differential.

This is the same type of differential case that was standard in the 2009 IS
F and means that the Torsen LSD could be a complete bolt-in for earlier IS Fs.

Based on this first look at the technical literature, it looks encouraging.

You wouldn't know for sure until someone lines up two cars on the lifts and
starts dropping parts on the floor. There's always the possibility that
TMC might have changed something like the number of splines on the side
gears, or the threads for the mounting bushings, etc.

The new IS F Torsen unit also seems likely to fit in earlier IS 350s, since
they come with a type FS21F (though not IS 250s, which have a narrower type
F19SX diff with different mountings for the subframe).
Preliminary info we have so far does not indicate any change to the gear
ratio of the IS F final drive. TMC rarely changes the final drive ratio
unless there are other drivetrain changes (engine output increase,
transmission change, tire size change, etc.).

Based on that, we assume that the 2010 IS F final drive gear ratio is
unchanged from the current 2.937:1.

Now, as for the auto-limited slip (A-LSD) function of the brake control
system on the 2008-09 IS F:

It's not clear that the LSD-equipped IS F would have to lose the A-LSD
function. We've had models in the past that integrated a LSD with VSC (a
Torsen was available on the original IS 300), and the two did not conflict
with each other.

Theoretically, the Torsen acts instantaneously, while all electro-hydraulic
systems have some time-lag. So if the Torsen works first and can limit
side-to-side wheelslip, the A-LSD may not be called upon, and there may be
no issue.

In any case, I cannot think of any way to permamently disable A-LSD: there
are no specific parts or sensors dedicated just to A-LSD that could be
removed from the circuit. It's just completely integrated into the brake
control network & hardware for VDIM. A-LSD is going to come on when the
VDIM system feels it's needed.
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post #7 of 35 Old 09-12-2009, 12:24 AM
doublexl
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so from that i gathered that it would most likely fit, and if you turned off the vdim, then you would get all the benefits of the mechanical lsd, without the a-lsd getting involved. but it might and probably would still cut in if you left the vdim on

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post #8 of 35 Old 09-12-2009, 04:48 AM
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Quote:
Originally Posted by FChampOH View Post
Based on that, we assume that the 2010 IS F final drive gear ratio is
unchanged from the current 2.937:1.
The Lexus Literature does state that the axle ratio for the 2010 model IS-F does indeed remain unchained at 2.937:1

Lou

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post #9 of 35 Old 09-12-2009, 06:16 AM Thread Starter
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Good info Doug.....

I pretty much figured it was a direct fit.

Is there going to be a replacement part made available for the actual Torsen LSD Unit??
Opposed to buying a whole new rear end..

It would be interesting to know the price for the whole differential verses the price of just the LSD unit..


Some data that was dug up over on Club Lexus, states that the 2010 skid control Ecu location was redesigned and changed to under the hood...


I too hope that the mechanical LSD is not interrupted by the electronics, after a successful swap is completed..

Joe Z

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post #10 of 35 Old 09-12-2009, 01:14 PM
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Quote:
Originally Posted by doublexl View Post
so from that i gathered that it would most likely fit, and if you turned off the vdim, then you would get all the benefits of the mechanical lsd, without the a-lsd getting involved. but it might and probably would still cut in if you left the vdim on


What I re-read from what I posted was that the A-LSD most likely would not interfere with Torsen if retrofitted. Which is a good thing!
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