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 :)

6. Differential

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



http://www.clublexus.com/gallery/data//4605/2010_LSD.JPG

http://lexus.jp/models/isf/performance/suspension/images/img_performance_lsd_01.jpg



Joe Z

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

Yes please!! :D

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...

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.

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

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

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

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!

now a torsen 4.08 gear would be the bee's knees

Fo' rizzle!

Hey Doug, if your shop wants a test mule... i know an F with the 4.08 already installed, and is just dying for LSD.. ;)

J,
I will keep that in mind! Have you had your IS-F out much this summer? I trust that you are still enjoying the heck out if it. :D

Doug

Doug,

Have any part numbers made there way through the system yet??

I am waiting to know if the actual 2010 Torsen LSD unit will be made available as a service replacement part..

or if it will be easier to just replace the entire Rear Diff...

2008-2009 shown below....
http://www.sewellpartsonline.com/images/assembly/5084.JPG


Joe Z :D

Hey Doug..

So 3 months later... No one has done this yet..

Here is some info.

I confirmed earlier today.

The 2010 Torsen LSD (entire differential unit) Part number is 41110-53290 MSRP is $4,313 :eek:

I found it online for $3,034..


Happy Holidays!!

Joe Z :D

If it fits and works with the electronic LSD, that would be great.

has there been any more speculation/info from this idea? i recently read that a 2010 isf went around fuji 2 seconds faster then any 2008-2009 because of the lsd. that is some serious time savings.

Hi all,


Any futher news of this happening..?

I spoke to my service manager today and he said if i order it they can fit it , but he was worried bout the VDIM not liking it too much , but kudos to anyone who has it done.?

Any replys/thoughts.?

Richie.

Richie,
I don't know of anyone who has made this swap yet. You have permission to be the first! :D

Richie,
I don't know of anyone who has made this swap yet. You have permission to be the first! :D

Doug,

If we can work something out... I don't mind being the 1st to try...
See my post#16..

Joe Z :cool:

I am up for testing as well. It will be a great compliment to the new stuff I got on now in testing.

any updates??

subscribed, very interesting info.

Has anyone installed the LSD?

Hi guys,

Im in Sydney, Australia. Am currently doing a bit of research in this regard, however the 2010 spec lsd diff is priced at a hefty $5k here. so not sure if Doug could get me a price including shipping to Sydney ,(pm me if you need my exact address.)

I need to know if the Drive shafts that go out to the wheels are the same for 2008 to 2010.,
Also if the ECu can be upgraded to 2010 spec for the VDIM system or will it work just dandy as is.?

Any extra info on this will be appreciated.!!

Richie

Hi guys,

So Ive just found out the Part number on the driveshafts are the same from 2008 to 2010 , so you would only require the Diff assembly.
Also the VDIM also the same between the 2. So having said that , I will await to hear back from Doug and get a price as per my previous post .


Richie

Hi Richie,
please go ahead and e-mail your address to me and I'll do my best to assist you in your venture! I apologize for the delay in responding however I haven't been able to monitor the forum as often as I would like. Also, I will be away for our upcoming Thanksgiving holiday for a few days.

Doug

What exactly does a lsd do for the f?

Historically, a "posi" traction or Torsen rear end diff has been popular because it provides better launches, better road course track times. Not saying that "posi" and Torsen operate mechanically the same way but the end result is similar. The Torsen unit in the 2010 > IS-F's encourage engagement of both rear wheels with equal torque. This makes for awesome huge smoky burnouts with both wheels spinning instead of just one.
I found this cool little Lego video describing the difference between an open diff and the Torsen diff. We all loved (or still love) Lego's, right? I'm sure there are plenty of videos out there but this one seemed pretty easy to follow.

http://www.youtube.com/watch?v=osKLMzYxyyw&feature=related

Here is a very breif history of Torsen: Pay close attention to the year 2003.:)
http://www.torsen.com/history.htm

thanks for reply

I am very interested in this project! It has very good input from everyone which is refreshing from other forums that just have differences in opinions. Keep up the great work I will be following along to see the outcome!

3500$ for lsd with my employee pricing

Torsen LSD

Just had an interesting experience that I thought an LSD would fix but apparently not with a Torsen LSD.

Should one wheel loose complete traction i.e. in the air going into a steep driveway you will loose total drive from the wheel on the ground.

Apparently a Torsen Diff is a torque drive off a ratio of grip i.e. 5 to 1, i.e. 5 x 0 = 0.

Am I right in this assumption?

Thanks


PS: Oh, had to push the car off the drive way :o

Sorry if this has been addressed, but using the search did not yield any results. Has anyone swapped the new LSD or Suspension into an older IS-F yet? I know Joe and Lobux have provided a lot of information and interests in one or both of these swaps, but I have not seen or heard of anyone actually taking the 'plunge'.

Thanks,
Charles