As stated in the title, does anybody know the torque bias ratio for the stock ITR helical LSD? Quaife would not disclose the torque bias ratio for their unit, as they said the information was proprietary. Translation, no sale for you! I'm just curious.

 

Nobody on here can answer this?

 

Here ya go (complement of "Todd" from "clubintegra.com":

"...here's a little info on lsd percentages
The limited slip percentage (S) is also called the locking factor.
It describes the maximum applied torque difference between rear wheels
compared with total applied torque. Passenger car LSDs are usually
in the 25-40% locking factor range. Most BMW LSDs are 25%.


Limited Slip Locking Factor or Percentage S
(note: drive torque is torque applied to road surface)

Drive Torque Difference Between Rear Wheels
S = ------------------------------------------- x 100%
Total Drive Torque of Both Rear Wheels


Think of a situation where the two rear wheels are on
different surfaces with different coefficients of friction:

H = Higher traction, more torque can be applied to road surface
L = Lower traction, less torque can be applied to road surface


H - L
S = ------- x 100 %
H + L

By rearranging the equation a little, you see that for a 25% LSD,
the High torque side can be as much as 62.5% of the total while the
Low torque side can be as little as 37.5% of the total.

25% LSD Example:

S + 1 0.25 + 1
H = ------- = -------- = 0.625
2 2

-S + 1 -0.25 + 1
L = ------- = -------- = 0.375
2 2

The H/L ratio, called the bias ratio, is easier for me to think about
because it quickly shows how much more torque can be sent to the high
side. With a 25% limited slip, it is possible to have 1.67 times as
much torque applied to the high side. A 40% LSD works out to a 2.33
bias ratio.

25% LSD Example:

H S + 1 0.25 + 1
--- = ------- = -------- = 1.67 (Bias Ratio)
L -S + 1 -0.25 + 1


A locked differential has a 100% locking factor (infinite bias
ratio) because all torque can be applied to one wheel (e.g. one
wheel on ice or in the air). For a limited slip, the initial
preload, or break-away torque, allows power application when one
drive wheel is on ice or in the air. Open differentials are
another story

In theory, an open differential has 0% locking factor (1.00 bias
ratio) because the torque to each wheel is balanced (H = L). In
actual practice, there is some bias because the differential is
not friction free."

Hope this help,
Chris

 

That is a good general description of LSD behavior, however I'm looking for the torque bias ratio (TBR) for the ITR LSD. Torsen's site shows that their T-2 LSD typically has a TBR of 1.5-3.0 for a FWD car. The TBR is similar to the limited slip percentage mentioned above, but is the direct ratio of the high and low wheel torques.

TBR = (maximum high wheel torque)/(low wheel torque)

I'm looking for the actial TBR number for the ITR LSD. It can be back calculated for the helix angle of the planetary helices, but that is complicated.

 

Yo D!! How's that thing holding up? I found a few bolts on my garage floor when you left!!! HAHAHA

 

I am trying to get this info to, got a contact at torsen, but were not even 100% sure the ITR diff is a Torsen model, maybe made under liscence by another OEM manufacturer. Not even sure if the ITR diff is type 1 or 2, assume its 2 but never seen one opened up

If i ever find the info i will let you know. Got a few contacts at Quaife too, so will try and get a comparrison too

Would be very surprised if the TBR is more than 2 though, doesnt feel grabby enough to be that high

 

Wickmaster and I installed the ITR LSD in my GSR last week. This is a huge change over the open differential. I agree with the ratio of 2 for FWD. One major thing that I now notice is that on wet, tar-patched parking lots, the tires squeek a bit when making normal 90 degree turns, which possibly a side effect of moderate locking. Unfortunately I haven't been able to fully explore the functionality due to the Blizzak WS-50s that are currently mounted.

The ITR unit is a Torsen based design. The helix gears are parallel to the differential rotation axis as in the Torsen T-2 design. Good luck with getting information from Quaife, as Ralph Hollack would not disclose the TBR to me.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wickmaster &raquo;</TD></TR><TR><TD CLASS="quote">Yo D!! How's that thing holding up? I found a few bolts on my garage floor when you left!!! HAHAHA</TD></TR></TABLE>

Those bolts? Oh, their from your GSXR.


Modified by Dogginator at 10:58 AM 2/17/2005

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dogginator &raquo;</TD></TR><TR><TD CLASS="quote">As stated in the title, does anybody know the torque bias ratio for the stock ITR helical LSD?</TD></TR></TABLE>

The stock ITR LSD is at about 30%. I read this information from some aftermarket LSD advertisement, saying how much their product would perform compare to the stock unit. So it's not really an "official" answer from Honda.