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Is LSD neede for a FI gs3?

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Old 08-11-05, 07:58 PM
  #16  
JBrady
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Originally Posted by D2-AUTOSPORT
yeah i was thinking of that after i posted. the GS3 has shorter stock gearing than the GS4, I think a GS4 stock is 3.32 or something like that. RMM would actually give taller gearing!
Here are the various years and gears from Toyota:
92-00 Lexus SC300A 4.272
92-98 Lexus SC300M 4.080
92-97 Lexus SC400 3.912
98-01 Lexus SC400 3.266
02-03 Lexus SC430 3.266
92-96 Toyota SupraNA 4.272
97-98 Toyota SupraNA 4.080
93-98 Toyota SupraTTm 3.133
93-98 Toyota SupraTTa 3.769

Going from a 3.912 to a 3.769 is a loss of less than 4% of RWTQ.

A nice upgrade for the non-FI guys would be to find a Limited Slip from a 93-96 naturally aspirated Supra with the 4.27 gears. This would give an increase of over 9% RWTQ.

Going from the GS400s 3.266 all the way to the 4.272 is a gain of almost 31% RWTQ

To put this in perspective, if a dyno "says" 250rwtq... that is actually calculated back to engine RPM. Truth is RWTQ is multiplied by the gears. 1st gear in the 400 tranny is 3.35 to one. Stock diff is 3.266. So, 250 x 3.357 x 3.266 = 2741rwtq in 1st gear

Change that to 4.272s and the number becomes over 30% greater... 3585rwtq

Last edited by JBrady; 08-11-05 at 09:41 PM.
Old 08-11-05, 08:20 PM
  #17  
slowdiver
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jbrady is the man.....

4.27 on the way....no rev limiter isues with 3.92 and 20's non FI........VSC has to be off.

rev limiter issues if you torque brake.

cornering with a clutch-type LSD is amazing......you'll never go back after clutch-type LSD....regardless of chatter.

Last edited by slowdiver; 08-11-05 at 08:30 PM.
Old 08-11-05, 11:58 PM
  #18  
joshoowa
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on that list you forgot to mention that all of those lexus rearends have no LSD.. i also believe not all supras have LSD either, i think all TT's have it for sure but not all N/A's
Old 08-12-05, 10:08 AM
  #19  
JBrady
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Originally Posted by joshoowa
on that list you forgot to mention that all of those lexus rearends have no LSD.. i also believe not all supras have LSD either, i think all TT's have it for sure but not all N/A's
I didn't forget I just didn't take the time in THIS thread to define them.

The ONLY available factory LSD available Lexus car is the IS300. I do not know if there is any compatibilty with the other carriers or housings.

All 1993-1996 Supra TTs had LSD. For 97-98 it became an option on the TT automatics. It was an option on the non turbos for all years.
Old 08-12-05, 03:47 PM
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bluelex
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I'll ask this Q and please don't laugh, where is the LSD installed in our car?
Old 08-12-05, 03:58 PM
  #21  
meZoom!
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Originally Posted by bluelex
I'll ask this Q and please don't laugh, where is the LSD installed in our car?

The actual "Limited Slip" mechanism (i.e. LSD) is a small portion located within the rear differential housing (often called a pumpkin). For some reason, many people confuse the final gearing ratio (i.e. 3.76, 3.91, 4.3, etc) with the LSD part. The two are there for different reasons, but they just happen to reside in the same pumpkin housing. The type of LSD you need will depend on the type of driving you will be doing. For most high-powered turning situations, a stock LSD from any car will NOT suffice, and a clutch type/mechanical LSD is a MUST.
Old 08-13-05, 08:13 PM
  #22  
chuckb
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Default get the complete supra LSD

the taller 3.76 gears compared to stock 3.90 might be a better match for FI anyways......longer gears for more time to make boost. plus you get the posi rear end

I think it'd be a wise choice.
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