KPCresta

Hello all

I recently acquired an 08 Lexus GS450H and wanted to enquire about changing to a shorter final drive to improve acceleration. From what I understand the GS450H has a 3.7 ratio with the CVT trans.

I am certain it is an 'A' series diff shared among numerous other Lexus and Toyota models of which there is a 3.91, 4.08 and 4.27 ratios available.

Have any other forum members with 3rd gen GS's fitted the Toyota factory Torsen centre to their diffs and changed the ratio? While I am sure mechanically the parts will fit I wanted to make sure electronically there won't be any gremlins (as with people having trans issues and the like when installing IS350 diffs in their ISF)

Does the CVT trans have any sensors or inputs from the diff which may cause issues if the ratio is changed?

Any help or other information would be most appreciated. Cheers

petershen

This is something I may try at some point. I believe our GS450h has the 3.266 final drive. An option is to try the GS350's 3.769. I'll update again if I can get it to work.

gs350fan

This will certainly change shift points and require some sort of tune.

Lwerewolf

There is a thread about it (amongst other things) on the Russian club lexus forums:
https://club-lexus.ru/forum/viewtopic.php?p=4284005#4284005

I've been looking into swapping a differential, and so far it appears that just about anything from an 2/3 gen IS or 3/4 gen GS... or certain LS's... and lots of JDM-only cars will work. OS Giken should work too. Will post details later.

petershen

The GS450h has a two stage planetary CVT so it has no "shift points", 3.266 to 3.760 is about 15% shorter... there's only one way to find out if it works

petershen

Great! Thanks for sharing. I hadn't thought of a mechanical LSD yet but that's an interesting option.

Lwerewolf

I suggest looking at the 2IS/3IS IS350 LSD threads over here (os giken, OEM torsen, so on) to get a feel for what's available. I will link a few at the bottom of this post, but there are more - make sure you search. I would avoid dremeling axle shafts as much as possible.

See below:
gs450h differential diagram: https://lexus-europe.epc-data.com/gs...is/4101/41301/

EDIT: all links to a certain site removed, forum seems to be censoring them. Amazing.

If you cross-reference the diff assembly... doesn't look so good: ---
...is220d, crown hybrid/gs450h (kind of the same cars).
Now, let's look at individual components:
Flange: ---
Open diff unit: ---
Cover: ---
Pinion (the actual final drive): ---
...and the 4.08 final drive of the is350:
---
---

Cross referencing the subframe: ---
Cross referencing axles: ---
Hub and bearing: ---
Axle carrier: ---
Suspension arm #1: ---
Suspension arm #2: ---
Toe control: ---
Upper arm #1: ---
Upper arm #2: ---

At any rate, this is pretty much the whole rear end. If you end up comparing the frame/floor panels and so on, it gets a bit funny. I've always liked the JDM-only (oh sorry, China too... now that got me thinking - LHD!) crown/mark X/etc body styles.... just need to swap the whole upper mid portion

Threads to read:
https://www.clublexus.com/forums/per...sd-thread.html
https://www.clublexus.com/forums/is-...-my-is250.html
https://www.clublexus.com/forums/is-...orsen-lsd.html - second post.

petershen

Great info! I'm looking to pick up the rear end from a GS350 and take it apart to see what I'm working with. The FIGS OS Giken one looks really good but super expensive and way over my budget.

Using an OBDII scan tool my cruising engine rpm at 100kph varies between 1,400-1,800rpm depending on the throttle load, MG2 traction motor is about 4,000rpm if active. If I go full throttle from standstill MG2 hits 10,000rpm before the 2nd stage gearing kicks in, engine rpm goes to about 5,000rpm and is held there by MG1, 0-100kph is clocked at about 5.4 seconds on 295/30R19 PSS tires, not too bad for such a heavy beast

The CVT transmission has two stage gearing, 3.90 and 1.90, I'm hoping that 3.769 can give a bit more performance.

Lwerewolf

A bit of a necro, but I just did some research and...

JDM - GWS191-BEXQH:
41110-50230 FINAL GEAR RATIO=49:13=3.769 (09/2007 - 02/2010)
41110-50231 FINAL GEAR RATIO=49:13=3.769 (03/2010 - 09/2011)
41110-50232 FINAL GEAR RATIO=49:13=3.769 (10/2011 - 11/2011)

US - GWS191L-BEXQHA:
41110-50230 FINAL GEAR RATIO=49:13=3.769 (09/2007 - 02/2010)
41110-50231 FINAL GEAR RATIO=49:13=3.769 (03/2010 - 09/2011)
41110-50232 FINAL GEAR RATIO=49:13=3.769 (10/2011 - 11/2011)

All's well until...
EUDM & General - GWS191L-BEXQHW, GWS191R-BEXQHW (resp. LHD & RHD):
41110-30A90 FINAL GEAR RATIO=49:15=3.266 (09/2007 - 02/2010)
41110-30A91 FINAL GEAR RATIO=49:15=3.266 (03/2010 - 09/2011)
41110-30A92 FINAL GEAR RATIO=49:15=3.266 (10/2011 - 11/2011)
Same diff assembly as the IS220D.

Drive & axles are the same.

So...
3.769 is the same diff assembly that the GS350 uses. Guess what my next mod is

petershen

EDIT I can't seem to confirm if our GS450h has the 3.266 or 3.769 ratio... Mine is a JDM RHD model... I'm getting conflicting information

OK mine is not JDM but the EU RHD model

petershen

OK based on my research, GS450h has 2 axle codes, B01A and B02A.
The US models seem to be all B01A, the RHD models in Europe/Japan export seem to be B02A

It *appears* that B02A = 3.266... which is what I have, still searching.. open to ideas.. thanks!

Lwerewolf

JDM models (RHD) should have the 3.769 ratio as well.

Are you sure that yours is a JDM model and not another RHD model? What is the model code of your car?

Mine's GWS191L-BEXQHW (EU, LHD) - W at the end is (I guess for) World.
Japan is GWS191-BEXQH - notice the lack of L/R at the end of GWS191.
USA is GWS191L-BEXQHA - A at the end is (I guess for) America.
World (I guess Asia/Pacific, South Africa, Middle East) is same as Europe - GWS191L (for LHD) / GWS191R (for RHD).

petershen

OK I checked the vin plate again, mine says
GWS191R-BEXQHW (I guess they sold the EU RHD model here instead of the JDM model)
2GR-FSE
L110 B02A

So I'm guessing your Axle Code is also B02A? Then we should have the same 3.266 FD I think... I could never make any sense of the axle codes for Lexus, seems to be different for different models

petershen

Anyway, I've ordered an RC350 AWD differential to try, will update!

Lwerewolf

Different pumpkin cover, but I guess you've already read that you'll have to swap yours over.