Important thing is that the diff is complete and you dont have to shim a new set of gear and pinion, thats a pain in the butt. If its just a diff cover thats easy to swap out.

 

Yes I was planning to do the bushings too, what I read from the ISF guys is that if you are doing the differential bushings as well, you can keep the RC cover on and just clock the left bushing 90 degrees. Might go with the Figs poly bushings while I'm at it...

 

I'm definitely going to just change the oil and swap it in... will swap covers if I have to, not planning to have to deal with shimming I'll probably wreck it :P

 

My differential has arrived! Got it on ebay from a wrecker and shipped it 10,000 miles to me... It came off a 2015 RC350 AWD, according to the IS guys it's a direct fit to the 3GS, so we will find out. I'll need to swap the carrier bushing to be vertical to accommodate the diff cover bolt pattern.

 

Any update on this? Just curious if there will be any difference with the CVT. Technically, with a sufficiently wide ranging CVT, final ratio doesn't matter. With the IS F, you'll see a quicker launch, but once you hit redline in first, all the rest of the numbers are the same. Power in = power out. Simple physics you can't escape. So what you gain is a shorter time to redline in your lowest ratio and higher cruising rpm with fixed gear transmissions. CVT might correct for that, but you'd have to try it to be sure.

 

I've been procrastinating on this one... oops, coz the damn thing is heavy, I might take it to my friend's shop with a lift and just pay him to do it together.

I've never done this on my car before, and based on the threads on the ISF forums, some guys managed to swap out the diff on ramps without taking off the wheels, others looked like they practically removed the entire rear drivetrain... I guess we'll find out.

I'll definitely try to do this before the end of the month. I'm pretty sure the wife would have thrown it away had it not been so heavy

 

I put an OS Giken spool in my IS F differential using jackstands. What seems to be hardest for home mechanics is removing the axles. You need a lot of leverage to get the circlips to compress, and you really need to do this before doing anything else to remove the diff housing from the car. I used a 5 lb hammer and a brass drift. Others have used 3+ foot prybars. The rest is pretty straight forward.

 

@lobuxracer did you do it on jackstands? I saw some comments from the ISF guys that it is easier on ramps with the wheels on, since the axle half shaft angles are near parallel instead of drooping, and gradually lowering the diff actually helps the axles come out... if the axles are drooping, lowering the diff will make the axles want to go back in... seems to make sense. Not looking forward to doing this one heh

 

I did it on jackstands. If I were doing it again, I could see how ramps and wheels on might be easier. The key is to remove the braces below the axles to allow the diff to drop unimpeded once you have the axles popped out of the spool. As the diff drops, you gain clearance to remove the axles without disassembling half the rear suspension. This is what I gather from the pics I have seen. I ended up pulling apart a lot of the suspension to get the axles out without removing them from the rear hubs. I also had a friend and my brother helping, so there was no shortage of hands to get things done.

 

While I'm waiting for the oil seals and some parts from Megazip, it struck me that going from 3.26 to 3.77 is not really pushing any boundaries, but converting my Euro RHD GS450h to a JDM/USDM GS450h...

It would still be very interesting from a before/after standpoint and I'm definitely looking forward to it.

 

In the end I'm paying my buddy's shop to do it, we dropped the whole subframe to check on the bushings, all seems OK, will try to button everything up tomorrow.

 

@Lwerewolf and @hybrid450 if you're thinking of this mod... just go do it I think the GS450h was designed for the 3.769... I'm able to sustain the pure electric mode much longer, energy recovery seems very slightly better, overall city driving experience is improved.

@lobuxracer
The car feels more responsive and muscular in a refined way, quite noticeable. Maybe going from 3.266 to 3.769 is not as drastic as going to 4.0+. I also put in the Figs pinion supplemental differential bushings maybe that helps as well.

 

Not anytime soon, got a lot on my plate... the 3.769 diff is the last thing on the list right now

 

Sorry for my English. Congratulations. Is this modification p&p? Do you have to change any parts to make it fit? Why did you choose diff from AWD and not from RHD?

 

There are a few different Lexus 3.769 differentials, US/JDM GS450h, GS350 and the AWD RC350. The RWD RC350 has a different ratio. It's a fairly straightforward mod, depending on the differential you get:
1. For the 3rd Gen GS350, GS450h differentials from US/JDM models, it's a direct bolt-on, no modification required
2. For the 4th Gen models like the RC350, you will need to either swap the differential cover, or the left carrier bushing needs to be clocked 90 degrees. You will need to remove the old bushing and put in the new RC/GS bushing, it's a different part number.

My personal view is that the newer vertically oriented bushing is a better design