I have finally got my suspension working well and upgraded to nice sticky tires but now the weak point is the dam open diff these cars came with. I am getting a lot of inside wheel spin on every tight corner at the track causing the back end to move all over the place. I was wondering if there were any affordable options for a LSD that have come on the market for the IS350. I contacted Quaife and they no longer produce their LSD's for the IS350. I have been unable to find one searching around. I can't afford a Giken. I have not found any confirmation that a IS-F unit will work on a is350. Those are all the options that I have found. Is there anything else out there. Any help would be appreciated.

 

^Here's your confirmation that the IS-F Torsen WILL fit in the IS350 carrier.

So besides that, you do have various LSD options :

*OS Giken
*Quaife (they are correct, they don't make them any more; but you could source a used one...if lucky)
*ATS
*TOMs

There are probably others, but these are the ones that come to mind. If I remember right, the Quaife and TOMs are helical diffs, while the OSG and ATS are plate.

Besides the Quaife @ a reasonable sub $1k price tage when new retail, everything else is probably in the $2k range.

 

When I checked months ago TOMs had seemed to stop making them.

ATS, at least for 2006-2008 requires some metal to be ground off the inside of the casing for the LSD to fit. They suggest dremel tool to do it, but you'll be there a long time. I had to grind off more than I had thought, but it is from a thick part of the housing, and I haven't seen any leaks (yet).

 

Thanks for all the advice. Sounds like there are not a lot of options out there. The TOMs and Quaife units seem to be discontinued. I don't really know how I feel about modifying my casing to get the ATS to fit in. And the OS Giken is well out of my budget. Might have to look around for a IS-F unit and see if I can get a used one relatively cheap as the new units seem to be in the same ballpark with the OS Giken price.

Gville350 is the IS-F unit a direct bolt in. I don't think I want to get an entire IS-F pumpkin as the gear ratio is different so I am assuming I will just have to swap the diff out and I will be good.

 

the is-f is supposed to be a swap in. I think there have been a few people here trying to find "used" ones. I don't think they have had much success.

Edit: Finally found the pdf they had sent. Grinding the pumpkin is required for the IS350 and the IS-F up to July 2009. So if you (or anyone else interested) could find a pumpkin from a July 2009+ IS-F, you could use the housing by itself with an ATS diff. Still probably going to be difficult to find, since they are not that old, but easier to find than one that includes the LSD.

 

That's what I've observed as well since 1) the IS-F is a fairly limited production run vehicle, 2) the Torsen LSD was available only on 2010-2014 IS-Fs, 3) the lack of wrecked IS-Fs in the US to cannibalize, and 4) multiple 08-09 IS-F owners are also waiting on a used IS-F torsen which make them pretty high-demand! I personally gave up on waiting for a used IS-F Torsen LSD after about a year.

 

Well my neighbor has a 2011 ISF. May be I can sneak into his garage one night and do a quick swap! I am sure he will never know the difference.

Sadly if the OS Giken is the only real option it is not in the budget. I have already had the car for 7 years and will probably just keep a few more years so I don't want to sink 4K into stalling a LSD. I will just try and keep my eye out for a used ISF unit or a Quaife that happens to be floating around.

 

If I'd gotten my IS a year earlier, it'd likely have a quaife in it right now, in all likelyhood. But when I started looking everyone was freshly out of them.

 

IDK how different the 250 from the 350 diff's are but Jeff used a Torsen from an IS300 which im pretty sure they have tons of more LSD options. May be worth the research. I just checked ebay and full is300 LSD assemblies can be had for <500

https://www.clublexus.com/forums/is-...-my-is250.html

 

I'll confirm this as well, I had a CC in my hand when I called and found out they had been discontinued.

I've seen before when Quaife discontinued a diff for another car that a vendor was able to convince them to start up production again. Money talks; if someone were to approach Quaife and agree to buy ~20 diffs I'm sure they would build them again.


IS250 has many options because it shares rear ends with the IS300, FRS, and I think Supra. Swapping an IS350 diff for an IS250 would require MANY changes. I think making the chages along with keeping the gear ratio similar would negate any savings in the cost of the LSD.

 

Yeah I looked at this late last year when I got tired of NOT finding a Torsen LSD from a 10+ ISF. The costs would negate paying up to a new OS Giken LSD from Figs.

The only + would be having TONS of options now sharing the same rear end as the is300. I wouldn't be surprised if someone ventures down this path though...it's def feasible and presents options.

 

After doing some research, it seems like the IS350 shares the same Diff as the GS430 (F21SF) from the 3UZ V8. Just did a search and it has the same part number and someone was just selling an LSD for it


https://www.clublexus.com/forums/2ge...tml?styleid=14