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If they're a GOOD mechanic, they'll know what to do without you telling them. Seals and shims will need to be purchased from Lexus/Toyota. If you're getting a OS Giken, yes you'll want to use their fluid ONLY and go by their recommended break-in procedure.
When I installed my Quaife LSD into my Honda Civic trans, I had to order a bunch of shims in order to get the right clearances; only used 2 out of the 6 I purchased. But they're so cheap I said it'll be better to have them and not need them than the other way around. Definitely a different process for a FWD platform than a rear diff, but many procedures are similar.
If they're a GOOD mechanic, they'll know what to do without you telling them. Seals and shims will need to be purchased from Lexus/Toyota. If you're getting a OS Giken, yes you'll want to use their fluid ONLY and go by their recommended break-in procedure.
When I installed my Quaife LSD into my Honda Civic trans, I had to order a bunch of shims in order to get the right clearances; only used 2 out of the 6 I purchased. But they're so cheap I said it'll be better to have them and not need them than the other way around. Definitely a different process for a FWD platform than a rear diff, but many procedures are similar.
Thanks, good to know. Thought the LSD kit would come with shims. Now how to find a good mechanic...hesitant to go to just any place because most I have seen are younger guys who mainly specialize in body kit, suspension and exhaust installations.
If anyone has recommendations on a good drivetrain specialist in Los Angeles please let me know. I wonder how much it would cost to go to the dealership, if they would even consider doing the work with an aftermarket part.
There were no adjustments necessary when I put the OS Giken in my ISF. It really was as simple as remove open spool, install Giken spool, reassemble, check tooth pattern, and drive away. My experience is not unique - everyone I have asked about this has said the same, so I really doubt you'll need shims. What may be problematic is fitting the spool into the housing without modifying the housing. I chose to grind on mine to make enough room for the spool to go in. It is also possible to do the install without grinding on the housing, but this requires a stub axle and putting the ring gear on the spool after the spool is in the housing. Much easier said than done.
If you take it to a competent driveline shop, you should not have any issues. If you are taking the whole car to someone to do this, expect it to be a bit pricey. If they are good at what they do, it won't be hard, but it will take a bit of time.
Like mentioned above, it's completely possible to have the backlash come out spot-on after the LSD install. A good shop won't let you leave until you're spot-on and within factory specs.
There were no adjustments necessary when I put the OS Giken in my ISF. It really was as simple as remove open spool, install Giken spool, reassemble, check tooth pattern, and drive away. My experience is not unique - everyone I have asked about this has said the same, so I really doubt you'll need shims. What may be problematic is fitting the spool into the housing without modifying the housing. I chose to grind on mine to make enough room for the spool to go in. It is also possible to do the install without grinding on the housing, but this requires a stub axle and putting the ring gear on the spool after the spool is in the housing. Much easier said than done.
If you take it to a competent driveline shop, you should not have any issues. If you are taking the whole car to someone to do this, expect it to be a bit pricey. If they are good at what they do, it won't be hard, but it will take a bit of time.
Thanks, that's very useful information. I wouldn't have thought that you still had to grind the housing to make the spool fit since it was presumably designed for that specific car. Was the amount of grinding extensive? I don't have any mechanical knowledge so I can't visualize the second part where you talk about the stub axle and ring gear as an alternative to grinding.
Is the toughest or most vital part the reassembly and setup of the LSD in the housing, or does it also require a lot of expertise to put the housed LSD back on the axle/drivetrain? Wondering if I should buy the LSD and housing, and send them to a good shop to assemble/setup and then bring the completed unit somewhere local to be installed (apparently I've read on some other American car forums that some are of the opinion that there are no really renowned drivetrain shops in SoCal).
About the gear ratio (or whatever you call it, sorry I'm really bad at this), the stock IS250 AT is 3.91 but if you use the LSD from a FRS/BRZ, it is 4.1 which is still useable on the IS but may decrease gas mileage? But supposedly may make the car have slightly faster take off speed? To what degree are these issues affected? And does the OS Giken LSD have a ratio of 3.91 or 4.1?
Oh, and what's this about a noise that can be heard coming from the LSD when driving hard? This is a normal thing? And how loud is that kind of noise supposed to be?
Sorry for all the newbie questions. Just wanted to see exactly what I would be getting into before taking the plunge. Basically my car is a daily driver that I plan to keep for a long time so I'd like to make it better handling and more fun to drive (while maintaining some practicality) with the possibility of someday retiring it from daily use and following friends to the track as family life and finances permit.
The spool has nothing to do with the final drive ratio. If you want to change the final drive ratio, you can, and this would be the time to do it, but your cost will be quite a bit greater because you will be buying a gearset, and it will need to be shimmed when it is installed. It is not possible to change ratios without re-shimming. The difference between a 3.91 and a 4.10 is so small it would hardly be worth the effort. I would not consider it a good use of resources.
There is no noise coming from the OS Giken unit when driven hard. It does make a very slight whine on neutral throttle, but you can only hear this if you drive with the sound system turned off. The typical complaint is chatter while turning under power. The Giken does not chatter, but some brands definitely do. This is why many opt for the OEM Torsen unit. It provides LSD functionality and integrates well with the existing electronic LSD on cars with VDIM. The upside of the Torsen is, it will never need to be rebuilt unless you break it. The downside is, it is a torque bias ratio device which means when one wheel slips, it transfers torque to the wheel with traction based on a fixed ratio determined by the gearset inside the spool itself as long as there is some traction available for the slipping tire. If either rear tire comes off the ground (as can happen under HPDE or racing conditions with OEM springs) then the Torsen behaves no differently than an open diff. It is imperative to have some grip available for it to work. This is also the reason it integrates well with the eLSD VDIM provides because VDIM will actuate the brake on the wheel off the ground to ensure the other wheel does not lose power.
At any rate, you have some options available to you. None are exactly cheap, but I have nothing but praise for the OS Giken Superlock on my ISF. It is truly an amazing piece of kit.
The spool has nothing to do with the final drive ratio. If you want to change the final drive ratio, you can, and this would be the time to do it, but your cost will be quite a bit greater because you will be buying a gearset, and it will need to be shimmed when it is installed. It is not possible to change ratios without re-shimming. The difference between a 3.91 and a 4.10 is so small it would hardly be worth the effort. I would not consider it a good use of resources.
There is no noise coming from the OS Giken unit when driven hard. It does make a very slight whine on neutral throttle, but you can only hear this if you drive with the sound system turned off. The typical complaint is chatter while turning under power. The Giken does not chatter, but some brands definitely do. This is why many opt for the OEM Torsen unit. It provides LSD functionality and integrates well with the existing electronic LSD on cars with VDIM. The upside of the Torsen is, it will never need to be rebuilt unless you break it. The downside is, it is a torque bias ratio device which means when one wheel slips, it transfers torque to the wheel with traction based on a fixed ratio determined by the gearset inside the spool itself as long as there is some traction available for the slipping tire. If either rear tire comes off the ground (as can happen under HPDE or racing conditions with OEM springs) then the Torsen behaves no differently than an open diff. It is imperative to have some grip available for it to work. This is also the reason it integrates well with the eLSD VDIM provides because VDIM will actuate the brake on the wheel off the ground to ensure the other wheel does not lose power.
At any rate, you have some options available to you. None are exactly cheap, but I have nothing but praise for the OS Giken Superlock on my ISF. It is truly an amazing piece of kit.
Wow, thanks for the detailed response. For some reason I thought I read that the gear ratios were different between the IS300, IS250 and the FRS/BRZ.
If you swap the entire assembly, there can be ratio differences, as you would also be changing the ring and pinion. If you only change the differential unit itself, you will reuse your existing gears.
The IS300 used the same gear ratios as the IS250 in North America (3.73:1 for MT, 3.91:1 for AT). The 2013-2016 FR-S/BRZ use 4.10:1 and the 2017 86/BRZ use 4.30:1 for MT models and 4.10:1 for AT models.
Just to clarify as I think the OP is non-clear on this; when you remove your factory open diff, you will need to remove the ring gear off of the diff and put it onto the LSD and then install the entire piece as a whole. If you chose to change up to a 4.10 rear gear, you'll need a matching pinion and ring gear. See pic below of the 2-way OS GIken in an IS350 carrier I owned a little while back.
Oh, and the grinding needed to get the LSD into the case is minimal; here's where you (your shop) would have to grind a tad bit off to get the LSD into the carrier :
No rebuild is required on the OS Giken. This is why the initial cost to purchase an OS Giken LSD is typically higher than other aftermarket clutch differentials but the upside of the OS Giken is having a lower Total Ownership Cost since the only maintenance you need to do is change the gear oil every 30k.
No rebuild is required on the OS Giken. This is why the initial cost to purchase an OS Giken LSD is typically higher than other aftermarket clutch differentials but the upside of the OS Giken is having a lower Total Ownership Cost since the only maintenance you need to do is change the gear oil every 30k.
Due to the design of a clutch type LSD, they do wear over time, that includes OS Giken's Super Lock LSD. That said, the OS design has many more clutches and, to quote OS, "rebuilds are rarely needed and is recommended to have fluids changed periodically to prolong the life of the unit." They last a really long time, especially with regular fluid changes.
I wouldn't be concerned about it if I was buying one, but it is a difference compared to a mechanical LSD like the Torsen.
If you swap the entire assembly, there can be ratio differences, as you would also be changing the ring and pinion. If you only change the differential unit itself, you will reuse your existing gears.
The IS300 used the same gear ratios as the IS250 in North America (3.73:1 for MT, 3.91:1 for AT). The 2013-2016 FR-S/BRZ use 4.10:1 and the 2017 86/BRZ use 4.30:1 for MT models and 4.10:1 for AT models.
Jeff
i think I was getting confused because I thought that the entire differential assembly from the FRS/BRZ could be put in place of the original stock IS differential assembly. But instead you would take the FRS/BRZ innards and place it in the IS housing, right? Sorry I don't know jack about how cars work.
Just to clarify as I think the OP is non-clear on this; when you remove your factory open diff, you will need to remove the ring gear off of the diff and put it onto the LSD and then install the entire piece as a whole. If you chose to change up to a 4.10 rear gear, you'll need a matching pinion and ring gear. See pic below of the 2-way OS GIken in an IS350 carrier I owned a little while back.
Oh, and the grinding needed to get the LSD into the case is minimal; here's where you (your shop) would have to grind a tad bit off to get the LSD into the carrier :
Awesome. Super helpful. Didn't know the OS Giken was 2-way. Not that I know what that means, but for daily driving I've been told 1.5 is suitable.
i think I was getting confused because I thought that the entire differential assembly from the FRS/BRZ could be put in place of the original stock IS differential assembly. But instead you would take the FRS/BRZ innards and place it in the IS housing, right? Sorry I don't know jack about how cars work.
You can swap in the whole thing, or the internals. Up to you.
