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Originally Posted by VVTIS
Torsen LSD to non-LSD equipped IS300.
It is possible to equip a non-LSD differential with a Torsen LSD differential for a fairly low cost. This is available for both manual and automatic tranny. It is also possible to swap the automatic tranny Torsen LSD with the manual to get a higher gearing. I used this process and can tell a difference. Below is a how-to, and snips from posts on .net about this conversion, if you have any questions, please post or pm me.
You can source a complete carrier from a junkyard. It is cost prohibitive to try and get one new from Lexus as it's $4,500. Look for a manual or an auto, depending on what you need. The manual has a ratio of 3.72 and the auto a 3.91. Your choice, but I wouldn't recommend it if you have an auto and get a manual carrier.
INSTALL ESTIMATES AND INFORMATION
As for install, it takes about 2-2.5 hours for a moderately skilled mechanic. With the general tools that I had lying around, you may have to buy:
*8mm Hex Bit socket
*10mm Hex Bit socket
*12mm Allen wrench (as this size didn't come in the Hex Bit socket)
Also, make sure you use WD 40 on the axle bolts prior to taking them out as the carrier is steel at this point, and there is some rust.
General outline is:
*Remove axles with 8mm Hex Bit socket
*Remove driveline with two 14mm open end wrenches
*Remove 12mm Allen heads from rear of carrier
*Put a jack underneath the carrier to support it
*Remove 19mm Mounting bolts
*Lower the carrier
AUTO LSD AND MANUAL LSD DIFFERENCES
After switching to the auto LSD in my manual I can tell that the higher gearing allows for more torque and faster acceleration. It will gain on the low end but loose some up top. I did not increase the gear much, so I will not loose much. I can tell that my 1st and 2nd gears are shorter, I have to shift at 60mph now, it will not make it to 62 when it was stock, that is not too much of a difference. I think the acceleration was increased by around 5% as stated from a source I have. The exhaust tone is a bit louder at high rpms in 5th gear, but not bad, I have the LTuned exhaust as well.
The auto LSD in my manual IS makes a major difference. The difference in gearing is that I came from a 3.72 to a 3.91 which is not that major, but makes a difference. I ran a guy down here on the team with a 5-speed, he had intake, exhaust, PLP heatshield, PLP panel and pulled from him rather easily. I am not sure if he would have caught back up in the top end, but we did not get that high to see, we slowed around 90 or so. I had to shift before him because some of the gears are shorter, but it pays off. There is more torque and quicker acceleration. All I had during the race was an Ltuned exhaust and body kit. I bought the carrier because I wanted an LSD and it being an auto carrier was an extra.
Yes, it is possible, I did it, but I did not go with the TRD because of the labor time and the way the LSD was set up. I was not going to go with crazy hp so it was not necessary. I got a new auto LSD for around 900 and Lexus installed it for 150. The ratio was switched from 3.72 to 3.91 so I have a lil edge on the stock manuals.
I would say it was well worth the cost. The traction that you get when cornering and being able to put on the power a lot sooner is well worth it. I haven't been able to try the LSD in wet conditions yet, but I'm sure there is a good safety factor as well.
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