First off im going to go ahead and ask if this thread could be stickied as with the other useful information because i belive that many people are going to be taking this route from now on and it will answer most if not any of the question that people might have: and now for the long awaited gs400 differential swap thread:
Hey guys, been some time since i could sit down and put together some useful info for you, but here it is:
*****THIS SWAP IS FOR LSD EQUIPED NA SUPRAS!!!! if you have an open diff and are buying a separate LSD (trd, ect.) you just need to follow half of the steps which include taking out the diff form the gs400 pumpkin and taking off its ring gear, you do not have to touch the na differential*****
*****keep in mind that you also could just put in the gs400 pumpkin and use it as an open lsd untill you buy one, in that case you just simply put the differential INTO THE CAR and everything bolts up, no taking apart required****
(***please keep in mind that i used a 2000 gs400 differential, i am not yet aware of what year lexus gs400's have come with the same differential)
(***also, another member used an LS400 differential with very minor adjustments from mine and made it work***)
***and one last thing before i start*** MAKE SURE THAT YOU UNTIGHTEN THE COMPANION FLANGE BOLT WHILE THE DIFFERENTIAL IS STILL IN THE CAR IF YOU ARE ALREADY USING A TT AUTO COMPANION FLANGE TO MATE TO A TT AUTO REAR HALF DRIVESHAFT, if you take down the differential that bolt is really hard to break loose and takes some thinking )
To ease everyones mind, this swap is just about as direct as it can get while upgrading your NA-t. Everything is pretty much interchangeable and bolt-in, and quite simple if you have the right tools @ hand.
to get teh differential out of your car, (its very simple, just need some stregth) follow this simple instructions from the toyota manual under STEP 2:
here is what the casing of the gs400 differential looks like (this is just an empty casing, the insides have already been taken out):
the stubs seen on the right are the first to come out from the differential when you have everything taken out, you simply "bang" them out, we used a peice of wood and a hammer and tapped it out of place around the circumference of the stub:
after both stubs are out, the bearing cap (seen on the left in the above picture) is taken out by unscrewing the 8 bolts that hold it in place.
after both of the caps are taken out, the differential simply pulls out of the casing, here is the GS400 OPEN differential:
the take-apart process for the Supra differential is the same exact way, except the LSD out of the supra needs to be turned in order to be taken out. here is the picture of my LSD that was taken out at the same time :
here is the picture of the pinion that is left inside of the casing (you do not touch this part at all!):
next step is to take of the ring gear from the differential, this is done by using a special "Start" socket (12mm I THINK!, im not exactly sure), there is 10 of them:
once they are removed (it takes some muscle) the ring gear just comes off :
this ring gear is reinstalled onto the LSD and the reverse process if followed to get the differential back together. only thing different is that if for those who are using the NA LSD, the NA LSD Axle stubs that were taken out from the NA pumpkin will have to be put into the gs400 pumpkin, other than that everything else is in reverse!
here is what it looks like:
on the star bolts that hold the ring gear to the LSD, make sure to use some THREAD LOCKER from Autozone, use the Red kind (the toughest kind) its only 9 bucks and will keep ure bots nice and tight.
once everything is assembled you simply follow the revese step and reinstall the differential into your car.
the driveshaft combition that was used previously works exactly with this swap, so you have nothing to worry about.
here is the gs400 pumpkin with the lsd, we also sanded and painted the housing, looks brand new !!!: