Replacing subframe bushings 1996 - 1990 Lexus LS 400

You shouldn't have to remove the sub frame in order to replace the sway bar bushings.

you can look at them and compare them to see if they are the same size and thickness. if not get new ones.

Do you mean the "Stabiliser bush"?
If so, then most cars have a front stabiliser or antirollbar fitted to the front subframe and attached to the front radius arms by links with bonded rubber bushes in. Some cars have a rear system as well working in the same manner as the front.
The only way to know whats worn, is to run it up on ramps in your drive, get down and dirty, and check the supports and bar ends for a worn bush. If this repair isn't within your skills then farm it out to a good DIY or garage.

possibly worn out shock absorbers. however could be top strut mounts , lower ball joint bushes, rear axle bushes , subframe bushes best to get it checked out at your local garage

Are you using an impact gun?

I just loosen the bolts of the subframe and use a bar to pull it down abit , while my lad changes the bush, or you could pull it down a bit and block it with a bit of wood, so you can change the bush safely.

it really isn too badd what you need to do is loosen all four then you just take ou the bolts in the front leave the rear in loose but in then the front will come down low enogh to get the upper pieces out then reassemble the front leaving bolt loose then do the same to the rear then tighten all the bolts back up

you will ned to have the front of the car well off the ground wheel and all to do this repair. once car is up it will need to be supported at the pinch welds behind the front wheels on the body and body only. because you will need to drop the subframe/craddle a few inches.

now once that is done you will need to work with 1/2" tool's for the added torque and leverage. the two rear bolts holding subframe up are where the mount bushing you speak of are located. the bolts are21mm or 22mm insize meaning you need that size socket to remove them. remove both rear ones but you will need a jack under the middle of the rear of the sun=bframe to lower and rise it too swap the mounts. once both bolts are out lower the jack to lower the subframe and you will be able to replace mounts and the install is reverse.

if you have any more question please ask and good luck. be very carefule

It is highly unlikely that the bushings will fail. They do tend to crack alittle, but the bolts will still hold the subframe on. Now if they are rusted out, this is a possibility. You do have 4 bushings holding the subframe on also. 2 at the front, and 2 at the back.