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you can replace that rear knuckle bushing. I bought a pair of them off Amazon PN Febest 42304-30040 Arm Bushing Rear Assembly for about $35. That immediately improved my straight line tracking in my 99' and made it less wandering on the highway. my right rear knuckle bushing had quite a lot of visible movement and play. They use the factory spherical bushing/floating design where it moves as the suspension moves. Be prepared to cut out all those suspension arms and have new ones and bolts handy. My car was an Ohio car, didn't look as bad as yours though and I had to cut and remove all 6 arms when I wanted to do an alignment. Luckily I moved to AZ so rust free LS400s were plentiful here in the junkyards so it didn't cost me a few thousand bucks more like a hundred bucks.
You would get a lot of tightness and control from the rear by refreshing all of those control arms. And I didn't even replace the floating bushings in my knuckles either.
you can replace that rear knuckle bushing. I bought a pair of them off Amazon PN Febest 42304-30040 Arm Bushing Rear Assembly for about $35. That immediately improved my straight line tracking in my 99' and made it less wandering on the highway. my right rear knuckle bushing had quite a lot of visible movement and play. They use the factory spherical bushing/floating design where it moves as the suspension moves. Be prepared to cut out all those suspension arms and have new ones and bolts handy. My car was an Ohio car, didn't look as bad as yours though and I had to cut and remove all 6 arms when I wanted to do an alignment. Luckily I moved to AZ so rust free LS400s were plentiful here in the junkyards so it didn't cost me a few thousand bucks more like a hundred bucks.
I have no idea. There are some kids on Youtube who did it. But again, these don't really address vibration. Not REALLY. The guy in the video at some point idk says something about how it moved around on the highway because the camber or toe or something would change. It felt sloppy and not predictable.
I have been chasing a vibration in my LS for years and put in three different driveshafts only to find out it’s not the driveshaft. It has been confirmed the vibration is coming from the torque converter. Not a cheap fix. Vibrations can be very difficult to diagnose.
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I'm guessing that the torque converter mounting bolts can be checked for tightness without a huge amount of trouble. If those bolts are loose that might be causing your intermittent vibration issue, and might be quite inexpensive to check.
Update: I'm kicking myself for not noticing earlier, but one of the tires (rear right) was very low pressure - like off the gauge low / 3psi. Since I put 50psi in it, it's been driving 99%. I've got a new set of bushings to put in, hopefully I'll be able to report back soon that it's running back to its regular 100%. Whatever is loose down there, it's enormously magnified by low air. The valve stem leaks slowly, like a few psi per week, which is why it's been going in long waves. When I put on the set of X-Ice on in November, the problem went away for a few weeks, but it gradually got worse again.
Update #2: Successfully changed out the rear left trailing arm bushing - pics attached. There is still play in the wheel so it is not all healthy, but the test drive was ok. In case anyone is doing this bushing - I used a 1-1/2" socket as a 'cup' into which I pulled the bushing using a central bolt and some washers. First I pushed out the central ball along with some seals, and then using a slightly bigger set of washers I pulled out the whole bushing shell. Honestly I was expecting to have to hacksaw the outer shell and chisel it out, but it pulled out no problem, nice and smooth all the way. I was using a grade-8 bolt plus 2 nuts together, and a ratchet to pull it out. No flames necessary
Pushing in the new bushing was also easy. I ground down any edges, including a little on the outer shell of the bushing itself to make it start going in easier. I pushed it with a 1-1/4" socket that just cleared the rubber but pushed on the steel shell. I could not get the last 1-2mm but I just left that be. You'd need a really thin cylindrical pusher (whatever these are called) to do that properly, as sockets are just too thick.
This has not resolved the play in the 12-6 o'clock direction that I can feel in the rear wheel. I'll ask on a new thread about this. I will update again here in a week if I run into an vibrations.
11671341[/url]]Update #2: Successfully changed out the rear left trailing arm bushing - pics attached. There is still play in the wheel so it is not all healthy, but the test drive was ok. In case anyone is doing this bushing - I used a 1-1/2" socket as a 'cup' into which I pulled the bushing using a central bolt and some washers. First I pushed out the central ball along with some seals, and then using a slightly bigger set of washers I pulled out the whole bushing shell. Honestly I was expecting to have to hacksaw the outer shell and chisel it out, but it pulled out no problem, nice and smooth all the way. I was using a grade-8 bolt plus 2 nuts together, and a ratchet to pull it out. No flames necessary
Pushing in the new bushing was also easy. I ground down any edges, including a little on the outer shell of the bushing itself to make it start going in easier. I pushed it with a 1-1/4" socket that just cleared the rubber but pushed on the steel shell. I could not get the last 1-2mm but I just left that be. You'd need a really thin cylindrical pusher (whatever these are called) to do that properly, as sockets are just too thick.
This has not resolved the play in the 12-6 o'clock direction that I can feel in the rear wheel. I'll ask on a new thread about this. I will update again here in a week if I run into an vibrations.
Very nice, not a ton of room with the knuckle on the car but it is doable.
I had the same play you are describing at 12 o’clock. It was worn ball joints in the rear upper control arm.
This is what the bushings look like inside, just in case you consider cutting one out. In my case I pulled the central ball and its plastic cover, plus one end of the seal, as the first step. Next came out the shell (bottom left in the pics) using bigger washers, as described above. Everything went in or out at the end towards the rear.
Last edited by deanbrown; Feb 18, 2024 at 08:25 PM.
