Hello Lexus komrades, I currently own a 92' SC300, recently it started vibrating heavily when I would hit about 45mph+ and when letting off the pedal then going below 45 it drives normal no vibration... Yes I got the tires new, balanced and rotated them ✔ Some mechanics were also saying it was a driveshaft issue so I switched it out from another salvaged SC300 ✔ and I replaced the coupler flex on it as well (new) ✔ and finally I got a very good condition Rear subframe from a 98' and installed it and well it still vibrate but not as bad before... Any help I'd appreciate ! If Mods can put this in the correct category please I'm a Newbie to the forum.

 

Engine mount or tranny mount?
I hope this isint the first time you've posted here about this problem. Seems like with all the combined knowledge here on CL it would have been fixed a long time ago rather than going through all the expensive fixes you've tried.

 

Your tyranny is going. Hard to find good mechanics these days. Look at it this way....you have a car with age, no longer in production. Prepare to replace EVERYTHING. Sometimes it's costly but so is maintenance on a new car. Replace the tyranny n and you should be ok.

 

I sense a 5 speed swap in your future.

 

It's NOT a tranny issue.

 

just do a 2jzgte swap next, see if that helps lol

 

Mine did this as well, it suddenly stopped so I never got around to seeing the cause.

 

My 97 sc400 did this as well. It turned out to be both of the rubber engine mounts had ripped in half. Although, I also had my 93 sc300 to have a similar problem back in the day. The front driveshaft had somehow got unbalanced and caused vibrations at certain speeds, but if you have replaced yours with one that you know for a fact to be good then you shouldnt have any problem there.

 

I highly doubt it's tranny.. I've already been thru that as well lol usually I can feel the gears slippin' even if

 

It's like a very "fixed" vibration.. I feel like its with the bushings and mounts somewhere...

 

Exactly! Even the coupler flex. I remember doing an engine mount replacement as well 1 1/2year ago, Il check those again maybe the heat is eating away at the rubber.

 

Any spare parts bud lol

 

Did you do both mounts? Did you also do the transmission mount?

 

Alrighty so it seems that there's an issue with the differential bushings.. What's your advice guys should I go ahead and sell it or is there another possibility? I've already went thru 3 things to try knocking out the issue... it's like having a crazy psychotic gf lol

 

Diff bushings arent very expensive. Why make that cause you sell it?
I still think its you're tranny mount. When I replaced mine it got rid of a lot of vibrations, some of which were very similar symptoms to yours.