relentLS

Greetings! After looking for about a year, I recently acquired a 1998 LS400 in really good shape. Currently has 116,000 on it and it's from down south, hardly any rust

Anyway, it has a low-pitched vibration that's loudest between 50-60 mph and worse under acceleration. I've replaced the suspension components that had play in them: front lower ball joints, strut rods, and a left rear adjustment arm including new tires and alignment. Suspension is now pretty tight. I've also replaced the transmission mount but not the motor mounts yet.

I've had it at a Lexus specialist shop and they couldn't find any excessive play in the motor mounts, diff mounts, flex discs, center support or rear axles and recommended taking it to a drive line specialist for further diagnosis.

I'm wondering if anyone would recommend replacing the motor mounts first before tearing into the drive shaft components. I'm hesitant to replace the motor mounts first since the shop didn't recommend replacing them. If anyone has any advice or experience I'd really appreciate it, thanks.

RA40

iTrader: (6)

How is the condition the the tranny and differential fluid?

relentLS

Transmission and diff fluids along with all others were replaced right after I got the car and the shop said the trans fluid looked like it was in good condition had been replaced before.

Superfast1

You may want to take another look at the 2 flex discs for cracks. If they're then make sure to replace them w/ OEM as the cheap aftermarket ones won't last.

relentLS

I looked at them today at the shop and I did see a few very small surface cracks on them but they looked pretty good considering they’re 20 years old. Do you think that warrants replacing them?

Fit1too

Might be an ignition thing. Do you know the history of the spark plugs? Have you taken the engine cover off and eyeballed the vacuum hoses and what not? If you haven't done so, go to: https://drivers.lexus.com/lexusdrivers/ and create a free account. After that you can enter the VIN# and see what has been done at the dealer. Sharp car, congrats!

relentLS

Thanks! I replaced the spark plugs and valve cover gaskets along with one ignition coil. I’ve visually inspected the vacuum hoses and while they are old they look OK. The motor is running very smooth under acceleration. I also did a full timing belt and water pump replacement. I have a Lexus drivers account and unfortunately there aren’t any dealer service records past the first 30k miles. I know the starter was replaced on the car fax 😎

Fit1too

I'm with Superfast1, and if they're 20 years old, I'd say that's it. Also, your user ID is brilliant!

Sin1UZFE

Those the rubber in between the drive shaft and the other side?

relentLS

roger that

relentLS

Cool, I'll look into replacing them, wow those are some expensive pieces of rubber My shop referred me to a good driveline shop in town they used to use when they worked at the Lexus dealer, I might take it to them and see what they think too, thanks!

Sin1UZFE

Anyone know the part number? 99

Fit1too

I believe it is 12361-50101. Amazon has a set for $312.50 with free shipping. Might be able to find them cheaper, I just threw that number out in Google and clicked in the first thing that popped up.

relentLS

https://lexuspartsnow.com/parts/lexu...511-30020.html

Lexus parts now says it’s this part for 07/97 and later cars

Sin1UZFE

Many thanks