peterls

(this is all on my 1990 LS400)
Just today I was on a steep downhill, and was going near 80mph briefly. When I noticed the speed, I hit the breaks to slow down, and noticed quite a vibration coming what seemed like from front end (rotors?).

A few weeks ago, I did hit the curb slightly at low speed, checked everything and could not find anything. There was no vibration after that.

Tried to repeat that vibration again, but it was all good. Could not get it to vibrate no matter what I did.

Now - what part would produce such noticeable vibration, but only sporadically like that??? Perhaps it was the road surface, but I kinda doubt it. I want to check and see if there is something in the suspension that could do the same thing... I thought it would be the rotor on the wheel that hit that curb, but if it were the rotor it would behave the same way every time, right?

LScowboyLS

this may sound surprising, but the first thing I would replace is the transmission mount, they go bad very early and cause many mystery vibrations (dirt cheap part & easy DIY)

strut rod bushing and upper control arms are my 2nd and 3rd guess, betcha it is one of the three!

peterls

Thank you LScowboy, I was hoping you'd chip in!

peterls

So, just out of curiosity, I went to rockauto and found these lower ball joints and upper control arms from raybestos (which seems to be the best aftermarket choice):

http://www.rockauto.com/catalog/x,ca...parttype,10070
(the part number 5051305 and 50501306 - both "pro grade")

and these:

http://www.rockauto.com/catalog/x,ca...parttype,10070

So for both left and right side I would be looking at $400 in parts, which does not sound that bad to me...

Now, since I know next to nothing about suspension, I am wondering - what else should I check before I buy these? And how can I even check them myself to see what may need changing?
additional info: there is light clunking noise, which seems to be coming from front right, only at low speeds and over tiny little bumps it is so light that for a while I thought it was some loose plastic part somewhere. Going over anything bigger than 2in makes no sound.
And one more bit: the car is pulling to the right, but I thought it was just wheel alignment, which I am going to do, just not before I change suspension parts, if need be.

I am thinking the previous owner probably pulled in to his/her driveway to the right, many times per day, cazillion times per year, and that made for wear on something... just don't know what - probably ball joints?

dc893

I have the Raybestos on mine. I would recommend those since they can be re-greased and are made by senkei 555.

LScowboyLS

which parts precisely do you have by Raybestos and where did you buy and what did you pay? - do you have the part number you ordered?

Yamae

We call the company "Sankei 555" and they are manufacturing products only for after market use and they are not supplying to any major automobile companies in Japan, according to shop owners whom I know. Their products are mostly good but sometimes they don't fit completely well enough, I also was heard.

Viewing posts here at CL, I find that you guys trust and prefer Japanese products to some country's ones in Asia or even in Europe. But you'd better to know the fact that there are many Japanese companies that only manufacture parts for after markets. I would say their quality is mostly good but they are not accepted by major companies like Toyota, Honda, Nissan and others. As a result, there sometimes happen some minor problems as shop owners say. Also those after market parts are not tested under extreme conditions as automobile companies do.

Before I had worked outside of Japan, I used to think that things were not well organized in Japan. But working in Europe, in Asia and in US, I finally found that Japan had many good points and things are relatively well organized. Of course there are many bad points too but honestly speaking, I choose Japan to live and I buy products made in Japan although things are a bit expensive.

peterls

So, some more symptoms:

- Just went over some slightly rough road, they were doing some construction there so lot of small potholes and even more loose gravel, of larger variety (i could hear it kicking the car from the bottom), and as I was going very slowly over all that, doing no more than perhaps 10-15 mph if that, the steering wheel kinda was fighting me, it almost wanted to steer on its own, in the direction of a bump that it was going over.
It also pulls slightly to the right.
But I could not get it to vibrate when braking...

A few years ago, when I had an Acura, I expereinced exactly the same symptom when going over smaller bumps with that steering fighting me, and wanting to go its own way. No one could figure it out, and finally I found some guy, a racer with an Integra Type-R, having the same problem and he figured it was the rubber bump stop on the front struts. They were inexpensive, I brought them to my mechanic and he was so certain that they were not the problem that he almost refused to change them. I asked him to do it anyway, and the old one came out broken completely. The steering problem never happened again.

Now, does LS400 have the same "bump stop" at all? I kinda doubt it, but it does not hurt to ask... If it does not, what would wear out in such a way to produce all these symptoms? I am somehow betting on strut bushings, the ones on the top, which I hope I can just replace from the engine compartment right? Is that a big deal of a job?

Thanks for any suggestions!
ps. I am not certain that ball joints are bad, or upper control arms, but will try to take a look at them with my friend when we do the TB this week...

LScowboyLS

yes, we realize Japanese products are the best engineered and best manufactured (this is why we drive Lexus!), so let me ask this, if your upper control arms went bad, and you could not afford the factory replacement part, and had to buy an aftermarket brand to save money, which Japanese brand would you buy?

Yamae

Thanks for liking Japanese products but I have never replaced any upper control arm and I have no idea to answer your question at the moment. I will be asking shop owners about this.

timmy0tool

iTrader: (7)

strut rod bushings gets my vote.

LScowboyLS

don't forget rack bushings, inner & outer tie rods, sway bar bushings, lower control arm bushings and lower ball joints!