jdog0411

Hey Everyone (sorry for the long post),

I'm posting this hoping someone on the forum can guide me as to how to resolve this issue because I'm about out of ideas.

Background:

My car is a 1990 LS400 with 81,000 miles. I have owned the car for just over a year and it is fantastic condition mechanically. The engine is strong and I have gone through it mechanically and she run's great. The car originally came with the Air Suspension and it really wasn't giving me any trouble with the exception of the height control. No matter what setting I put it on, the rear seemed to be stuck in the "high" position. There was a good 4-5 inch gap between the rear tires and the fender. Rather than deal with fixing the Air Ride I chose to overhaul the suspension completely.

I originally converted to a non air setup by installing Megan EZ coilover's. This was fine for a while, but I didn't care for the sacrifice in ride quality so I recently sold them. I decided to convert the car to a OEM non air suspension using all new Lexus OEM parts with the exception of the springs. Here is what I just replaced (did the work myself):

New Lexus struts on all four corners, including all associated parts (new Lexus isolators, new strut caps, new bump stops, etc. Everything that makes up the OEM strut assembly is new.

New Lexus front strut bar bushings

New Lexus ball joints and tie rod ends.

New Lexus sway bar links front and rear.

Previously, I replaced the upper control arm bushings with Daizen Poly bushings, and did the same with the lower front control arms and also the sway bar bushings front and rear.

The only suspension component (other than the Daizen bushings) that is not OEM are the springs...I chose to go with H&R performance springs so the car would sit moderately lower without giving up much ride quality. I didn't want to go OEM springs because I felt the car would sit too high at stock height for my liking.

Also, the car is riding on 19 inch rims with low profile tires.

So...this brings me to my issue. The car rides great, I'm happy with the way it performs, and the ride quality is close to stock with just a little more firmness due to the springs and the low profile tires. Everything seems to be fine. I haven't gotten the car re-aligned yet.

The problem is, there is an annoying slight "clack" sound over some of the bigger bumps coming from what sounds like the rear shock towers. I still have the back seat out of the car so the top of the shock mounts are accessible. Most driving doesn't produce any noise, but dips and sometimes going into a turn onto uneven streets produces the sound. Sometimes from one side or the other...sometimes from both sides. I have checked the torque settings on the shock cap nuts as well as the center strut rod nut. All is nice and tight. Everything visually appears fine. There are no noises at all coming from the front of the car, only the rear.

I have searched the forum as well as online, and most info points to bad sway bar links..but those are new. The sway bar link bolts are torqued to factory specifications. I really don't know what else it could be at this point since the struts are new. The only wildcard is the H&R springs, but I'm pretty certain I installed everything correctly. The springs are seated in their perches. I need to get this clunking sound resolved...the car is great otherwise. I don't want to admit defeat and take it in to a shop. Any ideas??

awdandrwd

iTrader: (1)

Simple things first. I'd eliminate the rear sway bar being a possible suspect by disconnecting it.

Is it a metallic clack or a deeper thud?

Stan

jdog0411

It's more of a metallic clack that isn't all that loud. Almost like a click sound that sounds like it is originating from the top of the strut mostly on the driver side. As an update...I went out and reinstalled the rear seat just to see if I was just hearing normal noises that are usually muffled by the seat. It actually improved because of the sound deadening and I don't hear much, but over the biggest bumps I still heard the clack a couple of times.

RA40

iTrader: (6)

The progressive windings on H&R and Eibach is similar under compression, the coils will contact each other and you will get that sound. I had it, Lexkost had it when he was running the Eibachs. Apply to the top 2-3 full coils and it will be silenced.

https://www.clublexus.com/forums/1348854-post73.html

This computer cable spiral organizer/wrap works as well. (Just noticed this pic is a different style but you get the drift.)

jdog0411

Awesome! Thanks man I'll give that a shot.

whit3b0y

also check the top bolt of the strut. think the factories you need a hex to hold the strut, and a 19(?hard to remember off the top of my head). Hold the strut with the hex and tighten the bolt with the socket.

PureDrifter

iTrader: (10)

you said all associated parts but just to make sure, the upper shock mounts were changed as well right?
an easy way to check for coil bind is to take the wheel offf and jack the suspension up from the lower arm, and see if the coils contact each other when compressed.


I am noticing a conspicuous lack of attention to the rear carrier bushings...

jdog0411

Yes, the upper shock mounts were changed as well. I haven't changed the rear carrier bushings..maybe I should swap them out as well. Just haven't heard much about those so far so didn't think about it.

jdog0411

I noticed those silencer's come in different sizes...I'm assuming I would need the large size for the H&R's since they are basically a standard coil?

jdog0411

Actually, the top strut rod nut is tightened with a standard 17mm socket. There is no hex in the rod, so it's not necessary to hold it with a hex while tightening (like you do with the sway bar end link nuts). Torque is 20 ft. lbs per spec which seats it as far down as it will go on the strut rod. Think I'm good to go there.

jdog0411

Wanted to update the thread....I haven't put the silencer's on the coils yet, but I did take the car and got it aligned today. The alignment made a huge difference actually. The car rides great and now there is basically no noise coming from the suspension at all. The car is quiet and drives like a new car (which it should since it has about 80% all new OEM suspension components). Almost every alignment spec was off from the rebuild, so I'm betting the out of whack geometry was causing additional spring binding causing a lot of the noise. I'm very happy with the result now.

I may not even need to put the silencer's on now, although I'm sure it could probably still use it. Much thanks to all those who posted while I worked through this issue.