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Mike Floutier

Front Suspension/steering Problem

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Ok first a bit of background. The car is 8 years old with 225,000 miles on the clock. No work done on suspension/steering except a new nearside hub/steering knuckle a few days ago. Oh, I also just replaced the anti-roll bar (sway?) bushes a few days ago. All the bushing and joints are original. Had 4 new cheap tires fitted about a week ago. I've checked the rotors for runout and they are both below 0.02mm (ie. within spec.)

The symptoms are:

1. A steady vibration felt through the seat and steering wheel at all speeds - it seems to make me feel sick/nauseous.

2. When braking, this vibration increases markedly and at some speeds sounds like a machine gun - varies a lot according to speed (when braking)

3. This vibration is felt and seen in the steering wheel BUT NOT at all through the brake pedal.

4. I'm getting a lot of noise into the car through the front suspension - eg. bumps and small pot-holes, especially at low speed, are very noisy.

5. I checked the radial runout on the new tires and got around 1.5mm (0.06"). Very obviously mishapen on visual inspection when spinning.

I've put a bar on all the bushes to check for movement but don't see any. The EXCEPTION is the rear bush on the lower arm which is very easy to push and has lots of movement (is this normal?)

I'm a bit stuck to know what to do next.

I wonder if it may be the combination of the mishapen tires and the soft lower suspension arm rear bushing causing the whole thing to vibrate (made worse by braking) but I don't really have a clue.

Can anyone throw any light on this?

Many thanks.

Mike

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First off, cheap tires are a big no-no. I would be thinking of upgrading soon. Have you checked for play in the tie rods ends? Lift the front and grab the tire at the 9 o'clock and 3 o'clock positions and wiggle back and forth. It should not have any play. Also, have you checked ball joints for excessive play? Wheel bearings? Does the car track straight at highway speeds or wander somewhat?

If all else fails, take it to a good (reputable) alignment shop and have them give it a good looking over. Might cost you a few coins but would be worth it.

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Thanks Landar,

I've had a chat with a local technician who says it definitely sounds like the discs. He says that it's not worth paying any attention to the disc runout reading in his experience when the symptoms are like this.

What I'm going to do to confirm this is to buy new Lexus discs and see what happens - I'll have to replace them sometime anyway so if the problem is still there with the new discs I can go back to the drawing board.

Will let you know how it goes, it will certainly be interesting if (within spec.) discs are causing this severe vibration.

Kind regards,

Mike

PS. I think the old discs (like the tires) were cheapo ones so maybe this is a lesson for me.

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Ok, having ordered the discs I have a few days to wait so I couldn't help tinkering. I removed the knuckle and hub from the lower arm to get a good play with the lower ball joint and track rod ball joint - both seem perfectly tight and full of grease.

Having re-checked the other bushes, I reassembled and decided to to find a suitable pot-hole to experiment with. Since I have a lot of noise (banging and bumping and general road noise) coming from the left front I thought I'd try the pot-hole at very low speed - thus ruling out the discs and tires.

It was obviously the wrong shape of pot-hole because it behaved fine on both sides. Now because I KNOW there is a problem with the left front suspension I thought I'd try driving the car very slowly into a kerb stone at 90 degrees (they are only about 4 inches high over here so not as crazy as it may sound). I was immediately rewarded as the left side would yield a gun-shot whereas the right hand side behaved perfectly.

Now which part of the suspension is causing this do you think?

With this noise I'm expecting to find something loose or a bush decomposing but it all looks fine to me.

I think I'll get my technician to have a look, he's supposed to good with suspension issues.

Will let you know how it goes.

Regards,

Mike

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Ok, having ordered the discs I have a few days to wait so I couldn't help tinkering. I removed the knuckle and hub from the lower arm to get a good play with the lower ball joint and track rod ball joint - both seem perfectly tight and full of grease.

Having re-checked the other bushes, I reassembled and decided to to find a suitable pot-hole to experiment with. Since I have a lot of noise (banging and bumping and general road noise) coming from the left front I thought I'd try the pot-hole at very low speed - thus ruling out the discs and tires.

It was obviously the wrong shape of pot-hole because it behaved fine on both sides. Now because I KNOW there is a problem with the left front suspension I thought I'd try driving the car very slowly into a kerb stone at 90 degrees (they are only about 4 inches high over here so not as crazy as it may sound). I was immediately rewarded as the left side would yield a gun-shot whereas the right hand side behaved perfectly.

Now which part of the suspension is causing this do you think?

With this noise I'm expecting to find something loose or a bush decomposing but it all looks fine to me.

I think I'll get my technician to have a look, he's supposed to good with suspension issues.

Will let you know how it goes.

Regards,

Mike

Mike, This kind of sounds like the same problem I was having on my 2001 LS430 (122k miles). There was a noise ( I called it the "pop corn" noise) coming form the front end drivers side and especially at low speeds. I took it into a shop and they told me the front end was tight and that it could possibly be the strut mounts. After posting in here for installation instructions for struts, someone said it shouldn't be the strut mounts because of the low mileage. This got me thinking and I had my son bounce the car up and down from the fenders. The noise was coming from drivers side but could only be detected by bouncing the passengers side. While I heard the noise, I grabbed the sway bar link and could feel movement with the noise. I went to the nearest auto parts store and picked up 2 sway bar links for about $42.00 each. It took 10 minutes to install on each side and this fixed the problem.I hope this helps. If you need help with installation, let me know.

Jon

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Thanks Jon, I did wonder about the sway bar links. I've changed the sway bar bushes but they old ones were in perfect contition so I guess I forgot about the links.

I'll have to give them a wiggle and see how much movement there is, being in England the left side is on the bumpy side of the road so I'd expect them to go first.

Will let you know how it goes.

Regards,

Mike

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I'm still struggling with this so I'd like to post a little more on the symptoms so perhaps someone can help me track down the culprit. I've read all there is on the sites on these suspension noises and so far I've heard that every single part can cause the problem so please hear what the symptoms are and help me think through how this is happening.

OK, apart from a general increase in road noise being transmitted into the body what I have is this:

A.

1. A loud heavy knock/clunk - coming from the left front.

2. In normal driving I get this when going over a pot-hole.

3. To get a better idea I purposely drove the car at 90 degrees into a kerbstone (4 1/2 inches high) VERY slowly. This reproduced the hard knock sound perfectly. (only on the left wheel - if I did it to the right it was fine).

4. I then did the same thing but with the steering wheel turned one revolution left and then right. ie. tire approaches kerb at 90 degs. (rather than car approaches....). With the right turn the noise is slightly worse. With the left turn the noise disappears. I repeated this several times to be sure.

B.

1. Driving over a corrugated surface eg. cobblestones it's very noisy.

2. When doing this, if I brake, the noise is greatly amplified.

So, what do you think it is and why? Bear in mind the car has done 230k miles.

Thanks

Mike

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Popping noises often involve ball joints. That would be the first thing I looked at. A car will often drive well even if they are bad.

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Thanks VB,

The truth is that I still don't really have a firm pointer towards diagnosing the cause of the clonking.

However, I'm encouraged by your advice and since this ball joint takes the entire burden of the road's undulations before sharing it with the rest of the suspension, I have decided is that (since I intend keeping the car for a further 200k miles +) it makes sense to replace it as I will probably have to replace it sometime anyway, so why not now?

As ever I will keep you posted.

Kind regards,

Mike

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I have the same problem and its only on the left side

dealer said replace strut it was leaking well i am going to try this

myself i will let you know

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Interesting that you should mention the strut FG, I assume you have air-ride since you mention it leaking.

As you may know from another thread, I am fixing a problem with my air-ride suspension at the moment. A fault had caused it to default to a failsafe position of max height and max damper hardness. As a temporary solution I pulled the 20amp air-ride fuse and manually adjusted the ride height to normal and the absorber damping to minimum.

I am wondering if the minimum damper setting is contributing to this noise. I've thought about it though and it doesn't add up as eg. it would affect both sides and not just the left.

My money is still on the No. 2 lower arm bush simply because - a) it looks rotten and has a lot of movement, and B) When driving slowly at a kerb the noise increases slightly on a small right lock but disappears on a left lock. If you look at the geometry of the left arm you can see that right lock increases the force acting on the No. 2 bush whereas left lock moves the force away from the No. 2 bush but towards the No. 1 bush. This would explain this change in the clonking symptom.

Does this hypothesis make sense?

Also, you may have seen in reveiws of this model that they mention "unseemly clonking on encountering large potholes". Well I've looked closely at the No. 2 bush area of the lower arm and the design means that there is only a 1/4 inch gap between the lower arm itself and the suspension sub-frame it's bolted to. Not sure but it looks very easy for a small amount of movement here to produce clonking - especially with a worn bush.

My plan is to insert a suitable piece of hard balsa wood into this gap and go back to driving the car gently against a kerb. I will observe, 1. What happens to the clonking, and 2. what happens to the balsa wood.

"Another fine theory", I hear my wife saying - hehe

Edited by Mike Floutier

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Mike, I own a '98 vvti LS400, and I have the exact same fault desciption at 212k miles. I 'feel' its a drop link. What makes this harder is our suspension will be worn out in many ways, leading to false diagnosis. A mechanic friend has been stuck without a car for 3 days and has borrowed my LS. He will take a good look in the next day or two. I will report the findings. I intend to buy a polyurethane bushing kit (lasts forever .. ish) and fit that to tighten the front back up again. any that are not available I will be making myself.

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My plan is to insert a suitable piece of hard balsa wood into this gap and go back to driving the car gently against a kerb. I will observe, 1. What happens to the clonking, and 2. what happens to the balsa wood.

"Another fine theory", I hear my wife saying - hehe

my solution to this issue was to use a bullet cam and recorder (activity sports junkie) inside the arch and replicate the problem. you can look back at the footage and SEE what is moving and clunking. Think of the footage from F1 GP cars where you see the suspension working hard.

the little £30 clip on sports cams are very useful and good quality if the idea interests you.

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Thanks Luke, quite a few people have suggested the sway bar links but the noise is so substantial (a real heavy knock) I've tended to dismiss it.

The other reason for not suspecting the links is that the noise is greatly increased under braking and I don't think they would be affected so dramatically.

I recently tried to remove the lower ball joint assembly (to see if I could). When putting some force on the bar to undo the joint's nut I noticed that the rear portion of the lower arm moved very close to the suspension subframe - Remember they are only 1/4 inch apart at rest.

My feeling is that, if the No. 2 bush is so slack as to allow this movement with just this effort, then the force of braking must bring those two parts so close together that any vibration - whether it be a pothole, a kerb, my previous warped disc or just a bumpy road - will inevitably result in the lower arm knocking/hammering/vibrating against the subframe.

I love your idea about the bullet cam Luke but my balsa wood arrived in the post this morning so I will be using that.

Will let you know how it goes.

Regards,

Mike

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Thanks Luke, quite a few people have suggested the sway bar links but the noise is so substantial (a real heavy knock) I've tended to dismiss it.

The size of that ARB .. so thick and weighty

The other reason for not suspecting the links is that the noise is greatly increased under braking and I don't think they would be affected so dramatically.

As i mentioned about general bush wear all sorts of movement can have knock on effects

I recently tried to remove the lower ball joint assembly (to see if I could). When putting some force on the bar to undo the joint's nut I noticed that the rear portion of the lower arm moved very close to the suspension subframe - Remember they are only 1/4 inch apart at rest.

This is the clue as I see it. Well observed :)

My feeling is that, if the No. 2 bush is so slack as to allow this movement with just this effort, then the force of braking must bring those two parts so close together that any vibration - whether it be a pothole, a kerb, my previous warped disc or just a bumpy road - will inevitably result in the lower arm knocking/hammering/vibrating against the subframe.

You could verify this and eliminate the sway bar / ARB by jabbing full hard on the brakes on a safe road/carpark/drive. the nose would dive, compressing the arb equally on both sides (prevents arb knocking) and the tyres would be tring to drag the wheel backwards hard, which should simulate stress to compress the bush to metal on metal contact

If we could find some reproducible tests/results....

I love your idea about the bullet cam Luke but my balsa wood arrived in the post this morning so I will be using that.

the simplest methods usually prove the best.. i'm sure i'll be posting photos of a smashed up suspenion cam soon enough

Will let you know how it goes.

Regards,

Mike

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Thanks Luke,

Well I've got somewhere in terms of eliminating things:

1. The balsa wood test was negative - it was slightly compressed but NOT broken and the noise was the same (no damping by the balsa)

2. I tried setting the absorber damping to max on the offending side (instead of min) but this made no difference.

3. I removed the ARB/Sway bar link BUT the noise remained.

This afternoon I'm taking it to my favourite mechanic and see what he says - after all he was the first one to point it out when he was listening to my bearings.

Will let you know....

Regards,

Mike

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Good news, it's fixed!

I took it to my mechanic who listened as I simulated the noise and he said; "lower arm rear (No. 2) bush, I can feel it knocking here".

So I bought the bush but couldn't remove the old one from the carrier bracket so I bought a new carrier bracket thinking it would slip in fairly easily - haha.

Ended up taking the two new parts to said mechanic for him to press in - he only wanted a bottle, good chap that he is.

So I have just fitted the bracket/bush and as you can imagine I was a little nervous when simulating the problem but highly rewarded by a smooth, silent response when mounting a kerb at 90 degs. This compared with the previous gun-shot noise I was getting.

The puzzle remained as to what was actually causing the noise (in view of the negative result to the balsa wood test - above) but hey, what do I care!

The real clue that had me keeping this bush as the no. 1 suspect was the fact that the noise would change according to the steering position. If you study the geometry of the lower arm together with the change in direction of the forces acting on it that follow steering changes it's easy to see that on one lock the force on the No. 2 bush is at maximum and on the other lock it is nearly zero.

Many thanks to everyone, especially Luke, for your encouragement, as usual I'm not sure I would have got this far or saved as much money without your help.

Kind regards,

Mike

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The way I find the problem is to take the car to have an alignment. Many of the places such as Firestone give you a printout showing any issues. In the event there is a suspension component that is failing, they will most certainly identify it for you. I had a bad strut (torsion bar) bushing and it did not make noise but caused the car to pull to the right. I also had a bad lower ball joint which had no impact on the handling characteristics but did make a rattling like noise especially at low speeds over rough pavement.

Having screwed around with so many suspension parts in the past, I found the easist method is to just shell out the $80 and find out for sure. Good luck with this.

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