Front end shake
11-17-22, 10:31 AM
#1
Driver
Thread Starter
Front end shake
1998 LS400, new pads and rotors up front, I did both because I was getting some front end shake and those parts were of unknown age. I am getting some clunking sounds going over bumps, the front shakes under light braking but gets better under heavy braking.
car now has 227K miles, we’ve put 50k of those on it.
strut rod bushings?
car now has 227K miles, we’ve put 50k of those on it.
strut rod bushings?
Last edited by sixty3; 11-17-22 at 04:32 PM.
11-17-22, 03:08 PM
#2
First thing that comes to mind is lower ball joints. Does the car "wander" a lot on the highway? You're constantly going left left right left right right right right left when you're just trying to keep it straight? While not a rule because there are some messy roads out there, generally speaking, the car should track pretty damn straight and with a good alignment, should never be "nervous" like this at all. Side note: I personally find more caster and toe-in to provide more stability and helps the car settle down on the highway. Within OEM spec, but bias towards those. Failing ball joints also make a faster, softer CLUNKncunkunknuknknnknnnnk that tapers off when going over certain types of road texture. Lower ball joints are considered a wear item, common to see them fail at 100k miles. Mine were completely ****ed at 140k but had no visible leakage or tearing or deflection on examination. They're cheap & easy to do as well so they are a common fix. The car just drives better. Front end feels more planted in corners. The car rolls less (you don't feel like you're falling out of your seat).
Strut rod is one clunk when you first hit the brakes at low speed. Not ruling it out - but that's the standard test to determine. May also be shock mounts (clunk from sharp impacts) or control arms (general clunking).
Hard to diagnose a sound. Can't really narrow things down. Control arms should be visibly damaged if they're bad enough to be making noise & causing drivability issues. Ball joints can fail while appearing perfectly healthy from the outside. So that's my blind guess.
Strut rod is one clunk when you first hit the brakes at low speed. Not ruling it out - but that's the standard test to determine. May also be shock mounts (clunk from sharp impacts) or control arms (general clunking).
Hard to diagnose a sound. Can't really narrow things down. Control arms should be visibly damaged if they're bad enough to be making noise & causing drivability issues. Ball joints can fail while appearing perfectly healthy from the outside. So that's my blind guess.
Last edited by 400fanboy; 11-17-22 at 03:17 PM.
The following users liked this post:
BNastee (12-05-22)
11-17-22, 03:19 PM
#3
The clunking over bumps - is this whether you brake or not, or only when braking? If it clunks when not braking, I suspect the strut tops/hats. A bearing assembly there wears out with use and will clunk over bumps. The shaking when braking is usually a rotor that needs truing; it can happen to new rotors.
11-17-22, 04:05 PM
#4
Driver
Thread Starter
Yeah, it actually drives fairly straight just shaking under light braking and the clunk.
the clunk is heard over even the smallest of road imperfections, even concrete seams, while not braking.
I’ll pull the front wheel and see what I see if it ever warms up.
the clunk is heard over even the smallest of road imperfections, even concrete seams, while not braking.
I’ll pull the front wheel and see what I see if it ever warms up.
Last edited by sixty3; 11-17-22 at 04:34 PM.
11-17-22, 07:34 PM
#5
Look at the top of the shock towers. There is a little rubber cup you can just pull off and inspect the shock mounts. Bounce the front of the car up and down to see if there are any hairline cracks. If they're cracked it should be pretty visible with a flashlight.
If not, my money is probably on the lower ball joints. Mine loved to "talk" across road surfaces.
Of course, this is based off of a couple of descriptions and not much evidence. It still may be other things. This is me hedging my bets lol.
If not, my money is probably on the lower ball joints. Mine loved to "talk" across road surfaces.
Of course, this is based off of a couple of descriptions and not much evidence. It still may be other things. This is me hedging my bets lol.
Last edited by 400fanboy; 11-17-22 at 07:37 PM.
The following users liked this post:
BNastee (12-05-22)
11-18-22, 03:31 AM
#6
Driver
Thread Starter
Gracias for the replies fellas, gives me a decent place to start, I’ll be honest, they might be original shocks in the car. The sound certainly seems to be coming from upper right front area, but I know how sounds are, that might not be where the sound is really coming from.
11-18-22, 08:16 AM
#7
Driver
Thread Starter
Look at the top of the shock towers. There is a little rubber cup you can just pull off and inspect the shock mounts. Bounce the front of the car up and down to see if there are any hairline cracks. If they're cracked it should be pretty visible with a flashlight.
If not, my money is probably on the lower ball joints. Mine loved to "talk" across road surfaces.
Of course, this is based off of a couple of descriptions and not much evidence. It still may be other things. This is me hedging my bets lol.
If not, my money is probably on the lower ball joints. Mine loved to "talk" across road surfaces.
Of course, this is based off of a couple of descriptions and not much evidence. It still may be other things. This is me hedging my bets lol.
too cold to really mess with it today.
Trending Topics
11-18-22, 09:11 AM
#8
Usually I wouldn't consider shock mounts to give a front-end shake\vibration. If you haven't really fixed any problems with the car and it's at 225k, there may be multiple layered problems here.
As for the clunking noise, you won't hear it just by bouncing the car. If it actually is the shock mounts, you should be able to visually see hairline cracks in them like the drivers side mount was. If they're fully failed it'll just be completely separated like my passenger mount was.
See this video & listen:
As for the clunking noise, you won't hear it just by bouncing the car. If it actually is the shock mounts, you should be able to visually see hairline cracks in them like the drivers side mount was. If they're fully failed it'll just be completely separated like my passenger mount was.
See this video & listen:
Last edited by 400fanboy; 11-18-22 at 09:14 AM.
11-20-22, 06:21 AM
#9
I have had the simmilar type of issue on two LS400. "clunkety clunk" slow of tarmac defects being the clearest tell tale.
On one of them it was quite bad when I bought the car. It was definitely the strut rod bushing that was the main culprit.
My clunk and vibration just stopped when I changed the strut rod bushings for new OEM ones.
This is a known "weak point" on LS400 as far as I have read. Only rubber bushings I have needed to change as of yet on my 1995 with 140Kmiles. ( weak is relative).
Vibrating brake rotors can reasonably aggravate the problems at speed.
EVEN if you manipulate the strut rod bushings with a crowbar or a mechanic checks them they may often not seem bad but they may stil be BAD.
Mechanic needs to follow the repair manuals Instructions when changing them. Correct rotation etc.
On one of them it was quite bad when I bought the car. It was definitely the strut rod bushing that was the main culprit.
My clunk and vibration just stopped when I changed the strut rod bushings for new OEM ones.
This is a known "weak point" on LS400 as far as I have read. Only rubber bushings I have needed to change as of yet on my 1995 with 140Kmiles. ( weak is relative).
Vibrating brake rotors can reasonably aggravate the problems at speed.
EVEN if you manipulate the strut rod bushings with a crowbar or a mechanic checks them they may often not seem bad but they may stil be BAD.
Mechanic needs to follow the repair manuals Instructions when changing them. Correct rotation etc.
The following users liked this post:
BNastee (12-05-22)
11-22-22, 10:58 AM
#10
Racer
sway bar to body bushings and sway bar endlinks could be the culprit here. Mine would make clunks over speedbumps, the sway bar to body bushings are worn out enough where I could slide the bar left to right when installed.
The following users liked this post:
BNastee (12-05-22)
12-04-22, 01:58 PM
#11
Driver
Thread Starter
I ordered the strut rod bushing, well the assembled parts. The drinker side was pretty easy to do and the bushing in the strut rod is shot…….however…..on the captains side…..I can’t get the strut bracket bolt to come out. I soaked it in some PB Blaster, only for an hour or so and hit it with my impact wrench and…..nothing but noise. Won’t budge, I hit it with fire, nothing.
I’ll let it soak and maybe try it tomorrow if the weather is ok. I hate thinking that a bold about an inch long is holding me up.
I’ll let it soak and maybe try it tomorrow if the weather is ok. I hate thinking that a bold about an inch long is holding me up.
The following users liked this post:
BNastee (12-05-22)
12-11-22, 02:41 PM
#12
Driver
Thread Starter
Hey, looking for a little help.
I’ve mangled the small bolt that holds the lower shock mount on the drivers side and it won’t move at all. I’m going to have to cut the top of the bolt off I think.
can someone point me to that short bolt part number? Not the one that goes into the bottom of the shock but the little one that attaches to the bracket.
I’ve mangled the small bolt that holds the lower shock mount on the drivers side and it won’t move at all. I’m going to have to cut the top of the bolt off I think.
can someone point me to that short bolt part number? Not the one that goes into the bottom of the shock but the little one that attaches to the bracket.
12-11-22, 02:50 PM
#13
Moderator
Hey, looking for a little help.
I’ve mangled the small bolt that holds the lower shock mount on the drivers side and it won’t move at all. I’m going to have to cut the top of the bolt off I think.
can someone point me to that short bolt part number? Not the one that goes into the bottom of the shock but the little one that attaches to the bracket.
I’ve mangled the small bolt that holds the lower shock mount on the drivers side and it won’t move at all. I’m going to have to cut the top of the bolt off I think.
can someone point me to that short bolt part number? Not the one that goes into the bottom of the shock but the little one that attaches to the bracket.
12-11-22, 03:12 PM
#15
Driver
Thread Starter
Close, that’s the one that goes through the shock, I’m trying to find the one that goes to the bracket. See part 48620, right above that part number is where a bolt goes. It’s a little short bolt, got the one out of the passenger side very easily and buttoned that side back up. I guess I could pull that bolt again and try to find a match.
guessing it’s 91629-61216
guessing it’s 91629-61216
Last edited by sixty3; 12-11-22 at 03:23 PM.