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Awful squeaking noise from the rear suspension, solutions?


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So I have a really loud and awful sounding squeaking noise coming from my rear suspension. it is happening only when I either go over a large bump, or I accelerate.

 

It is BY FAR worse when accelerating, its almost constant squeaking/metal on metal? screeching sound.

 

I'm having a lot of trouble trying to narrow down what could be causing it because I recently replaced all my bushings with urethane bushings, and replaced the struts. 

 

I have tried spraying my bushings with silicone spray, but that doesn't really help. I have tried having a passenger crawl back there and see if they can narrow down the problem area while I was driving but met with no success that way. I've tried taking out all the rear interior and driving with the hatch open but that did nothing. I've tried pulling the driver's side LCA (I'm convinced its on the driver's side... at least mostly) and re-greasing and sanding down the bushings to make them fit better, but that did nothing either.

 

What could be causing a squeak under acceleration? Which bushings should I look at?

 

Is it possible its the springs scraping the spring perch? Is there supposed to be some kind of pad between the two?

 

Its SO BAD when accelerating, even like 1/8th gas it will do it. But cruising and braking it is silent.

 

Any insight would be much appreciated. I apologize if this is in the wrong section, but I figure that since I have a 280z, this issue would be specific to that car, Mods please move if this is in the wrong section.

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I have already searched this problem, that's how I knew to try the common solutions. They helped some of the squeaking sound, but I can't figure out what is causing this last squeak. I was more asking if anybody else has had this problem of acceleration causing a rear end squeak, and if they were able to find a solution.

 

Also, is it possible that my springs are causing this noise by scraping against their spring perch? It sounds like it is coming from the rear driver's shock tower, and I recently installed camber plates there (the peasant, bolt on kind) and replaced the struts with KYBs. I've checked over that area multiple times and everything is torqued to spec etc... 

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hmmm, yea I used a bunch of that nasty lube on the bushings. I replaced the front diff mount with a brand new one from courtesy nissan. I can try tightening the mustache  bar bolts again, but I've been down there several times and even tightened the bolts down when the car was on a lift so they were "pre-stressed". My mechanic told me that was important, I've personally never heard of that before. I've replaced the bushings with urethane ones on my old rx7 before, and I didn't have any squeaking issues then, so I don't know what I could have done differently this time...

 

Why do you think it sounds like it is coming from the strut tower? Is that just acoustics playing tricks on me? Why only on acceleration? Which parts of the suspension are stressed/unstressed at that time?

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As far as lubricants go, when I installed the sway bar I had really bad squeaking, the end all solution was to use teflon tape to wrap the sway bar where the bushings went, no problem after that. I don't think sanding the bushings was the right choice, the extra movement can add to the squeaking. Making sure to grease one of the contact points is also an overlooked spot, the bushing essentially stays still while the suspension piece moves in the inner tube or against the bushing, if that area isn't greased or wrapped or what not, you are going to get a very pleasant metal on metal screech. If the bushing in question is supplied with an inner tube that will be held in place, lube the outside of the tube before inserting into the polyurethane sleeve, (lubing the inside doesn't hurt either), if no inner tube is supplied grease the suspension piece that goes through it.

 

During hard acceleration, the parts stressed starting with the suspension, is the strut top insulator, the spring seat, the spring, the bottom spring seat, the wheel bearing, the wheel hub, the wheel, the tire, the half shafts, the diff, the diff mount front and rear, the drive shaft angle changes a bit, the transmission mount, and the engine mounts.

 

I would check the strut top insulators  see if they are intact, make sure the spring is seated in the perches top and bottom, take a look at the e-brake routing, inspect the rear wheel bearings, liberally grease up the bushings, and tighten down the LCA captive bolts (the giant bolt front and back on the inner side of the LCA). Granted I really think liberal application of grease is the answer.

 

Regarding the preload thing, I've been told opposite, that you shouldn't pre-stress the bushings until they are compressed and supporting the car, or else you risk mushrooming the bushing or worse bending/stressing a suspension component, end links, etc etc. I make sure the pieces are all in their correct spots, hand tighten, or take up slack on the lock washers, lower the car onto blocks or ramps, compress suspension and then torque the bolts.

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As far as lubricants go, when I installed the sway bar I had really bad squeaking, the end all solution was to use teflon tape to wrap the sway bar where the bushings went, no problem after that. I don't think sanding the bushings was the right choice, the extra movement can add to the squeaking. Making sure to grease one of the contact points is also an overlooked spot, the bushing essentially stays still while the suspension piece moves in the inner tube or against the bushing, if that area isn't greased or wrapped or what not, you are going to get a very pleasant metal on metal screech. If the bushing in question is supplied with an inner tube that will be held in place, lube the outside of the tube before inserting into the polyurethane sleeve, (lubing the inside doesn't hurt either), if no inner tube is supplied grease the suspension piece that goes through it.

 

During hard acceleration, the parts stressed starting with the suspension, is the strut top insulator, the spring seat, the spring, the bottom spring seat, the wheel bearing, the wheel hub, the wheel, the tire, the half shafts, the diff, the diff mount front and rear, the drive shaft angle changes a bit, the transmission mount, and the engine mounts.

 

I would check the strut top insulators  see if they are intact, make sure the spring is seated in the perches top and bottom, take a look at the e-brake routing, inspect the rear wheel bearings, liberally grease up the bushings, and tighten down the LCA captive bolts (the giant bolt front and back on the inner side of the LCA). Granted I really think liberal application of grease is the answer.

 

Regarding the preload thing, I've been told opposite, that you shouldn't pre-stress the bushings until they are compressed and supporting the car, or else you risk mushrooming the bushing or worse bending/stressing a suspension component, end links, etc etc. I make sure the pieces are all in their correct spots, hand tighten, or take up slack on the lock washers, lower the car onto blocks or ramps, compress suspension and then torque the bolts.

 

Thanks for the info, I will try disconnecting the rear swaybar and tying it out of the way to see if that is the culprit!

 

I sanded the bushings down the tiniest amount. Really it was just to get the pieces to fit together without excessive force being applied. If you think of the bushings as little mushrooms, I sanded the top and the bottom less than a millimeter in total. Before I did that I was having a really hard time getting the LCA to fit against the wheel hub so putting the spindle pin in was a nightmare. After sanding I was able to fit them together much more easily. This may have been because my wheel hub was slightly damaged when the shop pressed my spindle pins out, so I had to sand the metal there flat as well.

 

Also I may have described my pre-stressing steps unclearly, because I meant exactly what you described. So good to know I did that right haha.

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I haven't gotten a chance to try disconnecting the swaybar yet, but as an update:

 

I filled up my gas tank and I had a passenger and some bags in the back and the noise is now happening when I brake, or just all the time. It kinda changes when it feels like it... but its definitely worse than when there was less weight in the car.

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I had the spindle pin bushings and the spindle pins pressed out at a local shop, so its possible they bent the LCA. They said they broke their press! And the hub was pretty banged up where the LCA bushing touches it. I had to take a grinder to it and then some sandpaper to get it as smooth and straight as possible. I'm no machinist though, so it was kinda just eye-ball straight unfortunately.

 

I use this car as my daily and I put like 60 miles on it every day, so I haven't had the chance to take it apart yet. But tomorrow I should have some time. How can I test if my LCA is bent? Wouldn't it be hard to get the spindle pin in or to bolt it up if it was bent? I had no such issues.

 

This noise used to happen on acceleration for a week straight, but now its only when the car is cold in the morning and when turning and braking. I was able to reproduce it in the parking lot at work finally, since before now I had to basically pile drive the car to get it to make noise it was too dangerous to stick you head under. Anyway, this time I stuck my head under there and as best as I can tell, it sounds like the LCA where it attaches to the hub.

 

So tomorrow I'm gonna take both (brand new) spindle pins out, bathe them in a tub of bushing grease, and then see what happens. Last week when I took them out they had some pretty noticeable scratch marks from the inner metal sleeve of the LCA bushings, is that expected? Maybe I'll lightly sand them smooth with some 220 grit while I have them out.

Edited by osirus9
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I would disconnect the LCA's from the inboard side and check how the LCA pivots on the spindle. Hopefully your 'repair' on the hub didn't make things unsquare. Did you use a t square or something to make sure the spindle bushing surfaces were 90 degrees flat to the spindle bolt ? The forward and rearward bushing surfaces should also be parallel to each other and perpendicular to the spindle bolt.

You might have filed or sanded at an angle .

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OK, so this weekend I took both spindle pins out and their bushings. I checked the hubs with a square and they were a pretty far cry from squrae. They also had some dents and machine marks on them that I had't sanded down apparently. I was in a rush to get the car running last time so I overlooked the hubs, assuming that the shop had done a decent job.

 

Anyway, I squared them as best as I could without a lathe, but they still have some minor depressions in them. I'd say at least 80% of the surface is flat and mirror smooth. I then regreased the pins and the inside of the metal bushing sleeve and replaced the spindle pins. At first this helped a lot and I thought I had figured out my problem, but after 30 miles the squeaking is back the same as last time! I got some more grease today finally, but I was wondering, which part of the LCA bushing actually moves? The spindle pin stays still obviously, but does the inner metal bushing sleeve move against the pin, or does the bushing move against the inner metal sleeve and the sleeve and the pin remain locked together?

 

So I guess my next step will be to remove the sway bar and see if that's the culprit. Grrr... I hate doing the same job more than once...

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When you tighten down the nut -at the end of the spindle bolt- you should be pressing the large washer against the metal sleeve tight enough to keep it from moving. The urethane bushing should pivot around the metal sleeve. The metal sleeve should be long enough so that the urethane bushing- flanges also have room to move-but not too much to create slop.

Make sense? 

Sounds like you still have some bind somewhere

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Thanks for explaining that madkaw, it makes sense to me now. I haven't had time to mess with the car much lately, but I ordered a new set or LCA bushings (mine were a little shredded on the hub side) and when those come in I will take both LCAs out of the car completely, install new bushings again and grease the hell out of them. Gonna pray I just derped on a step and doing it over again will fix it. Also going to make sure to concentrate on greasing the bushing instead of the metal sleeve now that I know it isn't supposed to move. I'm thinking that, combined with my messed up hubs is the issue here.

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when I first went to install the bushings the LCA was SUPER tight against the hub so I forced it on. One of the bushings was definitely damaged by that, but I thought it would be ok. It squeaked, so I cut off the loose "flap" of bushing. It was really quite small. That didn't seem to affect the squeaking at all though.

 

After I went and sanded and squared the hubs the LCA slides right on no problem, so I'm assuming that that was the issue all along? Unless it could be something else?

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One thing you might check that is in a different direction is the U joints in your halfshafts. I've been dealing with a oscillating squeaking squealing noise for a while, sounded like it was coming from the rear strut towers, but my U joints were the culprit. Metal on metal action. Its easy to check, unbolt the halfshaft and if the mounting flange is loose or rattly replace the joint. Just a thought! Hope you find your squeak!

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