Critique my noise reduction idea
08-21-2008, 11:31 AM
#1
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Critique my noise reduction idea
Hey guys, the summer has been hot and rainy, so I haven’t tooled around with the car much, but I did have an idea I’d like to try once the weather improves.
The rear crossmember is flat against the body and attaches on 4 studs. Every bump from the wheels goes through the links, into the crossmember, and into the body, making noise. So I thought, why not put some rubber washers at each stud, to isolate the crossmember from the body a bit. The front crossmember has some rubber like that.
There a few potential trouble spots with this, and I’m hoping for some discussion on how significant these could be. Personally I don’t think they would be significant at all.
1) The crossmember would be more apt to bend, twist and shift position slightly, but I don’t think it would be noticeable considering what a big hunk of metal it is, and its shape.
2) The crossmember would be slightly lower relative to everything else, changing the angle of the links, but this also shouldn’t be a big deal, and if it is, then all 4 links can be made adjustable and just shortened a bit.
The rear crossmember is flat against the body and attaches on 4 studs. Every bump from the wheels goes through the links, into the crossmember, and into the body, making noise. So I thought, why not put some rubber washers at each stud, to isolate the crossmember from the body a bit. The front crossmember has some rubber like that.
There a few potential trouble spots with this, and I’m hoping for some discussion on how significant these could be. Personally I don’t think they would be significant at all.
1) The crossmember would be more apt to bend, twist and shift position slightly, but I don’t think it would be noticeable considering what a big hunk of metal it is, and its shape.
2) The crossmember would be slightly lower relative to everything else, changing the angle of the links, but this also shouldn’t be a big deal, and if it is, then all 4 links can be made adjustable and just shortened a bit.
08-21-2008, 11:39 AM
#2
It's not going to make much of a difference, if any at all. It will also adversely affect handling.
1. all of the suspension links on the car (parallel links, radius rods) already have rubber bushings in them. The noise isolation from the wheel to the chassis is already there.
2. most of the road noise in the back comes from transmitting through the thin sheet metal wheel wells, not the chassis.. A few layers of dynamat (or similar) over the rear wheel wells and rear deck area will make a VAST improvement in the noise back there.
3. the handling would be adversely affected because you're introducing more flex in a part that's supposed to be stationary. Any flex in the front crossmember does not affect your alignment- just the position of the engine relative to the chassis.
4. There's an incredible amount of road noise that comes through the front (and rear) doors. Another layer or two of dynamat on the door skins will help a ton.
If it wasn't nasty outside, I'd volunteer to bring my car over and let you take a ride in it and listen to the car and stereo and judge for yourself what some dynamat in proper places will do. Remember I have heim joints in the rear suspension and I can still hear myself breathe at 100mph in that car.
1. all of the suspension links on the car (parallel links, radius rods) already have rubber bushings in them. The noise isolation from the wheel to the chassis is already there.
2. most of the road noise in the back comes from transmitting through the thin sheet metal wheel wells, not the chassis.. A few layers of dynamat (or similar) over the rear wheel wells and rear deck area will make a VAST improvement in the noise back there.
3. the handling would be adversely affected because you're introducing more flex in a part that's supposed to be stationary. Any flex in the front crossmember does not affect your alignment- just the position of the engine relative to the chassis.
4. There's an incredible amount of road noise that comes through the front (and rear) doors. Another layer or two of dynamat on the door skins will help a ton.
If it wasn't nasty outside, I'd volunteer to bring my car over and let you take a ride in it and listen to the car and stereo and judge for yourself what some dynamat in proper places will do. Remember I have heim joints in the rear suspension and I can still hear myself breathe at 100mph in that car.
08-21-2008, 11:54 AM
#3
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Geez that was fast, slow day today Matt?
I'll try the dynamat then, I'm just sick of how loud everything is. I have poly on the rear links, and I wanted to re-grease them anyway because I've got all this creaking noise.
I had some good results after padding the rear deck and many of the trunk panels.
I'll try the dynamat then, I'm just sick of how loud everything is. I have poly on the rear links, and I wanted to re-grease them anyway because I've got all this creaking noise.
I had some good results after padding the rear deck and many of the trunk panels.
08-21-2008, 11:56 AM
#4
Yeah.. pull the rear seat and cover all the sheet metal behind there. a couple layers over the rear wheel wells.
then put a layer or two on each door skin- mainly the fronts.
Slow day? nah. just got back from 2 weeks offshore and taking the day off work. presently waiting on the rain to go away so I can finish replacing the front door on the house.
then put a layer or two on each door skin- mainly the fronts.
Slow day? nah. just got back from 2 weeks offshore and taking the day off work. presently waiting on the rain to go away so I can finish replacing the front door on the house.
08-21-2008, 11:58 AM
#5
It's not going to make much of a difference, if any at all. It will also adversely affect handling.
1. all of the suspension links on the car (parallel links, radius rods) already have rubber bushings in them. The noise isolation from the wheel to the chassis is already there.
2. most of the road noise in the back comes from transmitting through the thin sheet metal wheel wells, not the chassis.. A few layers of dynamat (or similar) over the rear wheel wells and rear deck area will make a VAST improvement in the noise back there.
3. the handling would be adversely affected because you're introducing more flex in a part that's supposed to be stationary. Any flex in the front crossmember does not affect your alignment- just the position of the engine relative to the chassis.
4. There's an incredible amount of road noise that comes through the front (and rear) doors. Another layer or two of dynamat on the door skins will help a ton.
If it wasn't nasty outside, I'd volunteer to bring my car over and let you take a ride in it and listen to the car and stereo and judge for yourself what some dynamat in proper places will do. Remember I have heim joints in the rear suspension and I can still hear myself breathe at 100mph in that car.
1. all of the suspension links on the car (parallel links, radius rods) already have rubber bushings in them. The noise isolation from the wheel to the chassis is already there.
2. most of the road noise in the back comes from transmitting through the thin sheet metal wheel wells, not the chassis.. A few layers of dynamat (or similar) over the rear wheel wells and rear deck area will make a VAST improvement in the noise back there.
3. the handling would be adversely affected because you're introducing more flex in a part that's supposed to be stationary. Any flex in the front crossmember does not affect your alignment- just the position of the engine relative to the chassis.
4. There's an incredible amount of road noise that comes through the front (and rear) doors. Another layer or two of dynamat on the door skins will help a ton.
If it wasn't nasty outside, I'd volunteer to bring my car over and let you take a ride in it and listen to the car and stereo and judge for yourself what some dynamat in proper places will do. Remember I have heim joints in the rear suspension and I can still hear myself breathe at 100mph in that car.
08-22-2008, 06:17 AM
#7
yea.. i gotta look into getting some more of that stuff... my car sounds like the window is always cracked open even when it's shut tight.
09-20-2008, 06:15 PM
#8
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Today I got a chance to work on the car and went back after the noise.
I got the car up on some boards so that the suspension would remain loaded, but I now had space to get under. I proceeded to rock the car up and down from beneath while listening for noise up close, and identified a few things:
1. The rear creak is not from poly bushings, they are fine. I think the creak comes from the two bolts which hold the links to the crossmember. It seems like the head of the bolt is moving against that round thing that sits on it. I am going to put extra washers and lube there tomorrow and see if it makes a difference.
2. I had a poorly secured radius rod, the nut was on with thread lock, but not all the way so it had some play. That was a huge source of noise, but now thats settled.
3. My sway bar and its links have a bit play in various areas and make noise, I will probably end up replacing one of the links and the bushings.
4. Unrelated... but my CV boot burst. There was a crack for a while so I expected it at some point. I'm going to try my hand at replacing the boot myself, its an outer on the driver side.
I havent nailed down the noise in the front yet, it may have gone away but I'll wait until the rear is settled before chasing that.
I got the car up on some boards so that the suspension would remain loaded, but I now had space to get under. I proceeded to rock the car up and down from beneath while listening for noise up close, and identified a few things:
1. The rear creak is not from poly bushings, they are fine. I think the creak comes from the two bolts which hold the links to the crossmember. It seems like the head of the bolt is moving against that round thing that sits on it. I am going to put extra washers and lube there tomorrow and see if it makes a difference.
2. I had a poorly secured radius rod, the nut was on with thread lock, but not all the way so it had some play. That was a huge source of noise, but now thats settled.
3. My sway bar and its links have a bit play in various areas and make noise, I will probably end up replacing one of the links and the bushings.
4. Unrelated... but my CV boot burst. There was a crack for a while so I expected it at some point. I'm going to try my hand at replacing the boot myself, its an outer on the driver side.
I havent nailed down the noise in the front yet, it may have gone away but I'll wait until the rear is settled before chasing that.
Last edited by mikekantor; 09-22-2008 at 07:41 AM.
09-20-2008, 10:23 PM
#10
. Put some tape on the axle end teeth while putting new one on. Good luck!
09-22-2008, 07:38 AM
#11
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The creeking noise is gone, I just replaced that weird thing around the head of the bolt with a normal washer. I also replaced a seized link so now I can have alignment done properly.
During the test drive I heard it ticking, so I'll be swapping the entire CV axle. Instead of grease I'll be dealing with a/t fluid, but its easier to contain. The problem is last time I tried to pull it out I ended up giving up because it just wouldnt come out, so I'm a bit worried about getting the axle out because that retainer ring keeps it in tight.
During the test drive I heard it ticking, so I'll be swapping the entire CV axle. Instead of grease I'll be dealing with a/t fluid, but its easier to contain. The problem is last time I tried to pull it out I ended up giving up because it just wouldnt come out, so I'm a bit worried about getting the axle out because that retainer ring keeps it in tight.
09-22-2008, 04:41 PM
#12
tinting mirrors?
front and rear mirrors?
put down the crack pipe and sober up before posting, please.
09-22-2008, 04:44 PM
#13
The creeking noise is gone, I just replaced that weird thing around the head of the bolt with a normal washer. I also replaced a seized link so now I can have alignment done properly.
During the test drive I heard it ticking, so I'll be swapping the entire CV axle. Instead of grease I'll be dealing with a/t fluid, but its easier to contain. The problem is last time I tried to pull it out I ended up giving up because it just wouldnt come out, so I'm a bit worried about getting the axle out because that retainer ring keeps it in tight.
During the test drive I heard it ticking, so I'll be swapping the entire CV axle. Instead of grease I'll be dealing with a/t fluid, but its easier to contain. The problem is last time I tried to pull it out I ended up giving up because it just wouldnt come out, so I'm a bit worried about getting the axle out because that retainer ring keeps it in tight.
Just jack up the left side of the car. if you can, jack the rear higher than the front. If you're lucky, the tranny will retain all the fluid. my 5mt will do that, but I'm not sure about the auto. I remember pulling an axle on my GXE and losing enough to make about an 8 ft puddle. probably more ATF on the ground than the entire volume of gear oil used in a 5mt.
09-22-2008, 07:12 PM
#14
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pull harder. or use a prybar against the tranny case and the head of the axle stub. either way you're junking that axle anyway.
Just jack up the left side of the car. if you can, jack the rear higher than the front. If you're lucky, the tranny will retain all the fluid. my 5mt will do that, but I'm not sure about the auto. I remember pulling an axle on my GXE and losing enough to make about an 8 ft puddle. probably more ATF on the ground than the entire volume of gear oil used in a 5mt.
Just jack up the left side of the car. if you can, jack the rear higher than the front. If you're lucky, the tranny will retain all the fluid. my 5mt will do that, but I'm not sure about the auto. I remember pulling an axle on my GXE and losing enough to make about an 8 ft puddle. probably more ATF on the ground than the entire volume of gear oil used in a 5mt.
09-22-2008, 08:44 PM
#16
yeah, we survived just fine.. minimal damage to my shed and the house was fine. lost a bunch of trees, so we now have a huge pile for a bonfire, but otherwise we're okay. power was out less than 24 hrs, no thanks to my next door neighbor being pretty high up in Boeing's safety & security dept. he's one of the guys that says "umm no, Mr. President. we can't launch your rocket into outer space today. the weather's too nasty and you'd kill the hairless monkeys inside."
09-22-2008, 08:52 PM
#17
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yeah, we survived just fine.. minimal damage to my shed and the house was fine. lost a bunch of trees, so we now have a huge pile for a bonfire, but otherwise we're okay. power was out less than 24 hrs, no thanks to my next door neighbor being pretty high up in Boeing's safety & security dept. he's one of the guys that says "umm no, Mr. President. we can't launch your rocket into outer space today. the weather's too nasty and you'd kill the hairless monkeys inside."
09-30-2008, 07:22 AM
#19
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Swapped the axle this past Saturday. Pulled out easily, no fluid lost by lifting only one side of the car. Thanks for the tip Matt, otherwise I would've drained the ATF just as a precaution.
The old axle was fine, the ticking was from something else. I'm going to put a new boot on it and have a spare.
Most of my noise issues are solved or at least pinpointed, so this thread is /
The old axle was fine, the ticking was from something else. I'm going to put a new boot on it and have a spare.
Most of my noise issues are solved or at least pinpointed, so this thread is /
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