mystery noise...any ideas?

[Vandy_B]

I have an '03 AWD Astro that I did a 2" OLV lift on. I also replaced the body mount bushings with poly bushings. Still have the original, stock springs in the back and have them on the lowest hole in the shackle for highest lift. Stock original shocks all around. Running 235/70R16 tires. Everything on the lift went smooth as silk (thanks in big part to all the reading I did here). Van rides nice and smooth and have put on maybe 3000 miles since lifting. Only thing is that the rear sits a bit lower than the front...probably because the springs are worn out.

Over the weekend while driving on a country highway I heard/felt a clunk/thud like I had run over something. Then it happened again. And a minute later, again. Fearing something maybe was loose and going to fall off I pulled over and checked things out and couldn't find anything loose, hanging, rubbing, etc. Just a single clunk/thud at a time. Hard to tell exactly where it's coming from, but sounds like towards the center or rear of the van. Started driving again have determined that it only happens when I get over 50 mph, and only seems to happen after vehicle is warm.

Driving over the weekend I tried to take note of when it would happen so I could isolate it, but there doesn't seem to be any pattern. Heard it once just after hitting an expansion joint on the highway going onto an overpass...but only once. Other expansion joints didn't cause it. It also has changed from a single clunk to 3-4 rapid-succession clunks (imagine pop-pop-pop-pop in quick succession lasting a total of less than a second.) It almost sounds like something is getting caught up in the wheel or the axle. I knew that I had a loose front wheel-well mud-guard but I removed the whole thing and the noise was still there.

I drove 100 miles on Sunday on the freeway and the noise happened twice within the first ~10 minutes driving on smooth flat road and then not at all the rest of the way home. I'm wondering if maybe the transfer case or differential or a cv joint is slipping...but the van doesn't seem to lurch or "miss" when the sound happens, so ???

It's driving me nuts not being able to figure out the source of the noise. Any ideas??? I'm not sure it is a suspension issues, but this is an active forum so I figured it was a good place to start. Sorry for the rambling post, but I've tried to include any details I could think of.

Thanks,
Andy

[TurnNburn]

If you have a 2003 awd like you say, then you have torsion bars in the front. Not springs. If the front is lower then the rear, then crank the torsion bar adjusting screws clockwise until the front is level.

As far as the clunking noise... if it popped 4 times in less then a second then that sounds like wheel speed related. Wheel bearing, CV's, diff, drive shafts?

If it indeed happens when suspension is being compressed then you have some bushings that are loose, or more likely, idler or ball joints that are loose.

You may be hearing 2 different noises

Jump on the rear bumper and bounce around. Can you get it to do the noise without moving?

[Mmusicman]

I had a van that would randomly clunk strongly in the rear.. turns out it was the brakes hanging up.
But it seems it mostly did it when leaving from a stop.
First time it happened it was so strong I thought I had been rear-ended.

Sway bars will make light clunking sounds while driving if bushings are shot... but are easy to diagnose as bad.

CV joints don't "slip"... U-joints will (sometimes) squeak when bad, and might clunk slightly when you first start rolling... but unlikely they would "clunk" at high speed.

I would certainly check the suspension (springs) for anything obvious.

PS: It just occurred to me one other time I once got a "clunk" or two... turns out I had just had my wheels balanced, and a couple of the fresh wheel weights flung off while driving. They had used the wrong type. I could tell they didn't look or fit right, so I marked the rim around the weights, and sure enough a couple big ones had disappeared.

[Vandy_B]

Yes. Torsion bars up front, and I do have them fairly well cranked up. What I meant was that the rear springs are probably shot...they sit about flat when the van is unloaded. I could crank them down a bit to level it out...but...but...I don't want to lose any altitude!

I can't get the noise bouncing on the rear bumper, and the idler arms were replaced about 5000 miles ago.

All the bolts on the springs/shackles are tight.

I thought about possibly the brakes hanging up...the wheel was not warm though, so if they are hanging up, they aren't dragging.

[kennysmoke]

I had a similar thing going on with my '03 AWD Astro as well... in my case it was the emergency brake shoe had disintegrated and was catching once in awhile. I never use the parking brake so I just pulled the inner shoes off. Hasn't done it since.

[1lowcab]

On my 03 the e-brake shoes would drag every once in awhile and make some pretty strange noises. Couldn't figure it out until I had the rear disks off and seen all the drag marks on everything.

[1lowcab]

LOL, you beat me too it Kennysmoke.

I took mine off too.

[Vandy_B]

KENNYSMOKE!!! I think you're on to something! That's exactly what it sounds like might be happening. And my e-brake is kind of messed up so I never use it. I'll have to pull the wheel and see if that's the culprit.

[kennysmoke]

As far as your springs the ones in my '01 Safari were shot. I had a spring added to the stack and gained close to 3 inches on stock springs and shackles.

[Vandy_B]

did you add a full leaf, or a "helper"? I'm considering replacing the whole spring pack. The question then is do I use OEM or use an S10 pack. Or do I go cheap and just do and "add-a-leaf".

[TurnNburn]

If your lifting your van anyways I think you will be happy with the S10 spring packs. But, even with stock shackles your going to get 4 inches or so. So with your shackles even on the lowest setting your going to be around 4.5-5 inches. The torsion keys can get you pretty close to those numbers.

[Vandy_B]

TurnNburn...are you saying that I can get close to that with the stock torsion keys? or is that with the reindexed keys? (Although the poly bushings add a little bit of height too) And does going that high in the front necessitate other mods? I've read about cv axles wearing out because of the more extreme angle, and ball joints needing to be replaced and mounted in upside down or something like that. I wasn't originally planning to go so high...but does ANYBODY ever say "nah...2" is good enough...I don't need to go 4+" "?

[TurnNburn]

yup, stock keys cranked up with 2 inch body lift will give you 4 inches. That's how everyone does it so you will be fine.

I have a 3 inch body lift with reindexed keys cranked up 4 inches. Its been like that for maybe 8k miles. I did run into a problem with CV angles when I first installed the keys. And bottomed out the new keys right off the bat for max kill lift. Well... It actually bottomed out the control arm onto the frame. And the second that thing rolled the CV bound up on itself and broke the inner joint... I didn't measure it like that but it was probably at 6+ inches of just torsion lift.

2 inches... 4 inches... nah... 7 inches...But that's because my name is Blake, and I am an Astroholic....

[Ironsides]

Nice choice on the '03 AWD and lift.

A lot of good info to look at here, you deleted the bumper cover, think like wind and give everything a tug up front also, wheel well skirting or fender. I like to get on the highway we have these water overpasses that get the van in a rhythm bounce, if you have anything like that by you check it out. You did move things from resting space, suspect bushings and shocks, if it isn't something catching wind during flex or brakes dragging. I'm just pointing out obvious, good luck.

[kennysmoke]

did you add a full leaf, or a "helper"? I'm considering replacing the whole spring pack. The question then is do I use OEM or use an S10 pack. Or do I go cheap and just do and "add-a-leaf".

Full leaf added to stock pack... and they cranked up the torsion bars. I gained close to 3" in the rear and about 2.5 in the front.

[The Drummer]

Hi kenny , did cranking the T bars made the front ride more harsh at all? , cause it would help on mine for tire clearance , nothing serious but when at lock it does rub a thad , thx

[kennysmoke]

Hi kenny , did cranking the T bars made the front ride more harsh at all? , cause it would help on mine for tire clearance , nothing serious but when at lock it does rub a thad , thx

It stiffened the ride but not harsh at all really. It corners much better... mine was sagged out pretty bad for 107,000 miles at the time... it's got 117 now. The whole ride is stiffer but a lot less roll cornering.

[Vandy_B]

Kennysmoke...so you were right on. Finally was able to pull the rotor off and one the shoe on one side was completely gone...in chunks inside the rotor. The other half had a few bites out of it but was still intact. Did you take the whole ring with the shoes out? I'm wondering about the spring mechanism that the ends of the ring fit into...did you just pull those out too and just running it empty?

Thanks for suggestion of where to look for that noise!

[WimpTech]

Glad you found it Andy.

Remember.. build to fit the need, not build then find out what you want to do. Also, ride quality is a subjective subject, so give it some thought before committing.

[kennysmoke]

Kennysmoke...so you were right on. Finally was able to pull the rotor off and one the shoe on one side was completely gone...in chunks inside the rotor. The other half had a few bites out of it but was still intact. Did you take the whole ring with the shoes out? I'm wondering about the spring mechanism that the ends of the ring fit into...did you just pull those out too and just running it empty?

Thanks for suggestion of where to look for that noise!

It's been so long since I did it... pretty sure I removed everything.