suspension shimmy

suspension shimmy

Postby five10freak [OP] » March 4th 2014, 9:41am

OK, so i didn't want to thread jack so i started my own.

so i have a vibration @70 mph, not in my steering wheel but the entire van has this slight vibration at 70 mph. i have gone through the entire suspension and all have been replaced.

but for the record items recently replaced or replaced within the last few months.
-bilstein front and rear shocks
- oem front springs with insulators
- heavy duty rear springs, all new hangers,bushings and hardware
- energy suspension lower and upper control arm bushings
- MOOG everything,lol. ball joints, inner outer tie rods, tie rod sleeves,left and right idler arms, drag link,all rubber caps replaced with energy suspension caps.
- energy suspension sway bar bushings and sway bar bushing end links
- energy suspension motor mounts
- hellwig rear sway bar
- oem style trans mount
- brakes are newish, within a year.( wheel bearings, rotors, new calipers and lines,etc,etc)

i'm sure i have forgotten a thing or two that have been replaced, but thats the bulk of things. and yet after all this work i still have this vibration,LOL

oh and rims and tires are about a year old, 20" iroc rims, tires are 245/45 20. i've had the rotating assembly checked for out of roundness and balancing. rotated tires just in case. had the van aligned again. the van drives straight as an arrow, even had the rear end serviced just in case with royal purple fluid.

at this point im clueless...
help
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Re: suspension shimmy

Postby Silverhawk » March 4th 2014, 1:37pm

Have you checked the universal joints on the driveshaft? The driveshaft itself has factory weights and if one has come off would cause some vibration.
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Re: suspension shimmy

Postby grandamle91 » March 4th 2014, 1:37pm

Bad motor mount and transmission mount :think:
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Re: suspension shimmy

Postby chevymaher » March 4th 2014, 1:44pm

Check the rear trans bushing. Wiggle the drive shaft where it enters the tranny.
Mine was frame bushings and alignment. Alignment being frame to body. As well as the normally thought of wheel alignment.
Camber change helped the most I think. I changed the toe in also.

Tires pointed in at the bottom coupled with a toe out and the wheels bounce. Unless your woodbutcher and you severely overload the van.
Just got to play with it untill you find what it wants.
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Re: suspension shimmy

Postby WoodButcher » March 4th 2014, 2:01pm

chevymaher wrote:Check the rear trans bushing. Wiggle the drive shaft where it enters the tranny.
Mine was frame bushings and alignment. Alignment being frame to body. As well as the normally thought of wheel alignment.
Camber change helped the most I think. I changed the toe in also.

Tires pointed in at the bottom coupled with a toe out and the wheels bounce. Unless your woodbutcher and you severely overload the van.
Just got to play with it untill you find what it wants.


Caster / camber is the one tires shops don't typically adjust and when we start playing with tire sizes, lifts and in my case overload conditions this really should be addressed.
My van has a rake to it unless it's fully loaded so the angles are off, a slight toe out rather than the stock toe in was my solution. Every setup will differ in some way so it isn't a one size fits all solution. If it is the suspension you will need to work with a knowledgeable suspension man or diagnose and adjust yourself. It isn't that complicated once you see the overall picture, kid of like shooting pool, it's all angles but in 3D.
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Re: suspension shimmy

Postby five10freak [OP] » March 4th 2014, 3:59pm

Silverhawk wrote:Have you checked the universal joints on the driveshaft? The driveshaft itself has factory weights and if one has come off would cause some vibration.


i was thinking about that this past weekend,lol

grandamle91 wrote:Bad <a class="vglnk" title="Link added by VigLink" target="_blank" rel="nofollow" href="http://shop.ebay.com/i.html?_nkw=motor+mount" sl-processed="1" style=""><span>motor </span><span>mount</span></a> and transmission mount :think:


not possible
new energy suspension motor mounts and new oem tranny mount

chevymaher wrote:Check the rear trans bushing. Wiggle the drive shaft where it enters the tranny.
Mine was frame bushings and alignment. Alignment being frame to body. As well as the normally thought of wheel alignment.
Camber change helped the most I think. I changed the toe in also.

<a class="vglnk" title="Link added by VigLink" target="_blank" rel="nofollow" href="http://motors.shop.ebay.com/eBay-Motors-/6000/i.html?_nkw=tires&_trksid=p5197.m570.l1313&_rdc=1" sl-processed="1" style=""><span>Tires</span></a> pointed in at the bottom coupled with a toe out and the wheels bounce. Unless your woodbutcher and you severely overload the van.
Just got to play with it until you find what it wants.


look above, :D , but a conversation was talked about the frame bushings this past weekend. i remember seeing a post/thread about frame bushings here somewhere, might have been one of ur threads, guess i need to find it again to see what u used.

i am planning on adding air bags to the rear for load leveling, although it's all new back there and the new rear springs are the HD ones, they are not the extra heavy type. so with my music setup( big box, two 15"subs, two amps ,etc,etc,etc, 4 batteries( two small kinetic 600's and two huge XS power 3400's) then all my CB garbage the rear sags a bit.not too bad but i can see it.
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Re: suspension shimmy

Postby Silverhawk » March 4th 2014, 4:39pm

Is it possible that one or more of the new mounts needs a spacer?
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Re: suspension shimmy

Postby five10freak [OP] » March 4th 2014, 4:53pm

Silverhawk wrote:Is it possible that one or more of the new mounts needs a spacer?


tranny mount is of oem height. now the energy motor mounts per instruction had to be somewhat compressed to fit the oem motor mount brackets, but in the end they at least looked to be stock height.

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Re: suspension shimmy

Postby Corsemoto » March 4th 2014, 5:36pm

Read this thread, there is a TSB for "Rolling Boom Noise Inside Vehicle"

https://www.astrosafari.com/viewtopic.php?f=9&t=47489
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Re: suspension shimmy

Postby five10freak [OP] » March 4th 2014, 9:38pm

Corsemoto wrote:Read this thread, there is a TSB for "Rolling Boom Noise Inside Vehicle"

https://www.astrosafari.com/viewtopic.php?f=9&t=47489



berry,berry interesting find!!!!

too bad it's NLA, time to search the web,lol
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Re: suspension shimmy

Postby Silverhawk » March 4th 2014, 11:07pm

Everything looks good! This may sound too simple to be the problem but check to see if you have lost a wheel weight on one of the rear wheels. It doesn't take much, I have chrome skull valve stem caps and forgot to put it back on after checking the tire pressure. When I drove it on I-80 it started to shimmy at 65 mph. I got off the next exit and did a walk-around and noticed the cap was missing. I had it in my pocket and put it back on, got back on I-80 took it up to 80 mph and the shimmy was gone. The chrome skull valve stem cap is steel and fairly heavy, maybe as heavy as a wheel weight.
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Re: suspension shimmy

Postby five10freak [OP] » May 8th 2018, 7:38am

4 years and 2 months later, My Vibration shimmy thing has been solved, sorta...

This might not fix your vibration but it fixed mine.

So in the last few weeks I have changed out a lot of parts on my van, most of the things were just preventive maintenance, some were necessary repairs and some were since I'm already there I might as well.

But I want to focus on the things that go Roundy Roundy. Lets see I changed the Dizzy, water pump, water pump pulley, idler pulley, tensioner pulley, harmonic balancer, timing chain, balance shaft gear set, oil pump and rear drums.

I will remove the dizzy, water pump, idler pulley, tensioner pulley and rear drum as theses have been replaced in the past and did not change the vibration at all.

So that leaves the water pump pulley, harmonic balancer, timing chain, balance shaft gear set and oil pump.

My first best guess would be the balance shaft gear set, although the old gears showed little to no wear. And my second best guess would be the harmonic damper.

Either way my vibration is now gone!!!!!!!!

What's your thoughts?
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Re: suspension shimmy

Postby 1lowcab » May 8th 2018, 12:23pm

It could have been the harmonic balancer or the gear set but what I have found out (after chasing a vibration on my old one forever) are these vans will pick up any rough running condition, even the smallest little misfire that you can't even feel and transmit it down the driveline and up into the body as a vibration/rumble.

Everything I did on mine helped a little, the biggest thing was the driveshaft harmonic balancer thing, but I still had a little bit of vibration until I replaced the engine, after that the vibration was gone.

So it might have just been your dizzy was wore just a bit or the timing chain was stretched just a bit or a combination of things, just enough so the van can pick it up and transmit/amplify it....it doesn't take much with these vans.

Congrats on the getting rid of the vibration, its a nice feeling to drive a smooth Astro isn't it!
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