Defective kyb = vibration 60-70mph?
 

When I bought the car 2 months ago it had dryed out tires and vibrated really bad on the highway but I figured it was just bad tires. I installed new wheels and tires(balanced) and drove the car yesterday to lower it a bit and to an allignment. The car still vibrated and felt very jumpy and i felt a bit of steering play. We tightned the steering box and helped the play. I still feel slight play, but I just figured that is normal for a 20 year old car?

As we began trying to lower the car with the coilovers, we noticed that the (front/pass) side wouldn't drop. We even lowered the perch all the way down on that side and it still wouldn't lower. We ended up raising the front drivers side so the car would be even, and did the allignment. Anyways, I drove the car home and the car is still vibrating.

So my question is, could this all be due to a bad shock? How can I test it?

(rear just for example) we lowerd the front all the way down and it still didn't drop.
http://img401.imageshack.us/img401/5091/cimg3071i.jpg

http://img706.imageshack.us/img706/9646/bay3z.jpg

the shock does not control the ride height...unless it was seized.

Defective KY generally results in friction, not vibration.

This couldn't possible be the infamous "65mph shimmy" could it?

Searching 65mph shimmy now!!!

F that shimmidy shit. Just found a a big crack on my dash because of it. I get it at 55 and 80-90.

You'll probably have more luck at miata.net, since it affects almost every miata.

You need a good balance on your tires if you don't want to drive a paint shacker.

SHAKE IS NOT SPELLED WITH C. a

Thanks fellas. Looks like I'll be looking for a better place to balancing my tires. So should I look for a shop that has one of these hunter machines?

Yes. You want a Hunter Road Force balance with no more than a road force of 10-12 on the fronts. You can live with a 25 on the rears. The shop may have to dismount the tires, turn them and remount a couple of times. Mine did.

Go to Hunter's site and they have a shop locator that has their equipment on there.

Or you can just invest in some decent bracing.

Frame rails, harness bar and a roll bar made mine go away. Now that I've taken those off I'm afraid to see how it rides on the highway. Another stock Miata headache I'd forgotten about...

First picture looks strange. I don't remember seeing coilovers installed on top of a perch.

is the sleeve taller than the shock body? They must be shortened if so. I have a feeling the body is riding on the sleeve...

I get the shimmy at like 35 mph and ~65 mph
Balancing doesnt seem to get rid of it
so idk, Miatas are weird

Can't see pics at work, so missed this, but yes, the eBay sleeves ARE longer than AGX shock body. When I did this last year before getting real suspension I had to cut nearly an inch off mine.

i had to as well on my konis....

I will have to look into the sleeves but how do I measure this? I guess I will need to remove the coilovers first and go from there. If anyone has a link or a pic of hoe to measure this I would appreicate it. Sorry for my ignorance, but this is my first time owning coilovers.

I'm still not getting how the car can't be lowered? Did you screw down the collar and then let it sit on the ground?

http://www.boostedmiata.com/gallery2...2/DSC_0037.JPG

the sleeve must be such that the collar does not extend past the shock body. if it does, the collar with hit the perch once compressed and severely limit your shock travel. there's a chance that the body is resting on the collar and that's why the car cannot lower and rides like shit.

well the car lowered just fine on all three sides when screwing down the spring seat. The front passenger side however didn't lower at all when I adjusted seat all the way down.

Is it possible that a front and rear shock were switched?

I will work on the car tomorrow and post some pics of the F/Right coilover setup.

Bent shock shaft?

The shimmy went away on my '99 when I put on the Konis.

I also have a '91 with 188k miles and AFAIK original, basically non-functional shocks. Couldn't even drive it at 65-70 on the highway. Got the wheels balanced properly (no need for road force, just round wheels and tires and a proper dynamic balance) and it's rock-solid at all speeds.

I bought a new one on ebay this morning. I'll post after installed to see if it fixed problems.

I have had my tires rebalanced like 3 times and still I have a shake at anything above 65ish. I wonder if it would have anything to do with only putting weights on the back of the wheel. I doubt it. I'm pretty sure it doesn't have anything to do with the 65mph shimmy though, since I have had it running smooth before with zero shake. So to the OP, just have the wheels balanced by someone who really takes their time to do it right, and has good equipment, and it may be OK.

Tierod? Wheel bearing?

I just had to replace a rear brake rotor for this problem.

No pedal pulsing and multiple wheel balance attempts did not fix it. It took a trip to the dyno where I saw the driver's side rear wheel wobbling to find this.

+1, any howl with the vibration?

I was under the impression kyb's have lifetime warranties? I know you're not the orginal purchaser but most decent autoparts stores will help you out anyways (costs them very little, encourages you to return to them for other parts)

I think you where right. The rear was flush, but the front sleeve was way taller(1"). It looks like the front sleeves are taller then the rears.

http://img526.imageshack.us/img526/8074/cimg3259.jpg

I raised the car about 1" on all sides, but the passenger front still sits 1/2" taller then all the other sides. Must be something wrong with that shock/shaft. Anyways the car rides much better now even though it doesn't look as nice anymore, but it will have to do untill my Vmaxx's arrive from FM.

Raised

http://img268.imageshack.us/img268/7614/cimg3263t.jpg

I've been chasing a vibration at 70 for months now. good luck.

You need to cut those massive bump stops down. Even threads everywhere is no way to go, just raise until even for now.

Stop doubting it. Take your wheels off, use a good wheel cleaner like Eagle One to get all the dust off the inside, then take them to a place that uses tape weights to do a proper dynamic balance. The weight on the inside only takes out the hop, not the wobble.