I did a search but I'm still not sure, please help!

About 6 months/2000 miles ago I bought four new tires. the old rears were pretty worn on the inside edges. My search results were that probably the rear shocks are toast, or the rear toe link bushings are worn out. But when I got the new tires, I had an alignment done and the guy said the rear shocks were fine, although he did admit that the alignment gave him trouble. Its too soon to tell if these new tires are going to wear out on the insides but I don't want to wait until they are ruined to find out!

For a long time I also have had a wiggle or shimmy at different speeds, it sort of feels like it is coming from the back but I can't tell. Its not so bad that it is going to throw me off the road or anything, but it sure doesn't feel right and I have had it through two sets of tires. I'm worried that this is a sign that the first mechanic is an idiot and the shocks are worn or he screwed up the alignment, or is it another problem that doesn't have anything to do with the alignment or suspension, the mechanic was right and thats why it has persisted through multiple tires? Ouch, my head hurts now.

I have the money to fix it whatever it is, but I don't like to replace parts with stock parts if an upgrade is available. So if I need rear shocks, I'll likely buy a whole suspension package like Tokicos, esp. now that people are making springs for the vert. If the toe bushings are worn out I'll get the Mazdatrix toe eliminator kit.

To narrow it down, I just had a bunch of work done, 4.3 LSD swap, light flywheel and new clutch, etc. and all the driveline mounts were checked and or replaced. That was a suggestion of a previous idiot mechanic who swore the tranny mounts were causing the shimmy. I have other people suggest a driveshaft that is out of balance or bad U-joints.

Any help would really make my day, and my car! Thanks!

 

Just to throw this out to you. First check with a tape to see what the toe-in/toe-out on the rear wheels are. An incorrect toe will chew up the tires very quickly. Just check reading from centerline to centerline on the front of the tires (as high as you can get-body/suspension will be the limiter) and across the back of the tires. Naturally the difference will be the toe. Toe can be adjusted by eccentric on each side. The camber can be checked via level set perpendicular on the ground next to the tire. Measure distance from top of rim to level on both sides to see if any difference. This is only a "back alley" way of checking, but will give you something to go on. Shocks could still be good, but if toe is way out, or front links are shot, tires will wear quickly. As no camber adj. is available with the stock suspension, individual adjustable links can be purchased, see Mazdatrix.
Also, as you stated, check the DTSS for wear which will cause a wonder effect.

 

This sounds like classic symtoms of worn out or cracked DTSS bushings.
(DTSS is the lateral G toe-out feature sometimes called rear-steer)
There are solid replacements available to eliminate the feature & make the handling more predictable.

Also high air pressure in low profile tires on the negative cambered rears will reduce the footprint & wear the inside tread.
I run 26-28PSI rear & 32-35PSI front, in my 225/50's.

 

Thanks. Well now that you mention it, I have been running 40 front and 34 rear pressure, so maybe thats too much. I'll change that right away. If I have to get the rear suspension ripped apart to replace the DTSS bushings with solid links, should I just go ahead and do the rear shocks anyway and save on the duplicate labor? The car has 110k miles, how much longer would I expect them to last anyway?

Oh yeah, now Racing beat has springs for the vert that are 20% stiffer than stock and an inch shorter, and they say that you dont have to change shocks. Anyone have any comments about the ride and handling of a stiffer spring with the stock shock?

 

My car has the factory suspension 172,000 miles and still going strong, but to play it safe, if your going for new springs, probably best to change all. Once the car is lowered, suspension angles change so adjustments will be needed.
The 40/34 air pressure is not causing the excessive wear on the inside of the rear tires. I'm sure you'll find geometry incorrect caused by worn parts, or just adjusted incorrectly.
The previous set 225 x50's were showing some inside wear. Too much toe in, so adjusted same. I now run 235 50's (30/32psi). No inside wear with about 18,000 miles.

 

Thanks for your help guys but thats bad news. After I use some of my "stash" on suspension fixes it'll just take that much longer to save up for the supercharger! Also Turbonut, what size rims and offset are you running? I used to have 225 50 16 all around but they rubbed in the front when hitting a bump on a corner. Now I have 205 60 16 and they are fine. Plenty of people on this site are running much bigger tires so I need new rims with the right offset. 225 all around would satisfy me, and it would be great if the new springs drop the car an inch and they still don't rub. Just wanted to ask someone who actually has them on his car!