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Old 06-07-2009, 09:07 PM   #1
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Default Wierd suspension reaction pulls under acceleration

I just picked up my 93 turbo. Amoung the numerous problems that it has, is that it does a strange thing under acceleration. When I hit the gas on the highway it definately noses up and wants to go to the left. When I let off the gas it tends to settle back in, the nose drops and it swings back to the right. It doesn't do any of this abruptly, it feels more like a boat in that when it comes back from the left it tends to occilate a bit untill it settles in and goes straight. Ideas?
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Old 06-07-2009, 09:09 PM   #2
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Check your tire pressures.

Check the alignment, sometimes when an alignment is done the tech might not tighten the adjusters tight enough and they get loose and the alignment changes under load.
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Old 06-07-2009, 09:25 PM   #3
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LSD or open diff? Current suspension setup?
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Old 06-07-2009, 09:33 PM   #4
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The car has (at least in the rear) what looks like bilstein coilovers. It is suppose to be an LSD, but the car was less than accurately represented by the person selling it so I won't really know about the rear untill I jack it up tomorrow and spin the tires.
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Old 06-07-2009, 10:03 PM   #5
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I have sorda noticed this in my car once in a while. Not sure wat to think of it.
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Old 06-08-2009, 09:53 PM   #6
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I have not had a chance to jack the car up yet, but I can say the reaction is predictable and consistant and I wonder about a broken shock or bad bushing in the rear some where. The rear shocks are bilsteins, but not coil overs. Tire pressures are at 30 psi. The car feels very wobbly (like it wants to swap ends) turning to the left at any kind of speed esp. on a high speed sweeping curve.
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Old 06-08-2009, 10:14 PM   #7
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The fact that it feels so wobbly, especially since it's only in one direction, is worrisome.
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Old 06-10-2009, 06:46 PM   #8
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id say bushing, if theres play in them your alignment will change as the bushing moves.
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Old 06-10-2009, 07:28 PM   #9
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sway bars entact? Sounds like it could be a broken endlink on one side.

I'd also wonder if the torque arm is tight, although I'd guess you're be hearing some noise if it were a little loose.
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Old 06-10-2009, 10:00 PM   #10
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Quote:
Originally Posted by Project84 View Post
sway bars entact? Sounds like it could be a broken endlink on one side.

I'd also wonder if the torque arm is tight, although I'd guess you're be hearing some noise if it were a little loose.
If the endlink was broken, the swaybar would have no functionality.

Also, it's "intact".
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Old 06-10-2009, 10:08 PM   #11
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I knew it was intact... guess I was just typing fast.

Well, wouldn't a non functioning swaybar give some unwanted feedback through the suspension? Especially on the front when cornering?
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Old 06-10-2009, 10:29 PM   #12
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Without being connected at both sides, it simply rotates inside its bushings. There would have to be an awful lot of drag inside the mounts to get any resistance from a swaybar disconnected in this manner.
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Old 06-10-2009, 10:34 PM   #13
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This issue is obviously unique to this car, meaning it is not a common issue with Miatas.

Does the car show signs of being in an accident? An easy way is to look for the factory VIN stickers an all the body panels as a sign of prior accidents.

Are the tires new? Can you see any abnormal wear?

Do a jounce test, push down on each corner and see how long the vehicle bounces before it stops oscillating. On these cars, it should just come right up without any oscillations.

According to what you are saying it only does it while accelerating. Is it safe to assume that if you throw the car in neutral at high way speeds it tracks straight?

I would suggest raising up the car on jack stands and checking the rear suspension for either loose, worn or bent components. If visually everything is ok, grab a long pry bar and go after the same components but prying at them from different angles. The issue is in the rear suspension unless the vehicle doesn't track straight in neutral.

A sway bar link or the sway bar would not cause this issue under acceleration. The sway bar is not active during this time.

Good luck.
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Old 06-11-2009, 08:02 AM   #14
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sounds like worn ball joints to me, if your lifting the car, lift the front, and at 12 o clock and 6 o clock, grab the tire, and shake it, there shouldn't be any play, if there is it's the ball joints,. next grab 3 o clock and 6, and do the same, there shouldn't be any play, if there is you have a bad tie rod end.
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Old 06-12-2009, 01:06 PM   #15
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nose lift = squat...it happens because of simple physics upon accelerating in a turbocharged Miata. Turn up the dampening on the shocks...they could be set to soft. Even with my stiff Ohlins, I can get noticable squat/dive when they are on soft.

The pull is probably from unequal air pressure in the rear tires OR from two different tires on the back OR from one tire having more wear than the other. Disconnected swaybar will not cause this.
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