Problem with my Miata's steering, advice needed..

[SlowMiata]

Hi guys
So i have developed a steering problem over the last week and I need some advice on what it may be.
My miata is a 1993 with power steering and about 140k, and as of about a week ago it has been harder to turn the steering wheel when i am at a speed of more then 25mph; slower speed the steering feels fine. The bigger problem, after a corner the cars steering doesn't want to return to center, and it is very difficult to turn the wheel to get the car going straight again, this too happens at speeds greater then 25mph or so. I dont hear any noises coming from the front end or the steering, and other then this problem the car runs great.
Here is what i have tried so far: flushed and refilled the PS with lucas PS fluid, last night I had the alignment redone (so its not a problem with my toes or anything like that), about 8 months ago I installed coilovers and replaced my tie rods and end links and lower ball joint.

I am thinking either upper ball joints or my PS rack, anyone have any suggestions where I should start 1st.
thanks

[drv2fst]

Since it is speed dependent, I would think it's the pump. May want to try changing the belt first.

[SlowMiata]

if it was the belt i think I would hear a squealing while turning

[EMMI]

what ball joints did u get?

[kung fu jesus]

I thought your caster might be crazy. What were the alignment specs?

Emmi's question pertains to some cheaper TREs (tie rod ends) on Ebay. A few guys in SOCAL have had them freeze in position. I have them, but haven't had any issues over the last 3 years.

The upper ball joints aren't under a lot of stress like the lowers are.

A few questions: what is your ride height? What is your tire/wheel combo?

Also, are you leaking any PS fluid?

I would inspect the PS belt for wear.

[SlowMiata]

the ball joints i got where from ebay, but they look to be in good shape, and there is no play in the wheels, so i dont think my problem is coming from those.

I am kinda low, not slammed, but I have been at this hight for a while now with NP, I can still make it over speed bumps so I must not be too low.
i am running 15x8 rotas with a +25 offset and a 6mm spacer so the wheels just clear my brakes, I have been on this setup for about 4 months.
No PS leak or funky noises coming from the pump or the rack.

It was just too dam hot this weekend to work on the car, so I am taking it to a shop and see if they can figure it out.
thanks for the help all the help, I'll let you guys know the verdict as soon as I get this fixed...

[SlowMiata]

Ok so my mechanic thought the problem was my rack, after he confirmed that the pump is in good working order. So I gave him the go ahead to replace the rack. 600 bucks later and the problem is not fixed, but now I know there is no problem with the PS system.
I guess it could be a ball joint (although they do look good) or maybe it could be my alignment.
I checked out the alignment specs and they seem to be good, I just had it done last week to try and fix this problem but it didn't help.
my spec are about a -2 camber front and back and a 4.5 caster (this seems very high to me), and a 0 toe.

what do you guys think????

[xjdesertfox]

I hope you didn't actually pay for that...he mis diagnosed the problem...

[SlowMiata]

we'll see, he still has the car and has not talked $ yet.
I regret bringing it to my corner mechanic now, cause he tried to blame the problem on too wide of wheels.
He is usually good, but then again, I usually diagnose the problem before I bring the car to him to do the work.

[SlowMiata]

so I figured out the problem.
Turns out is was a busted ball joint, so I must have gotten one of those bunk ball joints from ebay.
thanks for all the help, I had the mechanic reinstall my stock PS rack, and going to install some mazda ball joints.

thats what i get for buying ebay replacement parts i guess, I am just lucky it didnt fully seize or break while I was on the freeway.

[EMMI]

I'm running an experimental set with tapped zirc fittings to make sure they are constantly greased... so far so bueno

[MX595]

i am glad i read this before purchasing new ball joints

[kung fu jesus]

Oh man, yeah. I bought the Ebay cheapies for my wife's NB. They, the lowers, last less than 8k miles before one separated. Fortunately, I was driving the car at a relatively low speed, but I was approaching the freeway on-ramp. This could have been deadly.

Please, learn from my mistake. Do_not buy cheap, unknown brand balljoints.

One of the SOCAL guys bought these as well and his separated the first time he backed out of his driveway.