Question on tie rods

I'm not getting much help on the :batman: board with this question, so I'm going to ask here as well. And bear with the length of my post - I'm trying to provide as much info as possible. ;)

I've been freshening the suspension on my manual rack '99 Sport (96k miles) this off season. Here's what has been replaced in the last 2000 miles:

• New tires
• New shocks
• New upper control arms (front)
• New sway bar mounts (front)
• alignment to my own specs (aggressive autox alignment)

Everything has been reassembled and torqued to spec (I've checked twice), and the lower control arm bushings look fine (that's why I chose to only replace the upper control arms).

Here's the problem: I'm still getting in intermittent shimmy/vibration out of the front end. Before anyone suggests wheel balancing, note that I've got new tires on both sets of wheels I own, both sets have been balanced by a trusted tech on a Hunter 9700 twice, and the shimmy doesn't change regardless of which set I use.

It's not the "65mph shimmy" either. It's intermittent, is prominent above 80-85mph, and is most noticeable when traveling in a straight line. When the front wheels hit a slight bump or pavement irregularity, especially at speeds above 60mph, there feels like a "jiggle" that travels up through the steering, but it doesn't feel like a damping issue. There is also a "looseness" in the steering when the car isn't heeled over in a corner (it tracks well when cornering steady state, but is twitchy and "loose" feeling when changing lanes on the freway, for example). I don't think it's an alignment issue either, due to the intermittent nature and the fact that I've used variations on this alignment for the past three years without the same sort of issue.

Lastly, the problem hasn't appeared suddenly. I think it's been getting worse over time, but replacing the blown shocks, worn tires, a bad upper control arm bushing, and cracked front sway bar mounts just removed all of the other issues that were masking this particular problem. :(

I'm thinking that after three and a half years of hard autox, track, and daily driving abuse, it might be time to replace the tie rods. At least, that's the next set of parts I'll be throwing money at, unless someone has a better suggestion. :D

Also, if I do need to replace the tie rods, do I need to order inner and outer tie rods for both sides, or would just replacing the outer tie rods suffice? From the diagram in the service manual it appears the inner tie rods are merely threaded rods, while the outer tie rods carry the actual ball joint (which is where I would suspect the wear would be?)

Any suggestions?

Is their any run out in the front bearing assemblies, rotors, or rims? An 85 MPH shimmy sounds like something is not rotating in spec.

The tie rods will keep things in position but I don’t see how they would cure/cause the shimmy.

I can't detect any play in the front bearings, the rotors are new OEM in the last 5000 miles, and the shimmy is the same regardless of what wheels I have on the front end (noticed it with the street wheels, noticed last night while heat-cycling the race tires on the OEM wheels, and it's still the same even after I rotated the street wheels).

I've centered on the tie rods because the problem feels more like a "looseness" or ever so slight slack/slop in the steering linkage. Like there is just enough play that it is allowing the wheels to respond laterally and incontrolled just a fraction to bump inputs. I guess the rack itself could be worn, but I figured I'd start with tie rods (unless someone else can see seomthing that I could have overlooked), and if that didn't take care of it I'd replace the rack.

I tend to think you're on the right track, but...

Are you confident that your wheel bearings are good? Loose bearing will cause a tendency to wander, and could certainly better account for the high speed vibration better than the tie rod/rack.

If the rack is worn, the wear would most likely be at the center, meaning all should be well in a turn. Any vibrations in 85 mph turns?

Nope. Once the car is loaded up in a steady-state corner there is no wander, jiggling, or looseness. It only manifests itself going straight or when making light turns such as lane changes.

Wouldn't wheel bearing issues also be accompanied by a noise? I've got no strange noises coming from the front end, and I can't feel any vertical play in the front wheels.

Wheel bearing don't always make a racket, but you should actually feel them more during cornering.

Sounds more and more like the rack.

Bollocks. Well, I can't afford to replace the tie rods and the rack at the moment, so I'm going to order inner & outer tie rods for both sides and see what happens. If that doesn't cure it than it looks like I'll be asking the wife for a steering rack for my birthday. :mrgreen:

Sooner or later I'll run out of parts to replace and the problem should go away, right? :wink:

Since you're not driving a Triumph, you're probably correct.

No one has enough money to replace parts on a Triumph fast enough to fully correct a problem before the first parts replaced have failed again...

Quote:

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Originally Posted by tailchaser

Since you're not driving a Triumph, you're probably correct.

No one has enough money to replace parts on a Triumph fast enough to fully correct a problem before the first parts replaced have failed again...

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I've lived that dream! That is truth! :lol:

Is there anyway to measure play in the rack? What about the rack mounts themselves aren't they made out of the same low quality rubber as the motor mounts??

Quote:

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Originally Posted by tailchaser

Since you're not driving a Triumph, you're probably correct.

No one has enough money to replace parts on a Triumph fast enough to fully correct a problem before the first parts replaced have failed again...

---

That's funny. I had a Saab like that once. :mrgreen:

Quote:

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Originally Posted by POS Racing

Is there anyway to measure play in the rack? What about the rack mounts themselves aren't they made out of the same low quality rubber as the motor mounts??

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They very well could be shot. However, if replacing the tie rods doesn't take car of it, I'll probably just replace the entire rack. The tie rods don't look like a tough job. I'd be pissed if I went to the trouble of removing the rack, pressing out the bushings, pressing new ones in, replacing the old rack, only to find that the rack itself was the problem.

You need to peek at how the rack is mounted to the subframe. :wink:

Also when you change the tie rods you get to get another alignment. :cheers:

If you can figure out how to check it, there's one other potential for the symptoms you describe (although it may be worse than replacing the rack).

Depending on which is softer, the u-joints in the steering shaft can wear instead of the wear appearing at the center of the rack.

are you lowered at all? my car gets the cases of bump steer occasionally.

No, stock Sport springs and KYB AGXs.

This isn't bump steer. I've experienced that, and this isn't the same sensation. It's rather hard to describe in words.

Oh well. I ordered new inner & outer tie rods from Mazdacomp this afternoon, along with overnight shipping so that I *should* have time to install them and get the car realigned before Saturday. We'll see what happens.