Front Suspension Upgrades

FlashGuy

Been driving my G37S coupe with upgraded suspension for about 1 year now, and I think the stiffer suspension is taking it's toll on my stock suspension components. My current predicament is a growing dead spot (~ +/- 2 degrees) in the centerline steering and more pronounced rattles at low speed sharp bumps. I'm suspecting that the front lower control arm and front lower impact bushings are shot, thus contributing to the rattle and play in the steering.

Upgrades: Tein Mono Sport, SPL UCA, SPL rear camber arms, SPL lockout kit for camber, SPC toe bolt kit, SPL F&R endlinks, Whiteline diff bushings, and F&R Hotchkis ARB.

Usage: I track the car and take long road trips to the mountains every year.

I just wanted to reach out to the community for some thoughts on the next path to take.

1. Replace the current front lower control arm bushings with SPL spherical bushings.

2. Buy new control arms and install the SPL bushings. The reason being is there 80k miles on the car now and hedging a possible non-serviceable ball joint failure. Don't know if there are alternatives out there. I would like to move away from the OEM arm design to something more serviceable.

3. Replace the rear shock bushing with the SPL bushing first and address the rest in the knuckle at a later time.

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cv129

Based on your usage, is it possible worn steering rack bushing is causing the increasing play and clunk?

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FlashGuy

I have not thought of that and will need to get under the car to inspect that area. It hasn't been an issue that I've run across before. Makes me think of double checking the outer tie rods again.

While doing some research, it appears the steering rack bushing is not sold separately. A whole new rack seems excessive. Do you know of manufacturers that sell universal bushings beside Energy Suspension?

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MaysEffect

My bet is on sway bar endlinks.

littlejuanito

I second that

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Hotrodz

Your list of replacement parts is spot on. I would strat replacing those parts first before missing with the steering column. If your issue persist after replace the front suspension parts you listed then you can start trouble shooting other possible issues.

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OptionZero

I don't know if the tie rod-ends could be causing your issues, but SPL makes replacements that you might as well throw on as well:

Improved Front Outer Tie Rod Ends for 370Z and G37 | SPL Parts

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Rusty

If you are going to throw parts at the front. Here's a thread I did on it.

The Complete SPL Front Suspension

Since you said that you have 80,000 miles on the Z. If you are going to replace the lower ball joint, it comes with the lower arm and bushings. If the lower bushings was bad. I think you would know it. The rear is a big silicone fill donut. Just like the diff bushing that leaks.

I would check the sway bar end links to see if there is any looseness or play. Mine will squeak after they get wet, then dry out.

The dead spot you are feeling could be from loose tie-rod ends, OR the rack itself. Check the ends first. If they are tight. Then it's the rack.

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FlashGuy

Thanks for all the feed back everyone. I didn't want to get tunnel vision trying to solve this, and you guys have given lots food for thought.

I was under the car 2 weeks ago and actually checked tautness of the front endlinks. It was tight and there was no articulation bind. The rod ends wiped clean side to side. Even though the SPL rod ends are supposed to be Teflon lined and self lubricating, I shot some lithium spray at it. I'll check the endlinks again per recommendations.

Regarding the ps rack, anyone have an opinion on A-1 Cardone remans? Link
I'm keeping this in my back pocket if this is the root cause.

Also, anyone see the new SPL Bumpsteer Adjustable Front Outer Tie Rod Ends. Looks like you can get more steering angle from this version.

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Invidia|Tein|SPL|K&N|Hotchkis|Whiteline|Cusco| Goodridge|Z1

Rusty

To check the sway bar end links. You should disconnect one side. Because the bar might have a bind on it. Making the links tight.

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MaysEffect

To add to Rusty's post. Both wheels on the axle need to be either fully unloaded or loaded when you disconnect the endlinks.

The bar orientation makes a slight difference as well. The arm angle should be as parallel with the ground as possible when at ride height. you may need to modify the perch levels on the coilovers as well after making changes to endlink preload. Most of this should be done by a pro shop if possible.

Trouble shooting in a garage may give you a massive headache and not really get you any closer to properly fixing the problem.

Excuse my pessimism.