Void

TL;DR: When I brake at low speeds, steering wheel and consequently the car turns to the right a bit if I let go of the wheel. Could the rim and tire difference cause the steering wheel to turn right when braking at low speeds? Maybe the +15 spacer is a factor too? Took it to one of the best mechanics in town for alignment. They told me it ***could*** be the aftermarket bigger & wider wheel setup (Still diagnosing; see below). Maybe someone could offer some insight if it happened to them and under what circumstances. Maybe I’m way off here. Also, it’s not the brake caliper binding. Tested.

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I don’t notice it almost at all at high speeds but at low speeds when I brake sometimes the steering wheel turns to the right. Not even every time but it still has nothing to do with the slope of the road that was 100% tested. Wheel alignment doesn’t seem to solve the issue, though it made it a little better. I was told it may have something to do with the size of the wheel (rim & tire setup combined). Like running bigger rims and wider tires may affect how the car handles those wheels and tires and to avoid the two front wheels fighting each other, it’s best to keep it as is. By leaving it “as is” the mechanic was referring to the steering wheel position not being 100% center for the car to go straight.



Here are my exact aftermarket specs:

-Tires: Continental ExtremeContact DWS06+

245-40-r18 front - 22lb

295-35-r18 rear - 26lb

-Wheels: RPF1

18x8.5 +30mm offset front - 18.3lb

18x10.5 +15mm offset rear - 19.7lb

-Hub centric 15mm spacer front so offset now +15 front (could the spacer also be a factor?)



This is opposed to the factory 2003 350z Touring edition which I believe comes from factory as 7.5x17” wheel front 225/50R17 tire specs.

still diagnosing but the shop doesn’t specialize in 350z’s so maybe someone could offer some insight as to what could be causing this from experience and just best guess, apart from alignment and caliper binding. Thanks!

nizzan4u2nv

iTrader: (1)

Check your caliper slider pins if you still have factory floating calipers. One side may not be moving freely cause side to side brake bias issues. Radius rod bushings, if worn, could be causing caster oscillations under heavy braking.

icer5160

iTrader: (4)

If this only happens when braking, then it's most likely the brakes. Larger wheels & tires or BBK won't cause this type of issue unless they are mismatched (Left vs. Right). You could have a sticking caliper (checked already), oil/grease contaminated brake rotor(s) or pad(s), warped rotors, uneven wear/contact on pads, mismatched brake pads and/or rotors if this is an area of the vehicle you never inspected or serviced since purchased, or a really bad wheel bearing (would be obvious and easy to diagnose). Also check your soft brake lines, make sure they are routed properly (there shouldn't be any twists in the lines). Check the brake fluid, if it's dark flush it all and replace with fresh fluid. If it looks clean, do a basic bleed on all 4 corners. Note the front calipers are a little tricky to bleed. Air bubbles in the system could cause this type of problem.

Sometimes the suspension could be the cause. If you have worn out ball joint(s) or bushing(s), this could potentially cause alignment issues which wouldn't be immediately noticeable until under a braking load. Have you ever had a 4-wheel alignment checked or done? This is an area I would consider if the brakes themselves check out good. Another possibility is accident damage. Was this vehicle ever in a front end collision? Frame damage will cause all kinds of issues with alignment in the suspension that will translate into weird handling characteristics.

There's a lot of geometry that goes into play whenever you hit the gas or brakes (weight transfer and all that good stuff).

Keep it simple and start with the basics. If it was my car, I would 1st do a detailed inspection of all the front suspension bushings and brakes with added care to the common failure points. Then, I would swap out both front rotors and pads if they are 50%+ used up or some cheap auto-parts brand (O'Reilly or Autozone stuff). Use quality pads and rotors, install them right. Service the caliper pins (non-brembo), clean all the surface rust off the wheel hub to ensure good runout, only grease the areas that need it, etc. If the brake fluid is dark/black I would flush and replace with fresh fluid. If any bushings are torn, ripped, or leaking, get those replaced and have a 4-wheel alignment done.

Hope you get it sorted! I know I wrote a lot, but there's a lot of possibilities. A visual inspection will be able to clear out many of these potential faults.
-Icer

bre240z

maybe the brake caliper on that side is sticking. I would check the brakes first