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-   -   Extreme bump steer?? (http://www.the370z.com/brakes-suspension/119582-extreme-bump-steer.html)

rambo 02-02-2017 11:10 AM
Extreme bump steer??
 
Hey guys, I recently bought my 2014 touring/sport 370z with 10,000 miles.
What I noticed after driving for a few weeks is that this car has an extreme amount bump steer. It's so bad that I'm sure if a cop were behind me he/she would think i was driving under the influence. The car just follows the bumps in the road.

I know wider front tires can cause this but I'm coming from a lowered 350z with 255 front tires and never experienced this.

I bought the car from Carmax and they supposedly aligned it when I brought it back to complain. No difference.

Any ideas? My only thought is that Carmax either gave it a **** alignment or possibly may have not aligned it at all? Or could the tires (OEM Bridgestones) be the problem?

Also something I just remembered is if I'm at a stop, turn the wheel all the way to the left and slowly accelerate, the tires seem as if they're slipping. (imagine making a u-turn in a cul-de-sac)

OptionZero 02-02-2017 11:12 AM
don't trust Carmax's alignment, do your own.

Also get a front suspension inspection to see if anything is obviously damaged

Jayhovah 02-02-2017 11:17 AM
http://vignette4.wikia.nocookie.net/...20111017172251

rambo 02-02-2017 11:21 AM
Quote:
Originally Posted by OptionZero (Post 3610922)
don't trust Carmax's alignment, do your own.

Also get a front suspension inspection to see if anything is obviously damaged

Yeah that's actually what I was starting to consider. I'm almost certain the toe settings are way out of line.

Not the mention Carmax never gave me the before and after specs of the alignment like every other alignment I've ever gotten at other shops.

Hotrodz 02-02-2017 12:12 PM
What kind of tires do you have on the car and how much wear are on them? This can cuase trammeling on rutted or roads with groves in them.

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rambo 02-02-2017 12:26 PM
Quote:
Originally Posted by Hotrodz (Post 3610941)
What kind of tires do you have on the car and how much wear are on them? This can cuase trammeling on rutted or roads with groves in them.

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I have the OEM Bridgestone Potenzas on the car. Decent wear. Seems the front left tire has more wear on the outer edge of the tire.
If I remember correctly I think the outside tread was measuring at 3-4/32nds and the remaining tread about 6-7/32nds.
Toe out of spec?

Hotrodz 02-02-2017 12:42 PM
Quote:
Originally Posted by rambo (Post 3610945)
I have the OEM Bridgestone Potenzas on the car. Decent wear. Seems the front left tire has more wear on the outer edge of the tire.
If I remember correctly I think the outside tread was measuring at 3-4/32nds and the remaining tread about 6-7/32nds.
Toe out of spec?
With that kind of uneven ware I would get two new front tires and an alignment.

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NoHyperbole 02-02-2017 01:22 PM
You and I share many similarities. I too have a 2014 Sport/Touring on the OEM Bridgestone RE050 tires (now at 18,500 miles and 90% worn), and you've described exactly what I've been experiencing the entire time I've owned the car. Further, my previous car was a 350Z that never exhibited these traits, so I understand where you're coming from.

Regarding what you've called "bump steer," here is my take. When driving straight on road with a bunch of minor imperfections, if I take my hands off the steering wheel, it will "dance" or shimmy side to side, although the car will generally track straight. When I hit a moderate to major bump with one front wheel, the steering wheel will do a quick left-right-left (or right-left-right) shake. Again, this is something I never experienced in my 2007 350Z. My thought is that the extra caster in stock 350Zs (around +7.0) versus 370Zs (around +5.0) is a contributing factor in reducing this steering trait.

As for the sensation that the (front) tires are slipping during slow-speed turns at full lock, I know this sensation well, although it seems to happen only when the ground (after rain) or tires (after car wash) are wet. Do you experience this in dry conditions?

As for alignment specs, my numbers on the OEM suspension are as follows:

Camber: LF = -0.6 RF = -0.9 (non-adjustable)
Caster: LF = +4.7 RF = +4.4 (non-adjustable)
Toe: LF = +.05 RF = +.05

Camber: LR = -1.6 RR = -1.5
Toe: LR = +.10 RR = +.10

What are your alignment numbers? I'm curious to see if they differ greatly from mine.

I've tried taking the car to the dealership to have them investigate this issue, but they don't seem to think anything is abnormal. You and I both know something is not quite right. I wonder if this is an issue only a certain number of 2014 Sport/Touring Zs have.

NoHyperbole 02-02-2017 01:27 PM
Quote:
Originally Posted by rambo (Post 3610945)
I have the OEM Bridgestone Potenzas on the car. Decent wear. Seems the front left tire has more wear on the outer edge of the tire.
If I remember correctly I think the outside tread was measuring at 3-4/32nds and the remaining tread about 6-7/32nds.
Toe out of spec?
I too thought I had outside tire wear, but upon closer inspection, it's actually the inside that has worn more. The tread near the channel closest to the outer edge of the tire will appear more worn than the tread surrounding the three inner channels; on each of my tires, mine is almost completely worn down in this area, but I have a bit of tread remaining above the wear bars in the three inner channels. This outermost channel does not have a wear bar and should not be used to gauge tread depth.

If you are able to see the very inner edge of your tires, then you may see excessive wear in that area. I didn't realize this until I had the wheels off the car and looked closely at the tires.

rambo 02-02-2017 03:28 PM
Quote:
Originally Posted by NoHyperbole (Post 3610978)
You and I share many similarities. I too have a 2014 Sport/Touring on the OEM Bridgestone RE050 tires (now at 18,500 miles and 90% worn), and you've described exactly what I've been experiencing the entire time I've owned the car. Further, my previous car was a 350Z that never exhibited these traits, so I understand where you're coming from.

Regarding what you've called "bump steer," here is my take. When driving straight on road with a bunch of minor imperfections, if I take my hands off the steering wheel, it will "dance" or shimmy side to side, although the car will generally track straight. When I hit a moderate to major bump with one front wheel, the steering wheel will do a quick left-right-left (or right-left-right) shake. Again, this is something I never experienced in my 2007 350Z. My thought is that the extra caster in stock 350Zs (around +7.0) versus 370Zs (around +5.0) is a contributing factor in reducing this steering trait.


As for the sensation that the (front) tires are slipping during slow-speed turns at full lock, I know this sensation well, although it seems to happen only when the ground (after rain) or tires (after car wash) are wet. Do you experience this in dry conditions?

As for alignment specs, my numbers on the OEM suspension are as follows:

Camber: LF = -0.6 RF = -0.9 (non-adjustable)
Caster: LF = +4.7 RF = +4.4 (non-adjustable)
Toe: LF = +.05 RF = +.05

Camber: LR = -1.6 RR = -1.5
Toe: LR = +.10 RR = +.10

What are your alignment numbers? I'm curious to see if they differ greatly from mine.

I've tried taking the car to the dealership to have them investigate this issue, but they don't seem to think anything is abnormal. You and I both know something is not quite right. I wonder if this is an issue only a certain number of 2014 Sport/Touring Zs have.


Wow well I certainly hope it has nothing to do with the 2014s although that wouldn't make any sense.
I don't have my last alignment numbers. I dropped the car off at carmax a few weeks after purchase to have them align it and they never gave me the before/after configurations. I wish I asked for them.
I'll likely look into getting new front tires and another alignment.

Are you still currently on the Bridgestone tires?
I was really hoping that I may have incorrect toe settings but if you're experiencing the same problem with good toe settings....

It just sucks considering these cars typically have outstanding handling/suspension and I don't even feel comfortable driving with one hand on certain roads now.

rambo 02-02-2017 03:31 PM
Oh and for the tires slipping sensation I experience it in both dry and wet although wet is certainly worse.

Hotrodz 02-02-2017 03:41 PM
What kind of tire pressure are you running?

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rambo 02-02-2017 03:48 PM
35 psi

NoHyperbole 02-02-2017 03:55 PM
I'm at 35 psi cold as well, and I do check often with an accurate gauge.

I'm also still on the OEM Bridgestone tires, and they have 18,500 miles on them.

I purchased lifetime alignments at Firestone, so I have had maybe 10 (!) alignments so far, some of which were at different locations to make sure the numbers were the same on different machines. And they were.

I feel like I've tried everything to fix this issue. Perhaps the easiest move--and my next one in a few months--will yield an improvement: getting new tires.

Hotrodz 02-02-2017 05:39 PM
Yup, I think new tires are in order as everything else seems to within standard. I know my car drove a lot better when I put a new set of tires on.

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SouthArk370Z 02-02-2017 06:42 PM
Quote:
Originally Posted by rambo (Post 3611018)
Oh and for the tires slipping sensation I experience it in both dry and wet although wet is certainly worse.
Happens with wide tires; normal for a Z. Bad alignment may be making it worse.

Jhill 02-02-2017 08:06 PM
Quote:
Originally Posted by rambo (Post 3611018)
Oh and for the tires slipping sensation I experience it in both dry and wet although wet is certainly worse.
If your talking about slow speed like tight parking maneuvers etc. this is normal I would say. Mine does it too and new corvettes do it really bad or last gen vetted when people but wider wheels. Seems to be a trait with wide wheels and lots of caster.

We're talking about a slip like a skipping feel kinda?

rambo 02-02-2017 11:36 PM
Quote:
Originally Posted by Jhill (Post 3611140)
If your talking about slow speed like tight parking maneuvers etc. this is normal I would say. Mine does it too and new corvettes do it really bad or last gen vetted when people but wider wheels. Seems to be a trait with wide wheels and lots of caster.

We're talking about a slip like a skipping feel kinda?
Yeah exactly some type of skipping feeling.
Strange thing is I don't recall my 350z doing this and that had wider front tires.
To make sure we're talking about the same thing I am not talking about the possible power steering whine sound when the steering wheel is turned to its max.

NoHyperbole 02-03-2017 09:11 AM
Quote:
Originally Posted by rambo (Post 3611244)
Yeah exactly some type of skipping feeling.
Strange thing is I don't recall my 350z doing this and that had wider front tires.
To make sure we're talking about the same thing I am not talking about the possible power steering whine sound when the steering wheel is turned to its max.
That's exactly what it is: skipping, slipping, shuddering.

And my 350Z didn't do this either, and it had almost identical front camber and toe settings to my 370Z.

SouthArk370Z 02-03-2017 09:37 AM
Tire compound and tread pattern have a big effect on tire slip/noise at extreme angles. This may (or may not) be why y'all didn't notice it on other cars. It happens to all cars; just not very noticeable on many.

NoHyperbole 02-03-2017 10:03 AM
Quote:
Originally Posted by SouthArk370Z (Post 3611342)
Tire compound and tread pattern have a big effect on tire slip/noise at extreme angles. This may (or may not) be why y'all didn't notice it on other cars. It happens to all cars; just not very noticeable on many.
That is true; however, in this case, both my 350Z and 370Z were equipped from the factory with the same Bridgestone RE050 tires, just in different sizes.

As I pointed out in an earlier post, the only major difference between the two cars is their caster specifications (about +7.0 for the 350Z, but about +5.0 for the 370Z). More positive caster, among other things, equals more heft in the steering and a feeling of more stability; less positive caster equals less heft and a feeling of quicker turn-in. Driving both cars back-to-back will reveal this immediately.

Hotrodz 02-03-2017 10:12 AM
Quote:
Originally Posted by SouthArk370Z (Post 3611342)
Tire compound and tread pattern have a big effect on tire slip/noise at extreme angles. This may (or may not) be why y'all didn't notice it on other cars. It happens to all cars; just not very noticeable on many.
^^^ This, the stiffer the sidewall the more you will feel this and as pointed out, this often happens at low speeds but when the car is at speed and the loads on the tires and suspension are increased it will not be noticeable as long the tires do not have excessive wear or the alignment is off.

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Hotrodz 02-03-2017 10:19 AM
Quote:
Originally Posted by NoHyperbole (Post 3611350)
That is true; however, in this case, both my 350Z and 370Z were equipped from the factory with the same Bridgestone RE050 tires, just in different sizes.

As I pointed out in an earlier post, the only major difference between the two cars is their caster specifications (about +7.0 for the 350Z, but about +5.0 for the 370Z). More positive caster, among other things, equals more heft in the steering and a feeling of more stability; less positive caster equals less heft and a feeling of quicker turn-in. Driving both cars back-to-back will reveal this immediately.
There are enough differences in the geometry and design of the two cars that you should not expect them to act or feel similarly. Some folks prefer the handle characteristics of the 350 over the 370.

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Jhill 02-03-2017 11:49 AM
Quote:
Originally Posted by Hotrodz (Post 3611361)
There are enough differences in the geometry and design of the two cars that you should not expect them to act or feel similarly. Some folks prefer the handle characteristics of the 350 over the 370.

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Yes we're talking about the same thing, it is not a power steering noise etc it is an actually skipping feel at tight radius at slow speed. Felt it the first day with the z but really didn't pay any attention to it after being a GM tech and working on tons of corvettes that have this same trait but even more so. Honestly would not worry about that at all as everyone here has the same thing so it's not as if yours is doing anything different. As for bumpsteer I don't feel that at all and usually doesn't become an issue on cars in general untill people lower them.

And that's weird it wasn't supposed to quote hotrodz but whatever.

rambo 02-03-2017 06:37 PM
Quote:
Originally Posted by Jhill (Post 3611426)
Yes we're talking about the same thing, it is not a power steering noise etc it is an actually skipping feel at tight radius at slow speed. Felt it the first day with the z but really didn't pay any attention to it after being a GM tech and working on tons of corvettes that have this same trait but even more so. Honestly would not worry about that at all as everyone here has the same thing so it's not as if yours is doing anything different. As for bumpsteer I don't feel that at all and usually doesn't become an issue on cars in general untill people lower them.

And that's weird it wasn't supposed to quote hotrodz but whatever.


Lol I was reading this thinking "I'm pretty sure that was meant to be quoting my last comment".
I'm thinking I'm just going to buy a new pair of front tires and get a proper alignment done together.
On my way home from work today I was on this horrible rode filled with pot holes and cracked pavement and I could not keep the car straight for the life of me, even with both hands on the steering wheel. It really is dangerous.

rambo 02-03-2017 06:39 PM
NoHyperbole, I paid closer attention today as I was driving and noticed my car actually pulls to the left pretty severely if I let go of the wheel. You stated that your car will drift left/right but generally stay centered.

My assumption is your problem is from bad tires, and mine is from a bad alignment and bad tires.

NoHyperbole 02-03-2017 08:26 PM
Very interesting. Thanks for the input.

I hope you get this issue sorted out soon, as I'm sure driving an unsafe car is no fun. Keep us posted.

littlejuanito 03-27-2017 11:05 PM
Quote:
Originally Posted by rambo (Post 3611598)
NoHyperbole, I paid closer attention today as I was driving and noticed my car actually pulls to the left pretty severely if I let go of the wheel. You stated that your car will drift left/right but generally stay centered.

My assumption is your problem is from bad tires, and mine is from a bad alignment and bad tires.
Why don't you replace your outer tie rods with some SPL's ? That may fix the bump steer issue. Any else care to chime in?


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