_
_ Dork
1/10/20 8:26 p.m.

My brand new to me, low mile nc Miata has an interesting "feeling" when I turn at full lock in reverse slowly. It's almost as if I'm repeatedly hitting a small patch of ice with the passenger front tire, but it's sort of rhythmic. I noticed it backing out of the garage just now. I then Ran to the grocery store and hit my two favorite roundabouts (a tight, left hand circle, and a larger radius of the same). I did about 720° around them, no issue, no random slidy feeling forwards.

When I got back home, I pulled into the garage, and backed out a few times, same results. And only with the wheel cranked to the left (locked). 
 

then I crawled under and cranked the wheels, took some pics. I got nothin'. Here's pics. 



kinda sucks, cause I crawled under there when test driving and didn't see anything out of the ordinary. Also didn't feel anything crazy during the test drive, but I also didn't back it out of the garage, I went forward almost the whole time.

_
_ Dork
1/10/20 8:29 p.m.

Another way to explain the feeling is that it's like when you turn a low speed 90 with a locked diff. It's that lurching, hopping, sliding feeling.

Knurled.
Knurled. MegaDork
1/10/20 8:48 p.m.

Could just be a steering geometry thing.  Driving in reverse at full lock is not a high priority.

 

I hear tell that C7s do similar things going forwards, with less lock. 

 

Anyway, the point of the story is this:  Go wash the car off very, very thoroughly, and put it away until May.  NCs allegedly rust the fronts off like nobody's business.  I say allegedly because I have never had opportunity to fondle an NC, they are so rare.  With the salt coverage I see on your suspension, I give your car three years before it's an Exocet donor.

Keith Tanner
Keith Tanner MegaDork
1/10/20 8:56 p.m.

Ah, it’s a car. Drive it. 

I agree that it’s probably slip from steering geometry, probably Ackerman. 

Patrick
Patrick MegaDork
1/10/20 8:59 p.m.

Not enough MaXpeedingRods coilovers

_
_ Dork
1/10/20 9:00 p.m.

Uh, ok. there's no salt on our roads, that's water and mud.

_
_ Dork
1/10/20 9:00 p.m.

In reply to Patrick :

Thank god this one didn't come with those.

Knurled.
Knurled. MegaDork
1/10/20 9:05 p.m.
_ said:

Uh, ok. there's no salt on our roads, that's water and mud.

GOOD.

 

That is what salt coverage looks like.  It gets everywhere.

 

The roads here are all bone white with salt up until today, which was nonstop rain that washed it mostly away.  Which means they will drop another cubic mile of salt on the roads the next time the temps drop below 40.

dps214
dps214 Reader
1/10/20 9:06 p.m.

 Does it have a limited slip diff of some sort?

_
_ Dork
1/10/20 9:50 p.m.

No.  Very much open diff. And this is the front wheels, definitely. 

dps214
dps214 Reader
1/10/20 10:45 p.m.

A tight clutch diff will definitely do the same thing when turning tight at low speed. In any case it's not uncommon for weird things like that to happen at full lock in reverse. If that's the only situation where it happens don't worry about it.

Shadeux
Shadeux Reader
1/11/20 6:36 a.m.

In reply to Knurled. :

C7's do that mostly in reverse. Ours really lurches when backing out of the garage. It depends on the surface as well.

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
1/11/20 7:28 a.m.

In reply to _ :

I know the feeling exactly, I get it when backing my wife's Scion xB out of the garage. I've gone over the suspension and I'm convinced it's the Ackerman effect.

APEowner
APEowner Dork
1/11/20 11:48 a.m.

It's most likely a steering geometry thing.  If nothing's loose and you don't have tire rub with the wheels turned then don't worry about it.

iceracer
iceracer UltimaDork
1/11/20 11:54 a.m.

How do you back out of your garage at full lock ?wink

_
_ Dork
1/11/20 12:05 p.m.

In reply to iceracer :

You should see my "driveway"...

yes, it seems it is just Ackerman. There are a few NC forum threads about this very issue. It stems from Ackerman, cold tires, short sidewalls, and cold ambient. 
 

sorry for the mass hysteria, it's a new to me car, and the newest car I've ever financed that wasn't a brand new car off the lot. Paranoid much? Lol. 

BlindPirate
BlindPirate Reader
1/11/20 12:17 p.m.
iceracer said:

How do you back out of your garage at full lock ?wink

Ask my wife, she did it once. Well she tried.

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