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Rear end wants to step out

Valhalla

Valhalla

Legendary Member
Joined
4 April 2011
Messages
2,436
Location
Fountain Hills, AZ
A little background. '91 NSX with 445rwhp. Axles and boots repacked 1500 miles ago. BC Racing coilovers on 10/8 Swift Springs F/R. NA2 rear sway bar and Dali Trophy front sway on Carbon6 end links. Stoptech BBK on all four wheels. Tires are Yokohama S Drives 215/40 & 275/35 on Advan Model 5's 17/8 in front and 18/10 n the rear. Rear beam bushing has been replaced with TiDave's non-compliant bearing. Front Steering rack rebuild by Matt Lindsey and realigned to Type R specs in the front.

I sustained a flat rear tire which killed the tire and I replaced with a new S Drive. The old tires only had a couple of thousand miles on them so the stagger from new tire to old is minimal with the rears. I have heat cycled the new tire on over a dozen trips of at least 30 miles each. But ever since replacing this one tire, the rear end wants to step out on hard acceleration. The car doesn't seem as stable at speed either. It seems to want to move the rear of the car to the left (toward the new tire) and the car seems to float a little at high speed.

I've checked the damper settings and they match up. I pulled the wheels off to check the axle nuts. They are torqued correctly and the nuts are staked. The only thing I have noticed is on the passenger side, if I grab the rotor at 3 and 9 o'clock positions and tug in and out, I will get a fairly slight "clunk" in both directions. Nothing on vertical tugging, only on the horizontal. I can't see any movement in the toe link, ball joint or end links while doing this and I can't really identify where this "clunking" sound is coming from.

Westend alignment is 2 1/2 hours away and I don't want to travel that far for an alignment knowing that something will have to be replaced before they can align the car properly. If something is broken/worn/not right, I'd just as soon purchase that part and have them install before we align the car. Oh, previous to the car blowing a tire, there were no issues at all with the way the car handled. It was perfect. I mean it was the best handling, most perfect handling car I've ever owned. So any suggestions out there?
 
sorry to say my first thing I would do is get the car aligned...
 
Passenger front or rear has the clunk? Does it happen on the other side?

You should really replace tires as a set, not just 1. What pressures are you running? S-Drives aren't great tires and have soft sidewalls and tread blocks.
 
stuntman said:
Passenger front or rear has the clunk? Does it happen on the other side?

You should really replace tires as a set, not just 1. What pressures are you running? S-Drives aren't great tires and have soft sidewalls and tread blocks.
Click to expand...

Thanks for weighing in Billy. Only the passenger side clunks and it's just a little bit. Nothing obvious to see. I had recently purchased the wheels and these tires were mounted on them. I was previously running Dunlop Star Spec 2's and loved them. But the S drives had a lot of miles left on them so I just replaced the one tire. I'm running F/R 31/34 cold on the street.
 
My first thought was the mold release agent on the new tire hadn't worn off yet, but you say you've put over 300 miles on the new tire so that probably isn't it.

The S- drives are inexpensive enough that I would buy another new rear tire to match. If tire manufacture dates are more than two years different I like to replace them as a set. What is the manufacture date on your old rear tire you didn't replace? If you bought them used it could have been sitting for a long time and hardening up.

Not sure how this would make the car feel "floaty" though.
 
My first thought was the mold release agent on the new tire hadn't worn off yet, but you say you've put over 300 miles on the new tire so that probably isn't it.

The S- drives are inexpensive enough that I would buy another new rear tire to match. If tire manufacture dates are more than two years different I like to replace them as a set. What is the manufacture date on your old rear tire you didn't replace? If you bought them used it could have been sitting for a long time and hardening up.

Not sure how this would make the car feel "floaty" though.
 
Mac Attack said:
My first thought was the mold release agent on the new tire hadn't worn off yet, but you say you've put over 300 miles on the new tire so that probably isn't it.

The S- drives are inexpensive enough that I would buy another new rear tire to match. If tire manufacture dates are more than two years different I like to replace them as a set. What is the manufacture date on your old rear tire you didn't replace? If you bought them used it could have been sitting for a long time and hardening up.

Not sure how this would make the car feel "floaty" though.
Click to expand...

Good call there. The original set was produced on the 43rd week of 2013. The new tire has a production of 29th week of 2017. I may just swap back in my Dunlop Direzza's 265/35/18's and see if there is this same tendency. If it goes away the question becomes do i buy one more S drive, or scrap them all and go back to the Star Spec for the rear until the front wear out? Whoops, there are no more Z2's as they are no longer being produced. So back to tire shopping again! Aarrggghhhhhhh.

Then there still is that little clunky thing in the passenger rear.....
 
Last edited:
Another idea to consider- perhaps the new tire isn’t/wasn’t balanced properly. Even after being balanced sometimes a tire won’t drive right. The way you described the driving issues reflects a problem I experienced. Same problem after a blown rear tire. Also make sure the wheel didn’t take damage. I had the rears rebalanced and the problem disappeared. Hth- ira
 
twentyfourth said:
Another idea to consider- perhaps the new tire isn’t/wasn’t balanced properly. Even after being balanced sometimes a tire won’t drive right. The way you described the driving issues reflects a problem I experienced. Same problem after a blown rear tire. Also make sure the wheel didn’t take damage. I had the rears rebalanced and the problem disappeared. Hth- ira
Click to expand...

Thanks for the thoughts. I did have the wheel re-balanced and also have concentric spacers so it does travel pure and with no bounce. it doesn't track straight under heavy load, but there is no tire bounce or shudder. Again, thanks.
 
stuntman said:
Tirerack sells the dunlops and AD08Rs.
Click to expand...

Tire Rack no longer sells the Z2 in 275/35/18 as it is discontinued by Dunlop. The latest word out is they are replacing it with a new tire/compound which will be called the Z3. Although there is no time frame on when it will be released here in the states. There is some rumor that it has been released already in Japan. And yes the ADo8R's are an option. Thanks.
 
Valhalla said:
The only thing I have noticed is on the passenger side, if I grab the rotor at 3 and 9 o'clock positions and tug in and out, I will get a fairly slight "clunk" in both directions. Nothing on vertical tugging, only on the horizontal. I can't see any movement in the toe link, ball joint or end links while doing this and I can't really identify where this "clunking" sound is coming from.
Click to expand...
Here's the source to your problem. As you've changed several parts for aftermarket it's hard to do a wild guess but certainly worth a closer look.
 
goldNSX said:
Here's the source to your problem. As you've changed several parts for aftermarket it's hard to do a wild guess but certainly worth a closer look.
Click to expand...

That was my thought too that the toe link is weakened enough that there is now some give either in the ball joint or the bearing. Will have to have someone look to see if that is where the clunk is generating. Thanks.
 
You should apply real world forces with a tire mounting bar or a pry bar. You could also mount a GoPro and watch what the wheel is doing under high load.
 
Update: I pulled everything apart again and looked over everything, again. Couldn't find anything out of sorts. Have driven the car some more and it appears the instability has mostly gone away. Will still set an appointment for a full alignment inclusive of corner balancing but is seems the new tire has finally settle in. Still won't trust these tires on the track but I have a bit more confidence on the street. I'll report back once the alignment is done if it was way out of wack.
 
JC, sorry to hear you're having issues after having fixed all the quirks and had the car running and driving perfectly. I had a similar issue as well back when I was running s-drives. My toe was stepping in on one side more than the other and, like you, on hard acceleration, my car felt like it wanted to sway to one side. I doubt there is any mechanical damage your car suffered from the flat that day, but my guess would be maybe a worn wheel bearing is causing a slight wobble? Hope you have a local "just for now" alignment place you can go to at least to check your toe settings? BTW- did you get in on the group buy for the spoon sports rigid collars? May be worth it to hold out just a bit longer and get your car re-aligned after installing those.
 

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