New Wheels - Now the Back end is loose

[smac2K]

So, I got these awesome Rota Boosts and they are 17's.

17x7.5" in the front (+48 offset)
17x8 in the rear (+50)

The car is still sitting at factory ride level (H&R springs are on the way), and the back of the car does not feel "planted" to the ground. I am getting a lot of, what feels like, extra movement whenever I hit a bump. It also does not feel stable going around corners.

Is this normal, and will it change once I lower the car?

Help...

[Justin6264]

Check you pressures. I usually run 33/34 or so.

[Kaiser442]

I assume you got new tires along with those new wheels... is it possible that they just aren't worn down enough to get past the oil and other gunk that gets on the surface of new tires?

[raymo19]

What tires and what sizes?

[Looter]

:eek: ....Here's another scenario...You can't use "STOCK" lug nuts, on aftermarket wheels....You have to have the tapered ones. Sometimes hubcentric rings are needed. Are you sure that the new wheels are correctly seated..??

[rioyellows2k]

I'm thinkin' tires. What are you running?

[S2Kouichi]

Assuming you have the correct tires and they are properly inflated, because you don't have as much sidewall flex your feedback should be enhanced. I think dropping the car will only make matters worse. When was your last alignment?

[IRUNFAR]

Looter knows nuts!!! :lol:

[1st07inOH]

Looter knows nuts!!! :lol:

I saw that coming!
:rofl:

[uwimage]

Looter knows nuts!!! :lol:

:highfive:

:laugh:

[Looter]

:bgbounce: Here we go....again...!!!! I'll see you..tonight...:LOL: Looter knows nuts!!! :lol:

[repiv]

As already posted, need to know about the tires (sizes, brand, series, etc) and pressures being used. Also need to know if you're using hubcentric rings and what kinds of lugnuts are you using. It may just be a bad combination of several different things. Can't really comment much till all the details are provided.

[RevgasumAp1]

I never had any issues running this exact set up (my old wheels) the tires are kumho MX was a treadware of 220, They run better warm. Due to the cold roads the tires might have trouble hooking up. Those tires run **** in the summer. Reciently i havent relized any differences from these wheels to the stockers im running

[repiv]

I never had any issues running this exact set up (my old wheels) the tires are kumho MX was a treadware of 220, They run better warm. Due to the cold roads the tires might have trouble hooking up. Those tires run **** in the summer. Reciently i havent relized any differences from these wheels to the stockers im running

Since nobody has given details as to the exact size of the tires or the pressures used and the OP hasn't indicated the brand and type of tire, noone can say they have the "exact" set up. We also don't know if rings were used or what lugnuts were used. Treadwear number is a pretty insignificant part of the overall equation in what's going on here.

[Jays2k]

All I know is that he was running 255/40/17 on the rear and his pressures were at 27 all around. Last I heard he was putting more air in the tires and going to take a ride.

[RevgasumAp1]

Since nobody has given details as to the exact size of the tires or the pressures used and the OP hasn't indicated the brand and type of tire, noone can say they have the "exact" set up. We also don't know if rings were used or what lugnuts were used. Treadwear number is a pretty insignificant part of the overall equation in what's going on here.


These are my old wheels. I sold these EXACT wheels to J

Tires
F- 215/45/17 PSI 32 Kumho 711
R- 255/40/17 PSI 30 Kumho MX
No hub centric rings were used, Stock lugs were used

If the wheels werent seated correctly the wheel would vibrate, not make your traction worsen.

[smac2K]

WOA!!!

I'm back...didn't expect this type of response...:laugh:

OK...As Chris said...These are the tires...

F- 215/45/17 PSI 32 Kumho 711
R- 255/40/17 PSI 30 Kumho MX

The PSI's were a little lower than what is posted, so I put some air in them...the rears I put up to 33/34 and the fronts are about at 32...

It rides much better, and I might put a touch more in the rears and play around with it to see what happens and how it acts :thumbsup:

Oddly enough...no one said anything about lowering...So, I guess I am just learning as I go. Am I understanding correctly that the way the car sits does not relate how loose the "butt" is of a car?

I am serious, I have no clue...

Thanks for ALL your responses and sorry I didn't give enough info in the OP :duh:

Justin

[uwimage]

I am serious, I have no clue...

Justin

I just wanted to quote you on this so I can show it to Sara...and keep it archived forever :rofl:

on a side note, this is an awesome board :D

[s2kmugen]

rotas............................................. ...................jk :D

[repiv]

OK, who's who at the zoo? You guys seem to know each other and know the details about the rims and tires. You have me at a disadvantage. No information was ever given about rims being the same or tires being the same from one poster to another. I had no clue as to the relationship of one poster to another. I'm no fortune teller. I only go by what's been posted. Go back and read what's been posted and tell me if any of it makes sense to an unbiased onlooker. Saying that you have the "same" rims and tires ("my old wheels") doesn't immediately tell me that you sold them to the OP. I interpretted it as your old wheels also being Rotas. Come on, fellas, would it have been tough to just say, "I sold those rims and tires to so-n-so and they didn't have a problem for me". So "Rev" sold them to "J", but how does "Smak" fit into all this? :think:

Had ALL the details been given right off the bat, ESPECIALLY the bit about the low tire pressures, maybe this thread wouldn't have gone 2 pages long. I "think" I've figured out who's who here, so carry on.

[smac2K]

Dave,

I apologize for the confusion. This was my fault. I started this thread, and then someone helped me in the shoutbox...I should have cleared this up before I left for the afternoon.

It was definately air pressure, and the problem is solved. This was simply an example of my lack of education about cars in general.

Thank you for the attention, and I will make sure that the next time I post in the "Den" that I give the whole story up front...:thumbsup:

I will close the thread after you respond, or feel free to close it yourself.

Bye the way...I am Justin, screen name is "smac"...just to clear up even further confusion...

Justin

[repiv]

F- 215/45/17 PSI 32 Kumho 711
R- 255/40/17 PSI 30 Kumho MX

Oddly enough...no one said anything about lowering...So, I guess I am just learning as I go. Am I understanding correctly that the way the car sits does not relate how loose the "butt" is of a car?
17x7.5" in the front (+48 offset)
17x8 in the rear (+50)

First, do you mean Kumho "712"? I'm not familiar with a "711".
This combination of rim specs and tire sizes is nearly perfect for the S2000 in so far as fitment. However, your rear track is just a wee bit bigger than what would be considered "OEM" when matched with the front. No matter, this would give your car less "tail happiness". As perfect as the fitment may be, the offsets are still much less than stock and this could create some undue stress on the alignment, making it possibly necessary to do an alignment. Since the fitment is really good, lowering shouldn't be an issue from a fitment point of view (within reason). The instability you've felt in the rear can be attributed primarily to tire pressure and somewhat to alignment. Also, the MX and the 712 have different tread patterns and this may result in different rolling resistance, which in turn, can affect stability.
Continue to experiment with the tire pressures and I think you'll find the desired results. Beyond this, an alignment would be suggested. But if you're going to lower the car, do the alignment after the lowering since that's the time to do it.

[repiv]

then someone helped me in the shoutbox
Justin, all's good. This whole "shout box" thing is new to me and confuses me and I confuse easily. I don't pay much attention to the shout box. I'm an old geezer and I'm not sure what that's all about. Obviously, quite a bit of info went through the shout box and it's easy to forget we're having 2 different conversations. Happens to me all the time. :o

[photodavo]

Justin, all's good. This whole "shout box" thing is new to me and confuses me and I confuse easily. I don't pay much attention to the shout box. I'm an old geezer and I'm not sure what that's all about. Obviously, quite a bit of info went through the shout box and it's easy to forget we're having 2 different conversations. Happens to me all the time. :o

I think it's those big cheeks of yours getting in the way Dave. :)

Thanks, once again, for helping the members out. You're a great asset to the S2000 community. :thumbsup:

[smac2K]

Dave,

I was JUST getting ready to tell you that the 712 was the successor to the 711, but I did my homework and they are not even close...

711
http://www.tirerack.com/tires/tires.jsp?tireMake=Kumho&tireModel=ECSTA+711

712
http://www.tirerack.com/tires/tires.jsp?tireMake=Kumho&tireModel=ECSTA+Supra+712

Anyway, when it is time for tires I was thinking I would make them all match...Is putting the MX's on the rear a good idea?

Thanks...

[photodavo]

You should get out more Justin. ;)

Bridgestone RE01R FTW! They :rockon:

[repiv]

Dave,

I was JUST getting ready to tell you that the 712 was the successor to the 711, but I did my homework and they are not even close...

711
http://www.tirerack.com/tires/tires.jsp?tireMake=Kumho&tireModel=ECSTA+711

712
http://www.tirerack.com/tires/tires.jsp?tireMake=Kumho&tireModel=ECSTA+Supra+712

Anyway, when it is time for tires I was thinking I would make them all match...Is putting the MX's on the rear a good idea?

Thanks...
I just learned something today. I didn't know about the 711. I currently run 712's on all 4 corners (225 front and 255 rear) on Volk CE 28N (correct offset for the car and ideal width for the tires). My back end (tires at 35 psi) dances around like a Cajun stick man when pushed hard. I believe it's the 712s. They just don't stick to the road very well at the limit.
MX's, by the description given to me from friends who use them on the S2000, is a far better tire when pushed. I'm a fan of the 712s in the wear department, but I'm really not fond of them in the performance department. The fronts work OK, but I'm going to get something else when the rears wear out, maybe even the MX. I have another driving season to make my mind up.
In your case, I really believe it's was the tire pressure. Do the alignment later if you plan to lower. That might sharpen up the handling even more. Don't drop it too much or you may find it impossible to do a proper alignment.

[smac2K]

Thanks again...I will keep you updated on any changes...:thumbsup:

[RevgasumAp1]

Wow, no needed for the confusion. Sorry about the miss communication!

[drobbins]

So, I got these awesome Rota Boosts and they are 17's.

17x7.5" in the front (+48 offset)
17x8 in the rear (+50)

The car is still sitting at factory ride level (H&R springs are on the way), and the back of the car does not feel "planted" to the ground. I am getting a lot of, what feels like, extra movement whenever I hit a bump. It also does not feel stable going around corners.

Is this normal, and will it change once I lower the car?

Help...

I am a brand new S2000 owner (picked up low-miles '05 at a great deal last week) but I played around with my suspension on my former vehicle ('06 MX-5.)

It sounds like you found out your tire pressure was too low. Normally too-low tire pressure will reduce the amount of feedback you get through the tires and make things feel too soft to the point of not being able to feel anything, and should reduce wobble rather than increase it.

So if you are still experiencing extra movement when you hit a bump, I'd guess that your springs are under-damped. This means that the H&R's could make the problem a bit worse since they are probably slightly stiffer than stock.

If your shocks aren't stiff enough then the springs will keep oscillating after they hit a bump, and you'll end up feeling an "echo" of the bump you just went over.

In an ideal world, you would have a set of adjustable shocks that you can dial in so that they dampen your springs just enough so that they don't oscillate on the roads you typically drive and this will minimize extra movement going over bumps while keeping ride quality good. Also understand that if you get adjustable shocks you will be optimizing for certain types of roads at certain speeds and balancing this with trying to find a setting that works for you pretty well on all roads you encounter. It is easier to optimize for one particular type of road and harder to optimize for lots of different roads.

Another option is to go with thicker sway bars which will keep your tires from "dipping" as easily into road irregularities. If you take sway bars off a car, you will notice that your tires tend to do a better job of following the all the irregularities in the pavement. So it's possible you could move slightly in the other direction with stiffer sways. Sways are generally less expensive than playing with springs and shocks so it may be an option to try.

I would recommend stiffer sways if you feel like each tire seems to have a mind of its own and seems to be dipping and following too many wobbles in the road. Stiffer/adjustable shocks will likely help if you have "after-wobble" (undamped oscillation) after going over bumps. H&R spring will lower the car, and the wobbles will be "faster" since as you go with a stiffer spring, it's rate of oscillation increases. The H&R springs will also move less when they do compress.

Also remember that you won't be able to have a 100% perfect ride all the time. You may want to put up with some low-speed wobbling to have the suspension set up how you like it when you are going faster.

Overall, the S2000 suspension is set up pretty well from the factory. FYI, my first MX-5 suspension mod was H&R springs, then sways, then Ohlins coilovers. This was my first time messing with a car's suspension. If I had to do it again, I would do sways first, then maybe stop there. If I felt I needed more, I would have gone to Ohlins or maybe adjustable shocks and I would be careful about just doing springs alone.

The tricky part about messing with springs is that OEM springs and shocks are normally chosen as a matched pair, so when you swap out your springs your shocks are probably going to be too soft but the OEM ones are not adjustable so you can't really compensate for this without going for a set of Konis or other adjustable shock. It can be tricky once you start to mess with the suspension to restore that perfect balance.

If you put the wheels/tires on and don't like them, I strongly recommend that you DO NOT try to "fix" this last mod by performing other mods. Just put the wheels/tires back the way they were or try to diagnose the problem your car is currently having first. Once you love your wheel/tire combo, then look at further improving your car. Otherwise you will end up spending a lot of money.

For the wheels, make sure you have hub centering rings and that the wheels are mounted well. It is also possible that if your wheel/tire combo is lighter than stock, this may affect how the car handles and make things "bouncier," and adjustable shocks may allow you to compensate. You may also want to look at your tire sidewalls. Are they "plump" or are the wheels stretching the sidewalls out? If the wheels are stretching the sidewalls out a bit, then you will have a stiffer sidewall and you will feel more irregularities. Also, a change in tires can have a major impact on ride quality. Fix the problem now before moving on to springs, because then it will get way too complicated to sort out, I think.

[bimdub]

another tip Justin, ALWAYS expect the tires to feel funny cold! mine feel FLAT.....when cold and they are as slippery as vasoline until warmed up.....this takes about two miles on a cold day to get rid of.....of course I am running the 18" variety of shoe.....

[smac2K]

Just an update...

I have been running at about 32 (rears) for the last couple days. I am going to go up to 34 and see if it gets even better. It seems like the problem is gone, but I just want to play around with it and see what the best is...

:thumbsup: