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is it possible to spin a wheel inside a tire during an autox?

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Old May 26, 2009 | 04:15 PM
  #21  
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Originally Posted by warmmilk
if i reduce roll stiffness in the rear, it will let the car roll more in the rear, therefore the inside of the car goes higher, therefore less weight on the inside tire.

or is there an error in my logic?

(not trying to sound like a smart ***, just trying to understand)

No.

The sway bar changes roll stiffness by trying to make both sides do the same thing. This is an over simplification, but let's say you turn to the right...

The weight of the car will shift to the left and the suspension components on that side will start to compress.

The sway bar will move up and transfer some portion of that same energy to the connection point on the other side of the car.

So if the inside part of the car wants to lift up, it will have to carry some portion of the unsprung weight to do it.

A super-stiff sway bar will force the inside "side" to take all of the unsprung weight, or at least a larg enough portion to unload or even lift the inside tire(s).

On the other hand, a really "loose" bar will let the body roll without taking to much of the unsprung weight with it and the wheel, brakes, and other suspension components will just "sag".

That "droop" will give the inside tire a better chance of getting some load and some traction.
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Old May 26, 2009 | 04:44 PM
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ahh, ok, that makes sense.

thanks
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Old May 27, 2009 | 12:40 PM
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everyone has said it already, but I'll echo it.....

Tirespin is very common on a race tire equipped Z cause you are unweighting the inside rear tire. The VLSD is not all that quick to go from open to locked, so you get wheelspin. Blown front shocks that make the front roll more will make it worse. I put the stranoparts bar on my car and it made a world of difference. No more wheelspin and it didn't add any understeer. Win win mod.

Opposite effect: At a local autox, the front endlink broke mid run, meaning NO front bar for the run.....rear wheel was off the ground for most of the run. Spotters said over a foot off the ground!

Just my $.02

JR
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Old May 27, 2009 | 12:58 PM
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Originally Posted by TractionCircle
everyone has said it already, but I'll echo it.....

Tirespin is very common on a race tire equipped Z cause you are unweighting the inside rear tire. The VLSD is not all that quick to go from open to locked, so you get wheelspin. Blown front shocks that make the front roll more will make it worse. I put the stranoparts bar on my car and it made a world of difference. No more wheelspin and it didn't add any understeer. Win win mod.

Opposite effect: At a local autox, the front endlink broke mid run, meaning NO front bar for the run.....rear wheel was off the ground for most of the run. Spotters said over a foot off the ground!

Just my $.02

JR
their sway bar? or do they make some other kind of bar to?
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Old May 27, 2009 | 01:09 PM
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i have another autox coming up this weekend, i'll set the front sway bar one hole stiffer and see if there is a difference...
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Old May 27, 2009 | 01:09 PM
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Originally Posted by warmmilk
their sway bar? or do they make some other kind of bar to?
He sells it, but it is made by Addco I think. It's the same bar that Carter ran, and the same one that Cavanaugh is now running. It's like $130, but non adjustable. In hindsight, adjustability would have been nice. Perhaps he can get the adjustable version, call Sam and ask him. One of the nicest guys goin...
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Old May 27, 2009 | 01:14 PM
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well i have hotchkis bars front and rear, and i can still go 2 holes stiffer on the front, so i think i'll try that before buying another sway bar.

hopefully this helps till i can get a real lsd...
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Old May 27, 2009 | 03:49 PM
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Originally Posted by warmmilk
i have another autox coming up this weekend, i'll set the front sway bar one hole stiffer and see if there is a difference...
make sure you go full soft on the rear bar too. The middle setting is way to stiff out back for what your doing
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Old May 27, 2009 | 04:36 PM
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so second from stiffest in front and full soft in rear?

damn, not really looking forward to all the understeer, would i be ok leaving the front as is, and just going to full soft in the rear?
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Old May 28, 2009 | 06:37 AM
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is it more important to add roll stiffness to the front or remove roll stiffness from the rear?
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Old May 28, 2009 | 07:28 AM
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is it more important to add roll stiffness to the front or remove roll stiffness from the rear?
It sounds like you need a big change to get the wheelspin under control. Go full stiff in front and full soft in back. Then adjust from there (stiffen rear first if needed). Bring tools to the next event and make adjustments between runs.

To reiterate, you will need to really change your driving style to make this work. Brake earlier because the absolute worst thing you can do is come into the corner even a smidgen too fast. And be careful about coming off the brakes too fast. Don't pop off the brake pedal, easy off it and then ease on the gas.
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Old May 28, 2009 | 07:34 AM
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Originally Posted by SOLO-350Z
The stock LSD being overpowered? I have never seen my car spin the inside wheel even when I have tried. That means only one thing and the LSD is starting to fail or it has already.
Our inside tire spins now. Nissan wont' warranty the LSD - it is failing.

Originally Posted by warmmilk
so just to make sure, it my lsd that went to sh*t? anybody have any different opinions?
Sounds like an LSD issue. Try this crude test:
-Jack the car up on one rear side
-Leave that side in the air with the other 3 tires on the ground.
-Put the car in gear
-Put a torque wrench on one lugnut and test the break away torque (i.e. the amount of tq it takes to make the wheel spin with the opposing wheel on the ground and the car in gear)
-Report back (I think breakaway tq is about 70#ft)
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Old May 28, 2009 | 07:48 AM
  #33  
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^^X2. It should only be doing this if the LSD is failing. A new LSD 350Z doesn't show this problem and you shouldn't need to modify any suspension parts.
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Old May 28, 2009 | 08:19 AM
  #34  
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Originally Posted by betamotorsports
It sounds like you need a big change to get the wheelspin under control. Go full stiff in front and full soft in back. Then adjust from there (stiffen rear first if needed). Bring tools to the next event and make adjustments between runs.
thanks

Originally Posted by betamotorsports
To reiterate, you will need to really change your driving style to make this work. Brake earlier because the absolute worst thing you can do is come into the corner even a smidgen too fast. And be careful about coming off the brakes too fast. Don't pop off the brake pedal, easy off it and then ease on the gas.
braking earlier shouldn't be to much of a problem, i think i brake to much as it is anyway cause i'm scared i'll spin out or i don't think the front will grip enough or lack of brass ***** (i'm still a noob)


Originally Posted by scotts300

Sounds like an LSD issue. Try this crude test:
-Jack the car up on one rear side
-Leave that side in the air with the other 3 tires on the ground.
-Put the car in gear
-Put a torque wrench on one lugnut and test the break away torque (i.e. the amount of tq it takes to make the wheel spin with the opposing wheel on the ground and the car in gear)
-Report back (I think breakaway tq is about 70#ft)
so if its under 70#'s, that means my lsd is shot, correct?
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Old May 28, 2009 | 08:51 AM
  #35  
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Originally Posted by warmmilk

so if its under 70#'s, that means my lsd is shot, correct?
It would be an indication that it is going bad. Mine turns at like 30#ft on the ZR.

BTW, BEST mod I ever made to my coupe was the NISMO LSD. The grip and power out of turns (in autox) was obvious and amazing.
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Old May 28, 2009 | 08:57 AM
  #36  
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well i am planning on a better lsd (before i even considered mine was going bad), but i want the quaife lsd. but i wanna do some other upgrades (bbk and oil cooler) that i think will provide more benefit to me... the diff will have to wait till late this year or early next year...
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Old May 28, 2009 | 09:37 AM
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Originally Posted by warmmilk
well i am planning on a better lsd (before i even considered mine was going bad), but i want the quaife lsd. but i wanna do some other upgrades (bbk and oil cooler) that i think will provide more benefit to me... the diff will have to wait till late this year or early next year...
If you mostly or exclusively do autoX, I'd think the lsd would serve you better than the bbk and oil cooler (both of which are recommended for DE's).
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Old May 28, 2009 | 09:51 AM
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Originally Posted by dnguyent
If you mostly or exclusively do autoX, I'd think the lsd would serve you better than the bbk and oil cooler (both of which are recommended for DE's).
1000x
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Old May 28, 2009 | 09:51 AM
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right now, i mostly do autox cause i don't have a bbk or an oil cooler, i'll start doing track days also once i get the those items

i did a couple of track days on the stock brakes (non brembo) with project mu b force pads and fresh motul fluid, and the fade was pretty bad. pedal got really soft and would hit the floor, and i can feel my stopping distance increase with each lap...
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Old May 28, 2009 | 10:18 AM
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Originally Posted by warmmilk
right now, i mostly do autox cause i don't have a bbk or an oil cooler, i'll start doing track days also once i get the those items

i did a couple of track days on the stock brakes (non brembo) with project mu b force pads and fresh motul fluid, and the fade was pretty bad. pedal got really soft and would hit the floor, and i can feel my stopping distance increase with each lap...
In that case, yes, BBK would be a good priority. Those Project Mu B Force pads are not race pads, so it's not surprising that you had fade with them. I'm thinking they work as well as Hawk HPS, and those do not hold up at all to track work. I have an oil cooler, but since I never installed a thermostat, I don't know how much improvement there is. All I know is that power loss without the cooler was more noticeable...but, I still notice some power loss on 95F+ days and in the latter half of a 25min session.

As for lap times, the LSD really came into play in the slow, sharp corners (stock power). On the track, it may reduce my lap times by 1 second or so, but I imagine that the benefits on an autoX course would be more substantial.
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