rcdash

iTrader: (18)

Ok, lots of power, but with a 100% lock up rear diff, I was hoping that when I experience rear wheel spin, the car would stay straight (while going straight). It pretty much used to, but I've noticed the rear end sliding to the right is getting a little more pronounced since my last alignment back in May. Attached is the spec sheet for that.

Any thoughts on what might be going on? I have the SPC rear toe bolts and camber rods in the rear. Stock in the front. Lowered on Tein Monoflex suspension, but not THAT much. The guy doing the alignment said he couldn't bring in camber any more in the front without the toe going out of whack and that pretty much limited the alignment for the rest of the car (according to him).

Can the alignment go out over several months time?

So what do I need to fix the front (other than raising the front)? Which A-arm assembly allows LESS negative camber correction and also toe correction?

Last question: can I use tire pressure to help correct this sliding (add more to the passenger side rear to reduce traction on that side)?

terrasmak

iTrader: (8)

Its called torque, and its going to happen.

rcdash

iTrader: (18)

Well, yes, but it always slides predictably with the rear end towards the passenger side, front to the driver's side. There must be some way to compensate... My thought is that I need to correct the camber in the front so that I can reduce camber in the rear. Sliding all over a two lane highway going 50 mph is not something I want to repeat. If there had been traffic I would've been hosed. I have no confidence punching the throttle at this point.

WTX350Z

iTrader: (8)

Less camber will give you more traction in a straight line. More tire/stickier tire will give you more traction in straight line. sliding pass side is torque at work.

You need more/better tire. a bit less camber in the rear wouldn't hurt for the traction issue.

I'd prefer to see the caster spread going the other way as well. so adjustable front upper A arms would be good.

Z1 Performance

iTrader: (564)

front toe is adjustable via the tie rod ends, not via the a arm

WTX350Z

iTrader: (8)

Yup, I left that one alone....wasn't worth it to me.

rcdash

iTrader: (18)

Thanks for the responses fellas. I'm running Michellin PS2 summer tires, 295R18 in the rear, 235R18 in the front - so not exactly a shabby setup for straight line traction in 80 degF weather.

I have never heard about aftermarket toe adjustment up front - are they available - how much does the stock equipment allow?

Are the cusco front A arms the ones that allow caster and camber adjustment, including more positive camber? Will the camber/caster adjustment with a new aftermarket A arm be wasted if toe cannot be compensated for up front?

Going to Z1's website now! Looks like the SPC can adjust both. The Cusco I think will too...

EDIT: Ok, Cusco looks good too. So now I just need to find out the difference between the two... anyone with insight? I'm off to search the forums...

EDIT 2: Got some conflicting reports on whether the Cusco could adjust caster. SPC no longer a consideration since there have been issues with the ABS bracket. SPL street version is a serious consideration - cost $200 more but definitely allows caster and camber adjustment.

terrasmak

iTrader: (8)

There is no aftermarket toe adjustment as said above, its only caster/ camber. You only need camber for the front, adding extra caster will only make your car more twitchy. Last thing stiffen up your chassis a bit, this will help reduce the tendency to turn on acceleration. Remember your battling the crank of the engine, thats what actually causes the problem.

Z1 Performance

iTrader: (564)

Part of your issue would be the massive stagger you have front to back - that is a recipe for general woes, even as grippy as the PS2 are. While I prefer (personal preference) a staggered setup, your stagger is greater that desirable. A wider front tire would be in order IMHO.

Cusco does not adjust caster, nor should caster really be played with IMHO unless you really have a solid idea about how it works, what else it affects, and are doing some serious track stuff. With a std front suspension layout using off the shelf parts as you are, caster will always fall within the factory specified range. On my car, I run the Cusco front a arms (in the car since early 2005 IIRC) soon to be switching to the Esprit arms - neither adjusts caster and I'm perfectly fine with that, as I have no need for it. I'm not switching for any other reason that I got a good deal on a used set of Esprit's, and I like trying new stuff sometimes.

Your rear camber is also far less than ideal for maximum traction - I would look towards setting static camber closer to -1.25 to 1.5 with 0 toe.

We don't sell the SPC front a arms at all due to their numerous issues over the years - this is why they are not on our website. Their rear kit works great, and is the same as the Eibach kit (SPC makes it for Eibach). Since our pricing on the Eibach is more advantageous than pricing for SPC, that is what we now try to keep on the shelves. We have more said to be arriving end of this week I believe.

You may also want to consider cornerbalancing the car to help equalize the weight across all four tires. While I'd generally say its going a bit over the top for a street car, with the power you're putting down, coupled to all the extra weight you've added, combined again with the fact that you have coilovers that allow for it - I would think the few hundred you spend on the cornerbalance/alignment could be worth it.

rcdash

iTrader: (18)

Thanks! The insight is greatly appreciated, WTX350Z, terrasmak & Adam!!!

WTX350Z

iTrader: (8)

dunno why you wouldn't want to alter caster, it can change the cars' behaviors quite easily. But you are very correct it will fall w/in OE range...but that is a HUGE range!