big tires and camber adjustment

[madkaw]

With all the choices of larger rims that seem to be popping up here lately for our s30's -Rota Rb's and sportmax- my question is to deal with tire wear and usability. I'll admit that my choice for bigger rims and tires is almost all cosmetic, I will probably not race or will rarely race my car. I am considering ZG flares because i love the look and of course I will put the rubber underneath to fill them if I go this route. So if I am talking atleast 245's on the rear am I looking at needing camber adjustment for my upgraded suspension(non coil over -suspension-tech 1" springs with KYB shocks). Yes i have searched under camber plates but my search brings up mostly folks that have already committed to coil overs and race applications.

Is there a breaking point where the "bling" factor of fat tires and wheels will be just be chewing up tires because I didn't do the job completely? I am at decision time with my car apart and i need to decide if I have to commit to camber plates-which then means coil overs-which then means new shocks- which then means $$$$-which then means I go to smaller ambitions and less bling.

If there is any direct threads to this please direct me.

 

So much information----So little brain

[JMortensen]

There are basically 3 common methods for adjusting camber in a Z.

 

1. Adjustable bushings. These don't really give you that much adjustment, but you might be able to even out both sides if you're lucky.

 

2. Adjustable control arms. This one is a bit misleading. In truth most adjustable arms shouldn't really be adjusted that far (5/8" rod end should be used for only 5/16" of adjustment), so maybe longer control arms is a better way to put this.

 

3. Camber plates or slotted strut towers. Slotting the strut towers doesn't give you much because the larger OD of the stock spring prevents you from adjusting very far at all. Like the camber bushings you might be able to even out the sides. Camber plates in conjunction with coilovers gives the spring a smaller diameter and that allows you more adjustment. This is really what you want if you're trying to dial in the handling of your car, but might not be the best choice for a street driver because it removes the strut insulator from the system which means a lot more NVH.

 

If I were working towards a street car and had no interest in racing I'd probably do the bushings first. If that didn't give enough adjustment then I'd seriously look at slotting the top of the strut tower. It's free for one, and you could keep the insulators. If that weren't enough then I'd consider the other two options. Keep in mind that you want a longer control arm for more negative camber and a shorter control arm for more positive camber, and buy your arms accordingly.

[madkaw]

My question was probably not clear with all my rambling . I was wondering if there a limit to tire size before you have to think about adjusting camber on a stock suspended Z with wider tires? I realize there is many factors involved here, but I was concerned about adverse tire wear from not adjusting camber after installing the larger wheels and tires?

[JMortensen]

I don't think so. Tire wear is going to depend on ride height and driving style. A stock Z driven like a commuter car doesn't wear the tires funny. A lowered Z will often times wear the insides of the tires, especially in the back where lowering the car makes it gain more negative camber. The front usually doesn't go anywhere near as negative as the rear, so what would likely lead to more wear on the inside rear tires than the fronts, but if you take turns hard that would probably mean that the fronts wear the outside of the tire and the rears wear more evenly. It's really not as simple as "Yes you need this" or "No, you don't". Have you had an alignment lately? Might be interesting to see where your alignment is at.

[blueovalz]

If the body is only dropped by 1" with your current plans, you will be fine with the 245 tires on the rear. The camber will increase, but not so much with only a 1" drop that you'd have wear issues (unless you boil the tires at every green light). You can always keep a small amount of inside wear equal throughout the thread width by periodically putting some nice side loading through the clover-leaf as well

[kyle]

Agreed that camber wear isn't an issue - over 30K on my current setup with zero wear issues.

 

However, more camber is dreadfully needed unless you're askeered of oversteer.

 

I'm currently on the fence about cutting up my pretty pretty car for more camber - so I was planning to move the LCA pivot out, 1/2" or so, and up about 1/4" to correct the roll center.

 

But since I didn't see that on Jon's list of approaches, now I'm wondering about the wisdom of my plans (typical).

 

I will probably go coilovers with biscuits to avoid cutting, but that's a year or more away. Any problem with moving the LCA pivots in the meantime?

[JMortensen]

Agreed that camber wear isn't an issue - over 30K on my current setup with zero wear issues.

 

However, more camber is dreadfully needed unless you're askeered of oversteer.

 

I'm currently on the fence about cutting up my pretty pretty car for more camber - so I was planning to move the LCA pivot out, 1/2" or so, and up about 1/4" to correct the roll center.

 

But since I didn't see that on Jon's list of approaches, now I'm wondering about the wisdom of my plans (typical).

 

I will probably go coilovers with biscuits to avoid cutting, but that's a year or more away. Any problem with moving the LCA pivots in the meantime?

Relocating the pivot point works and there is nothing wrong with that approach. i just don't usually think of that one. Why up 1/4" to correct roll center by the way? Moving up will adjust bumpsteer more than it adjusts roll center. What I would do is move it up 7/16" and out whatever you want. 7/16" is what I found was the correct amount when I messed with my crossmember on this thread: http://forums.hybridz.org/showthread.php?t=106974

 

That amount may vary a bit from car to car, but that measurement should be in the ballpark, since I took it directly off my car and I had used a gauge to 0 the bumpsteer.

[kyle]

Thanks for the feedback, Jon... I still have a boogery brake bleed to do, so won't get to the LCA relocate for a week or two, plenty of time to research.

 

I'll keep the 7/16" in mind for the bumpsteer (car is stiffly sprung and has tallish tires, so bumpsteer hasn't been an issue), and will move the pivot out far enough to get about 2-3* camber, since I'm at about .5-1 now.

 

Mostly I'm just going to try to keep the damn thing on the track this time