Need some suspension help

[JoeBoxer]

Originally Posted by Ryephile

*Fix the alignment. 1/16" total toe-in front and rear. None of this toe-out business if you're looking for confidence.
*Get good springs with balanced spring rates, Swift or RCE? GC coil conversion with Koni Yellow is a great option but pricier.
*Remember that adding too much camber on the street will add tramlining and destabilize the car in a straight line. There's always a trade-off. There's little need for >2° camber on a street car unless you have magically twisty roads in your daily commute.

Honestly I think I was confused on the toe I'm going to check tomorrow. I have decided to try the Perrin 19mm adjustable front sway, I was going to go whiteline fixed 20mm but I like the fact the Perrin will give me some adjustment and the bar is just a bit larger than stock which for my daily driving should be fine.

I still don't know which dampers and springs to go with, I planned to wait on bilstein but how do I know which coils will work with them? The eibach coilovers I was looking at dont have spring rates that I like. This is such a tough decision if the racecomp yellows went just a little lower I would run them with koni's but I need just a little bit more drop.

[Sam Strano]

That's an interesting combination.....

I see two big issues, one minor one. The stock dampers are a problem. And yes a front bar will help. The shocks will slow the roll rate and quicken the turn in. The bar will give you some more front roll stiffness (not slowing the roll rate but lessening the total roll). The bar would do more for balance, the shocks and bars would both help response.

You shouldn't be running toe out in the rear, that's a band aid for your staggered tire/wheel setup and lack of front camber vs. the rear.

Now let's talk bars because I think you have a damper plan even if I don't think it's the best one (assumption based on past discussion). I'll be honest, I eventually will do an adjustable front bar... but it will be quite different than these, because if you consider the angle the bar comes over the tie-rod and then down, you aren't actually shortening the lever arm like you do on a straight run bar. I won't say that there is no difference, but it's not massive. When I do my adjustable bar, I will run a different end link and make the lever arm a lot more straight so you get a bigger change in leverage.

Frankly when you get to the point you are running coil-overs, can tweak rates, have adjustable dampers, alignment adjustment too. I just don't think you need, on such a light bar (this won't apply for all cars that are less adjustable in alignment or heavier cars that run much bigger bars) that fine a change. The way the rear bar is setup w/straight arms you get a more effective change in rate, and I will be working on a setup like that soon (but with a more stockish like rate bar... this to give you the fine trim adjustment I think you'd want).

[JoeBoxer]

I will make sure there is no toe out on the alignment rack in a few hours, if the alignment is good I will start with the front bar to see where that gets me. Koni's seem to be the only damper choice in my budget so I will try those and swift brz springs if I still need to make a change.

[seven]

You could...

-Buy a sway bar
-Swap your springs front to back (so you have stiff rates) - Although as they're not springs for a coilover setup, not sure if they'd fit.


Also it occurs to me (and maybe this is just personal preference) that your tires are a little narrow for the wheels they are on.

Toe in not toe out.


Admittedly a lot of this has been covered.

[Calum]

Originally Posted by JoeBoxer

I will make sure there is no toe out on the alignment rack in a few hours, if the alignment is good I will start with the front bar to see where that gets me. Koni's seem to be the only damper choice in my budget so I will try those and swift brz springs if I still need to make a change.

Why not the RCE's? If you're looking to go stiffer in the front, AFAIK they are the stiffest.

[JoeBoxer]

Originally Posted by Calum

Why not the RCE's? If you're looking to go stiffer in the front, AFAIK they are the stiffest.

Just not low enough, i'm not looking to slam it but 30mm would be better than the 20 they offer. They mentioned possibly making some later that *might* be a little lower and designed specifically for Koni's and if that's the case i will go that route for sure.

Since i don't have any way to get any more front camber right now should i bring the rear camber back close to what the fronts are?

[JoeBoxer]

Originally Posted by seven

You could...

-Buy a sway bar
-Swap your springs front to back (so you have stiff rates) - Although as they're not springs for a coilover setup, not sure if they'd fit.


Also it occurs to me (and maybe this is just personal preference) that your tires are a little narrow for the wheels they are on.

Toe in not toe out.


Admittedly a lot of this has been covered.

Can't swap the springs without coilovers and that would put a very, very low rate in the back. Tires are a little more stretched in the rear than i expected but i didn't want to go 255/35 rear until i have some more power available. If/when i go FI i will change them out to 235/40 front and 265/35 rear.

I was confused about the alignment too, no toe out just a hair of toe in on the rear.

[Shankenstein]

@ CSG Mike and ScoobySouth, could you guys explain the role of toe in the rear of RWD vehicles?

I understand the idea in general (toe in is more stable, toe out is more responsive), but every discussion I've had was regarding steerable wheels (front). No doubt it would add some stability in the rear, but wouldn't it also wear the tires significantly more?

[Sccabrz192]

Originally Posted by Shankenstein

@ CSG Mike and ScoobySouth, could you guys explain the role of toe in the rear of RWD vehicles?

I understand the idea in general (toe in is more stable, toe out is more responsive), but every discussion I've had was regarding steerable wheels (front). No doubt it would add some stability in the rear, but wouldn't it also wear the tires significantly more?

Just because those wheels dont have a steering rack doesn't mean they dont "steer" . Toe, as with camber, is dynamic as the tire moves through it's travel. When you have toe out, as the wheel travels it gains more toe, which means that tire will want to pull the car off line. In low speed, some can be beneficial as it helps the car to rotate, but in high speed it can make the car very nervous.
Toe in means the tires will be opposing each other, so the car wants to turn into itself, which leads to more stability at high speed, but can cause a car to tend towards understeer in low speed because the rear is less willing to rotate.

Significant toe also increases drag, so it's usually best to pick a toe setting which keeps you as close to 0 toe in the rear as much of the time as possible and tune out any ill-effects with the rest of the suspension.

[Scooby South]

Sccabrz192 Nailed it.... I will add that on a RWD car..if you do 0 toe in the rear..it skates all over the place... because it has no definition.. no purpose.. its trying to follow the front.. but it lacks direction.. Pinching the wheels in a bit... lets the rear end feel more settled..

Bill

[Shankenstein]

Thanks for the explanation.

Whenever we've designed suspensions, the mantra has always been "never let the rear see any toe-out." If it's under alot of lateral stress and has rubber bushings... I've heard of using up to 1.5 degree toe-in for prevention. If it's a autocross miata on spherical bearings, less than 1/2 a degree is usually enough.

What kind of setting would you guys recommend for stock 86's (given the modest power and bushing stiffness)?