Footman

iTrader: (2)

I haven't done alignment since it was lowered so I don't know. There is visible negative camber in the front, and only ever so slightly in the rear. That would be another question which I will look around first as I'm going to be doing an alignment in spring, will research and find out what camber/toe I would need.

GeorgeH

iTrader: (2)

In that case, I wouldn't look so quick to sway bars to fix the problem. In fact, adding sways without first having the car aligned could just mask another problem problem.

While having more front negative camber is a good thing, it's also possible to have too big a split - which is to say, if you have, say, -2 in the front and -0.5 in the rear that could also cause corner exit oversteer. And I'd also say your toe is in question too. Again, even a little toe-out in the rear can cause power-induced oversteer.

Did you relax the suspension bushings (commonly called "pre-load" around here but I think that's a poor description) after you installed the springs?

Don't get me wrong, you may still like the car better with stiffer sways. But get the car aligned first, before you start diagnosing handling problems. Trust me on this.

BTW, I think it's great that you are asking questions. It's the only way to learn.

EricMeyer

Let's pretend you do have an oversteer problem. The more correct way to address this is to understand what could be happening on a GLOBAL context

For example:

-Does the car Oversteer (OS) in both right and left hand turns?
-Does it OS in slow, med or fast turns?
-Is there any reason to beleive the tires are better (or worse) on the rear of the car? How about the front?
-Is it possible that this is an overinflated rear tire pressure issue? Why? What are the actual off track pressures of all four tires?
-Could the alignment settings be the issue? Why or why not? What do the tire temperatures say?
-Is something broke or improperly installed on the car?
-And the tough one----is it driver induced (which is often the case when describing car handling characteristics).

Assuming you've been done this road, chances are you'll want to soften up the rear of the car. The goal is to ADD GRIP to the REAR of the car. Because the car has poor traction (oversteering) we want to add more grip to reduce this undesired effect.

One way we can do this is to soften up the rear. This can be done in a few different ways. You can/could: Lower the rear ride height to lower the rear roll center (one of THE primary benefits of an adjustable height coilover system is ride height adustment and this is an easy trick to cure oversteer). Keep in mind that lowering or raising rear ride height will effect your static camber. Raise the car and you'll add positive. Lower the car and you'll receive more negative. Toe is favorable as lowering the car brings more toe in and raising gets you toe out. So, with coilovers you could lower the rear a big (assuming it's not slammed already---which i do not recommend).

Another way is to reduce the size of the rear bar, make the rear bar softer or remove the rear bar all together. Again, this has the effect of walking gingerly on the ice for the REAR of the car.

Depending on rear tire pressures you may be able to lower then and find more grip. You could also run a larger rear tire. Or even a more grippier rear tire in the rear only.

You could also decrease your rear spring rates which also slows down the rate of loading and unloading of the rear tires (think of dad's cadillac and how it rolls over big time).

I'm giving you several ideas because often a car driven to the track has few choices to fix suspension ailments. At each track we go to we are always tweaking something--- .2 more of less camber, a small change to the front bar and always, always, always record tire data. You HAVE to get good tire data or your barking up the wrong tree.

YOU COULD ALSO ADDRESS THE FRONT OF THE CAR TO REDUCE OVERSTEER

Because we have too little grip in the back of your car it is natural that we would have more in the front. Well let's steal some of that front grip. Where will it go? To the rear!

By taking away front grip (adding more understeer to the front) this will earn us more grip in the rear. Sometimes you only need a little. It is possible that your new suspension go-faster goodies had your car ending up with TOO MUCH front grip. Let's reposition some of this to the rear so the car handles better and we can drive her faster. You could do this by adding more bar to the front (makes the car understeer = less grip up front = more rear grip). You could do this by increasing front spring rate. You could overinflate your tires a bit. You could raise the front of the car which has an impact of the geometry and will reduce your OS a bit (think about a car that is waaaaay too lowered in front----can you see how the rear end would want to swing around or pivot around the front a lot?)

So there are lots of options. What is the best method to pursue? The one that is the most factual. The most scientific. The one that removes the "seat of the pants" feel to determine the problem in your equation. What are these options? Measuring tools.

-Tire pressure gauge
-Tire pyrometer
-Camber and toe gauge
-Ride height measurement device

Also, a good naked eye and a buddy with an open mind.

Here is what I would do if I were at a track and someone came up to me and asked for my help.

First off, I would ask them WHY they think they have this problem (see above questions). Then I'd ask to look at their tire data (and if they didn't have it I'd tell them to go obtain it). Then I'd ask them about their car and it's mods and when the last time it was aligned. I'd walk around the car and eyeball the camber and toe (which you get really good at after a few years). If it wasn't any of the items immediately above with tire temps, pressures, improperly maintained car or misalignment then I'd address the front or the rear of the car (see above).

MOST OF THE TIME a DIY suspension person boogers up their handling. When you add to this that they have often become better drivers (which is why they modified their car in the first place) they are exposing flaws in their cars that were already there but they had not driven fast enough to expose. The faster you drive the more you expose a cars flaws. This is normal. MOST novice drivers just keep driving these slightly flawed cars. SOME drivers mod their car, get undesireable results and blame the mods WHEN IT'S ACTUALLY THEM that is causing the problem. This is very, very, very typical in understeering feedback---it is often more a driver issue than the car. The idea behind adjustable suspension is exactly that---to adjust it. I would suggest to people to do the gross things first: springs and bars. THIS IS ASSUMING YOUR TIRE DATA IS TELLING YOU THAT YOU'RE GETTING SOLID CONTACT. Solid contact is defined by pulling into the pits BEFORE your cool down lap (and do it quickly and assertively) and taking temps and pressures (or your best friend does this for you). You then return to the track, go drive the crap out of the car and pull in again BEFORE the cool down lap and take data again. Data, data, data. If you are getting a 15F spread from inside to out on your tires you are in a good place with your camber settings. If your temps are higher in the center of the tire then you have an overinflated tire. Too hot on the outside? Then you need more camber. Assuming the tires are looking like a 15F spread (+/-5F) you then work on your ADJUSTABLE suspension: Bars and springs. Shocks are for fine tuning in my book and people who have 82 way adustable shocks have more problems than those that don't. Shocks require someone who drives very, very well to make them perform correctly. Springs and bars are easier to adust.

Having problems figuring out if the car is oversteering or understeering? Look closely at the pressure and temperature growth of the tires. If the rears are on average 30 degrees F higher, your car is sliding around in the azzzz (OS). The inverse is true if your fronts are both higher temps and greater pressure growth than the rears.

So.......if I were you I'd try something. Bars are super easy to change at the track so I'd get adjustable front and rear bars. Which means I would purchase swaybars that have a fair amount of adjustment. I'd also start taking tire data religously. Some people feel goofy because they may be the only one capturing this data but that is how your car has the ability to go fast---data collection.

Did that make sense?

Footman

iTrader: (2)

Yeah, it was preloaded, I have been driving around for almost 8 months now unaligned. Well actually the timeline goes like this...

1) Eibach springs installed
2) Alignment done immediately
3) A year later, Bilstein B8's installed
4) 8 months later, I am here with this thread.

When the B8's were first installed, they actually dropped the car a little bit more. Most people say shocks won't lower the car, but in this case the B8 did (shortened shock, like Koni Yellows).

I will do the alignment in spring first and then see how the car handles, a lot of stuff is going to happen simultaneously in spring..

As right now my observations are based on my winter setup, which is 18 x 7.5 +42 on 225/45/18 Wintersport M3's

In spring:
A) Mount and install new 18 x 9 +36, 245/40 new rubber
B) Alignment
C) Transmission/diff flush

Maybe a lot of the car handling will change drastically. The more I think about it, the oversteering problem is becoming worse and worse could be because of my tires are getting old/worn. Both my summer/winter sets are getting old. At the same time, I'm getting more and more aggressive and discovering the car's limits.
If this is daily driver, with occasional track, do you recommend I just go with the manufacturer alignment settings?

Footman

iTrader: (2)

Eric, that is really sound advice. I think I will start doing that from now on at trackdays. CASC-ON is quite organized for events. It's timed, I like it.

EricMeyer

I would definitely add more camber to the car. Tire data will tell you this big time.

Side note: We align our race cars BEFORE we leave the shop, AS SOON AS we arrive at the track, AT the track, check the scales and then AT the track again and then when we return to the shop. THINGS MOVE. For bumpy tracks things move more. Does your home track have huge curbs? Things move.

I'm a big fan of adding camber to a stock car.

GeorgeH

iTrader: (2)

As always, great detail & advice from Eric.

I agree, if you enjoy pusing the car in turns, you will benefit from more negative camber than stock. It is hard for most of us to take temps and tweak, since alignments are expensive if you have to pay for them, but they are important. I'd say something like -1.5/-1.0 (F/R) or -2.0/-1.5 is a pretty good starting point for most street drivers, but there are always variables. I run -2.5/-2.0 for autocross, but it's hard on the inside corners of my street tires, especially if I put on lots of freeway miles.

As for tires, yes, tires have a huge impact on how the car handles. Don't judge the setup based on winter tires or worn summer tires. I once wore a set of Toyo T1-S tires down to the wear bars on a 100 hp Miata, and man could that thing oversteer on corner exit! It was fun, but slow, and as soon as I put fresh tires on the problem went away.

So yes, get your good tires on and get it aligned. Find a shop with a 30 day policy and maybe they will tweak it for you for free if you don't like your initial choice. But, as Eric says, your driving habits are a big part of it too.

04Green

iTrader: (1)

As suggested, dial in some negative camber. I would start with the same setting as whatever they are able to get on the front (will be -1.5 or so) then tweak from there. This is what one of those 3 or 5 year alignments are great for. I would not play with toe on a DD. Tires are too expensive. There are several discussions on this froum, I think one is in the tire section. One school says that for a road course, have 0.5 degrees more negative camber on the rear than the front. I am going to shoot for that for an event in a few weeks.

Then get a set of adjustable sways (with grease fittings). Start softest, and then you can use the sway bar adjustments to tune over or under steer (stiffen the end that is NOT sliding, front for oversteer, back for understeer). Alignments are hard to mess with, and mucking with tire pressure off of what gives the best contact patch s hard on the tires. I got the progress ones from BHR and drilled and tapped for grease fittings. There are ones out there that come with them for about $100 more.

Good luck. Gotta Run.

Mike

Chad D.

iTrader: (19)

Great advice guys. 1up!
Since I put my coilovers on last summer I have been getting schooled.
It is so beneficial to know all this stuff if you love your car.