THSCC Forums

This one is for all you Sube drivers out there (Tom,kevin).What's the max negative camber that I can expect to get on the front of my WRX by going to an alignment shop.

_________________
2003 Matrix XRS notaminivan
2004 Subaru WRX #38
2000 Rally Focus
2007 Honda NFR S2000

Depends on which alignment shop you go to - some won't touch camber bolts even though you're paying them to do so.

Here's my suggestion:

jackstand the car & remove the wheels.

raise the hood & barely loosen the 3 nuts at the top of the struts.

push the top mounts toward the transmission & tighten the nuts (15 lb-ft).

loosen the two big bolts at the bottom of each of the rear struts.

place a small jack under the non-swept part of the rotor & jack up slightly so that the suspension compresses a little, then tighten the bolts (120 lb-ft).

loosen the two big bolts at the bottom of each of the front struts, and turn the top bolts so that the tick marks are pointing inward - if you point the top of your head at the transmission & stick it under the fender, you should be able to read the "10" on the bolt head.

place a small jack under the non-swept part of the rotor & jack up slightly so that the suspension compresses a little, then tighten the bolts (120 lb-ft).

Now take the car to the alignment shop and tell them to zero the thrust angle & toe. They won't have to deal with the camber, because you've already maximized it at home.

This should get you around -1.2 in the rear & maybe the same in the front (could be anywhere from -1 to -1.5, from what I've heard)

If you want more negative camber in the front, and you're running ST or SP, you can add camber bolts to the bottom holes & get around -2.5 (what I did)

My '03 was able to get -1.4 in the front and about the same in the rear without going through anything Kevin and Tom seem to have to do. I guess mine was made on a Wednesday...

--Kevin H.

_________________
2003 WRX (again!)

Thanks. So is the goal to get as much neg camber in the front and rear or just the front?

_________________
2003 Matrix XRS notaminivan
2004 Subaru WRX #38
2000 Rally Focus
2007 Honda NFR S2000

The goal is to get as much grip as you can in the front, then work on the rear to get the car to rotate well. If that means 450 lb springs & 24 mm sway bar in front and 550 lb springs and 26 mm sway bar in rear, -3° camber in front & -1° camber in rear, then that's what you do. (Tom)

How far do YOU want to go?

Kevin makes some great suggestions. One additional point - don't "throw away" rear grip with non-optimal rear camber or tire width. Maximize "tire" grip, then take rear grip away with stiffness to achieve balance. The fine point here is this - rear grip reduction via springs (and swaybars) actually INCREASES front grip. Rear grip reduction via less negative camber or narrower tires does NOT. So the tire contact patch and geometry should be maximized back there too. Pyrometer = friend. Monitor tire wear - if it's not wearing nearly even across the whole width of the tire, you're not at optimal.

When playing with camber, keep in mind though that there are trade-offs. Too much camber in front and braking can be affected. Too much in the rear and acceleration can be affected (in RWD). But I think with anything under 4 degrees this isn't prevalent. But what do I know.

Mike <- whose tires usually cord in the middle, but sometimes nearer the outside or inside. Oh, and they usually last 120+ runs. And I ain't exactly easy on them!

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

Not exactly true. Sometimes you HAVE to. It really all depends on the car, tire and suspension that you can do.
If I have a car that is balanced but has less rear grip I will destroy someone who has optimal rear grip whose car pushed like a pig.

First off, I'm going to assume DS class and an otherwise stock car. I'll talk STX in a sec.

You will NEED to take away rear grip because with the limited camber, limited tire width and weight on the front of the car. With optimal rear tire grip, the car will push endlessly. I ran 3/4" toe out and 55psi to lose enough grip to have the car rotate.

Alignment - Here is what I do/did in stock class. You want max negative front camber and the least amount of rear negative camber. 1/8" (for trailered car) or 0 (for daily driven) toe out front and 0 rear toe to start off with. That is something you can play with later.

1) Loosen every bolt in the front suspension. All 3 top mount bolts, two lower strut bolts, all lower control arm bolts, everything. Take 1 ratcheting tie down and use it to pull the bottom of the hub forward. Take a second one and pull the bottom of the hub out to the side. Now, with all the pulling and pressure on everything adjust the camber bolt for max negative camber, then tighten down the ratchets some more to make sure all the slack is taken out, and then tighten all the bolts. You should be able to get -1.5 front camber, and -4.0 or more front caster.

2) Loosen every bolt in the rear suspension. Take a ratcheting tie down and pull the bottom of the rear wheels closer together. Then tighten down all the bolts. There are no camber bolts in the rear, but you can take the slack out of everything.

3) A little front toe out (1/8" total) will give you a tiny bit more turn in (while wearing out the tires a bit more). On a trailered car, I would definetly toe the front out a bit. On a daily driven one, you might want to keep it at 0 to save on tires.

If you feel like the car is pushing and you want a little more rotation, you can adjust the rear toe at the track. Mark where the eccentric bolt is, and adjust a few ticks per wheel. Then you can adjust back to 0 after the event.

In STX, my car is setup to have WAY less optimal grip in the rear. I am on STREET tires. Even though I can have perfect front tire contact and a stiff spring in the back of the car, I cannot generate enough front grip with a 225 or 245 STREET tire to have a nose heavy car rotate. I have to run the rear camber at -1 (and toe out 1/8" sometimes) in order to have the car balanced.
If you have ever seen my car rotate through a slalom you would understand

-Tom

You didn't even read my next sentence, did you. IT IS EXACTLY TRUE, and you never "have" to. Read Puhn. To get rid of push, you always want to increase rear stiffness (or decrease front), not go away from optimal rear grip.

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

When you are talking about a "real" car, yes you are correct. On a nose heavy, Mcpherson strutted WRX, those "normal" concepts do not apply.

For example, on a WRX, you could not increase rear stiffness enough and keep the car driveable (in autox situations). The car with 550lb rear springs and a 26mm rear bar is too stiff as is. Any more spring and it would be undriveable on a bumpy autox.

Also, roll stiffness is just how fast and how much you transfer weight, correct? Once you have all the weight off the inside wheel and on the outside wheel (such as I do with the current bar/spring setup), how do you transfer MORE weight to that wheel?

-Tom

Soften the front and increase rear shock travel (if it's lifting a tire).

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

Softening the front will allow the bad camber curve to rear its ugly head, making the car push MORE.

What will allowing a rear tire to stay on the ground do?

-Tom

Tom,

Question,

How stiff are your rear shocks and what rear wheel rates do you have when the car becomes undriveable on bumpy autocrosses? I've had good luck with wheel rates (FF not Mustang) equal to the corner weights but the shock valving is probably relatively soft, especially for high shaft speeds (Koni 3011/12 monotube high pressure gas).

_________________
Dick Rasmussen

FS 50 2018 Mustang GT

Lift the other inside wheel.. j/k.

_________________
In need of car.

Back when THSCC hosted the big Evo school I ended up talking about setup of my VW with Guy Ankeny. He stated (like Dick) that a good starting point on spring rates is to get a wheel rate that matches the corner weight.

I was fairly flabbergasted by this as it was quite different from what lots of people were running and I was worried about the chassis holding up or becoming undrivable at the high rates. His reaction was that the chassis was _already_ under the stress it would be at the high spring rate and any harshness was caused by inappropriate shock valving. This made sense after thinking about it for a long time. I never got a chance to try this on the SP car (sold it because I was broke at the time) but I'd love to try it on my WRX when/if it ever becomes an ESP/STX/SM car.

--Kevin H.

_________________
2003 WRX (again!)

How do you calculate the "wheel rate" that you are talking about?

I looked at this
http://www.swayaway.com/Suspension%20Worksheet.htm where Wheel Rate = Sprung Weight / (0.4 * wheel travel)

That doesn't include the spring that I'm running

-Tom
suspension noob