Alignment Advice

[Bill K.]

My car's ready for alignment and I'd like to hear what you think about my plan for alignment considering my suspension setup. It's a modified street bug (std) with 150 hp. I want a moderately aggressive setup for weekend hill climbs and some autocrossing.

Front alignment plan/questions:
*-2 degrees camber -- are extra eccentric camber adjusters needed?
*2mm toe out -- will this be quick, but not too twitchy?
*extra caster with 1 set of shims -- stable high speed and cornering?

Rear alignment plan/questions:
*-2 degrees camber -- more or less?
*2mm toe in -- want a little oversteer...

FYI, the front has:
*adjustable ball joint beam -- set to neutral height
*2.5" lowered spindles
*Stock 70 bug steering
*GR2's
*20mm Whiteline adjustable sway bar -- set to medium-soft
*+4" wider track
*205/55 Yokahama ES100's on 16x6 Fuchs
*spare tire in well
*chin spoiler (Kamei style) -- coming soon

and rear has:
*24.5mm torsion bars with urethane sping plate bushings
*2.5" lowered with urethane control arm bushings
*GR2's
*24mm Whiteline adjustable sway bar -- set to medium-hard
*+6" wider track
*225/50 Yokahama ES100's on 16x7 Fuchs
*roof spoiler -- coming soon

I plan on tweaking the sway bar stiffness and raising the front a bit to experiment.

Thanks for your advice, Bill

[Bill K.]

What's up, no opinions on alignment? What works/doesn't work for you?

[starmember]

you dont need castersims if you are lowering the back of the car

[zen]

i still have yet to get a good feel for mine and my whole back setup is going to change anyway since it is too low. question...why would you want to create more oversteer with that back setup? there is plenty of oversteer by default. with that engine you will only have to twitch the throttle to slip the back out anyway.

[Bill K.]

Kuhl, now we're talkin...

Originally Posted by starmember

you dont need castersims if you are lowering the back of the car

I agree, a raked car NEEDS caster adjustment. Even though I have a level ride height, I'm adding caster to compensate for the front 2mm toe-out. Front toe-out helps turn-in, but hurts straight-line stability. Rear wheel drive cars push the fronts toward toe-out when driving so starting in toe-out makes some sense. Caster helps straight-line stability and adds camber during cornering, but makes steering harder. The air dam should help stabilize the front also. I'm trying to get the best balance of turning and high speed stability.

Originally Posted by zen

...question...why would you want to create more oversteer with that back setup? there is plenty of oversteer by default. with that engine you will only have to twitch the throttle to slip the back out anyway.

I don't really want more oversteer. I'm going to set up the rear with 2mm toe-in and -2 deg. camber to combat the oversteer we get from the rear wheel drive. I just don't want to over do it and have it tight in corners. I doubt this will happen with the stiffer rear torsion/sway bars and bushings.

I built the car following what I have seen others do, but now that I have to dial it in I need to understand how it all works together. It seems like the stiffer rear torsion bar (24.5mm) and sway bar (24mm) are to limit suspension travel so dynamically the rear stays toed-in and in negative camber while under power and in a corner, keeping the rubber planted. Too stiff then too much oversteer, so that's why we use rear toe-in and negative camber. Right?

In the end, it's a matter of picking a setup and testing it. I'd like to hear from those of you who have gone through the tweaking and what you learned. Thanks for helping me pick the best starting point for my setup.

P.S. I found this helpful -- http://www.ozebiz.com.au/racetech/theory/align.html

[Supa Ninja]

Hey Bill your where I wish I was, everything done just dialing her in. I would set it up neutral/to specs and see how that feels in the corners then adjust one setting at a time. For example I'd start with the front toe in to stock specs and see how that works in the corners, i set mine to 1/8" an it worked great in the twisties. I had also driven the Supa with too much sway-bar in the rear and it created a dangerous amount of oversteer, so be careful with that. This is a very important step your on and if you get it dialed in properly you'll be able to do some amazing things with that car. Just adjust one thing at a time and take it for a test drive. This might sound funny but I learned about most of the suspension adjustments from the Gran Turismo video games.

Nick

[zen]

wish i had the ability to even test against stock specs. although at least my front beam is stock.

bill, i misread your initial post a little. i think your logic makes sense. i do not have a sway bar in the rear yet (still have to decide how i am going to mount it). i am curious to see if it reduces any oversteer considering the rest of my setup. i don't have my alignment setting handy and doesn't matter much since they couldn't do squat with the back. here is what i have:

FRONT:
stock beam with stock rubber
2.5" drop spindles
3/4" sway with urethane bushings
1.5" spacers
17x7" rims with 205/40's
set to .5mm toe in or so
no shims

REAR:
late 951 arms and spring plates (~+3 inches on track)
stock spring plate rubber
urethane control arm bushings
no sway currently
hellacious camber and the moment
toe: don't recall, will have to look up

[Kafer_Mike]

Bill, I have a similar setup on my '69 Bug (see below). How was/is the handling with the alignment settings you listed? Have you made any changes to dial in the suspension? I'm finalizing the assemby of my pan before the body comes back from paint and could use some advice.

-------

Front:
*2.5" narrowed adjustable ball joint beam set to neutral height
*2.5" lowered spindles
*Stock '69 bug steering
*GR2's
*3/4" Sway-Away sway bar
*205/55's on 16x6 Fuchs
*spare tire in well

Rear:
*24.5mm torsion bars with urethane sping plate bushings
*2.5" lowered with adjustable spring plates and urethane bushings
*GR2's
*3/4" Sway-Away sway bar
*225/50's on 16x7 Fuchs

[Bill K.]

I've been in slo mo on the car with my new job. So, it's not aligned yet. I took it to a local Porsche race shop for alignment advice and they recommended the adjustable spring plates so the car can be corner weighted with ease. I have yet to install them...

I also added extra eccentric camber bushings for maximum adjustability and a set of caster shims.

All of these additions would have been easier with the body off, so it's good you ask now...

Even with just an eye-ball alignment, it handles great. Low, wide, and stiff makes a big difference.

Bill

[LOAF]

Bill what are these caster shims..

I will do some research, but curious as to who make it..

I have been bitten by the Camber/Caster Plate idea.. for some time know.. specially since both these setting will come into play as I start to dial the car in.. aways for now, but still want to have a solution..

I would second the whole start with a neutral setting..
Both front and rear toe to about zero.. maybe a little camber in the front, and rear.. see how you like it..

Remember to much camber and you will be flipping tires on each rim to get even wear..

Not having raced or driven a rear car around.. I can't comment on the handling characteristics.. but from what I have heard, with a little power, power on over steer is quite easy.. so you want to be careful how much oversteer you want via that rear swaybar.. On my AWD scooby, I actually have an adjustable, and ended up dropping it to the weakest setting which is tighter than stock.. That was done because I was able to modulate the weight quite easy on that chasis via braking and gas.. and while it was fun at street speeds, since you can get the rear to pop out, I felt that it would be to difficult from getting myself in trouble on the track.. That being said, I was right.. started from neutral or understeer and work your way to where you like it.. may cost more but definitely safer..
My 1 cent
Alex

[G-force]

Originally Posted by starmember

you dont need castersims if you are lowering the back of the car

I don't mean to contradict for the hell of it, but that's not entirely true.

You see on the torsion bar front beam, the top trailing arm is about one centimetre (almost half an inch) shorter than the bottom arm. It makes enough difference to make a noticeable effect on caster when the front is lowered a few inches by turning the torsion bars inside the beam - as on a sway-away or puma adjustable front beam. So lowering by rotating the torsion bars inside the front beam always causes an additional loss of caster

If drop spindles are used the problem is avoided.