Need alignment/corner bal suggestions

ckelly · 04-25-2003, 08:03 PM

I've installed new torsion bars front and rear. I decided to go with solid 22f and 30r, along with neatrix bushings, bump steer kit, turbo tie rods, solid motor mounts, sport trans mounts, swepco trans fluid, oil/filter change,,,,wheeew

Anyway, now I need to have the car aligned, there's a competent mech here in town, but I'd like to be able to have him align it the way I want it.

The car will be used for street (70)/ track (30). Looking for max performance street, not concerned with cushy ride or anything like that. Tires are currently 215/45/17 f and 275/40/17 rears, they will be changed to 225 and 255's soon. Car is lowered to euro height.

What are some good F/R alignment specs to go with? Should ballast be added to simulate drivers weight for alignment??

I can't find anyone to corner balance the car in my area, so, I'll be doing that myself once it's aligned. Ballast here again?

makaio · 04-25-2003, 08:42 PM

I may be all messed up, but I believe you want to corner balance the car before the alignment.

As for the other questions, I'm no help.

ckelly · 04-25-2003, 08:57 PM

Really?? I guess I figured it didn't make a difference, but I suppose if the height is changing, the alignment may as well too.....hmmm.

Okay, I'm going to corner balance it first, then have it aligned. SO,,,,ballast or not for the corner balance?

Anyone on the alignment specs?

makaio · 04-25-2003, 09:02 PM

I have heard of people doing it with ballast and without.

I would think if you are doing a lot of track driving with an instructor, or street driving with a passenger, you would want to do it with no ballast.

I believe Steve W. Motorsports has info about this on his site. Hang on, I'll see if i can find a link to his site.

makaio · 04-25-2003, 09:03 PM

http://www.rennsportsystems.com/

Here it is.

masraum · 04-25-2003, 09:24 PM

Personally since I drive my car 90% alone I will ballast mine when it is balanced, even for DE you probably won't have an instructor most of the time right?

As for alignment I understand this to be a good street track

front
-1.0 cam, max cas, and 0 - 1/32 toe

Rear
-1.5 cam, and 1/32 - 1/16 toe

If you drive very aggressively on the street mostly curvey then you can add up to .5 deg of camber front and rear (-1.5 and -2.0)

No expert, just what I have heard repeatedly

dickster · 04-26-2003, 03:13 AM

clay

have you driven it yet?

i'm doing 22/31 bars and would be interested in your comments following the install........esp. for street use.

ckelly · 04-26-2003, 05:30 AM

No, haven't driven it yet, still have to install stainless brake lines, and flush/fill system with ATE Super Blue. Hopefully in a few days though. I've got a DE event to go to on May 10/11 and have a lot to accomplish before then.

I think I will add the ballast, I too drive my car alone about 90% of the time.

Anyone else have more alignment suggestions or should I go with what's listed above?

jluetjen · jluetjen's Garage

Set-up for maximum performance isn't a set of figures, it's a journey.

You do want to corner weight your car before you align it. I'd do it with ballest in the driver's seat.

When you align it you should also have it ballested if you really want it done right.

The alignment specs that are listed seem fine, but the only thing that I would add is that rather then just trying to get "Maximum caster", I'd modify that to "Maximum caster that is equal on both sides" Getting the caster equal is far more important then the last half a degree that you can dial in. Especially if you already have a lot of camber dialed in.

As far as camber is concerned; more will make the car generate more cornering force as well as make it dartyier into the turns. It will also make the car wander and burn through tires pretty quickly during the 70% of the time/miles that the car is on the road. It's a trade-off, so pick your compromise. Note that race cars may spend 60% of their time in the corners, and so camber will decrease their tire wear. Street cars spend less then 10% of their time or miles cornering hard so their tires will last a lot longer with the tires closer to straight up.

Once you start DE'ing and trialing the car,you may find that it pushes here or it's loose there. You'll then need to change something to resolve that. What issues you have depends on the car, the track and the driver and will ultimately require somewhat of a personal solution.

There's no silver bullet.

ckelly · 04-26-2003, 06:10 AM

I know there's no silver bullet, but just wanted a good solid starting point. I'll go with the specs above, with max (equal) caster, and ballast in the drivers seat as well. I'm sure some follow up tuning will be in order.

Even though it spends 70% on the street, it's only driven about 3k miles per year. So....even if I have to buy a set of tires every 3-5k miles, that's okay with me. New rubber every spring would be fine, it's the price to pay if you want to play, I understand it and welcome it.

dad911 · 04-26-2003, 07:08 AM

Ride height changes will change alignment, and alignment changes will affect corner balancing. If you are corner balancing yourself, but sending it out for alignment, I would get the ride height and balance reasonably close, then fine-tune after alignment. If you don't, and need to re-index rear bars, you will need to get rear aligned again.

If you'v done all that work yourself, why not try the alignment? You can get if pretty close with a digital level & strings, then have the shop check it & fine tune.

IMO if the local shop hasn't done a 911 before, don't waste your time. BTDT, to the tune of stripped parts (which were new), torn bushings, and wrong settings.

911pcars · 04-26-2003, 12:43 PM

Clay,
Most folks set up with 1/2 to 3/4 fuel tank. If you're an optimistic person, it's 1/2 a tank .... full rather than empty.

Sherwood Lee
http://members.rennlist.org/911pcars

ckelly · 04-26-2003, 01:58 PM

Okay great, I will add ballast for me ( lots!! ), and make sure there's 1/2 tank of fuel. I'll even top off the antifreeze as well

I've got someone here that has aligned 911's before, just not too familar with performance changes though. I don't have the foggiest idea about it myself, so even if I had the digital level, strings, and etc, I still wouldn't have a clue. Plus, if I have to have them check it and mount it on the rack, I might as well have them do it. But it would be nice to have it close for the test drive and settle in time.

logician · 04-26-2003, 02:57 PM

Hi,

> What are some good F/R alignment specs to go with?

I would recommend nominally 2 degrees of negative camber front and back. Ideally you want more in back than in front, but I think 2 degrees pretty much all you can get with a stock suspension. That's what I've used on two street/track cars ('85 and 73 911s), and it seems reasonable. You may actually need large camber numbers to get your relatively wide wheels to fit without rubbing.

For toe, I would do zero front and back. For track, people actually toe out the front a bit, but I feel that makes the car is just a little to jumpy for the street. You might add just a little toe in the rear, but mine is set to zero. Interestingly enough, the factory spec for my 911s is zero toe front and back.

> Should ballast be added to simulate drivers weight for alignment??

Definitely balast for drivers weight. I usually include 1/2 tank of gas. Check the ride height to make sure that it's where you want it before and after you corner balance. I put in sway-away adjustable spring plates to make ride height adjustment and corner balancing easier. The spring plates came in handy at the track to make a quick height adjustment to cure some rubbing that I was getting with the addition of a passenger.

Beware that the suspension will bind a little, so repeatability is difficult with corner balance and ride height adjustments. After you are done, drive the car around the block and check the corner balance again. Actually, it would be good to check the balance after the alignment is done too.

-Juan