Car lowered, too much or not??
 

Hi guys,

I need some style advice from the PP braintrust.

My car has been lowered and it looks better now but I feel like it may be a tad too low in the rear.
I am inclined to have the rear raised a bit, half an inch or so and lower the front by the same.

What say you?

Thanks

http://forums.pelicanparts.com/uploa...1336630855.jpg


http://forums.pelicanparts.com/uploa...1336630873.jpg


http://forums.pelicanparts.com/uploa...1336630892.jpg

Rear is nice, front is too high.

+1

Measure the line at the bottom of the door front and back. If the front is any higher, the rear is too low by that much. The aero of a typical Porsche is for the front to be slightly lower, up to 2° rise from front to back. Where I notice this on my cars is when traveling at speeds above 120. The front gets light and the car gets twitchy. Your Mileage May Vary.

Thinking a bit, with your roads, you may want to raise the rear just a bit, but the front needs to go down.

Rear looks good, G.
Front a bit high. :)

A shop did this and they worked on both front and rear? That's a poor result IMHO and obviously in your opinion too! Generally the car should be at least flat or have a slight rake angle forward 1 degree is often quoted. That means the front hast to come down some. I also think the rear needs to go up a little too from the images.

The way you measure ride height on a torsion bar car is from the center of the torision bar to the ground. I would not rely on fender lip to ground measurements.

I would look for another shop that does a better job and sets you up for performance driving with a corner balance as well. Only taking corner weight into account will the car be set up right. Your local performance porsche club friends will have a reference!

G

That's exactly what I was thinking when I looked at the pictures of the car. Corner balance is the key. If the corner balance is correct and the vehicle is aligned properly, I would just leave it be. If the shop just lowered your car and set the toe, chances are they might not know correct procedure for proper set-up. When you had the work completed you should have received a spec sheet with alignment adjustments and corner balance weight percentages, what does it say? This is important for you to know because an improperly balanced car will do some really goofy things when you are driving it at speed.

As it sits now, it is level.
They did not work on the front yet.
I'll ask them to raise the rear by half an inch and drop the front as well.
A bump steer kit is on the way too.

Glad to hear the front wasn't touched.

I had set up my SC at home and thought I had a pretty good ride height and it looked nice. After driving and autocrossing it for about a year I went and had it professionally set up at a shop that did a full corner balance, align etc. The difference in performance was profound. IT actually did not sit completely flat, but the weights were nicely balanced. I would not just treat this as a cosmetic exercise. Even if you do not track the car, you will want the best performance for safety in case you do need to corner hard in an emergency.

G

+1

Love the low look.

A good starting rule is to be able to slip your hand over the rear tire and stop at the knuckles and be able to slip your hand all the way over the tire in the front.
Once you CB your car,your height setting might not be even anymore anyways ...

A slammed 911 doesn't look good in my opinion !

Cheers !
Phil

G-man, Porsche publish specs on what is "normal" it does not come down to looks, it is science and math with an alignment rack. Most folks take those figures and go lower yet. My car is at Euro spec height. I have a hard time getting into or out of many driveways because I will drag the skid plates. No way could I go any lower.

You might check out Elephant Racing and see if he publishes the alignment specs he recommends. Chuck is a nice guy, he might even reply to an email with his recommendations for ride height.

In the end it is more important to have a 911 that handles properly. Adjusting a car for ride hight just for looks is for posers not drivers.

I know my '84 I now have is set low, much like yours in the rear on both ends. My previous 911 was stock and set higher but handled much better, especially at higher speeds, my old car the faster the more stable it felt. I think the rake is my issue, it needs to be raised in the rear to get the 2 degrees.

This is the only advice I'd suggest you follow. Consider also what the fuel level was when the photo was taken.

JR

We lower our 911s for two reasons:
Obvious is the ‘coolness factor’. Our 911s look better slightly lower than ‘stock’.
The other is cornering ability. A lower center-of-mass vehicle will corner at higher speeds.

A critical issue with lowering is how much suspension travel remains before the suspension hits the bump-stops in the shocks.
Part of this is the spring rate (torsion bar size).

No matter what suspension height, you can (under ‘normal’ driving) hit the bump stops.
The questions become “how often?” and “how hard?”

More available suspension travel reduces the ‘often’ & ‘hard’.
This can be done by raising the ride height or by modifying the suspension to allow for more travel before hitting the stops.

Higher spring rates (larger torsion bars) permit greater forces (bigger bumps) before the suspension runs out of available travel.
Again this reduces the ‘often’ & ‘hard’.

Most use a combination of the two in order to lower the center-of-mass of the car while still having effective suspension.
Effective suspension means having remaining suspension travel available on hard braking, cornering at the limit-of-traction and adding a ‘bump’ to the combination.
Many a 911 driver has incorrectly blamed the rear weight bias for the rear ‘stepping out’ on hard cornering when it was due to the loaded rear suspension hitting on the bump stop.

There is similar effect with too low front.
On hard braking, the suspension runs out of travel, hits the bump stops and the brakes lock-up at the first bump.

A 911 sitting on (or too close to) the bump stops rides and handles terribly.
Without adequate suspension travel, you loose many of the benefits of a 911’s handling ability.
Many a ‘too low’ 911 will actually handle better if raised to ‘stock’ height.

The ‘art’ is a combination of ride height, spring rate and modifications allowing more travel on ‘bump’.

Best,
Grady

I'd like to add bump steer as a consideration, in the front. The further you deviate from "stock" height, the greater this problem becomes. I don't know what the toe curve looks like for the rear, so I don't know if that's a problem.

JR

Grady nailed it

I run Euro height and 23F - 30R T-bars
when I am hard on it, my suspension has a buffer for the bumps - that said with the wider tires I have to roll the fenders up front because on a serious dip in the road I can tag the tire up front -

make sure your suspension can handle lower - and you might consider a bump steer kit....check fender clearances. There are reasons for those numbers in those books :D

As expected, Grady is correct. I run at the stock "euro" hight adjustment.

My understanding is that the factory developed that ride height as the ideal but had to raise the US cars to meet bumper height laws.

The ride height difference was eventually dropped. Not all US cars were "US height".

JR