Setup question

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1 year 2 weeks ago #4875 by Antonio Tavares
Antonio Tavares created the topic: Setup question
Hi there,

I was wondering if anyone knows why the 911 2.5 ST default setup sets a higher ride height at front of the car - default is 10cm at front and 9cm at the rear, and I don't understand why especially being a rear engine car, that is having a lot of weight over the rear axle.

I've read over the years many articles, books, etc, about racecraft and car setups, and generally most race cars have a higher ride height at rear than the one at the front. I believe that one of the reasons is to help to mantain the chassis leveled exiting corners, as the front end tends to lift under acceleration while the rear has the opposite tendency.

The first thing I do when seting up the 911 is to put the rear higher than the front, normally around 1cm. Anyone care to share their view/experience?

“Racing is life. Anything before or after is just waiting.”

(Steve McQueen)

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1 year 1 week ago #4876 by Mikko Nieminen
Mikko Nieminen replied the topic: Setup question
Hi
I don't have any advice or experience how the 911 should be set up. It does sound reasonable to have the rear little higher than front. Atleast thats what most of the time FR cars are set up. However RR cars are behaving so much differently than FR cars so there might be some tought behind the opposite tune. Maybie Toni does have opinion about this?

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1 year 1 week ago #4888 by Antonio Tavares
Antonio Tavares replied the topic: Setup question
The 911 are known to be good at corner exit, and generally not so good at turn-in as other RWD cars with front engine. This is due to weight distribution: At corner exite the engine weight over the rear axle helps to obtain higher levels fo grip compared to RWD cars with engine placed in the front. But under acceleration, the front tends to go up and the rear to go down, and if the front is too high, or in other words have few weight over the axle, steering is imprecise due to lack of grip in the front wheels.
That's one more reason why I find this height difference even more odd in the 911. being good at corner exit due to extra weight over the rear axle, why would the rear be lower than the front? It would seem logic that if the rear was higher than the front the car bance would be better during braking and turn-in phases, due to the extra grip that the weight over the front axle provides, thus compensating for the 911 weak points. And at corner exit the extra wight over the rear axle already offers extra grip/traction compared to RWD/front engine cars, so once again why make the rea lowr thus unbalancing the car taking out grip front the front wheels?

Many race cars use higher rebound values in relation to the ones used in bump; when setting up a 911 I normally use even higher difference than I'd use in a RWD/front engine car. Let's say that if I would set the bump at 4 and rebound at 5 (harder), in a 911 I'd probably set the bump at 4 and the rebound at 6. Why? To prevent the front from raising under acceleration; due to the lack of weight, in the 911 the front can lift faster than a car with front engine.

I once read that a race car driver is a weight manager. So true...

“Racing is life. Anything before or after is just waiting.”

(Steve McQueen)

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