Suspension In Compression / In Rebound - Ground Clearance and Travel.

[doozer]

Ok, beyond measuring the fender lip and measuring the height to the torsion bar, how far does a street 911 suspension move up and down?

I know it is a function of spring / torsion bar rate so it will be different from car to car, but what is the minimum acceptable travel and still be comfortable to drive on the street.

What is the suspension in compression and in rebound on a normal 911 ( say 84 ).

What is the required minimum ground clearance regardless of fender clearance.

I was told by a suspension designer that I needed a minimum 3" compression and 2" in rebound.
Does this hold true on a 911???



EDIT----------------------------------------------


There are a bunch of photos at this link:
http://hypertec.ws/todd_porsche/photos/front_suspension/front_suspension.html

Just a preview...




EDIT----------------------------------------------

Thanks
Todd

[Wil Ferch]

Based on the travel allowed on old shocks....my *recollection* ( buyer beware !) is that the total range is about 7".

Anyone else ??

Wil

[doozer]

Thanks Will,

I am really looking for the minimum allowed travel on the compression motion for a street 911... 2" .... 3" ...??

[Wil Ferch]

I would think you'd split the 7" equally both ways...but 2-3" for "jounce" sounds reasonable.....watch out for total shock travel and where "midpoint" is for the shock. May need to shorten shock shaft to get to the "sweet" spot at normal ride height....

Wil

[doozer]

Thanks Wil!

Any input on ground clearance? Someone said 4.5" but that sounds high for a 911

[doozer]

Ok well I have the car on stands and a jack under the front wheel and I am going to run it through its travel and take some photos along the way...

I still meed an answer on ground clearance and minimum acceptable travel in front..

[doozer]

Jack asked what I was doing so I am posting this:


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Re: Suspension Question

Thanks Jack,

I am actually prototyping a pair of air ride front struts for 911 and I am trying to figure the ideal heights for four settings.
- normal ride - daily driving
- raised ride - to clear obstacles
- low ride - for profiling
- full dump - setting car down on bump-stops 1" off bottom of suspension

Yes I know - too much free time...

Thanks
Todd


quote:
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JackOlsen wrote on 01-03-2005 11:54 PM:
I saw your post. Are you looking to reduce the amount of suspension travel? Normally, guys raise the spindles on their struts so that the effects of lowering the car don't reduce the range too much. You want to have as much as you can get, bcause -- believe me -- bottoming out the suspension travel when you hit a big bump or an expansion joint gets old really fast. It'll tear the chassis apart, over time.

I think I have a little over four inches of clearance, and I still bottom out a lot on driveways and access aprons. I run 600#/400# springs.

Jack

[doozer]

Hey Will you were correct!!

I ran it through its full travel with the torsion bar disconnected and got 7.25" of travel ( at the outside lip of the wheel rim 18x11 front wheel + 1" spacer).

I took a photo with fender on and with fender off at:

- 0.00" Full up - where the shock ran out
- 1.25" down - where I could first turn the wheel without hitting the fender lip
- 2.00"
- 3.00"
- 4.00"
- 7.25" Full down where shock ran out

I will post them later today..

[Wil Ferch]

Doozer:
I just love when you say I'm correct with exclamation points...like...ummm...it's a surprise I may be right ??? ......

Wil

[MotoSook]

Hey "doozer" where was the wheel when the a-arm is horizontal?

[doozer]

Sorry Will - I never dobuted you!!!

Souk - Derrrr... I forgot to measure that but I will tonight...

[Wil Ferch]

Just playin' ....

Wil

[MotoSook]

Originally posted by doozer
Souk - Derrrr... I forgot to measure that but I will tonight...

Thanks!

[doozer]

Ok got some photos here...

http://hypertec.ws/todd_porsche/photos/front_suspension/front_suspension.html




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[magic930]

Does adjusting the ride height effect the hardness of the suspension?

[doozer]

On OEM 911 suspension or my prototype air ride suspension?

[magic930]

OEM 911, with torsion bars.

[doozer]

It affects the available suspension travel and geometry unless you do the lowering by raising the spindles.

I believe that some gas charged shocks/struts are affected by lowering the car as it compresses the gas more.

I dont think you would be able to notice the difference in stiffness on your 930 as you could not lower it far enough.