luckett

In this article, some of the specs are incorrect in the table of t-bar sizes. Best use another reference for the sizes.

GlenL

I was thinking about the base problem to this query, which comes up a lot, and that is how to improve high-speed performance without sacrificing street driving behavior.

The core of the dilema is that street cars need to be tuned to handle poor pavement characterized by sudden events. On-track racing, despite the high speeds, is characterized by much slower events. That is, a suspension designed to handle a pothole that is hit and gone in 0.01 seconds is very different then a suspension tuned for, say, an "S" pair of corners that will be covered in 5 seconds.

Makes me want to break out the old Dynamics textbook. (But only sorta.) What would be really cool is to make a web page where you could give what sort of behavior you want and it would calculate what spring and shock (damper) values would give you that. It's nice that springs have real numbers given and not just "stiff" and "even stiffer" that shocks get away with.

Has anyone seen any hard engineering numbers for shocks? I'll bet the shock dynomometers give it. (OK, know it. Used to work in similar test equipment.)

Dave in Chicago

Glen - Good point. Fact is, you actually don't have to do ANYTHING to imporve the car and sacrifice street behavior. It seems to be the most common new Porsche owner misconception.

Note that ALL of these cars, in stock form, in good working order, are superb performers in high-speed driving. It just kills me when I see a new 944 owner's first post of "upgrading the brakes, suspension, fill-in-the-blank" (not that this was the point of this particular thread - no flaming intended).

Drag any one of these cars in good condition and properly aligned (even factory stock alignment is good) out onto the highest speed tracks in the country... and you will be very impressed. Until you've actually put a helmet on and have learned to drive on a race track, you really have no business talking about improving performance.

Folks that want to drag from the stoplights should buy a nice Mustang. Folks that want to truly learn to drive a high performance car competently should take their 944 and head to their nearest autocross or driver's ed event. Repeat many times, truly explore the capabilities and capacities of both car and driver... Then, and only then, should we start trying to out-guess the professionals that designed the car in the first place.

Okay, I'm getting down off my soapbox now. Thanks for the bandwidth.

GlenL

Dave,

You're so right. The important part is the driving. No one wants to be told "learn how to drive" but it's so true.

I've tracked my 928 for three years. Didn't do _any_ additional power or handling improvements this winter. I need to work on the driving! (#865 Nord Stern)

I'm setting up the 944 for my son to use at the track. As a plain-jane N/A it does offer several improvements. Like a rear swaybar. Having just replaced the front struts, springs and swaybar, it handles much better. Previously did a big nose-dive on braking (bad struts) and seemed too lightly sprung. Now at 200#. Nothing radical.

Legoland951

When I took a stock 944 to Willow Springs small track, the experience showed me how well the factory brakes worked and how crappy the "leaning tower of Piza" feel of stock springs, sway bars, torsion bars, and shock/struts. They handle great in stock form compared to other "street cars" but by no means are they designed anywhere near a track"able" car. Compare the "factory" turbo cup car's suspension to the stock street car and we won't have to out guess the professionals who designed the car in the first place. They upgraded the suspension pretty heavily and lightened the car. I don't think Glen is saying it is possible to improve high performance without sacrificing street driving behavior. He is suggesting that the shocks/struts are designed for different purposes on or off the track. The pothole that accelerates the tire vertically 2 inches in 0.1 second requires a different dampening factor than an S turn that moves the suspension 2 inches in 5 seconds, which is the entire discussion over different suspension setups. I would love to have access to a program where you input the parameters and get a set of results to set up the suspension that best suits the purpose. Stiffer is not better and there is always a point of diminished return.

Eyal 951

So which is it? .56, or .65?
~Eyal

luckett

Well said and spot on.

Based on a GENERAL consensus opinion from other posts, a min. level of stiffness for a track car is around 400# springs/30mm torsion bars with Welts/Tarret/Kokeln sway bar stiffness range.

Anything less than that would be considered a street setup. Where you want your car to be between stock and min. track depends on the condition of the roads you drive and YOUR personal tolerance for a stiff ride.

Now that we have that cleared up, what engine can I swap into my new early NA so I can out drag the mustangs at the local street races?

Serge944

Thats very similar to my suggested 350/550. The difference is a bit negligible Eyal, and can be fine tuned with swaybars. That is their purpose, afterall.

Dave in Chicago

Chris - The new Mustang is the BOMB! My first car was a '66 Mustang that I bought for $500 when I was 15. Man, I LOVED that car. Too bad I was young and stupid enough to sell it a couple of years later (frustrated with working on the broken beast). Pity too, as I had rebuild the engine and trans in that car by then. Still miss it to this day.

Ford really got the styling right with the new one. What a great blend of all the key nostalgic queues from years gone buy.

By all means, get a stop-light-racer 'Stang. I may buy one in a couple of years just for fun. Heck, they make a race-spec version too!

pete95zhn

If I just could find the thread... Guys had pretty impressive calculations to prove Skip that there's wrong info at Paragon's site.I hope that Skip would comment on this.
What I found myself is that the length from the point that rear suspension arms attach to the t-bar tube to the point that shocks / coilovers attach to the suspension arm is about 65% of the total length of the arm.

joseph mitro

0.56 is the effective rate for the coilover springs. see my post #31 in this thread and the link in serge's thread to paragon's website.

edit - chris - not to argue but to show a differnt viewpoint: M758 races in 944 spec with 350lb springs. i don't remember what his torsion bars are. i think the spring rate just depends on how heavy the car is, other suspension factors, what type of track you drive on, and how you want the car set up. i agree for the most part that 350lb springs in front is not the ideal for a track-only car, but for me it provides better handling than stock. heck, in last week's PCA autocross, i had the fourth fastest time behind some modified 951s and 930s on race tires, and i was on street tires. i was ahead of a couple 951S's and a 996TT as well as a Z06. not that i'm great, but it's a matter of optimizing all the factors for success, and i'm still learning how to do that.

luckett

I'm not much of an American car fan, but you gotta love the torque and sound of an "old tech" V8.

I'll take one of these please:

http://www.muscularmustangs.com/gtr.php

pete95zhn

Aaahhh...here they are:


https://rennlist.com/forums/showthre...hlight=.65+.56

https://rennlist.com/forums/showthre...ht=.65+paragon

luckett

"min. level of stiffness for a track car is around 400# springs/30mm torsion bars"

key word is around.

Different people like different setups. I used to race karts so I like it on the stiff side.

L8 APEKS

B16A2 DOHC VTEC.

Sorry, couldn't resist.