Thread: Car from scratch...?

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Whats the best wheel base for corner carving?
I noticed my 5.0 mustang seems to have too small of a wheel base to float thru the corners,if it comes loose it wants to go to complete steering lock{counter steering}
I had a 79 camaro and it seemed like the wheel base was a little long to corner good,it would not come out at all,and when it did,it wanted to keep going all the way around.
I want to build a corner carving machine,I know the weight must be kept as low in the chassis as possible ,but whats a good wheel base and weight distribution?
I guess I am looking for ideal wheel base and ideal weight distribution.

When we were racing go-karts (40" wheelbase), we found that the ideal front to rear was 60% on the rear. I don't know of anything that corners like a race kart. Take a look at the Formula 1 and Indy cars for wheelbase and weight distribution in a full-sized car. I would think they would be the standard to build from (mid-engine).
Here's a link to one of Foyt's cars. They have mistakenly used the word tread when they meant track.
http://www.foytracing.com/teams/indy/car_tech.html
Here's a link to one of Ferrari's Formula 1 cars (F2005) that shows 3050 mm (120")
http://www.motorsm.com/motorsport/auto/F1/2005_cars.asp

Thnx Tech!!!
Looks like 120 inch wheel base and a 57 inch track width is the hot ticket.
Now on to suspention,I figure independent rear is going to be the best for handling.
They list the suspention as double wishbones with a push rod....whats a push rod suspention?I know the wishbones are A arms,whats the push rod..a sway bar?
I also see some torsion bar suspentions too ,whats the advantage to those?

Ok I see the deal on a pushrod suspention,looks fairly easy to build.
The bottom is a pull rod.
The top is push rod.
Whats the difference other than design,I do not see where there would be a difference in handling.
It looks like the torsion bar replaces coil overs on the shock.
Would this design work with a coil over instead of a torsion bar,torsion bar looks big and heavy.
Just change the torsion bar to a pivot point?

I've never been around those cars, but I think the idea is to keep everything low and toward the center of the car. Less unsprung weight.

Coilovers would replace the torsion bar, Heidt's builds a nice one. There is a bit of geometry involved in figuring A-Arm lengths, spindle heights, and push or pull rod lengths. The length of these componets will effect the camber and caster. Placement and mounting height along with tie rod length on the rack and pinion will become critical to setiing the bump steer. You can draw it out and chart it on a graph, or I'm sure there are programs available that will do it for you.

Your 79 Camaro can be made to handle better, Chnage the front springs from the stock 250lb ones to a set of 800 lb ones, change the stock 5/8ths sway bar for a new addco 1 7/8th inch, place their 3/4 inch rear sway bar, swap over to a set up 400lb 5 leaf springs in the rear with the addition of a panhard bar to help keep the rear end centered under hard cornering. Of course you'll need frame connectors and a decent bolt in four point roll cage to stiffen the rest of the chassis, but doing what I suggested above is what the first basic steps to getting a 70-early 80's Camaro to handle the corners. After setting up the chassis you'll want to upgrade the brakes to a nice set of Wilwoods, and a decent 17" VR rated wheel/tire combination. I prefer the BFG KD's for mixed street and track use...........


HHHHHmmmm, sounds like maybe I've done this before .


Bill S.

Wheelbase is a consideration, but certainly not the only one on designing a chassis and suspension for a canyon racer. Look at an 85" wheel base USAC sprint car on pavement, close in handling to Richard's 60/40 weight distribution Kart. A 5.0 Mustang just needs a bit of stiffening as Bill suggested (though I much prefer a weld in roll bar and ties). Chassis flex and soft springs and bars are what granny likes when she drives to Wal Mart, but certainly not the answer to what Shawn wants when he goes to play on Muhlholland...... The 5.0 also really likes a tower brace, a solid one not one of the showy ones, and bigger sway bars with poly bushings vs. the soft rubber ones that are so nice when granny goes to Wal Mart.....

The 5.0 is a 86 lx ,with all the gt stuff underneath.I have the huge sway bar,poly bushings on the end links for the sway bar,gt springs ,etc.
I will pick up a real tower bar and look into the different roll bars,ohh its also a convertable ,soo I think it has some sort of re enforcement underneath.
I really do want a good roll bar ,being its a convertable.
I just found out I can put a big stroker windsor in there and still be cali emissions legal,if I can pass.

Bill ,I wish I still had the camero,sounds like it would handle pretty good with the mods you suggested,I was just using it as a example of handleing and wheel base.

The thing with the mustang is overall handleing,I have had straight line cars on the street,not much fun to try and turn it with meats ,pie cutters and no front sway
Would I see a major improvement from changing the front end on the mustang to one like I posted?
Or do I just need to use the formula that Dave and Bill suggested and stick with the stock geometry parts and add springs ,bushings and roll cage ,tower brace etc.
I do not want to spend a bunch of money on overkill,as it will never see a track and it will be on street tires.

The "Fox Body" Mustang is the easiest car to get to handle the corners. Of course an 86 5.0L motor is a bit of a dog (original destined for the 86 truck line and used for the Mustang when they ran short of time to develop a better engine for the line in time).

http://www.maximummotorsports.com/

If you have a limited budget start with the basics and in this order.
F&R Coil Springs (not lower than 1.5" below stock)
Adjustable Shocks and struts
Polyurethane suspension bushings
Panhard Bar
Strut Tower Brace
Subframe connectors

Look at MM as their products are well thought out and track tested (myself included). Used to point people to Kenny Brown, but due to family issues, he has sold out and closed shop.

Bill

Thnx,I will be doing that in those steps!!!!
I knew it had some inferior heads ,but was under the impression it was the only year for the forged flat tops,true flat tops with no valve notch?Which gave it a higher compression ratio than the rest?
Its the H.O. gt motor with the micro tube factory headers.
I consistenly pull away from the newer stock gts under hard throttle and just embarased a guy in a 93 gt from a dead stop the other day.
I know it was only rated at 220 hp,are the heads the downfall?Because it is done pulling 4500 5000 rpm.
Or is it more the overall package?
Cam,heads,drinking straw sized headers?
I also know the rear gear is numerically low,like 2.73 low as I can do 65 in second easily.
Open for any info on it you may know......

Having built a road race car from scratch, I can tell you that anything can be made to handle well, but where do you cross the comfort level? My Suzuki ran great and it only had a 98" wheelbase.

Getting a car right requires more than just a shopping list. Testing at the track is where it gets sorted out. This is where you find that the springs are too stiff (or not stiff enough), the shocks get adjusted (or replaced), the swap bar is adjusted (if adjustable) or replaced with a different size.

Don't take this the wrong way, but this is where the driver also gets sorted out. I know I'm not the fastest driver, so I know I have plenty left in the car. Some tracks I know far better than others. I know I wouldn't pick Road America to sort out my Suzuki. Whatever car you drive, take a driver's school and learn to get the most out of you and the car you're driving. My instuctors always advised to maximize the driver first before making changes. After that, you'll know where to make your changes.

Mustangs are excellent cars, but always finished second to Camaros in SCCA Showroom Stock. Check out the rules for American Sedan at SCCA.org. Maybe check out an event at a local autocross or regional race. Autocrossing is an extremely safe way to test the car without being a danger to you or the car. And have fun.