S197 suspension motion ratios

[kerrynzl]

Even though the people behind the Cobra Jet cars are skilled engineers, for sure the first S197 Cobra Jet was a case of emptying the spare parts stock. The spring choice indicates they simply picked the most suitable OEM springs based on their target. Maybe based on cost, maybe based on delivery times, maybe they were just good enough for the task…?

Later generations of S197 Cobra Jets did actually get special made springs, which I believe were sold under part numbers M-5300-R and RA. Again, difficult to find quality information regarding rates and free lengths.

Apparently, the R’s dropped the car a lot and were super stiff in the rear where the RA’s are said to be a lot softer but just marketed as ”new and improved rear springs compared to R’s”.

I find it hard to believe Ford’s engineers shifted strategy completely, so there is for sure something in this that ties in with the geometry of each car. In any case, interesting to analyze, but difficult to find quality information.

The 2008 Super Cobra Jet was originally built as a spec racer for "stock eliminator" racing.
Ford needed to replicate this as a customer car.

In original form ,they were a disappointment on paper [not as a collectable]
They weighed 3240 lbs with a heavy 5.4 4v supercharged engine rated at 425 hp

So in theory ,with a 180 lb driver they would get a 11.6 sec at 116 mph quarter.

My FR500C road racer weighs 3000 lbs and gets 425 hp from a N/A Roush R50 engine [so in theory it should be quicker if set up correctly]
both cars run 4.11 gears.


But the 2008 Super Cobra Jet could get the wick turned up to over double the hp [whereas my FR500C had to run restrictor plates as per SCCA regulations]

Now I love historic / vintage race cars so my opinion will always lean towards factory race cars [with history ,it is better]
Because of this way of thinking , I prefer modifications that have "sound engineering practices" instead on the approach of "machine gunning shiny hotrod parts at it"

I've owned a few "works" cars over the years, and these cars appear to be relatively unmodified [so you don't see the value] but they are demons on the track .
Also my younger years of "street racing" and "hustling" also made me think this way.

I always preach "Less is More" [for example , springs and shock inserts vs shiny anodized coil-over struts]


You can go a long way simply by corner weighing your car [then jack up one end and corner weigh it again, to get CGH ]
This will give you the basics to start with a "Grand plan"

Have you seen how loosely wound those M-5300-RA springs are ?
Most Mustang Springs are progressive windings [V6 rears are linear]

That kit would be a good starting point eve though it is made for a car with a 5.4 Iron block supercharged engine.
You would still need to pull a lot of weight to get your car down to 3240 lbs

 

[Pentalab]

Is that a question for me…?

yes

 

[Alatalo]

If you are talking about my car, there are no time slips as it has never been to the dragstrip. It’s just in the very early stages of planning, hence the collection of information.