S550 Road Race Car Build

[apex15stangPP]

Yes, street car.

On throttle coming out, just going to fast. Snapped right both times, both going left and right

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[RobBodle]

too much spring in the rear will make the car tight. So that shouldnt be your problem. Kind of sounds like it bottomed out or the suspension bottomed out

 

[apex15stangPP]

I think it may have bottomed out as well. Need to do some testing

 

[Plimmer]

400lbs front. 350lbs rear. this is not supposed to work but these are the rates where the car settles down.

I'm 400 and 400. Seems to work well for me.

 

[RobBodle]

street car? any additional from stock down force?

 

[ddozier]

I am guessing that 400 and maybe even 450 is not going to be enough spring if you are able to develope some usable downforce. I am still getting a handle on my setup and since shocks and shock settings will also impact the spring choice I guess I should say with my setup I do not think I will be able to get away with much softer than 500 in the rear once the aero is working.

I am running Ridetech shocks and 425f/600r. What little testing I have done was surprisingly well behaved but I need to get to a track like Putnam Park were I can let loose and really push the limits to dial things in better.

Dave

 

[RobBodle]

We havent run a "short track" yet. Road Atlanta, VIR, Watkins Glen. The car is stable at high speed. Our handling issues have been entirely been 2nd gear speed problems on the throttle. Which is why we are so soft.

We will have the big rear wing on the car for the next event and we will have to bump the rear spring rate up, but we wont do a lot at least to start.

 

[ddozier]

What bar are you running front and rear?

 

[RobBodle]

Steeda. Both front and rear

 

[ddozier]

Steeda. Both front and rear

Sorry for asking so many questions, but I am trying to understand the problem better.

So you are having problems with the car being too loose when on the power coming out of a corner primarily in slower 2nd gear corners? The solution so far was to drop rear springs rates from a start of 600 to a final rate of 350. This is a dramatic change in spring rate and should have effected much more than just corner exit.

If that much change corrected the problem them the car should have been crazy loose all the time on the original stiffer springs. If not then I am wondering if you have too much rear bar and it is causing the transition from mid-corner to corner exit to move from neutral to loose.

There are so many variables but it does not make much since to me, then again sometimes the car wants what the car wants and it is best not to fight it.

With my setup the car was running fairly neutral with a slight tendency to under-steer on turn in. That was with the Ridetech Shocks, 425f/600r, F=12 clicks from full soft, R=12 clicks from full soft, NT-01 275f/305r and stock bars. It may also be worth noting that I am at a ride height of about 4" measured from the rocker not the pinch weld and I am running about a 1/4" of rake Front to Rear. I moved the front shocks 2 clicks softer and the car was very well behaved with the ability to power slide the car if too aggressive with the throttle but front end was very well behaved. Turn in was precise and the rear was tracking very well on or off the throttle. It took very aggressive trail braking to get the rear to loosen up so I think I have some room to add a little front grip. I am tempted to try and soften the front shocks some more and see if the turn in will be more immediate and if the rear will stay controlled. I feel I am very close to having the car work well but am still playing with things mainly to figure out what each change will do. Of course all this will change yet again as I add the aero bits into the mix.

The only notable issue was at the limit on braking in a straight line from higher speeds (120+) the rear had a pronounced and predictable wag. Right now I have no rear aero and a full front splitter and undertray so that may correct itself with a more balanced aero.

I wish I could afford to run ride height sensors and data log the setup.

Dave

 

[RobBodle]

just to be clear. we softened the front as well. the suspension travel that we are seeing on the couple of continental series cars and the car that was tested for pwc showed the rear wheels all the way up the wheel well under loading. we have not seen anything like that and feel like softer may be coming.

but we first get the big wing on the car and see. and yes, you ask the car a question and dont argue with the answer it gives even if it doesnt make sense.

I dont get any rear end movement under high speed braking unless there is a camber set up causing it which is the case at Road Atlanta.

Running smaller tires in the front is a reason for understeer. We race square at all times. NT01's ugh. Better you than me

 

[ddozier]

Running smaller tires in the front is a reason for understeer. We race square at all times. NT01's ugh. Better you than me

I run the NT-01 for testing because for the most part they are a much more predictable tire then say a Hoosier, they stay more consistent over a longer number of heat cycles and that is what I need at the moment since I am still trying to dial everything in. Once I get a know good setup for the NT-01s I can move on to the R7s and then make the needed changes for them. I will likely have a fresh set of NT-01 or 888 for wet use anyway.

I will likely run a 295 square setup with the R7s, but maybe not. I will be on track at a higher HP than your setup so I will have to see about the rear tire size.

Dave

 

[RobBodle]

My experience with Toyos and Nittos is that the lack of grip requires a different kind of driving that a more sticky example like a Hoosier. The set up for one can't be very close to the set up for the other. Just as the set up for an actual racing slick is quite different than for a dot like an r7/a7

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