Making a car fast on any course is a combination of many things...first and foremost, the car needs to be neutral balanced so the driver isn't fighting one end of the car or the other loosing traction first. Once the car is neutral balanced, it is up to the driver to get the most speed out of the car in any given corner. Different driver inputs can affect the way the car handles (usually referred to as the driver mod) both positively and negatively. Then one might also have other mechanical issues the driver and car must work around that aren't really chassis related that affect speed. How a driver\tuner deals with all of the above is typically fluid and it is only once all of the above are almost perfect that one will run at or near the top of the speed charts in any given competition.
Throughout the multiple stages of development on this car (with Ron's fantastic help) we've done a pretty good job at keeping the car neutral. We reached a plateau last fall after the addition of the much stiffer front bar and the car had a loose condition mid roll through to corner exit that we could not tune out. Enter Stage 4 I call it, a huge jump in rear spring rate.
I ran one event last week with the new springs and had some tuning challenges. I could tell the springs fixed the issue we intended on fixing, but a few other issues popped up that we had to contend with and with only 4 runs at a typical SCCA event I didn't have enough time to dial everything in.
After some discussion with Ron, we came up with a few more tuning ideas and I entered another SCCA event in Topeka last Sunday with the intention of using multiple runs on a much faster freer flowing course to dial things in further. I can say now that the car is neutral once again and has MUCH more rear grip on mid roll through to corner exit. It took me about 4 runs to get the rear shocks and tire pressures set where I needed them and then I used the next 4 runs to work on the driver mod getting him used to the new setup.
Another issue reared it's ugly head once again though, I've wore out yet another clutch type posi unit and spent just about every right hand corner exit spinning the right rear tire while trying to put the power down which I'm certain really hurt my times. If you can't put the power down, you aren't going to go fast. Watch the right rear tire in the first run, you'll see the black marks it leaves on most corner exits. The second run in the video was my last one during the fun runs after the event was over and was my fastest run of the day (in the 96 degree afternoon heat even). I finally started to get a good feel for how the car was going to react and dealt with the posi issue the best that I could.
It'll take some more work (and $$$) to fix it even better but that's why we do this...right? I'm trying to decide now which direction to go with a diff replacement. I know a certain green car that has dealt with similar diff issues and just installed a locker...I can't wait to hear how it does on course with this new addition. Some autocross gurus recommend against a locker, while others like them. I have no idea which way I'll most likely go...all I know is it will NOT be another trac-loc going back in the car.
__________________
Lance
1985 Monte Carlo SS Street Car
I went with an Auborn Road Race diff in my '00 WS6 autoX car. I couldn't have been happier! Auborn even has a "racers rebuild" program where they'll swap it out
__________________
No Shop, No Money, No Time.... No problem!
I am continually honored and flattered by the attention this car seems to get. It is a huge testament to those that have helped me along the way, people like Ron Sutton, Bret Voekel, Ramey Wormer and Ryan Kirkwood, as well as my wife Terri for being so patient with my hobby and my good friend John Parman who never fails to come up with a fabrication solution for my never ending issues that pop up with it. Huge thanks to all of you...
__________________
Lance
1985 Monte Carlo SS Street Car
Also, I saw Ron's post about you and if you have gone from 80 something PAX time to top 20 PAX times in your local SCCA then way to go!! I'm impressed! My last San Diego event I paxed high 30 something out of around 130 and my last Cal Club event I paxed just over 100 out of 230. I'd love to consistently pax in the top 20 or even top 20%
Thanks... He was referring to raw times though...not PAX. My PAX times are generally further down the list than fastest raw times depending on the course design and number of entrants.
Participation in our local events has really stepped up the last year or so and we are getting many more faster entrants to our events. Our first event this year I raw timed 29th out of 142 timed runs and pax'd 31st.
Everyone else switching to Rivals and me being stuck on Falkens has hurt my finishes the past year or so. That is at least a 1-2 second advantage they have from what I can tell. I ran a wore out set of smaller Rivals last weekend to test and it is amazing how much more grip they had. Of course I had other issues which hurt my finishes there. Isn't that always the case? The short tight course at Midwest Musclecar dealt a death blow to my clutch posi, so the last two events I've been spinning just the right rear tire on every corner exit which really hurts on the stop watch. Working on a more permanent cure for that now.
__________________
Lance
1985 Monte Carlo SS Street Car
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
I'm trying to decide now which direction to go with a diff replacement. I know a certain green car that has dealt with similar diff issues and just installed a locker...I can't wait to hear how it does on course with this new addition. Some autocross gurus recommend against a locker, while others like them. I have no idea which way I'll most likely go...all I know is it will NOT be another trac-loc going back in the car.
Linear Mode
