Continuing Interview with a racing driver. Part 2 Hey David- Sorry to go dark on you there, I get so damn busy that sometimes I forget what the hell I was working on before a weekend started! We had 2 weekends in close proximity at Sonoma and I’m on a plane to Wisconsin today for a race before spending the next two weekends at Laguna Seca. Making up for lost time in the early part of 2020! Since I'm stuck in this plane I'll try to get through your questions now. In answer to the diff issue that Ethan the driver in this video had at the time. Quote: I’ll try to roll through these questions one by one as best as I can. Q1. In the video driving the Brabham @ Monterey 2018 for the benefit of your new fans on the forum!. What were the problems with the diff? Setup, mechanical issues? Just so I can clarify rather than members guessing/speculating this end what kind of diff settings you used or what the issues were. Though we don’t have the track in Automilista 2 atm. We do have Virginia raceway and many others. (I will list later to keep this short) Ans: The diff problems we were having in Monterey that year were two-fold. The ramp angles were not particularly suited to my driving style (45/45), but the problem we were facing was that we didn’t have enough friction faces or preload so as the clutch faces began to wear, the wear rate increased exponentially and once the preload was all gone the diff went open on me. So I was essentially driving a Formula Ford with 500hp. It forced me to have to wait on power until the car was 2/3 the way out and then steering like mad as the inside wheel lit up with wheelspin, killing forward bite and making the car very difficult to handle. The nature of our race weekends is such that to service/change the diff is something you wouldn’t take on due to time constraints, (and I was still in podium contention as it was) so it was left to me to make the best of it and adapt my driving style as best I could. I still ended up P4 to a couple of ground effect cars so it wasn’t a terrible result. After that, we changed to 30/80 ramps, 6 friction faces, with 15lbs of breakaway torque (I think this was ~.010" preload) and that cured the issue. Personally I like to run more faces with less preload than vice versa. It allows you a more progressive wear pattern on the diff as you are spreading out your load over 6 faces instead of just 2. He also has this to say about tyres on high power cars. Some interesting and real phenomenon. He describes driving our "bad boy Brabham" Quote: Something I should mention is that the big power cars of that era (Can-Am, F5000, F1, etc) have an issue with tire shake. The large diameter sidewall bias ply tires can get into a condition where when you are asking the tire to slide sideways and forward with wheelspin at the same time. So the carcass of the tire doesn’t know what to do and it loads and unloads in both directions rapidly causing a high frequency vibration. It is easily heard from outside the car and it sounds like hitting a serrated kerb or something of the sort, sortof a buzzing sound. From the driver's seat, it shakes your body quite badly, blurs your vision, and will knock the air from your lungs if you are not prepared. (You breathe out before going to power and hold your breath out until the shaking stops). All the big power cars do this when you get to the limit, but the Brabham with its short wheelbase is particularly susceptible to issues relating to tire shake. In the case of the BT44, extreme shaking causes the outboard drive axle flanges to break. I have had them break on me on two occasions; once at Elkhart Lake while braking for Canada Corner and the other time at the end of the back straight at Portland while going around 175 mph. You then have a car that has one wheel drive (and wants to lurch violently in one direction) and with the inboard rear brakes, you have three wheel brakes (and the car wants to snap in the opposite direction of the acceleration when you apply brake). It’s not much fun. So more wheelspin, more tire shake. More tire shake, more broken parts. The point of this is that controlling wheelspin and differential setup and function is of crucial importance with the BT44. As we got the diff setup zeroed in, the shaking was reduced to the point where it was acceptable. Q2 What tracks have you race the Brabham at.? I would like to correlate our in sims settings with some real life examples if possible. and benefits from the settings for each track. This may help us/me see how far we are off to a bad start with default settings. I am focused on the Brabham atm. Sims also has 1969 Brabham BT26, 1967 Eagle MK1, 1969 Ferrari 312, 1967 Lotus 49, 1974 Lotus72E, 1974 McLaren M23, 1988 McLaren MP4, There are many more but these are the ones of interest. ref your experience of. And if so at what Track? Ans: Q2: Of the cars on your list, I have driven a BT26, a ‘69 312, a Lotus 72, and several M23’s (high airbox early cars and low airbox late cars) I’ve driven historic F1 cars at a few tracks in North America. Sears Point, Portland, Mosport, Mont Tremblant/St. Jovite, Watkins Glen, Road America, Laguna Seca, COTA, Barber, Montreal, and a few laps at Mexico City one year. I have extensive knowledge of most of the tracks here in the US and have driven all sorts of different cars on them, but those are the ones I’ve driven F1 cars at. Q3 Somebody has asked: "Are the cars really that restrictive to turning, especially while loading the fronts, without locking,under braking? (Slight braking makes it break the rear lose better, for example) “ Ans: Q3: the cars are not at all restrictive to turning, especially while braking. In most cases they are like flying a fighter plane. They respond quite well to inputs but you can quite easily overload one end of the car and kill the tires in a few laps. The thing to remember is alloy tub cars don’t respond quickly to transient load like a carbon tub car does. That is, the tubs (even the best ones) have a bit of “wind up” in them and you have to account for that in your driving. The suspensions have a happy window of operation which in most cases was for the tires of the era. As I mentioned before, the dampers fade after a few laps and the more spring you are running makes this happen quicker. It has nothing to do with exhaust or brake radiant heat, dampers work by turning friction into heat. These cars all run hydraulic shocks only, no gas pressurized dampers allowed by rules, so without gas to stabilize the oil as it gets hot, the damper foams internally and will cavitate and more or less give up the fight. So the way the shock dampens at the start of a race is not the way it feels 30-40 minutes later. With regard to the shock temps and Ethans previous interview, I have mentioned elsewhere the temps in the sim do not seem to change and there is no noticeable drop off in performance imo. In my test race last night. The Brabham shock temps never changed from cold/blue. This is not as it should be. Therefor has anyone here had any drop off in performance or noticed heating of shocks? I know some of you guys have done 40+ laps. Q3b Also from the same chap to our developers and yourself. "Also what's about the negative pre-load setting? Is it a thing in real life for these cars? Maybe another question for Ethan and Renato.” Ans: I'm not sure what "negative preload" would be in reference to a differential or otherwise. To keep this post short, Interview part 3 will follow.