Formula-Retro drivability

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.

 

Very interesting lines to read ! thanks a lot for this contribution

When we meet Oscar Larrauri to talk about the Porsche 962, he told us the same about the driveshafts. He had an accident because that, the car turned in a wild way to the side of the broken driveshaft.

About damper's heat, I don't see temps represented, and I think none sim simulate it. Here in our country, local made dampers were build to try to save costs some years ago. But heat was a problem causing exactly what Ethan said, a lack of responde and a sponge effect because the oil lose his viscousity.

 

Ive definitely noticed some mild amount of wheelshake in my faster laps. It may not be on the level or type of what he is experiencing, but some part of the tire model is picking up on deformation and elasticity.

 

Yes for sure, as an armchair racer I have to say real racers have nuts, racers of older beasts have bigger nuts. Any issues at 175 Mph, not good, lol, reaction /response time ? what can you say. Blimey does not cut it.

Also I think none yet to be confirmed (

did offer to check with some app but I have no answer t/date),
Im assuming the colour Blue is used for temps indication of shocks from cold just like the tyres? or at least it could be. Madness engine? like yourself I dont know, Maybe an area for Renato to inform us.
Seems an important aspect to the cars changing behaviour,
I know from fast off road motorcycling that things get bouncy!! after a while and the shocks get damned hot

Yes I have noticed differences as have others, credit to the sim devs on the amount of change.
I have to say, for me Sim dev has come a long way over the updates we have had. Still early days, more to come

Thats good to hear, probably not able to feel its some much on my g29 if at all.

Interview part 3
In a previous post ref diffs and the Brabham (sorry cant find it) I posted a picture of a diff on the bench from Ethans workshop. I asked him what it was for.

Ans
Other stuff: the FT on my bench was one I built for a Ralt RT1 Formula Atlantic. The open diff was for a Formula Ford, as open diffs and steel diff carriers are required by the class. I build usually between 6-12 gearboxes a year for cars ranging from FJr to FB, FA/F2, F1, Can Am, 2L sports racers, etc. mostly Hewland and Staffs, an occasional Quaife box or a Ford Type 9 comes through the workshop.

Q4

Not that you would need to of course but thought I would ask. Have you used any of the sims racing, sims?

Ans
short Quote


"I bring these issues up because things like this are the reason I feel that no sim will ever be able to truly replicate what it is to drive one of the aluminum tub, bias ply shod, DFV powered F1 cars. They are nothing at all like driving modern cars. The engines buck and shake when given full throttle below a certain RPM as they are not electronically managed. You have things like tire shake to contend with. There are different gearboxes (a FG400 or FGA shifts very differently than a TL200 or a DG300). In the 67-82 era you have cars with tall sidewall tires, short sidewall tires, 13” wheels, 15” wheels, dual calipers, single calipers, etc. There is tub flex, suspension windup, rear wings that work really well and front wings that don’t work for ****, or vice versa, skirted tunnel cars vs non-skirted tunnel cars, skirted flat bottom vs non-skirted flat bottom cars, etc etc etc. There are simply TOO many variables to even get close. The cars are violent and incredibly hard to drive at the limit. All the sim experience I’ve had (admittedly not a lot, some R-factor, some Assetto Corsa, some Iracing and some GTSport) shows me that while they can replicate a modern car quite well (mega stiff platforms with suspensions that don’t move, radial tires, carbon brakes, hybrid systems, etc) no one in their right mind would go through the effort to really reproduce what it is to drive one of the cars from the 70’s or early 80’s. They are completely different beasts. And they are all hand built so each one is slightly different from the next, even two cars of the same model.
This is of course just my opinion and as such I’m sure in the coming years someone will tell me I’m wrong and show me that a sim can be made to replicate the experience.

I hope Ethans answers about the real cars have help a little to understand the cars we have in Ams2
We may have more feedback in a few weeks if you have any Qs

Given this last answer.

Personally speaking, I think we are fortunate to have these old cars handling like they do and with the feedback they have, even at this moment of development.
I had a blast last night after test retro race in the Brabham running TT default at Interlagos long historic. The track thankfully has many subtle bumps esp T1. Theres a lot of discussion elsewhere about TT and setups, exploits ect, but drive the car with care and even in default it can get around there pretty fast, its clear to me to have to learn all the bumps/ the car and the required throttle modulation intimately, to get around at a reasonable pace.
Have fun

 

I wonder how much Mercedes paid for theirs...

Any thoughts on the F-Retros after the update? They feel different but I cant quite put my finger on it yet. There are no crests at Hockenheim, so I havent been able to test that yet before my VR headset got all foggy and hot and I hung it up for the day. It does seem to feel a little more natural now.

 

I feel like the balance has improved... but the low speed understeer is still pretty annoying on default setup. You have to go to unrealistically low preload to turn without throttle at lower speed. And there is a weird threshold where suddenly once you get exactly below 50kmh (cant remember now), it turns on a dime. Very strange feeling. High speed off throttle is realtively good.

 

The new update has massively improved the retro’s! I have only driven the Brabham so far this morning and although not perfect, much improved over original version. Downforce has doubled and I’ve dropped from 8 to 4 and have the same level of grip, but more speed. I can now go full throttle, no lifting required at all at Imola 72 from the final corner to the first hairpin, love it! I no longer feel like I’m in dukes of hazard every time I hit a crest at Imola 72, but the car still becomes a little unstable going down over a crest. Definitely more planted, more balanced and more fun! I agree with Shadak the understeer around slow corners is too exaggerated and severe and stops you using momentum to get you round a hairpin, you have to slow right down to close to nothing and then suddenly the understeer vanishes and you can follow the kerbs round a hairpin. Well Done Reiza for the massive improvements in the Brabham, I reckon a increase for the downforce, less severe understeer and less twitchy over bumps and dips and we are there!

 

Interesting, sounds like its a whole lot better. Hope fully more people will give them a blast. I did not drive the Br yesterday first time this week, Just did a multiclass at Hock Historic and used the classic G1.instead. Will be trying later today. If its a big improvement then TT at Interlagos Long will show it or for Crimson Bathurst.
Being "not the easiest to drive" compared to modern stuff is and was part of these cars characters I hope we do loose this just to gain more appeal.

Should be fun online tonight.
Hock and Inter historic tracks sidenote the ai @ 100/60 seemed faster last night@

 

On the topic of damper temperature. The madness engine is based on the ISI physics engine and although it has been developed I'm pretty sure damper temperature hasn't been added. I don't think any sim models damper temperature. I've not played too much with the AMS2 hud but in PC2 I think the damper symbol actually indicates suspension damage. My assumption is all dampers will warm up and reach an equilibrium temperature. Your damper settings in sim are effectively those for the damper at equilibrium temperature. The issue with older dampers isn't just warming up - gas filled dampers still warm up - but the foaming.

 

Indeed, no current commercial sim does. I believe it is something being looked at by some devs, but there's a limited return on investment.

 

After not driving any of these in a while, I just gave the F-Retros another try. First at Historic Interlagos, then at Kyalami Historic.

Whew! What a blast! Now I'm not really an expert when it comes to this particular era of formula cars, but from what I can gather they are much closer to the real thing now. If they're not perfect yet, they should at least be pretty damn close. The Brabham is well-balanced overall, the McLaren feels light and is very nimble especially around slow corners, while the Lotus is still trying to kill the driver every chance it gets! Which is, to be fair, not as often as it used to be.

The generic ones are great fun too, though the V8 is a little too twitchy with its throttle response (too much torque? ); the V12 was a really nice surprise for me, though. One I shortened the final gear ratio by two clicks (the default is much too long!) I was considerably faster around Kyalami than with any of the others. Overall a very nicely balanced car. And the sound, oh my!

Next time I'm firing up AMS2 I'll be sure to see how much the F-Vintage has improved as well.

 

Yes, thanks David
It does seem to be the general consensus certainly for public consumption sims.

A lot of work for sure, factory teams would have it easier with all their data collection.
Oh well, one way to look at it is, if we had it then it would lead to more speculations in sim accuracy (hard enough with retros and older cars as it is) and setups!, I think we have enough of that already. Yes I also recall pc2 shocks changing colour when damaged, (may be wrong but it rings a bell). May have a look later as the weather here it no good for work outside

 

MMm just read yours as I posted my, more reason for me to give it a go now rather than later.
Glad to hear somebody else enjoying them more!
Good track choice. have you tried Hock Historic. (Will be running all 3 tracks online later)

 

The dampers images goes green when the damage is enabled on the race (always in TT). What I think is that the damage should be balanced a bit. From 0-10 the car is driveable with limitations, over 10 to 100 you have to go to the pits inmediately (if you can). I think the range of usable damage should be wider, I don't know up to 50% maybe, becuase the most little touch with another car causes big damage as it is now.

 

That was actually the plan, until I noticed the DLC wasn't added to my steam account yet...

Seriously though, these historic tracks and cars just go so incredibly well together. SO addictive.

 

Thanks @InfernalVortex for your setup help. It was a great recommendation! I did a test day with wings at F-1 R-4 and 35 power 55 coast in the Shadow and it was waaaay nicer over a longer run. Much easier driving alone than trying to chase your Lotus but still an improvement over my previous setup I think. If you want to test it grab my TT setup and adjust the above mentioned settings (oh and BB at 47 instead of 46 to even out the brake temps a bit.) Ostkurve still has me traumatized but it's mostly just in my head now.


Something I didn't notice whilst in MP is how much the brakes are getting cooked at Hockenheim!! Through and after the stadium section they are in the orange.

 

I think these cars have too much brake power. At Hockenheim we are braking after the 100 board mark at the first chicane. Brake discs get too hot and usually 80% brake pressure is the best choice.

Having less brake power will bring better fight for position on braking, will prevent tire pressure to rise so much.

Tires seems to have too much longitudinal grip, and poor transversal grip. With less brake power longitudinal grip could be decresed and transversal increased to have a better car balance.

This apply for the Vintage cars too.