Vintage formulas drivability

Here is what I found and what it works for me to setup the Formula-Vintage cars.

These are the things I change at every setup for G1M1 and G1M2 cars:

- Steeting lock at 26, becuase it works well with 360º
- Brake Duct Opening at 100% front and rear to keep the discs under 500ºC if possible and to avoid transfer heat from the discs to the wheel (if that exists).
- Brake pressure between 80-90% not more
- Tire pressure at 1.20 bars always for different reasons. First, because with the laps the pressure will rise. With pressure over 1.55 bars the car handling change a lot, making the traction too difficult. At practice and qualying you receive the car with the pressure you defined at the garage, but at the race you will get it with 0.20 bars more.
- Differential, since v1.0.0.3 I use always the "Clutched LSD" and I use the new default Preload of 40Nm and the Viscous Lock at 100 Nm. If you have old setups pre v1.0.0.3 verify these values.

Then, with those values already set, I do some laps to let the tire rise to his "operational temp/pressure" and to figure out what the car does. What I try to get, it's a car that turn in neutrally with just releasing the throttle.

The differential setting that gives me more confident and control is Power 45 and Coast 60 with the preload and viscous I wrote before. For some tracks 60/60 seems better, that's a bit about personal preferense.

About suspension, I try to change the least possible. At the front I only change the height, and uses it at 80mm to give the suspension a bit more of room to move without reach the limit.

With the rear suspension is how I fine tune the car. I keep the spring rate at 16 N/mm but I reduce the ARB to 8 or 12 N/mm to let the car move without spin up.

Then I use the Slow Bump and Rebound to get oversteer or understee. The Slow Bump I try to use it under the value at the front, usualy 1600 or 1800 N/m/s and with these values I manage the roll of the car on the turn in. For the turn out, Rebound is the value I change. The bigger the amount, more oversteer because the internal rear wheel stays more time rised, with a lower value the wheel goes down quickly and you get understeer. I use Rebound between 2000 and 3200 N/m/s.

How I try to drive. I don't try to make any crazy thing, I try to make the car drives by itself with the setup. I don't try to overbrake, I let the car slow down just by braking, and I make the downshifts at low RPM to not lose rear grip and consecuently lose front grip. Then I turn in and wait for the front tires to get grip because the weight transfer and then I maintain the speed or push with the throttle to find the best out line from the turn.

That's all, there is not more than that, but it's not as easy to do it as to write it. Focus on get consistance, not speed.

With the G2 cars I do the same, but the rear values are one click more than with the G1. I use full wings all the time, because wings on those years have few effect compared with modern cars.

 

Ive been off for a while, and pc issues. Cant wait to test with this advice. Thanks Damian.
I hope to hear back from Ethan after last weeks real races.

 

This is another OT post about the Vintage cars.

It would be nice to have a graphic update of the Cosworth engine using the same engine from the Retro cars. The engine on the Retro cars seem a lot more detailed too and better scaled.

Currently the engine is too small is relation with the rest of the car, in real cars the engine is as wide as the chassis.







Lotus 49






Matra MS10




MsLaren M7

 

Another thing to improve is the exhaust of the v12 engine, that currently have 6 to 1 shape arrangement (same in the Retro v12). All the v12 engines of those years had an arrange of 3 to 1 (Weslake, Ferrari, Honda, Maserati, BRM) creating a 4 tubes exit.

Only the Matra v12 on the the MS11 chassis of 1968 had an impresive 2 to 1 arrangement with 6 stuning tubes.

 

to have something more spectecular, we need the exhaust of the RA300

 

Or the Ferrari 312

 

The "spaghettis" exhaust. The Honda si for sure one of my preferred cars.

I don't know how Ferrari was able to put all those tubes in a 60º V engine.

Some pictures to decorate the post.

Ferrari 242


Honda RA273 with the first spaghetti version



Honda RA300, the most extreme and beautiful version

 

Nice pics you guys, just sat here over coffee grinning,

 

1966 to 1968 I think it was the era with more v12 engines on the f1 history.

Youtube have some great videos of the Honda RA300 and the Matra MS11

 

there's one more spectecular:
BRM P115 from 1967
16(!) cylinder in H-formation => crazy
but only with 'short spaghettis'


@Reiza: we need this as vintage GEN1 car, too

 

Jolly good idear
Was going to use an edit of sound track for a door bell. Turn up the volume and enjoy, Best enjoyed in stereo hi fi

 

check out this Matra MS11 rebuild. What kind of differential is that to fit into those ondulations inside the carcass?


Matra MS11 | Zul-Racing

 

If you're talking about picture 8, the weird wavy section, thats a cam and pawl locking differential mechanism. Here's one in an exploded diagram of a Hewland FT200:

Hewland FT200:
Hewland FT200 Differential Inboard Brakes

And here is a description of the mechanism:
https://www.taylor-race.com/sites/default/files/DIFFERENTIAL ESSAY W PHOTOS2.pdf

Page 4:

"Figure 4 shows a cam and pawl differential. It is one of the earliest “limited slip” differentials used in road racing and can be seen in many F1, Formula Atlantic and 2-Liter sports racers up to the late 1970’s. As with the Detroit Locker, the Cam and Pawl is a locking differential. The difference is that the diff locks with applied torque, driving both wheels as a spool. The path taken by the power is from the ring gear to the pawls (Chiclets) via the differential pawl carrier which pushes on the side face of the pawl. The pawls are forced into the notches in the inner cam track and outer cam track causing the differential to lock. The advantage of the cam and pawl over a spool or Detroit Locker is that the lockup is predictable, occurring whenever power is applied. It also has the better turn in performance of a Detroit Locker. Mid turn power on push is again a problem because the cam and pawl locks into a spool when power is applied."

 

it looks like parts 9 and 11 are the one I was looking at the restoration images.

I don't know exactly how it works, but it looks like parts 9 and 11 make contact through several part 10, working like a bendix.

EDIT: Well, with the new information you have added, it looks like the differential allows a small movement and then it completely locks.

It's very interesting, that the last setups I made for these cars use very low LSD power values, close to a spool.

 

I always try to use very tight power settings and very loose coast settings, so I can see how that would work well before they mastered the more adjustable clutched differentials.

That transaxle setup (Is this the word they use in other countries? This is the American term...) is, I believe some sort of Hewland. FT200 maybe?

Racing Transmissions

Edit: Did some more digging, looks like the Hewland FG400 was in use with the DFV in 1968.

Hewland FG400 main case

FT/ FG Gearbox

Hewland FT200 and FG400 Gearboxes



Definitely looks right.

Even found a manual for it!
http://hewlandclassic.com/assets/manuals/fg_400.pdf

And the smoking gun!

Matra MS11 - Wikipedia


Transmission Hewland DG300/FG 400 5 speed

It's on Wikipedia, so you know it's true! I also found some stuff saying these Hewland transaxles were originally based on a Porsche/VW Beetle differential/axle. Not sure how true that was up into the 60s and 70s, but it is interesting.

Edit 2:

This is an interesting thread: ZF/Hewland Cam and Pawl limited slip differential - The Technical Forum Archive - The Autosport Forums

"The following is quoted from Carroll Smith's "The Racing Differential" supplement from Racecar Engineering circa 1994. It is also used in his book "Drive to Win";


The Cam and Pawl diff consists of concentric inner and outer cams. The inner cam is splined to the left-side drive acle, while the other floats in the housing and is splined to the right drive axle. A series of pawls is captured between the cams and located by a cage (think rollers in a roller bearing - ben). The cage is integral with the housing and therefore the ring gear and drives the cams via the pawls.

Under normal, straight-line conditions, the inner and outer cams rotate at the same speed, the pawls wedge between the inner and outer cams, and the diff is inactive. In turn conditions under low torque, the pawls slip between the cams and allow differential action - the effect is the same as an open diff. Under heavy torque loads, lateral load transfer or in conditions of reduced traction, when one wheel starts to overspeed, the cam splined to that axle increaes speed - partially wedging the pawls between the inner and outer cams, and limiting the amount of slip that can take place.

The pawls actually 'ratchet' between the cams, allowing some slip. The amount of allowed slip can be varied by the design of the cams, but only within narrow limits. The best that can be hoped for is a bias ratio of about 3:1 (75% lock) when everything is new. Note that the device acts to limit slip only after the slip has begun.

The cam and pawl has a lot going for it;

It is light
Low moment of rotating inertia
Its on and off characteristics are PROGRESSIVE and BENIGN, making it easy to drive
No instability or tyre drag understeer on turn in
Soft and progresive locking action

There are no surprises lurking in the cam and pawl - this is why F1 teams who cannot afford much testing run them (this was written in 1994).

There are disadvantages. For example, 75% lock is the maximum. The rear of the car may tend to feel a little unstable under heavy torque loads, especially on a bumpy track.

The major disadvantage lies in the suicidal nature of the device. The mechanical design ensures that the cam and pawl is inherently self-destructive. When the thing is working, the hardened steel pawls ratchet between the hardened steel cams, ensuring a high rate of wear and a constantly decreasing amount of limiting. The more the parts wear, the more inside wheelspin develops - and the more the parts wear. It is the automotive equivilent of the graveyard spiral. In the wet, the wear rate approaches infinity.

Life can be prolonged somewhat by some of the proprietary dry-film lubricating processes and the better molybdenum disulphide additive greases, but parts replacement is constant and expensive. Frequent disassembly, cleaning and repacking the moly is a must - the grease tends to centrifuge out."

 

In the early 60s with the 1.5 litre formula cars, they used the Hewland HD500 gearboxes, later while the power increased, everybody moved to Hewland DG300.

Only Lotus used a ZF gearbox/differential on the Lotus 49, but eventualy switched to DG300 for the 49b. Jo Bonnier used a ZF on his Cooper T81, while all the other T81 and T86s used DG300.

 

This is all the information I have about 1966-1969 cars. It includes a simple graph showing weight/power ratio to have an idea of the cars.

Almost everything is there, weight, wheelbase, front-rear tracks, engine's info. What it's needed is fuel consumption.

 

I've been doing some tests today at Kyalami. I tried again "Spool" differential since v0.9.6.0 and to my surprise I was faster (1.18.5) than with any other differential and the driving was natural or armonic to say it someway, at least for five laps until the tires pressure f**** up all as usual. It was at Kyalami, where you don't have slow turns. I'm not saying that Spool is the best differential to use at every track, but at least in this track now it have had some sence.

The spool differential felt a lot like the clutched LSD when you use a low "power" value (30 or 45). Another surprise was that the turn in wasn't any bad, very linear, stable and with few understeer.

I tried "ratcheting" option ON too (I don't know what is it) while using Spool , and the result was the same as with it off, but with some unconsistence on the braking.

What I think about Spool LSD setting? It could be good choice in a very long race, something like 60 laps on Zeltweg (Österreichring and now called Spielberg), a kind of race where you want a stable and predictable car, maybe using a low fuel mixture to start the race with a bit less weight of fuel.

In resume, the car was very enjoyable and driveable, but ended bad as always with tire's pressuve rising and making the car unpredictable, unenjoyable and frustrating. At Kyalami starting with 1.20 bars the car was fine, with great steering feeling and good traction. Up until 1.35 bars the feeling stays, then it start to vanish. Over 1.45 bars you start driving in surviving mode and it become worse every lap. All this changes takes only 5 laps, and I think it's the worse invitation for a beginer.

 

Thank about "Ratcheting" clarification, didn't know about that, but it have correlation with how the car felt.

About tire's pressure, all I know is that it increases more because track contact than but friction. The dissipation it's all about wheel speed, so on a slow track you have a 5 laps sentense (same with brakes).

This problem is so obvious that I started to think that it was planned this way in porpose for some reason but it was wrong tested. I have weeks hosting races with the Vintage cars, and I only see drivers leave the server after 4 or 5 laps, because the cars are really undriveable. The potential is there, but is baffling see how bad it works.